+++ /dev/null
-////////////////////////////////////////////////////////////////////////////
-$Cambridge: exim/doc/doc-docbook/spec.ascd,v 1.4 2005/12/05 14:38:18 ph10 Exp $
-
-This is the primary source of the Exim Manual. It is an AsciiDoc document
-that is converted into DocBook XML for subsequent conversion into printing
-and online formats. The markup used herein is traditional AsciiDoc markup,
-with some extras. The markup is summarized in a file called AdMarkup.txt. A
-private AsciiDoc configuration file specifies how the extra markup is to be
-translated into DocBook XML. You MUST use this private AsciiDoc markup if you
-want to get sensible results from processing this document.
-////////////////////////////////////////////////////////////////////////////
-
-
-
-////////////////////////////////////////////////////////////////////////////
-I am abusing the <abstract> DocBook element as the only trivial way of getting
-this information onto the title verso page in the printed renditions. A better
-title page would be a useful improvement. The <abstract> element is removed by
-preprocessing for the HTML renditions, and the whole <docbookinfo> element is
-removed for ascii output formats.
-////////////////////////////////////////////////////////////////////////////
-
-Specification of the Exim Mail Transfer Agent
-=============================================
-:abstract: University of Cambridge Computing Service, New Museums Site, Pembroke Street, Cambridge CB2 3QH, England
-:author: Philip Hazel
-:copyright: University of Cambridge
-:cpyear: 2005
-:date: 01 November 2005
-:doctitleabbrev: The Exim MTA
-:revision: 4.60
-
-
-//////////////////////////////////////////////////////////////////////////////
-***WARNING*** Do not put anything, not even a titleabbrev, setting before
-the first chapter (luckily it does not need one) because if you do, AsciiDoc
-creates an empty <preface> element, which we do not want.
-//////////////////////////////////////////////////////////////////////////////
-
-Introduction
-------------
-
-////////////////////////////////////////////////////////////////////////////
-These are definitions of AsciiDoc "attributes" that are in effect "variables"
-whose values can be substituted. The first makes index entries shorter. The
-second avoids problems with literal asterisks getting tangled up with bold
-emphasis quotes. The others are here for convenience of editing.
-
-***WARNING*** The positioning of these definitions, after the first Chapter
-title, seems to be important. If they are placed earlier, they give rise to
-incorrect XML.
-////////////////////////////////////////////////////////////////////////////
-
-:ACL: access control lists (ACLs)
-:star: *
-:previousversion: 4.50
-:version: 4.60
-
-
-////////////////////////////////////////////////////////////////////////////
-This chunk of literal XML implements index entries of the form "x, see y" and
-"x, see also y". It didn't seem worth inventing AsciiDoc markup for this,
-because is it not something that is likely to change often.
-////////////////////////////////////////////////////////////////////////////
-
-++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-<indexterm role="concept">
- <primary>$1, $2, etc.</primary>
- <see><emphasis>numerical variables</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>address</primary>
- <secondary>rewriting</secondary>
- <see><emphasis>rewriting</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>Bounce Address Tag Validation</primary>
- <see><emphasis>BATV</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>Client SMTP Authorization</primary>
- <see><emphasis>CSA</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>CR character</primary>
- <see><emphasis>carriage return</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>CRL</primary>
- <see><emphasis>certificate revocation list</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>delivery</primary>
- <secondary>failure report</secondary>
- <see><emphasis>bounce message</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>dialup</primary>
- <see><emphasis>intermittently connected hosts</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>exiscan</primary>
- <see><emphasis>content scanning</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>failover</primary>
- <see><emphasis>fallback</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>fallover</primary>
- <see><emphasis>fallback</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>filter</primary>
- <secondary>Sieve</secondary>
- <see><emphasis>Sieve filter</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>ident</primary>
- <see><emphasis>RFC 1413</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>LF character</primary>
- <see><emphasis>linefeed</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>maximum</primary>
- <see><emphasis>limit</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>monitor</primary>
- <see><emphasis>Exim monitor</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>no_<emphasis>xxx</emphasis></primary>
- <see>entry for xxx</see>
-</indexterm>
-<indexterm role="concept">
- <primary>NUL</primary>
- <see><emphasis>binary zero</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>passwd file</primary>
- <see><emphasis>/etc/passwd</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>process id</primary>
- <see><emphasis>pid</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>RBL</primary>
- <see><emphasis>DNS list</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>redirection</primary>
- <see><emphasis>address redirection</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>return path</primary>
- <seealso><emphasis>envelope sender</emphasis></seealso>
-</indexterm>
-<indexterm role="concept">
- <primary>scanning</primary>
- <see><emphasis>content scanning</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>SSL</primary>
- <see><emphasis>TLS</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>string</primary>
- <secondary>expansion</secondary>
- <see><emphasis>expansion</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>top bit</primary>
- <see><emphasis>8-bit characters</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>variables</primary>
- <see><emphasis>expansion, variables</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>zero, binary</primary>
- <see><emphasis>binary zero</emphasis></see>
-</indexterm>
-++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-
-
-////////////////////////////////////////////////////////////////////////////
-OK, now we start with the real data for this first chapter.
-////////////////////////////////////////////////////////////////////////////
-
-Exim is a mail transfer agent (MTA) for hosts that are running Unix or
-Unix-like operating systems. It was designed on the assumption that it would be
-run on hosts that are permanently connected to the Internet. However, it can be
-used on intermittently connected hosts with suitable configuration adjustments.
-
-Configuration files currently exist for the following operating systems: AIX,
-BSD/OS (aka BSDI), Darwin (Mac OS X), DGUX, Dragonfly, FreeBSD, GNU/Hurd,
-GNU/Linux, HI-OSF (Hitachi), HI-UX, HP-UX, IRIX, MIPS RISCOS, NetBSD, OpenBSD,
-OpenUNIX, QNX, SCO, SCO SVR4.2 (aka UNIX-SV), Solaris (aka SunOS5), SunOS4,
-Tru64-Unix (formerly Digital UNIX, formerly DEC-OSF1), Ultrix, and Unixware.
-Some of these operating systems are no longer current and cannot easily be
-tested, so the configuration files may no longer work in practice.
-
-There are also configuration files for compiling Exim in the Cygwin environment
-that can be installed on systems running Windows. However, this document does
-not contain any information about running Exim in the Cygwin environment.
-
-The terms and conditions for the use and distribution of Exim are contained in
-the file _NOTICE_. Exim is distributed under the terms of the GNU General
-Public Licence, a copy of which may be found in the file _LICENCE_.
-
-The use, supply or promotion of Exim for the purpose of sending bulk,
-unsolicited electronic mail is incompatible with the basic aims of the program,
-which revolve around the free provision of a service that enhances the quality
-of personal communications. The author of Exim regards indiscriminate
-mass-mailing as an antisocial, irresponsible abuse of the Internet.
-
-Exim owes a great deal to Smail 3 and its author, Ron Karr. Without the
-experience of running and working on the Smail 3 code, I could never have
-contemplated starting to write a new MTA. Many of the ideas and user interfaces
-were originally taken from Smail 3, though the actual code of Exim is entirely
-new, and has developed far beyond the initial concept.
-
-Many people, both in Cambridge and around the world, have contributed to the
-development and the testing of Exim, and to porting it to various operating
-systems. I am grateful to them all. The distribution now contains a file called
-_ACKNOWLEDGMENTS_, in which I have started recording the names of
-contributors.
-
-
-
-Exim documentation
-~~~~~~~~~~~~~~~~~~
-[revisionflag="changed"]
-cindex:[documentation]
-This edition of the Exim specification applies to version {version} of Exim.
-Substantive changes from the {previousversion} edition are marked in some
-renditions of the document; this paragraph is so marked if the rendition is
-capable of showing a change indicator.
-
-This document is very much a reference manual; it is not a tutorial. The reader
-is expected to have some familiarity with the SMTP mail transfer protocol and
-with general Unix system administration. Although there are some discussions
-and examples in places, the information is mostly organized in a way that makes
-it easy to look up, rather than in a natural order for sequential reading.
-Furthermore, the manual aims to cover every aspect of Exim in detail, including
-a number of rarely-used, special-purpose features that are unlikely to be of
-very wide interest.
-
-cindex:[books about Exim]
-An ``easier'' discussion of Exim which provides more in-depth explanatory,
-introductory, and tutorial material can be found in a book entitled
-'The Exim SMTP Mail Server', published by UIT Cambridge
-(*http://www.uit.co.uk/exim-book/[]*).
-
-This book also contains a chapter that gives a general introduction to SMTP and
-Internet mail. Inevitably, however, the book is unlikely to be fully up-to-date
-with the latest release of Exim. (Note that the earlier book about Exim,
-published by O'Reilly, covers Exim 3, and many things have changed in Exim 4.)
-
-[revisionflag="changed"]
-cindex:[Debian,information sources]
-If you are using a Debian distribution of Exim, you will find information about
-Debian-specific features in the file
-&&&&
-_/usr/share/doc/exim4-base/README.Debian_
-&&&&
-The command ^man update-exim.conf^ is another source of Debian-specific
-information.
-
-cindex:[_doc/NewStuff_]
-cindex:[_doc/ChangeLog_]
-cindex:[change log]
-As the program develops, there may be features in newer versions that have not
-yet made it into this document, which is updated only when the most significant
-digit of the fractional part of the version number changes. Specifications of
-new features that are not yet in this manual are placed in the file
-_doc/NewStuff_ in the Exim distribution.
-
-Some features may be classified as ``experimental''. These may change
-incompatibly while they are developing, or even be withdrawn. For this reason,
-they are not documented in this manual. Information about experimental features
-can be found in the file _doc/experimental.txt_.
-
-All changes to the program (whether new features, bug fixes, or other kinds of
-change) are noted briefly in the file called _doc/ChangeLog_.
-
-cindex:[_doc/spec.txt_]
-This specification itself is available as an ASCII file in _doc/spec.txt_ so
-that it can easily be searched with a text editor. Other files in the _doc_
-directory are:
-
-[frame="none"]
-`--------------------`------------------------------------------
-_OptionLists.txt_ list of all options in alphabetical order
-_dbm.discuss.txt_ discussion about DBM libraries
-_exim.8_ a man page of Exim's command line options
-_experimental.txt_ documentation of experimental features
-_filter.txt_ specification of the filter language
-_pcrepattern.txt_ specification of PCRE regular expressions
-_pcretest.txt_ specification of the PCRE testing program
-_Exim3.upgrade_ upgrade notes from release 2 to release 3
-_Exim4.upgrade_ upgrade notes from release 3 to release 4
-----------------------------------------------------------------
-
-The main specification and the specification of the filtering language are also
-available in other formats (HTML, PostScript, PDF, and Texinfo). Section
-<<SECTavail>> below tells you how to get hold of these.
-
-
-
-FTP and web sites
-~~~~~~~~~~~~~~~~~
-cindex:[web site]
-cindex:[FTP site]
-The primary site for Exim source distributions is currently the University of
-Cambridge's FTP site, whose contents are described in 'Where to find the Exim
-distribution' below. In addition, there is a web site and an FTP site at
-%exim.org%. These are now also hosted at the University of Cambridge. The
-%exim.org% site was previously hosted for a number of years by Energis Squared,
-formerly Planet Online Ltd, whose support I gratefully acknowledge.
-
-As well as Exim distribution tar files, the Exim web site contains a number of
-differently formatted versions of the documentation, including the
-cindex:[FAQ] FAQ in both text and HTML formats. The HTML version comes with
-a keyword-in-context index. A recent addition to the online information is the
-cindex:[wiki]
-Exim wiki (*http://www.exim.org/eximwiki/[]*).
-We hope that this will make it easier for Exim users to contribute examples,
-tips, and know-how for the benefit of others.
-
-
-
-Mailing lists
-~~~~~~~~~~~~~
-cindex:[mailing lists,for Exim users]
-The following are the three main Exim mailing lists:
-
-[frame="none"]
-`-------------------------------`----------------------------------------
-'exim-users@exim.org' general discussion list
-'exim-dev@exim.org' discussion of bugs, enhancements, etc.
-'exim-announce@exim.org' moderated, low volume announcements list
--------------------------------------------------------------------------
-
-You can subscribe to these lists, change your existing subscriptions, and view
-or search the archives via the mailing lists link on the Exim home page. The
-'exim-users' mailing list is also forwarded to
-*http://www.egroups.com/list/exim-users[]*, an archiving system with searching
-capabilities.
-
-[revisionflag="changed"]
-cindex:[Debian,mailing list for]
-If you are using a Debian distribution of Exim, you may wish to subscribe to
-the Debian-specific mailing list, which is
-'pkg-exim4-users@lists.alioth.debian.org'.
-
-
-Exim training
-~~~~~~~~~~~~~
-cindex:[training courses]
-From time to time (approximately annually at the time of writing), training
-courses are run by the author of Exim in Cambridge, UK. Details can be found on
-the web site *http://www-tus.csx.cam.ac.uk/courses/exim/[]*.
-
-
-Bug reports
-~~~~~~~~~~~
-cindex:[bug reports]
-cindex:[reporting bugs]
-Reports of obvious bugs should be emailed to 'bugs@exim.org'. However, if
-you are unsure whether some behaviour is a bug or not, the best thing to do is
-to post a message to the 'exim-dev' mailing list and have it discussed.
-
-
-
-[[SECTavail]]
-Where to find the Exim distribution
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[FTP site]
-cindex:[distribution,ftp site]
-The master ftp site for the Exim distribution is
-
-&&&
-*ftp://ftp.csx.cam.ac.uk/pub/software/email/exim[]*
-&&&
-
-This is mirrored by
-
-&&&
-*ftp://ftp.exim.org/pub/exim[]*
-&&&
-
-The file references that follow are relative to the _exim_ directories at these
-sites. There are now quite a number of independent mirror sites around the
-world. Those that I know about are listed in the file called _Mirrors_.
-
-Within the _exim_ directory there are subdirectories called _exim3_ (for
-previous Exim 3 distributions), _exim4_ (for the latest Exim 4
-distributions), and _Testing_ for testing versions. In the _exim4_
-subdirectory, the current release can always be found in files called
-
-&&&
-_exim-n.nn.tar.gz_
-_exim-n.nn.tar.bz2_
-&&&
-
-where 'n.nn' is the highest such version number in the directory. The two
-files contain identical data; the only difference is the type of compression.
-The _.bz2_ file is usually a lot smaller than the _.gz_ file.
-
-cindex:[distribution,signing details]
-cindex:[distribution,public key]
-cindex:[public key for signed distribution]
-The distributions are currently signed with Philip Hazel's GPG key. The
-corresponding public key is available from a number of keyservers, and there is
-also a copy in the file _Public-Key_. The signatures for the tar bundles are
-in:
-
-&&&
-_exim-n.nn.tar.gz.sig_
-_exim-n.nn.tar.bz2.sig_
-&&&
-
-For each released version, the log of changes is made separately available in a
-separate file in the directory _ChangeLogs_ so that it is possible to
-find out what has changed without having to download the entire distribution.
-
-cindex:[documentation,available formats]
-The main distribution contains ASCII versions of this specification and other
-documentation; other formats of the documents are available in separate files
-inside the _exim4_ directory of the FTP site:
-
-&&&
-_exim-html-n.nn.tar.gz_
-_exim-pdf-n.nn.tar.gz_
-_exim-postscript-n.nn.tar.gz_
-_exim-texinfo-n.nn.tar.gz_
-&&&
-
-These tar files contain only the _doc_ directory, not the complete
-distribution, and are also available in _.bz2_ as well as _.gz_ forms.
-cindex:[FAQ]
-The FAQ is available for downloading in two different formats in these files:
-
-&&&
-_exim4/FAQ.txt.gz_
-_exim4/FAQ.html.tar.gz_
-&&&
-
-The first of these is a single ASCII file that can be searched with a text
-editor. The second is a directory of HTML files, normally accessed by starting
-at _index.html_. The HTML version of the FAQ (which is also included in the
-HTML documentation tarbundle) includes a keyword-in-context index, which is
-often the most convenient way of finding your way around.
-
-
-Wish list
-~~~~~~~~~
-cindex:[wish list]
-A wish list is maintained, containing ideas for new features that have been
-submitted. From time to time the file is exported to the ftp site into the file
-_exim4/WishList_. Items are removed from the list if they get implemented.
-
-
-
-Contributed material
-~~~~~~~~~~~~~~~~~~~~
-cindex:[contributed material]
-At the ftp site, there is a directory called _Contrib_ that contains
-miscellaneous files contributed to the Exim community by Exim users. There is
-also a collection of contributed configuration examples in
-_exim4/config.samples.tar.gz_. These samples are referenced from the FAQ.
-
-
-
-Limitations
-~~~~~~~~~~~
-- cindex:[limitations of Exim]
-Exim is designed for use as an Internet MTA, and therefore handles addresses
-in RFC 2822 domain format only.
-cindex:[bang paths,not handled by Exim]
-It cannot handle UUCP ``bang paths'', though simple two-component bang paths can
-be converted by a straightforward rewriting configuration. This restriction
-does not prevent Exim from being interfaced to UUCP as a transport mechanism,
-provided that domain addresses are used.
-
-- cindex:[domainless addresses]
-cindex:[address,without domain]
-Exim insists that every address it handles has a domain attached. For incoming
-local messages, domainless addresses are automatically qualified with a
-configured domain value. Configuration options specify from which remote
-systems unqualified addresses are acceptable. These are then qualified on
-arrival.
-
-- cindex:[transport,external]
-cindex:[external transports]
-The only external transport currently implemented is an SMTP transport over a
-TCP/IP network (using sockets, including support for IPv6). However, a pipe
-transport is available, and there are facilities for writing messages to files
-and pipes, optionally in 'batched SMTP' format; these facilities can be used
-to send messages to some other transport mechanism such as UUCP, provided it
-can handle domain-style addresses. Batched SMTP input is also catered for.
-
-- Exim is not designed for storing mail for dial-in hosts. When the volumes of
-such mail are large, it is better to get the messages ``delivered'' into files
-(that is, off Exim's queue) and subsequently passed on to the dial-in hosts by
-other means.
-
-- Although Exim does have basic facilities for scanning incoming messages, these
-are not comprehensive enough to do full virus or spam scanning. Such operations
-are best carried out using additional specialized software packages. If you
-compile Exim with the content-scanning extension, straightforward interfaces to
-a number of common scanners are provided.
-
-
-
-
-
-Run time configuration
-~~~~~~~~~~~~~~~~~~~~~~
-Exim's run time configuration is held in a single text file that is divided
-into a number of sections. The entries in this file consist of keywords and
-values, in the style of Smail 3 configuration files. A default configuration
-file which is suitable for simple online installations is provided in the
-distribution, and is described in chapter <<CHAPdefconfil>> below.
-
-
-
-Calling interface
-~~~~~~~~~~~~~~~~~
-cindex:[Sendmail compatibility,command line interface]
-Like many MTAs, Exim has adopted the Sendmail command line interface so that it
-can be a straight replacement for _/usr/lib/sendmail_ or
-_/usr/sbin/sendmail_ when sending mail, but you do not need to know anything
-about Sendmail in order to run Exim. For actions other than sending messages,
-Sendmail-compatible options also exist, but those that produce output (for
-example, %-bp%, which lists the messages on the queue) do so in Exim's own
-format. There are also some additional options that are compatible with Smail
-3, and some further options that are new to Exim. Chapter <<CHAPcommandline>>
-documents all Exim's command line options. This information is automatically
-made into the man page that forms part of the Exim distribution.
-
-Control of messages on the queue can be done via certain privileged command
-line options. There is also an optional monitor program called 'eximon', which
-displays current information in an X window, and which contains a menu
-interface to Exim's command line administration options.
-
-
-
-Terminology
-~~~~~~~~~~~
-cindex:[terminology definitions]
-cindex:[body of message,definition of]
-The 'body' of a message is the actual data that the sender wants to transmit.
-It is the last part of a message, and is separated from the 'header' (see
-below) by a blank line.
-
-cindex:[bounce message,definition of]
-When a message cannot be delivered, it is normally returned to the sender in a
-delivery failure message or a ``non-delivery report'' (NDR). The term 'bounce'
-is commonly used for this action, and the error reports are often called
-'bounce messages'. This is a convenient shorthand for ``delivery failure error
-report''. Such messages have an empty sender address in the message's
-'envelope' (see below) to ensure that they cannot themselves give rise to
-further bounce messages.
-
-The term 'default' appears frequently in this manual. It is used to qualify a
-value which is used in the absence of any setting in the configuration. It may
-also qualify an action which is taken unless a configuration setting specifies
-otherwise.
-
-The term 'defer' is used when the delivery of a message to a specific
-destination cannot immediately take place for some reason (a remote host may be
-down, or a user's local mailbox may be full). Such deliveries are 'deferred'
-until a later time.
-
-The word 'domain' is sometimes used to mean all but the first component of a
-host's name. It is 'not' used in that sense here, where it normally
-refers to the part of an email address following the @ sign.
-
-cindex:[envelope, definition of]
-cindex:[sender,definition of]
-A message in transit has an associated 'envelope', as well as a header and a
-body. The envelope contains a sender address (to which bounce messages should
-be delivered), and any number of recipient addresses. References to the
-sender or the recipients of a message usually mean the addresses in the
-envelope. An MTA uses these addresses for delivery, and for returning bounce
-messages, not the addresses that appear in the header lines.
-
-cindex:[message header, definition of]
-cindex:[header section,definition of]
-The 'header' of a message is the first part of a message's text, consisting
-of a number of lines, each of which has a name such as 'From:', 'To:',
-'Subject:', etc. Long header lines can be split over several text lines by
-indenting the continuations. The header is separated from the body by a blank
-line.
-
-cindex:[local part,definition of]
-cindex:[domain,definition of]
-The term 'local part', which is taken from RFC 2822, is used to refer to that
-part of an email address that precedes the @ sign. The part that follows the
-@ sign is called the 'domain' or 'mail domain'.
-
-cindex:[local delivery,definition of]
-cindex:[remote delivery, definition of]
-The terms 'local delivery' and 'remote delivery' are used to distinguish
-delivery to a file or a pipe on the local host from delivery by SMTP over
-TCP/IP to another host. As far as Exim is concerned, all hosts other than the
-host it is running on are 'remote'.
-
-cindex:[return path,definition of]
-'Return path' is another name that is used for the sender address in a
-message's envelope.
-
-cindex:[queue,definition of]
-The term 'queue' is used to refer to the set of messages awaiting delivery,
-because this term is in widespread use in the context of MTAs. However, in
-Exim's case the reality is more like a pool than a queue, because there is
-normally no ordering of waiting messages.
-
-cindex:[queue runner,definition of]
-The term 'queue runner' is used to describe a process that scans the queue
-and attempts to deliver those messages whose retry times have come. This term
-is used by other MTAs, and also relates to the command %runq%, but in Exim
-the waiting messages are normally processed in an unpredictable order.
-
-cindex:[spool directory,definition of]
-The term 'spool directory' is used for a directory in which Exim keeps the
-messages on its queue -- that is, those that it is in the process of
-delivering. This should not be confused with the directory in which local
-mailboxes are stored, which is called a ``spool directory'' by some people. In
-the Exim documentation, ``spool'' is always used in the first sense.
-
-
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-Incorporated code
------------------
-cindex:[incorporated code]
-cindex:[regular expressions,library]
-cindex:[PCRE]
-A number of pieces of external code are included in the Exim distribution.
-
-- Regular expressions are supported in the main Exim program and in the Exim
-monitor using the freely-distributable PCRE library, copyright (c) University
-of Cambridge. The source is distributed in the directory _src/pcre_. However,
-this is a cut-down version of PCRE. If you want to use the PCRE library in
-other programs, you should obtain and install the full version from
-*ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre[]*.
-
-- cindex:[cdb,acknowledgement]
-Support for the cdb (Constant DataBase) lookup method is provided by code
-contributed by Nigel Metheringham of (at the time he contributed it) Planet
-Online Ltd. which contains the following statements:
-+
-++++++++++++++++++++++
-<blockquote>
-++++++++++++++++++++++
-+
-Copyright (c) 1998 Nigel Metheringham, Planet Online Ltd
-+
-This program is free software; you can redistribute it and/or modify it under
-the terms of the GNU General Public License as published by the Free Software
-Foundation; either version 2 of the License, or (at your option) any later
-version.
-+
-This code implements Dan Bernstein's Constant DataBase (cdb) spec. Information,
-the spec and sample code for cdb can be obtained from
-*http://www.pobox.com/{tl}djb/cdb.html[]*. This implementation borrows some code
-from Dan Bernstein's implementation (which has no license restrictions applied
-to it).
-+
-++++++++++++++++++++++
-</blockquote>
-++++++++++++++++++++++
-+
-The implementation is completely contained within the code of Exim.
-It does not link against an external cdb library.
-
-- cindex:[SPA authentication]
-cindex:[Samba project]
-cindex:[Microsoft Secure Password Authentication]
-Client support for Microsoft's 'Secure Password Authentication' is provided
-by code contributed by Marc Prud'hommeaux. Server support was contributed by
-Tom Kistner. This includes code taken from the Samba project, which is released
-under the Gnu GPL.
-
-- cindex:[Cyrus]
-cindex:['pwcheck' daemon]
-cindex:['pwauthd' daemon]
-Support for calling the Cyrus 'pwcheck' and 'saslauthd' daemons is provided
-by code taken from the Cyrus-SASL library and adapted by Alexander S.
-Sabourenkov. The permission notice appears below, in accordance with the
-conditions expressed therein.
-+
-++++++++++++++++++++++
-<blockquote>
-++++++++++++++++++++++
-+
-Copyright (c) 2001 Carnegie Mellon University. All rights reserved.
-+
-Redistribution and use in source and binary forms, with or without
-modification, are permitted provided that the following conditions
-are met:
-+
-. Redistributions of source code must retain the above copyright
-notice, this list of conditions and the following disclaimer.
-
-. Redistributions in binary form must reproduce the above copyright
-notice, this list of conditions and the following disclaimer in
-the documentation and/or other materials provided with the
-distribution.
-
-. The name ``Carnegie Mellon University'' must not be used to
-endorse or promote products derived from this software without
-prior written permission. For permission or any other legal
-details, please contact
-+
-&&&
- Office of Technology Transfer
- Carnegie Mellon University
- 5000 Forbes Avenue
- Pittsburgh, PA 15213-3890
- (412) 268-4387, fax: (412) 268-7395
- tech-transfer@andrew.cmu.edu
-&&&
-///
-The need to indent that block explicitly is a pain.
-///
-
-. Redistributions of any form whatsoever must retain the following
-acknowledgment:
-+
-``This product includes software developed by Computing Services
-at Carnegie Mellon University (*http://www.cmu.edu/computing/[]*).''
-+
-CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO
-THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
-AND FITNESS, IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE
-FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
-WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
-AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
-OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
-
-///
-Note, no "+" line there, because we want to terminate the inner list item
-before ending the block quote.
-///
-+
-++++++++++++++++++++++
-</blockquote>
-++++++++++++++++++++++
-
-- cindex:[Exim monitor,acknowledgement]
-cindex:[X-windows]
-cindex:[Athena]
-The Exim Monitor program, which is an X-Window application, includes
-modified versions of the Athena StripChart and TextPop widgets.
-This code is copyright by DEC and MIT, and their permission notice appears
-below, in accordance with the conditions expressed therein.
-+
-++++++++++++++++++++++
-<blockquote>
-++++++++++++++++++++++
-+
-Copyright 1987, 1988 by Digital Equipment Corporation, Maynard, Massachusetts,
-and the Massachusetts Institute of Technology, Cambridge, Massachusetts.
-+
-All Rights Reserved
-+
-Permission to use, copy, modify, and distribute this software and its
-documentation for any purpose and without fee is hereby granted,
-provided that the above copyright notice appear in all copies and that
-both that copyright notice and this permission notice appear in
-supporting documentation, and that the names of Digital or MIT not be
-used in advertising or publicity pertaining to distribution of the
-software without specific, written prior permission.
-+
-DIGITAL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
-ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
-DIGITAL BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
-ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
-WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
-ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
-SOFTWARE.
-+
-++++++++++++++++++++++
-</blockquote>
-++++++++++++++++++++++
-
-- Many people have contributed code fragments, some large, some small, that were
-not covered by any specific licence requirements. It is assumed that the
-contributors are happy to see their code incoporated into Exim under the GPL.
-
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[titleabbrev="Receiving and delivering mail"]
-How Exim receives and delivers mail
------------------------------------
-
-
-Overall philosophy
-~~~~~~~~~~~~~~~~~~
-cindex:[design philosophy]
-Exim is designed to work efficiently on systems that are permanently connected
-to the Internet and are handling a general mix of mail. In such circumstances,
-most messages can be delivered immediately. Consequently, Exim does not
-maintain independent queues of messages for specific domains or hosts, though
-it does try to send several messages in a single SMTP connection after a host
-has been down, and it also maintains per-host retry information.
-
-
-
-Policy control
-~~~~~~~~~~~~~~
-cindex:[policy control,overview]
-Policy controls are now an important feature of MTAs that are connected to the
-Internet. Perhaps their most important job is to stop MTAs being abused as
-``open relays'' by misguided individuals who send out vast amounts of unsolicited
-junk, and want to disguise its source. Exim provides flexible facilities for
-specifying policy controls on incoming mail:
-
-- cindex:[{ACL},introduction]
-Exim 4 (unlike previous versions of Exim) implements policy controls on
-incoming mail by means of 'Access Control Lists' (ACLs). Each list is a
-series of statements that may either grant or deny access. ACLs can be used at
-several places in the SMTP dialogue while receiving a message from a remote
-host. However, the most common places are after each RCPT command, and at
-the very end of the message. The sysadmin can specify conditions for accepting
-or rejecting individual recipients or the entire message, respectively, at
-these two points (see chapter <<CHAPACL>>). Denial of access results in an SMTP
-error code.
-
-- An ACL is also available for locally generated, non-SMTP messages. In this
-case, the only available actions are to accept or deny the entire message.
-
-- When Exim is compiled with the content-scanning extension, facilities are
-provided in the ACL mechanism for passing the message to external virus and/or
-spam scanning software. The result of such a scan is passed back to the ACL,
-which can then use it to decide what to do with the message.
-
-- When a message has been received, either from a remote host or from the local
-host, but before the final acknowledgement has been sent, a locally supplied C
-function called 'local_scan()' can be run to inspect the message and decide
-whether to accept it or not (see chapter <<CHAPlocalscan>>). If the message is
-accepted, the list of recipients can be modified by the function.
-
-- Using the 'local_scan()' mechanism is another way of calling external
-scanner software. The %SA-Exim% add-on package works this way. It does not
-require Exim to be compiled with the content-scanning extension.
-
-- After a message has been accepted, a further checking mechanism is available in
-the form of the 'system filter' (see chapter <<CHAPsystemfilter>>). This runs
-at the start of every delivery process.
-
-
-
-User filters
-~~~~~~~~~~~~
-cindex:[filter,introduction]
-cindex:[Sieve filter]
-In a conventional Exim configuration, users are able to run private filters by
-setting up appropriate _.forward_ files in their home directories. See
-chapter <<CHAPredirect>> (about the ^redirect^ router) for the configuration
-needed to support this, and the separate document entitled 'Exim's interfaces
-to mail filtering' for user details. Two different kinds of filtering are
-available:
-
-- Sieve filters are written in the standard filtering language that is defined
-by RFC 3028.
-
-- Exim filters are written in a syntax that is unique to Exim, but which is more
-powerful than Sieve, which it pre-dates.
-
-User filters are run as part of the routing process, described below.
-
-
-
-[[SECTmessiden]]
-Message identification
-~~~~~~~~~~~~~~~~~~~~~~
-cindex:[message ids, details of format]
-cindex:[format,of message id]
-cindex:[id of message]
-cindex:[base62]
-cindex:[base36]
-cindex:[Darwin]
-cindex:[Cygwin]
-Every message handled by Exim is given a 'message id' which is sixteen
-characters long. It is divided into three parts, separated by hyphens, for
-example `16VDhn-0001bo-D3`. Each part is a sequence of letters and digits,
-normally encoding numbers in base 62. However, in the Darwin operating
-system (Mac OS X) and when Exim is compiled to run under Cygwin, base 36
-(avoiding the use of lower case letters) is used instead, because the message
-id is used to construct file names, and the names of files in those systems are
-not always case-sensitive.
-
-cindex:[pid (process id),re-use of]
-The detail of the contents of the message id have changed as Exim has evolved.
-Earlier versions relied on the operating system not re-using a process id (pid)
-within one second. On modern operating systems, this assumption can no longer
-be made, so the algorithm had to be changed. To retain backward compatibility,
-the format of the message id was retained, which is why the following rules are
-somewhat eccentric:
-
-- The first six characters of the message id are the time at which the message
-started to be received, to a granularity of one second. That is, this field
-contains the number of seconds since the start of the epoch (the normal Unix
-way of representing the date and time of day).
-
-- After the first hyphen, the next six characters are the id of the process that
-received the message.
-
-- There are two different possibilities for the final two characters:
-
-. cindex:[%localhost_number%]
-If %localhost_number% is not set, this value is the fractional part of the
-time of reception, normally in units of 1/2000 of a second, but for systems
-that must use base 36 instead of base 62 (because of case-insensitive file
-systems), the units are 1/1000 of a second.
-
-. If %localhost_number% is set, it is multiplied by 200 (100) and added to
-the fractional part of the time, which in this case is in units of 1/200
-(1/100) of a second.
-
-After a message has been received, Exim waits for the clock to tick at the
-appropriate resolution before proceeding, so that if another message is
-received by the same process, or by another process with the same (re-used)
-pid, it is guaranteed that the time will be different. In most cases, the clock
-will already have ticked while the message was being received.
-
-
-Receiving mail
-~~~~~~~~~~~~~~
-cindex:[receiving mail]
-cindex:[message,reception]
-The only way Exim can receive mail from another host is using SMTP over
-TCP/IP, in which case the sender and recipient addresses are transferred using
-SMTP commands. However, from a locally running process (such as a user's MUA),
-there are several possibilities:
-
-- If the process runs Exim with the %-bm% option, the message is read
-non-interactively (usually via a pipe), with the recipients taken from the
-command line, or from the body of the message if %-t% is also used.
-
-- If the process runs Exim with the %-bS% option, the message is also read
-non-interactively, but in this case the recipients are listed at the start of
-the message in a series of SMTP RCPT commands, terminated by a DATA
-command. This is so-called ``batch SMTP'' format,
-but it isn't really SMTP. The SMTP commands are just another way of passing
-envelope addresses in a non-interactive submission.
-
-- If the process runs Exim with the %-bs% option, the message is read
-interactively, using the SMTP protocol. A two-way pipe is normally used for
-passing data between the local process and the Exim process.
-This is ``real'' SMTP and is handled in the same way as SMTP over TCP/IP. For
-example, the ACLs for SMTP commands are used for this form of submission.
-
-- A local process may also make a TCP/IP call to the host's loopback address
-(127.0.0.1) or any other of its IP addresses. When receiving messages, Exim
-does not treat the loopback address specially. It treats all such connections
-in the same way as connections from other hosts.
-
-
-cindex:[message sender, constructed by Exim]
-cindex:[sender,constructed by Exim]
-In the three cases that do not involve TCP/IP, the sender address is
-constructed from the login name of the user that called Exim and a default
-qualification domain (which can be set by the %qualify_domain% configuration
-option). For local or batch SMTP, a sender address that is passed using the
-SMTP MAIL command is ignored. However, the system administrator may allow
-certain users (``trusted users'') to specify a different sender address
-unconditionally, or all users to specify certain forms of different sender
-address. The %-f% option or the SMTP MAIL command is used to specify these
-different addresses. See section <<SECTtrustedadmin>> for details of trusted
-users, and the %untrusted_set_sender% option for a way of allowing untrusted
-users to change sender addresses.
-
-Messages received by either of the non-interactive mechanisms are subject to
-checking by the non-SMTP ACL, if one is defined. Messages received using SMTP
-(either over TCP/IP, or interacting with a local process) can be checked by a
-number of ACLs that operate at different times during the SMTP session. Either
-individual recipients, or the entire message, can be rejected if local policy
-requirements are not met. The 'local_scan()' function (see chapter
-<<CHAPlocalscan>>) is run for all incoming messages.
-
-Exim can be configured not to start a delivery process when a message is
-received; this can be unconditional, or depend on the number of incoming SMTP
-connections or the system load. In these situations, new messages wait on the
-queue until a queue runner process picks them up. However, in standard
-configurations under normal conditions, delivery is started as soon as a
-message is received.
-
-
-
-
-
-Handling an incoming message
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[spool directory,files that hold a message]
-cindex:[file,how a message is held]
-When Exim accepts a message, it writes two files in its spool directory. The
-first contains the envelope information, the current status of the message, and
-the header lines, and the second contains the body of the message. The names of
-the two spool files consist of the message id, followed by `-H` for the
-file containing the envelope and header, and `-D` for the data file.
-
-cindex:[spool directory,_input_ sub-directory]
-By default all these message files are held in a single directory called
-_input_ inside the general Exim spool directory. Some operating systems do
-not perform very well if the number of files in a directory gets very large; to
-improve performance in such cases, the %split_spool_directory% option can be
-used. This causes Exim to split up the input files into 62 sub-directories
-whose names are single letters or digits.
-
-The envelope information consists of the address of the message's sender and
-the addresses of the recipients. This information is entirely separate from
-any addresses contained in the header lines. The status of the message includes
-a list of recipients who have already received the message. The format of the
-first spool file is described in chapter <<CHAPspool>>.
-
-cindex:[rewriting,addresses]
-Address rewriting that is specified in the rewrite section of the configuration
-(see chapter <<CHAPrewrite>>) is done once and for all on incoming addresses,
-both in the header lines and the envelope, at the time the message is accepted.
-If during the course of delivery additional addresses are generated (for
-example, via aliasing), these new addresses are rewritten as soon as they are
-generated. At the time a message is actually delivered (transported) further
-rewriting can take place; because this is a transport option, it can be
-different for different forms of delivery. It is also possible to specify the
-addition or removal of certain header lines at the time the message is
-delivered (see chapters <<CHAProutergeneric>> and <<CHAPtransportgeneric>>).
-
-
-
-Life of a message
-~~~~~~~~~~~~~~~~~
-cindex:[message,life of]
-cindex:[message,frozen]
-A message remains in the spool directory until it is completely delivered to
-its recipients or to an error address, or until it is deleted by an
-administrator or by the user who originally created it. In cases when delivery
-cannot proceed -- for example, when a message can neither be delivered to its
-recipients nor returned to its sender, the message is marked ``frozen'' on the
-spool, and no more deliveries are attempted.
-
-cindex:[frozen messages,thawing]
-cindex:[message,thawing frozen]
-An administrator can ``thaw'' such messages when the problem has been corrected,
-and can also freeze individual messages by hand if necessary. In addition, an
-administrator can force a delivery error, causing a bounce message to be sent.
-
-[revisionflag="changed"]
-cindex:[%timeout_frozen_after%]
-cindex:[%ignore_bounce_errors_after%]
-There are options called %ignore_bounce_errors_after% and
-%timeout_frozen_after%, which discard frozen messages after a certain time.
-The first applies only to frozen bounces, the second to any frozen messages.
-
-cindex:[message,log file for]
-cindex:[log,file for each message]
-While Exim is working on a message, it writes information about each delivery
-attempt to its main log file. This includes successful, unsuccessful, and
-delayed deliveries for each recipient (see chapter <<CHAPlog>>). The log lines
-are also written to a separate 'message log' file for each message. These
-logs are solely for the benefit of the administrator, and are normally deleted
-along with the spool files when processing of a message is complete.
-The use of individual message logs can be disabled by setting
-%no_message_logs%; this might give an improvement in performance on very
-busy systems.
-
-cindex:[journal file]
-cindex:[file,journal]
-All the information Exim itself needs to set up a delivery is kept in the first
-spool file, along with the header lines. When a successful delivery occurs, the
-address is immediately written at the end of a journal file, whose name is the
-message id followed by `-J`. At the end of a delivery run, if there are some
-addresses left to be tried again later, the first spool file (the `-H` file)
-is updated to indicate which these are, and the journal file is then deleted.
-Updating the spool file is done by writing a new file and renaming it, to
-minimize the possibility of data loss.
-
-Should the system or the program crash after a successful delivery but before
-the spool file has been updated, the journal is left lying around. The next
-time Exim attempts to deliver the message, it reads the journal file and
-updates the spool file before proceeding. This minimizes the chances of double
-deliveries caused by crashes.
-
-
-
-[[SECTprocaddress]]
-Processing an address for delivery
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[drivers,definition of]
-cindex:[router,definition of]
-cindex:[transport,definition of]
-The main delivery processing elements of Exim are called 'routers' and
-'transports', and collectively these are known as 'drivers'. Code for a
-number of them is provided in the source distribution, and compile-time options
-specify which ones are included in the binary. Run time options specify which
-ones are actually used for delivering messages.
-
-cindex:[drivers,instance definition]
-Each driver that is specified in the run time configuration is an 'instance'
-of that particular driver type. Multiple instances are allowed; for example,
-you can set up several different ^smtp^ transports, each with different
-option values that might specify different ports or different timeouts. Each
-instance has its own identifying name. In what follows we will normally use the
-instance name when discussing one particular instance (that is, one specific
-configuration of the driver), and the generic driver name when discussing
-the driver's features in general.
-
-A 'router' is a driver that operates on an address, either determining how
-its delivery should happen, by assigning it to a specific transport, or
-converting the address into one or more new addresses (for example, via an
-alias file). A router may also explicitly choose to fail an address, causing it
-to be bounced.
-
-A 'transport' is a driver that transmits a copy of the message from Exim's
-spool to some destination. There are two kinds of transport: for a 'local'
-transport, the destination is a file or a pipe on the local host, whereas for a
-'remote' transport the destination is some other host. A message is passed
-to a specific transport as a result of successful routing. If a message has
-several recipients, it may be passed to a number of different transports.
-
-cindex:[preconditions,definition of]
-An address is processed by passing it to each configured router instance in
-turn, subject to certain preconditions, until a router accepts the address or
-specifies that it should be bounced. We will describe this process in more
-detail shortly. First, as a simple example, we consider how each recipient
-address in a message is processed in a small configuration of three routers.
-
-To make this a more concrete example, it is described in terms of some actual
-routers, but remember, this is only an example. You can configure Exim's
-routers in many different ways, and there may be any number of routers in a
-configuration.
-
-The first router that is specified in a configuration is often one that handles
-addresses in domains that are not recognized specially by the local host. These
-are typically addresses for arbitrary domains on the Internet. A precondition
-is set up which looks for the special domains known to the host (for example,
-its own domain name), and the router is run for addresses that do 'not'
-match. Typically, this is a router that looks up domains in the DNS in order to
-find the hosts to which this address routes. If it succeeds, the address is
-assigned to a suitable SMTP transport; if it does not succeed, the router is
-configured to fail the address.
-
-The second router is reached only when the domain is recognized as one that
-``belongs'' to the local host. This router does redirection -- also known as
-aliasing and forwarding. When it generates one or more new addresses from the
-original, each of them is routed independently from the start. Otherwise, the
-router may cause an address to fail, or it may simply decline to handle the
-address, in which case the address is passed to the next router.
-
-The final router in many configurations is one that checks to see if the
-address belongs to a local mailbox. The precondition may involve a check to
-see if the local part is the name of a login account, or it may look up the
-local part in a file or a database. If its preconditions are not met, or if
-the router declines, we have reached the end of the routers. When this happens,
-the address is bounced.
-
-
-
-Processing an address for verification
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[router,for verification]
-cindex:[verifying address, overview]
-As well as being used to decide how to deliver to an address, Exim's routers
-are also used for 'address verification'. Verification can be requested as
-one of the checks to be performed in an ACL for incoming messages, on both
-sender and recipient addresses, and it can be tested using the %-bv% and
-%-bvs% command line options.
-
-When an address is being verified, the routers are run in ``verify mode''. This
-does not affect the way the routers work, but it is a state that can be
-detected. By this means, a router can be skipped or made to behave differently
-when verifying. A common example is a configuration in which the first router
-sends all messages to a message-scanning program, unless they have been
-previously scanned. Thus, the first router accepts all addresses without any
-checking, making it useless for verifying. Normally, the %no_verify% option
-would be set for such a router, causing it to be skipped in verify mode.
-
-
-
-
-[[SECTrunindrou]]
-Running an individual router
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[router,running details]
-cindex:[preconditions,checking]
-cindex:[router,result of running]
-As explained in the example above, a number of preconditions are checked before
-running a router. If any are not met, the router is skipped, and the address is
-passed to the next router. When all the preconditions on a router 'are' met,
-the router is run. What happens next depends on the outcome, which is one of
-the following:
-
-- 'accept': The router accepts the address, and either assigns it to a
-transport, or generates one or more ``child'' addresses. Processing the original
-address ceases,
-cindex:[%unseen% option]
-unless the %unseen% option is set on the router. This option
-can be used to set up multiple deliveries with different routing (for example,
-for keeping archive copies of messages). When %unseen% is set, the address is
-passed to the next router. Normally, however, an 'accept' return marks the
-end of routing.
-+
-Any child addresses generated by the router are processed independently,
-starting with the first router by default. It is possible to change this by
-setting the %redirect_router% option to specify which router to start at for
-child addresses. Unlike %pass_router% (see below) the router specified by
-%redirect_router% may be anywhere in the router configuration.
-
-- 'pass': The router recognizes the address, but cannot handle it itself. It
-requests that the address be passed to another router. By default the address
-is passed to the next router, but this can be changed by setting the
-%pass_router% option. However, (unlike %redirect_router%) the named router
-must be below the current router (to avoid loops).
-
-- 'decline': The router declines to accept the address because it does not
-recognize it at all. By default, the address is passed to the next router, but
-this can be prevented by setting the %no_more% option. When %no_more% is set,
-all the remaining routers are skipped. In effect, %no_more% converts 'decline'
-into 'fail'.
-
-- 'fail': The router determines that the address should fail, and queues it for
-the generation of a bounce message. There is no further processing of the
-original address unless %unseen% is set on the router.
-
-- 'defer': The router cannot handle the address at the present time. (A
-database may be offline, or a DNS lookup may have timed out.) No further
-processing of the address happens in this delivery attempt. It is tried again
-next time the message is considered for delivery.
-
-- 'error': There is some error in the router (for example, a syntax error in
-its configuration). The action is as for defer.
-
-If an address reaches the end of the routers without having been accepted by
-any of them, it is bounced as unrouteable. The default error message in this
-situation is ``unrouteable address'', but you can set your own message by
-making use of the %cannot_route_message% option. This can be set for any
-router; the value from the last router that ``saw'' the address is used.
-
-Sometimes while routing you want to fail a delivery when some conditions are
-met but others are not, instead of passing the address on for further routing.
-You can do this by having a second router that explicitly fails the delivery
-when the relevant conditions are met. The ^redirect^ router has a ``fail''
-facility for this purpose.
-
-
-Duplicate addresses
-~~~~~~~~~~~~~~~~~~~
-
-[revisionflag="changed"]
-cindex:[case of local parts]
-cindex:[address duplicate, discarding]
-Once routing is complete, Exim scans the addresses that are assigned to local
-and remote transports, and discards any duplicates that it finds. During this
-check, local parts are treated as case-sensitive.
-
-
-
-[[SECTrouprecon]]
-Router preconditions
-~~~~~~~~~~~~~~~~~~~~
-cindex:[router preconditions, order of processing]
-cindex:[preconditions,order of processing]
-The preconditions that are tested for each router are listed below, in the
-order in which they are tested. The individual configuration options are
-described in more detail in chapter <<CHAProutergeneric>>.
-
-- The %local_part_prefix% and %local_part_suffix% options can specify that
-the local parts handled by the router may or must have certain prefixes and/or
-suffixes. If a mandatory affix (prefix or suffix) is not present, the router is
-skipped. These conditions are tested first. When an affix is present, it is
-removed from the local part before further processing, including the evaluation
-of any other conditions.
-
-- Routers can be designated for use only when not verifying an address, that is,
-only when routing it for delivery (or testing its delivery routing). If the
-%verify% option is set false, the router is skipped when Exim is verifying an
-address.
-Setting the %verify% option actually sets two options, %verify_sender% and
-%verify_recipient%, which independently control the use of the router for
-sender and recipient verification. You can set these options directly if
-you want a router to be used for only one type of verification.
-
-- If the %address_test% option is set false, the router is skipped when Exim is
-run with the %-bt% option to test an address routing. This can be helpful when
-the first router sends all new messages to a scanner of some sort; it makes it
-possible to use %-bt% to test subsequent delivery routing without having to
-simulate the effect of the scanner.
-
-- Routers can be designated for use only when verifying an address, as
-opposed to routing it for delivery. The %verify_only% option controls this.
-
-- Individual routers can be explicitly skipped when running the routers to
-check an address given in the SMTP EXPN command (see the %expn% option).
-
-- If the %domains% option is set, the domain of the address must be in the set
-of domains that it defines.
-
-- cindex:[$local_part_prefix$]
-cindex:[$local_part$]
-cindex:[$local_part_suffix$]
-If the %local_parts% option is set, the local part of the address must be in
-the set of local parts that it defines. If %local_part_prefix% or
-%local_part_suffix% is in use, the prefix or suffix is removed from the local
-part before this check. If you want to do precondition tests on local parts
-that include affixes, you can do so by using a %condition% option (see below)
-that uses the variables $local_part$, $local_part_prefix$, and
-$local_part_suffix$ as necessary.
-
-- cindex:[$local_user_uid$]
-cindex:[$local_user_gid$]
-cindex:[$home$]
-If the %check_local_user% option is set, the local part must be the name of
-an account on the local host. If this check succeeds, the uid and gid of the
-local user are placed in $local_user_uid$ and $local_user_gid$ and the user's
-home directory is placed in $home$; these values can be used in the remaining
-preconditions.
-
-- If the %router_home_directory% option is set, it is expanded at this point,
-because it overrides the value of $home$. If this expansion were left till
-later, the value of $home$ as set by %check_local_user% would be used in
-subsequent tests. Having two different values of $home$ in the same router
-could lead to confusion.
-
-- If the %senders% option is set, the envelope sender address must be in the set
-of addresses that it defines.
-
-- If the %require_files% option is set, the existence or non-existence of
-specified files is tested.
-
-- cindex:[customizing,precondition]
-If the %condition% option is set, it is evaluated and tested. This option uses
-an expanded string to allow you to set up your own custom preconditions.
-Expanded strings are described in chapter <<CHAPexpand>>.
-
-
-Note that %require_files% comes near the end of the list, so you cannot use it
-to check for the existence of a file in which to lookup up a domain, local
-part, or sender. However, as these options are all expanded, you can use the
-%exists% expansion condition to make such tests within each condition. The
-%require_files% option is intended for checking files that the router may be
-going to use internally, or which are needed by a specific transport (for
-example, _.procmailrc_).
-
-
-
-Delivery in detail
-~~~~~~~~~~~~~~~~~~
-cindex:[delivery,in detail]
-When a message is to be delivered, the sequence of events is as follows:
-
-- If a system-wide filter file is specified, the message is passed to it. The
-filter may add recipients to the message, replace the recipients, discard the
-message, cause a new message to be generated, or cause the message delivery to
-fail. The format of the system filter file is the same as for Exim user filter
-files, described in the separate document entitled
-'Exim's interfaces to mail filtering'.
-cindex:[Sieve filter,not available for system filter]
-(*Note*: Sieve cannot be used for system filter files.)
-+
-Some additional features are available in system filters -- see chapter
-<<CHAPsystemfilter>> for details. Note that a message is passed to the system
-filter only once per delivery attempt, however many recipients it has. However,
-if there are several delivery attempts because one or more addresses could not
-be immediately delivered, the system filter is run each time. The filter
-condition %first_delivery% can be used to detect the first run of the system
-filter.
-
-- Each recipient address is offered to each configured router in turn, subject
-to its preconditions, until one is able to handle it. If no router can handle
-the address, that is, if they all decline, the address is failed. Because
-routers can be targeted at particular domains, several locally handled domains
-can be processed entirely independently of each other.
-
-- cindex:[routing,loops in]
-cindex:[loop,while routing]
-A router that accepts an address may assign it to a local or a remote transport. However, the transport is not run at this time. Instead, the address is
-placed on a list for the particular transport, which will be run later.
-Alternatively, the router may generate one or more new addresses (typically
-from alias, forward, or filter files). New addresses are fed back into this
-process from the top, but in order to avoid loops, a router ignores any address
-which has an identically-named ancestor that was processed by itself.
-
-- When all the routing has been done, addresses that have been successfully
-handled are passed to their assigned transports. When local transports are
-doing real local deliveries, they handle only one address at a time, but if a
-local transport is being used as a pseudo-remote transport (for example, to
-collect batched SMTP messages for transmission by some other means) multiple
-addresses can be handled. Remote transports can always handle more than one
-address at a time, but can be configured not to do so, or to restrict multiple
-addresses to the same domain.
-
-- Each local delivery to a file or a pipe runs in a separate process under a
-non-privileged uid, and these deliveries are run one at a time. Remote
-deliveries also run in separate processes, normally under a uid that is private
-to Exim (``the Exim user''), but in this case, several remote deliveries can be
-run in parallel. The maximum number of simultaneous remote deliveries for any
-one message is set by the %remote_max_parallel% option.
-The order in which deliveries are done is not defined, except that all local
-deliveries happen before any remote deliveries.
-
-- cindex:[queue runner]
-When it encounters a local delivery during a queue run, Exim checks its retry
-database to see if there has been a previous temporary delivery failure for the
-address before running the local transport. If there was a previous failure,
-Exim does not attempt a new delivery until the retry time for the address is
-reached. However, this happens only for delivery attempts that are part of a
-queue run. Local deliveries are always attempted when delivery immediately
-follows message reception, even if retry times are set for them. This makes for
-better behaviour if one particular message is causing problems (for example,
-causing quota overflow, or provoking an error in a filter file).
-
-- cindex:[delivery,retry in remote transports]
-Remote transports do their own retry handling, since an address may be
-deliverable to one of a number of hosts, each of which may have a different
-retry time. If there have been previous temporary failures and no host has
-reached its retry time, no delivery is attempted, whether in a queue run or
-not. See chapter <<CHAPretry>> for details of retry strategies.
-
-- If there were any permanent errors, a bounce message is returned to an
-appropriate address (the sender in the common case), with details of the error
-for each failing address. Exim can be configured to send copies of bounce
-messages to other addresses.
-
-- cindex:[delivery,deferral]
-If one or more addresses suffered a temporary failure, the message is left on
-the queue, to be tried again later. Delivery of these addresses is said to be
-'deferred'.
-
-- When all the recipient addresses have either been delivered or bounced,
-handling of the message is complete. The spool files and message log are
-deleted, though the message log can optionally be preserved if required.
-
-
-
-
-Retry mechanism
-~~~~~~~~~~~~~~~
-cindex:[delivery,retry mechanism]
-cindex:[retry,description of mechanism]
-cindex:[queue runner]
-Exim's mechanism for retrying messages that fail to get delivered at the first
-attempt is the queue runner process. You must either run an Exim daemon that
-uses the %-q% option with a time interval to start queue runners at regular
-intervals, or use some other means (such as 'cron') to start them. If you do
-not arrange for queue runners to be run, messages that fail temporarily at the
-first attempt will remain on your queue for ever. A queue runner process works
-its way through the queue, one message at a time, trying each delivery that has
-passed its retry time.
-You can run several queue runners at once.
-
-Exim uses a set of configured rules to determine when next to retry the failing
-address (see chapter <<CHAPretry>>). These rules also specify when Exim should
-give up trying to deliver to the address, at which point it generates a bounce
-message. If no retry rules are set for a particular host, address, and error
-combination, no retries are attempted, and temporary errors are treated as
-permanent.
-
-
-
-Temporary delivery failure
-~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[delivery,temporary failure]
-There are many reasons why a message may not be immediately deliverable to a
-particular address. Failure to connect to a remote machine (because it, or the
-connection to it, is down) is one of the most common. Temporary failures may be
-detected during routing as well as during the transport stage of delivery.
-Local deliveries may be delayed if NFS files are unavailable, or if a mailbox
-is on a file system where the user is over quota. Exim can be configured to
-impose its own quotas on local mailboxes; where system quotas are set they will
-also apply.
-
-If a host is unreachable for a period of time, a number of messages may be
-waiting for it by the time it recovers, and sending them in a single SMTP
-connection is clearly beneficial. Whenever a delivery to a remote host is
-deferred,
-
-cindex:[hints database]
-Exim makes a note in its hints database, and whenever a successful
-SMTP delivery has happened, it looks to see if any other messages are waiting
-for the same host. If any are found, they are sent over the same SMTP
-connection, subject to a configuration limit as to the maximum number in any
-one connection.
-
-
-
-
-Permanent delivery failure
-~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[delivery,permanent failure]
-cindex:[bounce message,when generated]
-When a message cannot be delivered to some or all of its intended recipients, a
-bounce message is generated. Temporary delivery failures turn into permanent
-errors when their timeout expires. All the addresses that fail in a given
-delivery attempt are listed in a single message. If the original message has
-many recipients, it is possible for some addresses to fail in one delivery
-attempt and others to fail subsequently, giving rise to more than one bounce
-message. The wording of bounce messages can be customized by the administrator.
-See chapter <<CHAPemsgcust>> for details.
-
-cindex:['X-Failed-Recipients:' header line]
-Bounce messages contain an 'X-Failed-Recipients:' header line that lists the
-failed addresses, for the benefit of programs that try to analyse such messages
-automatically.
-
-cindex:[bounce message,recipient of]
-A bounce message is normally sent to the sender of the original message, as
-obtained from the message's envelope. For incoming SMTP messages, this is the
-address given in the MAIL command. However, when an address is
-expanded via a forward or alias file, an alternative address can be specified
-for delivery failures of the generated addresses. For a mailing list expansion
-(see section <<SECTmailinglists>>) it is common to direct bounce messages to the
-manager of the list.
-
-
-
-
-Failures to deliver bounce messages
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[bounce message,failure to deliver]
-If a bounce message (either locally generated or received from a remote host)
-itself suffers a permanent delivery failure, the message is left on the queue,
-but it is frozen, awaiting the attention of an administrator. There are options
-that can be used to make Exim discard such failed messages, or to keep them
-for only a short time (see %timeout_frozen_after% and
-%ignore_bounce_errors_after%).
-
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-Building and installing Exim
-----------------------------
-
-cindex:[building Exim]
-
-Unpacking
-~~~~~~~~~
-Exim is distributed as a gzipped or bzipped tar file which, when upacked,
-creates a directory with the name of the current release (for example,
-_exim-{version}_) into which the following files are placed:
-
-[frame="none"]
-`--------------------`--------------------------------------------------------
-_ACKNOWLEDGMENTS_ contains some acknowledgments
-_CHANGES_ contains a reference to where changes are documented
-_LICENCE_ the GNU General Public Licence
-_Makefile_ top-level make file
-_NOTICE_ conditions for the use of Exim
-_README_ list of files, directories and simple build instructions
-------------------------------------------------------------------------------
-
-Other files whose names begin with _README_ may also be present. The
-following subdirectories are created:
-
-[frame="none"]
-`--------------------`------------------------------------------------
-_Local_ an empty directory for local configuration files
-_OS_ OS-specific files
-_doc_ documentation files
-_exim_monitor_ source files for the Exim monitor
-_scripts_ scripts used in the build process
-_src_ remaining source files
-_util_ independent utilities
-----------------------------------------------------------------------
-
-The main utility programs are contained in the _src_ directory, and are built
-with the Exim binary. The _util_ directory contains a few optional scripts
-that may be useful to some sites.
-
-
-Multiple machine architectures and operating systems
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[building Exim,multiple OS/architectures]
-The building process for Exim is arranged to make it easy to build binaries for
-a number of different architectures and operating systems from the same set of
-source files. Compilation does not take place in the _src_ directory. Instead,
-a 'build directory' is created for each architecture and operating system.
-
-cindex:[symbolic link,to build directory]
-Symbolic links to the sources are installed in this directory, which is where
-the actual building takes place.
-
-In most cases, Exim can discover the machine architecture and operating system
-for itself, but the defaults can be overridden if necessary.
-
-
-[[SECTdb]]
-DBM libraries
-~~~~~~~~~~~~~
-cindex:[DBM libraries, discussion of]
-cindex:[hints database,DBM files used for]
-Even if you do not use any DBM files in your configuration, Exim still needs a
-DBM library in order to operate, because it uses indexed files for its hints
-databases. Unfortunately, there are a number of DBM libraries in existence, and
-different operating systems often have different ones installed.
-
-cindex:[Solaris,DBM library for]
-cindex:[IRIX, DBM library for]
-cindex:[BSD, DBM library for]
-cindex:[Linux, DBM library for]
-If you are using Solaris, IRIX, one of the modern BSD systems, or a modern
-Linux distribution, the DBM configuration should happen automatically, and you
-may be able to ignore this section. Otherwise, you may have to learn more than
-you would like about DBM libraries from what follows.
-
-cindex:['ndbm' DBM library]
-Licensed versions of Unix normally contain a library of DBM functions operating
-via the 'ndbm' interface, and this is what Exim expects by default. Free
-versions of Unix seem to vary in what they contain as standard. In particular,
-some early versions of Linux have no default DBM library, and different
-distributors have chosen to bundle different libraries with their packaged
-versions. However, the more recent releases seem to have standardised on the
-Berkeley DB library.
-
-Different DBM libraries have different conventions for naming the files they
-use. When a program opens a file called _dbmfile_, there are four
-possibilities:
-
-. A traditional 'ndbm' implementation, such as that supplied as part of
-Solaris, operates on two files called _dbmfile.dir_ and _dbmfile.pag_.
-
-. cindex:['gdbm' DBM library]
-The GNU library, 'gdbm', operates on a single file. If used via its 'ndbm'
-compatibility interface it makes two different hard links to it with names
-_dbmfile.dir_ and _dbmfile.pag_, but if used via its native interface, the
-file name is used unmodified.
-
-. cindex:[Berkeley DB library]
-The Berkeley DB package, if called via its 'ndbm' compatibility interface,
-operates on a single file called _dbmfile.db_, but otherwise looks to the
-programmer exactly the same as the traditional 'ndbm' implementation.
-
-. If the Berkeley package is used in its native mode, it operates on a single
-file called _dbmfile_; the programmer's interface is somewhat different to
-the traditional 'ndbm' interface.
-
-. To complicate things further, there are several very different versions of the
-Berkeley DB package. Version 1.85 was stable for a very long time, releases
-2.'x' and 3.'x' were current for a while, but the latest versions are now
-numbered 4.'x'. Maintenance of some of the earlier releases has ceased. All
-versions of Berkeley DB can be obtained from
-+
-&&&
-*http://www.sleepycat.com/[]*
-&&&
-
-. cindex:['tdb' DBM library]
-Yet another DBM library, called 'tdb', has become available from
-+
-&&&
-*http://download.sourceforge.net/tdb[]*
-&&&
-+
-It has its own interface, and also operates on a single file.
-
-cindex:[USE_DB]
-cindex:[DBM libraries, configuration for building]
-Exim and its utilities can be compiled to use any of these interfaces. In order
-to use any version of the Berkeley DB package in native mode, you must set
-USE_DB in an appropriate configuration file (typically
-_Local/Makefile_). For example:
-
- USE_DB=yes
-
-Similarly, for gdbm you set USE_GDBM, and for tdb you set USE_TDB. An
-error is diagnosed if you set more than one of these.
-
-At the lowest level, the build-time configuration sets none of these options,
-thereby assuming an interface of type (1). However, some operating system
-configuration files (for example, those for the BSD operating systems and
-Linux) assume type (4) by setting USE_DB as their default, and the
-configuration files for Cygwin set USE_GDBM. Anything you set in
-_Local/Makefile_, however, overrides these system defaults.
-
-As well as setting USE_DB, USE_GDBM, or USE_TDB, it may also be
-necessary to set DBMLIB, to cause inclusion of the appropriate library, as
-in one of these lines:
-
- DBMLIB = -ldb
- DBMLIB = -ltdb
-
-Settings like that will work if the DBM library is installed in the standard
-place. Sometimes it is not, and the library's header file may also not be in
-the default path. You may need to set INCLUDE to specify where the header
-file is, and to specify the path to the library more fully in DBMLIB, as in
-this example:
-
- INCLUDE=-I/usr/local/include/db-4.1
- DBMLIB=/usr/local/lib/db-4.1/libdb.a
-
-
-There is further detailed discussion about the various DBM libraries in the
-file _doc/dbm.discuss.txt_ in the Exim distribution.
-
-
-
-Pre-building configuration
-~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[building Exim,pre-building configuration]
-cindex:[configuration for building Exim]
-cindex:[_Local/Makefile_]
-cindex:[_src/EDITME_]
-Before building Exim, a local configuration file that specifies options
-independent of any operating system has to be created with the name
-_Local/Makefile_. A template for this file is supplied as the file
-_src/EDITME_, and it contains full descriptions of all the option settings
-therein. These descriptions are therefore not repeated here. If you are
-building Exim for the first time, the simplest thing to do is to copy
-_src/EDITME_ to _Local/Makefile_, then read it and edit it appropriately.
-
-There are three settings that you must supply, because Exim will not build
-without them. They are the location of the run time configuration file
-(CONFIGURE_FILE), the directory in which Exim binaries will be installed
-(BIN_DIRECTORY), and the identity of the Exim user (EXIM_USER and
-maybe EXIM_GROUP as well). The value of CONFIGURE_FILE can in fact be
-a colon-separated list of file names; Exim uses the first of them that exists.
-
-There are a few other parameters that can be specified either at build time or
-at run time, to enable the same binary to be used on a number of different
-machines. However, if the locations of Exim's spool directory and log file
-directory (if not within the spool directory) are fixed, it is recommended that
-you specify them in _Local/Makefile_ instead of at run time, so that errors
-detected early in Exim's execution (such as a malformed configuration file) can
-be logged.
-
-cindex:[content scanning,specifying at build time]
-Exim's interfaces for calling virus and spam scanning software directly from
-access control lists are not compiled by default. If you want to include these
-facilities, you need to set
-
- WITH_CONTENT_SCAN=yes
-
-in your _Local/Makefile_. For details of the facilities themselves, see
-chapter <<CHAPexiscan>>.
-
-
-cindex:[_Local/eximon.conf_]
-cindex:[_exim_monitor/EDITME_]
-If you are going to build the Exim monitor, a similar configuration process is
-required. The file _exim_monitor/EDITME_ must be edited appropriately for
-your installation and saved under the name _Local/eximon.conf_. If you are
-happy with the default settings described in _exim_monitor/EDITME_,
-_Local/eximon.conf_ can be empty, but it must exist.
-
-This is all the configuration that is needed in straightforward cases for known
-operating systems. However, the building process is set up so that it is easy
-to override options that are set by default or by operating-system-specific
-configuration files, for example to change the name of the C compiler, which
-defaults to %gcc%. See section <<SECToverride>> below for details of how to do
-this.
-
-
-
-Support for iconv()
-~~~~~~~~~~~~~~~~~~~
-cindex:['iconv()' support]
-cindex:[RFC 2047]
-The contents of header lines in messages may be encoded according to the rules
-described RFC 2047. This makes it possible to transmit characters that are not
-in the ASCII character set, and to label them as being in a particular
-character set. When Exim is inspecting header lines by means of the %\$h_%
-mechanism, it decodes them, and translates them into a specified character set
-(default ISO-8859-1). The translation is possible only if the operating system
-supports the 'iconv()' function.
-
-However, some of the operating systems that supply 'iconv()' do not support
-very many conversions. The GNU %libiconv% library (available from
-*http://www.gnu.org/software/libiconv/[]*) can be installed on such systems to
-remedy this deficiency, as well as on systems that do not supply 'iconv()' at
-all. After installing %libiconv%, you should add
-
- HAVE_ICONV=yes
-
-to your _Local/Makefile_ and rebuild Exim.
-
-
-
-[[SECTinctlsssl]]
-Including TLS/SSL encryption support
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[TLS,including support for TLS]
-cindex:[encryption,including support for]
-cindex:[SUPPORT_TLS]
-cindex:[OpenSSL,building Exim with]
-cindex:[GnuTLS,building Exim with]
-Exim can be built to support encrypted SMTP connections, using the STARTTLS
-command as per RFC 2487. It can also support legacy clients that expect to
-start a TLS session immediately on connection to a non-standard port (see the
-%tls_on_connect_ports% runtime option and the %-tls-on-connect% command
-line option).
-
-If you want to build Exim with TLS support, you must first install either the
-OpenSSL or GnuTLS library. There is no cryptographic code in Exim itself for
-implementing SSL.
-
-If OpenSSL is installed, you should set
-
- SUPPORT_TLS=yes
- TLS_LIBS=-lssl -lcrypto
-
-in _Local/Makefile_. You may also need to specify the locations of the
-OpenSSL library and include files. For example:
-
- SUPPORT_TLS=yes
- TLS_LIBS=-L/usr/local/openssl/lib -lssl -lcrypto
- TLS_INCLUDE=-I/usr/local/openssl/include/
-
-cindex:[USE_GNUTLS]
-If GnuTLS is installed, you should set
-
- SUPPORT_TLS=yes
- USE_GNUTLS=yes
- TLS_LIBS=-lgnutls -ltasn1 -lgcrypt
-
-in _Local/Makefile_, and again you may need to specify the locations of the
-library and include files. For example:
-
- SUPPORT_TLS=yes
- USE_GNUTLS=yes
- TLS_LIBS=-L/usr/gnu/lib -lgnutls -ltasn1 -lgcrypt
- TLS_INCLUDE=-I/usr/gnu/include
-
-You do not need to set TLS_INCLUDE if the relevant directory is already
-specified in INCLUDE. Details of how to configure Exim to make use of TLS
-are given in chapter <<CHAPTLS>>.
-
-
-
-
-Use of tcpwrappers
-~~~~~~~~~~~~~~~~~~
-cindex:[tcpwrappers, building Exim to support]
-cindex:[USE_TCP_WRAPPERS]
-Exim can be linked with the 'tcpwrappers' library in order to check incoming
-SMTP calls using the 'tcpwrappers' control files. This may be a convenient
-alternative to Exim's own checking facilities for installations that are
-already making use of 'tcpwrappers' for other purposes. To do this, you should
-set USE_TCP_WRAPPERS in _Local/Makefile_, arrange for the file
-_tcpd.h_ to be available at compile time, and also ensure that the library
-_libwrap.a_ is available at link time, typically by including %-lwrap% in
-EXTRALIBS_EXIM. For example, if 'tcpwrappers' is installed in
-_/usr/local_, you might have
-
- USE_TCP_WRAPPERS=yes
- CFLAGS=-O -I/usr/local/include
- EXTRALIBS_EXIM=-L/usr/local/lib -lwrap
-
-in _Local/Makefile_. The name to use in the 'tcpwrappers' control files is
-``exim''. For example, the line
-
- exim : LOCAL 192.168.1. .friendly.domain.example
-
-in your _/etc/hosts.allow_ file allows connections from the local host, from
-the subnet 192.168.1.0/24, and from all hosts in 'friendly.domain.example'.
-All other connections are denied. Consult the 'tcpwrappers' documentation for
-further details.
-
-
-
-Including support for IPv6
-~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[IPv6,including support for]
-Exim contains code for use on systems that have IPv6 support. Setting
-`HAVE_IPV6=YES` in _Local/Makefile_ causes the IPv6 code to be included;
-it may also be necessary to set IPV6_INCLUDE and IPV6_LIBS on systems
-where the IPv6 support is not fully integrated into the normal include and
-library files.
-
-Two different types of DNS record for handling IPv6 addresses have been
-defined. AAAA records (analagous to A records for IPv4) are in use, and are
-currently seen as the mainstream. Another record type called A6 was proposed
-as better than AAAA because it had more flexibility. However, it was felt to be
-over-complex, and its status was reduced to ``experimental''. It is not known
-if anyone is actually using A6 records. Exim has support for A6 records, but
-this is included only if you set `SUPPORT_A6=YES` in _Local/Makefile_. The
-support has not been tested for some time.
-
-
-
-The building process
-~~~~~~~~~~~~~~~~~~~~
-cindex:[build directory]
-Once _Local/Makefile_ (and _Local/eximon.conf_, if required) have been
-created, run 'make' at the top level. It determines the architecture and
-operating system types, and creates a build directory if one does not exist.
-For example, on a Sun system running Solaris 8, the directory
-_build-SunOS5-5.8-sparc_ is created.
-cindex:[symbolic link,to source files]
-Symbolic links to relevant source files are installed in the build directory.
-
-*Warning*: The %-j% (parallel) flag must not be used with 'make'; the
-building process fails if it is set.
-
-If this is the first time 'make' has been run, it calls a script that builds
-a make file inside the build directory, using the configuration files from the
-_Local_ directory. The new make file is then passed to another instance of
-'make'. This does the real work, building a number of utility scripts, and
-then compiling and linking the binaries for the Exim monitor (if configured), a
-number of utility programs, and finally Exim itself. The command 'make
-makefile' can be used to force a rebuild of the make file in the build
-directory, should this ever be necessary.
-
-If you have problems building Exim, check for any comments there may be in the
-_README_ file concerning your operating system, and also take a look at the
-FAQ, where some common problems are covered.
-
-
-
-Output from ``make''
-~~~~~~~~~~~~~~~~~~~~
-
-[revisionflag="changed"]
-The output produced by the 'make' process for compile lines is often very
-unreadable, because these lines can be very long. For this reason, the normal
-output is suppressed by default, and instead output similar to that which
-appears when compiling the 2.6 Linux kernel is generated: just a short line for
-each module that is being compiled or linked. However, it is still possible to
-get the full output, by calling 'make' like this:
-
- FULLECHO='' make -e
-
-The value of FULLECHO defaults to ``@'', the flag character that suppresses
-command reflection in 'make'. When you ask for the full output, it is
-given in addition to the the short output.
-
-
-
-
-[[SECToverride]]
-Overriding build-time options for Exim
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[build-time options, overriding]
-The main make file that is created at the beginning of the building process
-consists of the concatenation of a number of files which set configuration
-values, followed by a fixed set of 'make' instructions. If a value is set
-more than once, the last setting overrides any previous ones. This provides a
-convenient way of overriding defaults. The files that are concatenated are, in
-order:
-
-&&&
-_OS/Makefile-Default_
-_OS/Makefile-_<'ostype'>
-_Local/Makefile_
-_Local/Makefile-_<'ostype'>
-_Local/Makefile-_<'archtype'>
-_Local/Makefile-_<'ostype'>-<'archtype'>
-_OS/Makefile-Base_
-&&&
-
-cindex:[_Local/Makefile_]
-cindex:[building Exim,operating system type]
-cindex:[building Exim,architecture type]
-where <'ostype'> is the operating system type and <'archtype'> is the
-architecture type. _Local/Makefile_ is required to exist, and the building
-process fails if it is absent. The other three _Local_ files are optional,
-and are often not needed.
-
-The values used for <'ostype'> and <'archtype'> are obtained from scripts
-called _scripts/os-type_ and _scripts/arch-type_ respectively. If either of
-the environment variables EXIM_OSTYPE or EXIM_ARCHTYPE is set, their
-values are used, thereby providing a means of forcing particular settings.
-Otherwise, the scripts try to get values from the %uname% command. If this
-fails, the shell variables OSTYPE and ARCHTYPE are inspected. A number
-of 'ad hoc' transformations are then applied, to produce the standard names
-that Exim expects. You can run these scripts directly from the shell in order
-to find out what values are being used on your system.
-
-
-_OS/Makefile-Default_ contains comments about the variables that are set
-therein. Some (but not all) are mentioned below. If there is something that
-needs changing, review the contents of this file and the contents of the make
-file for your operating system (_OS/Makefile-<ostype>_) to see what the
-default values are.
-
-
-cindex:[building Exim,overriding default settings]
-If you need to change any of the values that are set in _OS/Makefile-Default_
-or in _OS/Makefile-<ostype>_, or to add any new definitions, you do not
-need to change the original files. Instead, you should make the changes by
-putting the new values in an appropriate _Local_ file. For example,
-cindex:[Tru64-Unix build-time settings]
-when building Exim in many releases of the Tru64-Unix (formerly Digital UNIX,
-formerly DEC-OSF1) operating system, it is necessary to specify that the C
-compiler is called 'cc' rather than 'gcc'. Also, the compiler must be
-called with the option %-std1%, to make it recognize some of the features of
-Standard C that Exim uses. (Most other compilers recognize Standard C by
-default.) To do this, you should create a file called _Local/Makefile-OSF1_
-containing the lines
-
- CC=cc
- CFLAGS=-std1
-
-If you are compiling for just one operating system, it may be easier to put
-these lines directly into _Local/Makefile_.
-
-Keeping all your local configuration settings separate from the distributed
-files makes it easy to transfer them to new versions of Exim simply by copying
-the contents of the _Local_ directory.
-
-
-cindex:[NIS lookup type,including support for]
-cindex:[NIS+ lookup type,including support for]
-cindex:[LDAP,including support for]
-cindex:[lookup,inclusion in binary]
-Exim contains support for doing LDAP, NIS, NIS+, and other kinds of file
-lookup, but not all systems have these components installed, so the default is
-not to include the relevant code in the binary. All the different kinds of file
-and database lookup that Exim supports are implemented as separate code modules
-which are included only if the relevant compile-time options are set. In the
-case of LDAP, NIS, and NIS+, the settings for _Local/Makefile_ are:
-
- LOOKUP_LDAP=yes
- LOOKUP_NIS=yes
- LOOKUP_NISPLUS=yes
-
-and similar settings apply to the other lookup types. They are all listed in
-_src/EDITME_. In many cases the relevant include files and interface
-libraries need to be installed before compiling Exim.
-cindex:[cdb,including support for]
-However, there are some optional lookup types (such as cdb) for which
-the code is entirely contained within Exim, and no external include
-files or libraries are required. When a lookup type is not included in the
-binary, attempts to configure Exim to use it cause run time configuration
-errors.
-
-cindex:[Perl,including support for]
-Exim can be linked with an embedded Perl interpreter, allowing Perl
-subroutines to be called during string expansion. To enable this facility,
-
- EXIM_PERL=perl.o
-
-must be defined in _Local/Makefile_. Details of this facility are given in
-chapter <<CHAPperl>>.
-
-cindex:[X11 libraries, location of]
-The location of the X11 libraries is something that varies a lot between
-operating systems, and there may be different versions of X11 to cope
-with. Exim itself makes no use of X11, but if you are compiling the Exim
-monitor, the X11 libraries must be available.
-The following three variables are set in _OS/Makefile-Default_:
-
- X11=/usr/X11R6
- XINCLUDE=-I$(X11)/include
- XLFLAGS=-L$(X11)/lib
-
-These are overridden in some of the operating-system configuration files. For
-example, in _OS/Makefile-SunOS5_ there is
-
- X11=/usr/openwin
- XINCLUDE=-I$(X11)/include
- XLFLAGS=-L$(X11)/lib -R$(X11)/lib
-
-If you need to override the default setting for your operating system, place a
-definition of all three of these variables into your
-_Local/Makefile-<ostype>_ file.
-
-cindex:[EXTRALIBS]
-If you need to add any extra libraries to the link steps, these can be put in a
-variable called EXTRALIBS, which appears in all the link commands, but by
-default is not defined. In contrast, EXTRALIBS_EXIM is used only on the
-command for linking the main Exim binary, and not for any associated utilities.
-
-cindex:[DBM libraries, configuration for building]
-There is also DBMLIB, which appears in the link commands for binaries that
-use DBM functions (see also section <<SECTdb>>). Finally, there is
-EXTRALIBS_EXIMON, which appears only in the link step for the Exim monitor
-binary, and which can be used, for example, to include additional X11
-libraries.
-
-cindex:[configuration file,editing]
-The make file copes with rebuilding Exim correctly if any of the configuration
-files are edited. However, if an optional configuration file is deleted, it is
-necessary to touch the associated non-optional file (that is, _Local/Makefile_
-or _Local/eximon.conf_) before rebuilding.
-
-
-OS-specific header files
-~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[_os.h_]
-cindex:[building Exim,OS-specific C header files]
-The _OS_ directory contains a number of files with names of the form
-_os.h-<ostype>_. These are system-specific C header files that should not
-normally need to be changed. There is a list of macro settings that are
-recognized in the file _OS/os.configuring_, which should be consulted if you
-are porting Exim to a new operating system.
-
-
-
-Overriding build-time options for the monitor
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[building Eximon,overriding default options]
-A similar process is used for overriding things when building the Exim monitor,
-where the files that are involved are
-
-&&&
-_OS/eximon.conf-Default_
-_OS/eximon.conf-_<'ostype'>
-_Local/eximon.conf_
-_Local/eximon.conf-_<'ostype'>
-_Local/eximon.conf-_<'archtype'>
-_Local/eximon.conf-_<'ostype'>-<'archtype'>
-&&&
-
-cindex:[_Local/eximon.conf_]
-As with Exim itself, the final three files need not exist, and in this case the
-_OS/eximon.conf-<ostype>_ file is also optional. The default values in
-_OS/eximon.conf-Default_ can be overridden dynamically by setting environment
-variables of the same name, preceded by EXIMON_. For example, setting
-EXIMON_LOG_DEPTH in the environment overrides the value of
-LOG_DEPTH at run time.
-
-
-
-
-Installing Exim binaries and scripts
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[installing Exim]
-cindex:[BIN_DIRECTORY]
-The command 'make install' runs the 'exim_install' script with no arguments.
-The script copies binaries and utility scripts into the directory whose name is
-specified by the BIN_DIRECTORY setting in _Local/Makefile_.
-cindex:[setuid,installing Exim with]
-The install script copies files only if they are newer than the files they are
-going to replace. The Exim binary is required to be owned by root and have the
-'setuid' bit set, for normal configurations. Therefore, you must run 'make
-install' as root so that it can set up the Exim binary in this way. However, in
-some special situations (for example, if a host is doing no local deliveries)
-it may be possible to run Exim without making the binary setuid root (see
-chapter <<CHAPsecurity>> for details).
-
-cindex:[CONFIGURE_FILE]
-Exim's run time configuration file is named by the CONFIGURE_FILE setting
-in _Local/Makefile_. If this names a single file, and the file does not
-exist, the default configuration file _src/configure.default_ is copied there
-by the installation script. If a run time configuration file already exists, it
-is left alone. If CONFIGURE_FILE is a colon-separated list, naming several
-alternative files, no default is installed.
-
-cindex:[system aliases file]
-cindex:[_/etc/aliases_]
-One change is made to the default configuration file when it is installed: the
-default configuration contains a router that references a system aliases file.
-The path to this file is set to the value specified by
-SYSTEM_ALIASES_FILE in _Local/Makefile_ (_/etc/aliases_ by default).
-If the system aliases file does not exist, the installation script creates it,
-and outputs a comment to the user.
-
-The created file contains no aliases, but it does contain comments about the
-aliases a site should normally have. Mail aliases have traditionally been
-kept in _/etc/aliases_. However, some operating systems are now using
-_/etc/mail/aliases_. You should check if yours is one of these, and change
-Exim's configuration if necessary.
-
-The default configuration uses the local host's name as the only local domain,
-and is set up to do local deliveries into the shared directory _/var/mail_,
-running as the local user. System aliases and _.forward_ files in users' home
-directories are supported, but no NIS or NIS+ support is configured. Domains
-other than the name of the local host are routed using the DNS, with delivery
-over SMTP.
-
-It is possible to install Exim for special purposes (such as building a binary
-distribution) in a private part of the file system. You can do this by a
-command such as
-
- make DESTDIR=/some/directory/ install
-
-This has the effect of pre-pending the specified directory to all the file
-paths, except the name of the system aliases file that appears in the default
-configuration. (If a default alias file is created, its name 'is' modified.)
-For backwards compatibility, ROOT is used if DESTDIR is not set,
-but this usage is deprecated.
-
-cindex:[installing Exim,what is not installed]
-Running 'make install' does not copy the Exim 4 conversion script
-'convert4r4', or the 'pcretest' test program. You will probably run the
-first of these only once (if you are upgrading from Exim 3), and the second
-isn't really part of Exim. None of the documentation files in the _doc_
-directory are copied, except for the info files when you have set
-INFO_DIRECTORY, as described in section <<SECTinsinfdoc>> below.
-
-For the utility programs, old versions are renamed by adding the suffix _.O_
-to their names. The Exim binary itself, however, is handled differently. It is
-installed under a name that includes the version number and the compile number,
-for example _exim-{version}-1_. The script then arranges for a symbolic link
-called _exim_ to point to the binary. If you are updating a previous version
-of Exim, the script takes care to ensure that the name _exim_ is never absent
-from the directory (as seen by other processes).
-
-cindex:[installing Exim,testing the script]
-If you want to see what the 'make install' will do before running it for
-real, you can pass the %-n% option to the installation script by this command:
-
- make INSTALL_ARG=-n install
-
-The contents of the variable INSTALL_ARG are passed to the installation
-script. You do not need to be root to run this test. Alternatively, you can run
-the installation script directly, but this must be from within the build
-directory. For example, from the top-level Exim directory you could use this
-command:
-
- (cd build-SunOS5-5.5.1-sparc; ../scripts/exim_install -n)
-
-cindex:[installing Exim,install script options]
-There are two other options that can be supplied to the installation script.
-
-- %-no_chown% bypasses the call to change the owner of the installed binary
-to root, and the call to make it a setuid binary.
-
-- %-no_symlink% bypasses the setting up of the symbolic link _exim_ to the
-installed binary.
-
-INSTALL_ARG can be used to pass these options to the script. For example:
-
- make INSTALL_ARG=-no_symlink install
-
-
-The installation script can also be given arguments specifying which files are
-to be copied. For example, to install just the Exim binary, and nothing else,
-without creating the symbolic link, you could use:
-
- make INSTALL_ARG='-no_symlink exim' install
-
-
-
-
-[[SECTinsinfdoc]]
-Installing info documentation
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[installing Exim,'info' documentation]
-Not all systems use the GNU 'info' system for documentation, and for this
-reason, the Texinfo source of Exim's documentation is not included in the main
-distribution. Instead it is available separately from the ftp site (see section
-<<SECTavail>>).
-
-If you have defined INFO_DIRECTORY in _Local/Makefile_ and the Texinfo
-source of the documentation is found in the source tree, running 'make
-install' automatically builds the info files and installs them.
-
-
-
-Setting up the spool directory
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[spool directory,creating]
-When it starts up, Exim tries to create its spool directory if it does not
-exist. The Exim uid and gid are used for the owner and group of the spool
-directory. Sub-directories are automatically created in the spool directory as
-necessary.
-
-
-
-
-Testing
-~~~~~~~
-cindex:[testing,installation]
-Having installed Exim, you can check that the run time configuration file is
-syntactically valid by running the following command, which assumes that the
-Exim binary directory is within your PATH environment variable:
-
- exim -bV
-
-If there are any errors in the configuration file, Exim outputs error messages.
-Otherwise it outputs the version number and build date,
-the DBM library that is being used, and information about which drivers and
-other optional code modules are included in the binary.
-Some simple routing tests can be done by using the address testing option. For
-example,
-
- exim -bt <local username>
-
-should verify that it recognizes a local mailbox, and
-
- exim -bt <remote address>
-
-a remote one. Then try getting it to deliver mail, both locally and remotely.
-This can be done by passing messages directly to Exim, without going through a
-user agent. For example:
-
-....
-exim -v postmaster@your.domain.example
-From: user@your.domain.example
-To: postmaster@your.domain.example
-Subject: Testing Exim
-
-This is a test message.
-^D
-....
-
-The %-v% option causes Exim to output some verification of what it is doing.
-In this case you should see copies of three log lines, one for the message's
-arrival, one for its delivery, and one containing ``Completed''.
-
-cindex:[delivery,problems with]
-If you encounter problems, look at Exim's log files ('mainlog' and
-'paniclog') to see if there is any relevant information there. Another source
-of information is running Exim with debugging turned on, by specifying the
-%-d% option. If a message is stuck on Exim's spool, you can force a delivery
-with debugging turned on by a command of the form
-
- exim -d -M <message-id>
-
-You must be root or an ``admin user'' in order to do this. The %-d% option
-produces rather a lot of output, but you can cut this down to specific areas.
-For example, if you use %-d-all+route% only the debugging information relevant
-to routing is included. (See the %-d% option in chapter <<CHAPcommandline>> for
-more details.)
-
-cindex:[``sticky'' bit]
-cindex:[lock files]
-One specific problem that has shown up on some sites is the inability to do
-local deliveries into a shared mailbox directory, because it does not have the
-``sticky bit'' set on it. By default, Exim tries to create a lock file before
-writing to a mailbox file, and if it cannot create the lock file, the delivery
-is deferred. You can get round this either by setting the ``sticky bit'' on the
-directory, or by setting a specific group for local deliveries and allowing
-that group to create files in the directory (see the comments above the
-^local_delivery^ transport in the default configuration file). Another
-approach is to configure Exim not to use lock files, but just to rely on
-'fcntl()' locking instead. However, you should do this only if all user
-agents also use 'fcntl()' locking. For further discussion of locking issues,
-see chapter <<CHAPappendfile>>.
-
-One thing that cannot be tested on a system that is already running an MTA is
-the receipt of incoming SMTP mail on the standard SMTP port. However, the
-%-oX% option can be used to run an Exim daemon that listens on some other
-port, or 'inetd' can be used to do this. The %-bh% option and the
-'exim_checkaccess' utility can be used to check out policy controls on
-incoming SMTP mail.
-
-Testing a new version on a system that is already running Exim can most easily
-be done by building a binary with a different CONFIGURE_FILE setting. From
-within the run time configuration, all other file and directory names
-that Exim uses can be altered, in order to keep it entirely clear of the
-production version.
-
-
-Replacing another MTA with Exim
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[replacing another MTA]
-Building and installing Exim for the first time does not of itself put it in
-general use. The name by which the system's MTA is called by mail user agents
-is either _/usr/sbin/sendmail_, or _/usr/lib/sendmail_ (depending on the
-operating system), and it is necessary to make this name point to the 'exim'
-binary in order to get the user agents to pass messages to Exim. This is
-normally done by renaming any existing file and making _/usr/sbin/sendmail_
-or _/usr/lib/sendmail_
-
-cindex:[symbolic link,to 'exim' binary]
-a symbolic link to the 'exim' binary. It is a good idea to remove any setuid
-privilege and executable status from the old MTA. It is then necessary to stop
-and restart the mailer daemon, if one is running.
-
-cindex:[FreeBSD, MTA indirection]
-cindex:[_/etc/mail/mailer.conf_]
-Some operating systems have introduced alternative ways of switching MTAs. For
-example, if you are running FreeBSD, you need to edit the file
-_/etc/mail/mailer.conf_ instead of setting up a symbolic link as just
-described. A typical example of the contents of this file for running Exim is
-as follows:
-
- sendmail /usr/exim/bin/exim
- send-mail /usr/exim/bin/exim
- mailq /usr/exim/bin/exim -bp
- newaliases /usr/bin/true
-
-
-Once you have set up the symbolic link, or edited _/etc/mail/mailer.conf_,
-your Exim installation is ``live''. Check it by sending a message from your
-favourite user agent.
-
-You should consider what to tell your users about the change of MTA. Exim may
-have different capabilities to what was previously running, and there are
-various operational differences such as the text of messages produced by
-command line options and in bounce messages. If you allow your users to make
-use of Exim's filtering capabilities, you should make the document entitled
-'Exim's interface to mail filtering'
-available to them.
-
-
-
-Upgrading Exim
-~~~~~~~~~~~~~~
-cindex:[upgrading Exim]
-If you are already running Exim on your host, building and installing a new
-version automatically makes it available to MUAs, or any other programs that
-call the MTA directly. However, if you are running an Exim daemon, you do need
-to send it a HUP signal, to make it re-exec itself, and thereby pick up the new
-binary. You do not need to stop processing mail in order to install a new
-version of Exim. The install script does not modify an existing runtime
-configuration file.
-
-
-
-
-Stopping the Exim daemon on Solaris
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[Solaris,stopping Exim on]
-The standard command for stopping the mailer daemon on Solaris is
-
- /etc/init.d/sendmail stop
-
-If _/usr/lib/sendmail_ has been turned into a symbolic link, this script
-fails to stop Exim because it uses the command 'ps -e' and greps the output
-for the text ``sendmail''; this is not present because the actual program name
-(that is, ``exim'') is given by the 'ps' command with these options. A solution
-is to replace the line that finds the process id with something like
-
- pid=`cat /var/spool/exim/exim-daemon.pid`
-
-to obtain the daemon's pid directly from the file that Exim saves it in.
-
-Note, however, that stopping the daemon does not ``stop Exim''. Messages can
-still be received from local processes, and if automatic delivery is configured
-(the normal case), deliveries will still occur.
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPcommandline]]
-The Exim command line
----------------------
-cindex:[command line,options]
-cindex:[options,command line]
-Exim's command line takes the standard Unix form of a sequence of options,
-each starting with a hyphen character, followed by a number of arguments. The
-options are compatible with the main options of Sendmail, and there are also
-some additional options, some of which are compatible with Smail 3. Certain
-combinations of options do not make sense, and provoke an error if used.
-The form of the arguments depends on which options are set.
-
-
-Setting options by program name
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:['mailq']
-If Exim is called under the name 'mailq', it behaves as if the option %-bp%
-were present before any other options.
-The %-bp% option requests a listing of the contents of the mail queue on the
-standard output.
-This feature is for compatibility with some systems that contain a command of
-that name in one of the standard libraries, symbolically linked to
-_/usr/sbin/sendmail_ or _/usr/lib/sendmail_.
-
-cindex:['rsmtp']
-If Exim is called under the name 'rsmtp' it behaves as if the option %-bS%
-were present before any other options, for compatibility with Smail. The %-bS%
-option is used for reading in a number of messages in batched SMTP format.
-
-cindex:['rmail']
-If Exim is called under the name 'rmail' it behaves as if the %-i% and
-%-oee% options were present before any other options, for compatibility with
-Smail. The name 'rmail' is used as an interface by some UUCP systems.
-
-cindex:['runq']
-cindex:[queue runner]
-If Exim is called under the name 'runq' it behaves as if the option %-q% were
-present before any other options, for compatibility with Smail. The %-q%
-option causes a single queue runner process to be started.
-
-cindex:['newaliases']
-cindex:[alias file,building]
-cindex:[Sendmail compatibility,calling Exim as 'newaliases']
-If Exim is called under the name 'newaliases' it behaves as if the option
-%-bi% were present before any other options, for compatibility with Sendmail.
-This option is used for rebuilding Sendmail's alias file. Exim does not have
-the concept of a single alias file, but can be configured to run a given
-command if called with the %-bi% option.
-
-
-[[SECTtrustedadmin]]
-Trusted and admin users
-~~~~~~~~~~~~~~~~~~~~~~~
-Some Exim options are available only to 'trusted users' and others are
-available only to 'admin users'. In the description below, the phrases ``Exim
-user'' and ``Exim group'' mean the user and group defined by EXIM_USER and
-EXIM_GROUP in _Local/Makefile_ or set by the %exim_user% and
-%exim_group% options. These do not necessarily have to use the name ``exim''.
-
-- cindex:[trusted user,definition of]
-cindex:[user, trusted definition of]
-The trusted users are root, the Exim user, any user listed in the
-%trusted_users% configuration option, and any user whose current group or any
-supplementary group is one of those listed in the %trusted_groups%
-configuration option. Note that the Exim group is not automatically trusted.
-+
-cindex:[``From'' line]
-cindex:[envelope sender]
-Trusted users are always permitted to use the %-f% option or a leading ``From ''
-line to specify the envelope sender of a message that is passed to Exim through
-the local interface (see the %-bm% and %-f% options below). See the
-%untrusted_set_sender% option for a way of permitting non-trusted users to
-set envelope senders.
-+
-cindex:['From:' header line]
-cindex:['Sender:' header line]
-For a trusted user, there is never any check on the contents of the 'From:'
-header line, and a 'Sender:' line is never added. Furthermore, any existing
-'Sender:' line in incoming local (non-TCP/IP) messages is not removed.
-+
-Trusted users may also specify a host name, host address, interface address,
-protocol name, ident value, and authentication data when submitting a message
-locally. Thus, they are able to insert messages into Exim's queue locally that
-have the characteristics of messages received from a remote host. Untrusted
-users may in some circumstances use %-f%, but can never set the other values
-that are available to trusted users.
-
-- cindex:[user, admin definition of]
-cindex:[admin user,definition of]
-The admin users are root, the Exim user, and any user that is a member of the
-Exim group or of any group listed in the %admin_groups% configuration option.
-The current group does not have to be one of these groups.
-+
-Admin users are permitted to list the queue, and to carry out certain
-operations on messages, for example, to force delivery failures. It is also
-necessary to be an admin user in order to see the full information provided by
-the Exim monitor, and full debugging output.
-+
-By default, the use of the %-M%, %-q%, %-R%, and %-S% options to cause Exim
-to attempt delivery of messages on its queue is restricted to admin users.
-However, this restriction can be relaxed by setting the %prod_requires_admin%
-option false (that is, specifying %no_prod_requires_admin%).
-+
-Similarly, the use of the %-bp% option to list all the messages in the queue
-is restricted to admin users unless %queue_list_requires_admin% is set
-false.
-
-
-*Warning*: If you configure your system so that admin users are able to
-edit Exim's configuration file, you are giving those users an easy way of
-getting root. There is further discussion of this issue at the start of chapter
-<<CHAPconf>>.
-
-
-
-
-Command line options
-~~~~~~~~~~~~~~~~~~~~
-The command options are described in alphabetical order below.
-
-///
-We insert a stylized DocBook comment here, to identify the start of the command
-line options. This is for the benefit of the Perl script that automatically
-creates a man page for the options.
-///
-
-++++
-<!-- === Start of command line options === -->
-++++
-
-
-*{hh}*::
-oindex:[{hh}]
-cindex:[options, command line; terminating]
-This is a pseudo-option whose only purpose is to terminate the options and
-therefore to cause subsequent command line items to be treated as arguments
-rather than options, even if they begin with hyphens.
-
-*--help*::
-oindex:[%{hh}help%]
-This option causes Exim to output a few sentences stating what it is.
-The same output is generated if the Exim binary is called with no options and
-no arguments.
-
-*-B*<'type'>::
-oindex:[%-B%]
-cindex:[8-bit characters]
-cindex:[Sendmail compatibility,8-bit characters]
-This is a Sendmail option for selecting 7 or 8 bit processing. Exim is 8-bit
-clean; it ignores this option.
-
-*-bd*::
-oindex:[%-bd%]
-cindex:[daemon]
-cindex:[SMTP listener]
-cindex:[queue runner]
-This option runs Exim as a daemon, awaiting incoming SMTP connections. Usually
-the %-bd% option is combined with the %-q%<'time'> option, to specify that
-the daemon should also initiate periodic queue runs.
-+
-The %-bd% option can be used only by an admin user. If either of the %-d%
-(debugging) or %-v% (verifying) options are set, the daemon does not
-disconnect from the controlling terminal. When running this way, it can be
-stopped by pressing ctrl-C.
-+
-By default, Exim listens for incoming connections to the standard SMTP port on
-all the host's running interfaces. However, it is possible to listen on other
-ports, on multiple ports, and only on specific interfaces. Chapter
-<<CHAPinterfaces>> contains a description of the options that control this.
-+
-When a listening daemon
-cindex:[daemon,process id (pid)]
-cindex:[pid (process id),of daemon]
-is started without the use of %-oX% (that is, without overriding the normal
-configuration), it writes its process id to a file called _exim-daemon.pid_ in
-Exim's spool directory. This location can be overridden by setting
-PID_FILE_PATH in _Local/Makefile_. The file is written while Exim is still
-running as root.
-+
-When %-oX% is used on the command line to start a listening daemon, the
-process id is not written to the normal pid file path. However, %-oP% can be
-used to specify a path on the command line if a pid file is required.
-+
-The SIGHUP signal
-cindex:[SIGHUP]
-can be used to cause the daemon to re-exec itself. This should be done whenever
-Exim's configuration file, or any file that is incorporated into it by means of
-the %.include% facility, is changed, and also whenever a new version of Exim is
-installed. It is not necessary to do this when other files that are referenced
-from the configuration (for example, alias files) are changed, because these
-are reread each time they are used.
-
-*-bdf*::
-oindex:[%-bdf%]
-This option has the same effect as %-bd% except that it never disconnects from
-the controlling terminal, even when no debugging is specified.
-
-*-be*::
-oindex:[%-be%]
-cindex:[testing,string expansion]
-cindex:[expansion,testing]
-Run Exim in expansion testing mode. Exim discards its root privilege, to
-prevent ordinary users from using this mode to read otherwise inaccessible
-files. If no arguments are given, Exim runs interactively, prompting for lines
-of data.
-+
-If Exim was built with USE_READLINE=yes in _Local/Makefile_, it tries
-to load the %libreadline% library dynamically whenever the %-be% option is
-used without command line arguments. If successful, it uses the 'readline()'
-function, which provides extensive line-editing facilities, for reading the
-test data. A line history is supported.
-+
-Long expansion expressions can be split over several lines by using backslash
-continuations. As in Exim's run time configuration, white space at the start of
-continuation lines is ignored. Each argument or data line is passed through the
-string expansion mechanism, and the result is output. Variable values from the
-configuration file (for example, $qualify_domain$) are available, but no
-message-specific values (such as $domain$) are set, because no message is
-being processed.
-
-*-bF*~<'filename'>::
-oindex:[%-bF%]
-cindex:[system filter,testing]
-cindex:[testing,system filter]
-This option is the same as %-bf% except that it assumes that the filter being
-tested is a system filter. The additional commands that are available only in
-system filters are recognized.
-
-*-bf*~<'filename'>::
-oindex:[%-bf%]
-cindex:[filter,testing]
-cindex:[testing,filter file]
-cindex:[forward file,testing]
-cindex:[testing,forward file]
-cindex:[Sieve filter,testing]
-This option runs Exim in user filter testing mode; the file is the filter file
-to be tested, and a test message must be supplied on the standard input. If
-there are no message-dependent tests in the filter, an empty file can be
-supplied.
-+
-If you want to test a system filter file, use %-bF% instead of %-bf%. You can
-use both %-bF% and %-bf% on the same command, in order to
-test a system filter and a user filter in the same run. For example:
-
- exim -bF /system/filter -bf /user/filter </test/message
-+
-This is helpful when the system filter adds header lines or sets filter
-variables that are used by the user filter.
-+
-If the test filter file does not begin with one of the special lines
-
- # Exim filter
- # Sieve filter
-+
-it is taken to be a normal _.forward_ file, and is tested for validity under
-that interpretation. See sections <<SECTitenonfilred>> to <<SECTspecitredli>> for a
-description of the possible contents of non-filter redirection lists.
-+
-The result of an Exim command that uses %-bf%, provided no errors are
-detected, is a list of the actions that Exim would try to take if presented
-with the message for real. More details of filter testing are given in the
-separate document entitled 'Exim's interfaces to mail filtering'.
-+
-When testing a filter file,
-cindex:[``From'' line]
-cindex:[envelope sender]
-cindex:[%-f% option,for filter testing]
-the envelope sender can be set by the %-f% option,
-or by a ``From '' line at the start of the test message. Various parameters that
-would normally be taken from the envelope recipient address of the message can
-be set by means of additional command line options (see the next four options).
-
-*-bfd*~<'domain'>::
-oindex:[%-bfd%]
-cindex:[$qualify_domain$]
-This sets the domain of the recipient address when a filter file is being
-tested by means of the %-bf% option. The default is the value of
-$qualify_domain$.
-
-*-bfl*~<'local~part'>::
-oindex:[%-bfl%]
-This sets the local part of the recipient address when a filter file is being
-tested by means of the %-bf% option. The default is the username of the
-process that calls Exim. A local part should be specified with any prefix or
-suffix stripped, because that is how it appears to the filter when a message is
-actually being delivered.
-
-*-bfp*~<'prefix'>::
-oindex:[%-bfp%]
-This sets the prefix of the local part of the recipient address when a filter
-file is being tested by means of the %-bf% option. The default is an empty
-prefix.
-
-*-bfs*~<'suffix'>::
-oindex:[%-bfs%]
-This sets the suffix of the local part of the recipient address when a filter
-file is being tested by means of the %-bf% option. The default is an empty
-suffix.
-
-*-bh*~<'IP~address'>::
-oindex:[%-bh%]
-cindex:[testing,incoming SMTP]
-cindex:[SMTP,testing incoming]
-cindex:[testing,relay control]
-cindex:[relaying,testing configuration]
-cindex:[policy control,testing]
-cindex:[debugging,%-bh% option]
-This option runs a fake SMTP session as if from the given IP address, using the
-standard input and output. The IP address may include a port number at the end,
-after a full stop. For example:
-
- exim -bh 10.9.8.7.1234
- exim -bh fe80::a00:20ff:fe86:a061.5678
-+
-When an IPv6 address is given, it is converted into canonical form. In the case
-of the second example above, the value of $sender_host_address$ after
-conversion to the canonical form is `fe80:0000:0000:0a00:20ff:fe86:a061.5678`.
-+
-Comments as to what is going on are written to the standard error file. These
-include lines beginning with ``LOG'' for anything that would have been logged.
-This facility is provided for testing configuration options for incoming
-messages, to make sure they implement the required policy. For example, you can
-test your relay controls using %-bh%.
-+
-*Warning 1*:
-cindex:[RFC 1413]
-You cannot test features of the configuration that rely on
-ident (RFC 1413) callouts. These cannot be done when testing using
-%-bh% because there is no incoming SMTP connection.
-+
-*Warning 2*: Address verification callouts (see section <<SECTcallver>>) are
-also skipped when testing using %-bh%. If you want these callouts to occur,
-use %-bhc% instead.
-+
-Messages supplied during the testing session are discarded, and nothing is
-written to any of the real log files. There may be pauses when DNS (and other)
-lookups are taking place, and of course these may time out. The %-oMi% option
-can be used to specify a specific IP interface and port if this is important.
-+
-The 'exim_checkaccess' utility is a ``packaged'' version of %-bh% whose
-output just states whether a given recipient address from a given host is
-acceptable or not. See section <<SECTcheckaccess>>.
-
-*-bhc*~<'IP~address'>::
-oindex:[%-bhc%]
-This option operates in the same way as %-bh%, except that address
-verification callouts are performed if required. This includes consulting and
-updating the callout cache database.
-
-*-bi*::
-oindex:[%-bi%]
-cindex:[alias file,building]
-cindex:[building alias file]
-cindex:[Sendmail compatibility,%-bi% option]
-Sendmail interprets the %-bi% option as a request to rebuild its alias file.
-Exim does not have the concept of a single alias file, and so it cannot mimic
-this behaviour. However, calls to _/usr/lib/sendmail_ with the %-bi% option
-tend to appear in various scripts such as NIS make files, so the option must be
-recognized.
-+
-If %-bi% is encountered, the command specified by the %bi_command%
-configuration option is run, under the uid and gid of the caller of Exim. If
-the %-oA% option is used, its value is passed to the command as an argument.
-The command set by %bi_command% may not contain arguments. The command can use
-the 'exim_dbmbuild' utility, or some other means, to rebuild alias files if
-this is required. If the %bi_command% option is not set, calling Exim with
-%-bi% is a no-op.
-
-*-bm*::
-oindex:[%-bm%]
-cindex:[local message reception]
-This option runs an Exim receiving process that accepts an incoming,
-locally-generated message on the current input. The recipients are given as the
-command arguments (except when %-t% is also present -- see below). Each
-argument can be a comma-separated list of RFC 2822 addresses. This is the
-default option for selecting the overall action of an Exim call; it is assumed
-if no other conflicting option is present.
-+
-If any addresses in the message are unqualified (have no domain), they are
-qualified by the values of the %qualify_domain% or %qualify_recipient%
-options, as appropriate. The %-bnq% option (see below) provides a way of
-suppressing this for special cases.
-+
-Policy checks on the contents of local messages can be enforced by means of
-the non-SMTP ACL. See chapter <<CHAPACL>> for details.
-+
-The return code
-cindex:[return code,for %-bm%]
-is zero if the message is successfully accepted. Otherwise, the
-action is controlled by the %-oe'x'% option setting -- see below.
-+
-The format
-cindex:[message,format]
-cindex:[format,message]
-cindex:[``From'' line]
-cindex:[UUCP,``From'' line]
-cindex:[Sendmail compatibility,``From'' line]
-of the message must be as defined in RFC 2822, except that, for
-compatibility with Sendmail and Smail, a line in one of the forms
-
- From sender Fri Jan 5 12:55 GMT 1997
- From sender Fri, 5 Jan 97 12:55:01
-+
-(with the weekday optional, and possibly with additional text after the date)
-is permitted to appear at the start of the message. There appears to be no
-authoritative specification of the format of this line. Exim recognizes it by
-matching against the regular expression defined by the %uucp_from_pattern%
-option, which can be changed if necessary.
-+
-The
-cindex:[%-f% option,overriding ``From'' line]
-specified sender is treated as if it were given as the argument to the
-%-f% option, but if a %-f% option is also present, its argument is used in
-preference to the address taken from the message. The caller of Exim must be a
-trusted user for the sender of a message to be set in this way.
-
-*-bnq*::
-oindex:[%-bnq%]
-cindex:[address qualification, suppressing]
-By default, Exim automatically qualifies unqualified addresses (those
-without domains) that appear in messages that are submitted locally (that
-is, not over TCP/IP). This qualification applies both to addresses in
-envelopes, and addresses in header lines. Sender addresses are qualified using
-%qualify_domain%, and recipient addresses using %qualify_recipient% (which
-defaults to the value of %qualify_domain%).
-+
-Sometimes, qualification is not wanted. For example, if %-bS% (batch SMTP) is
-being used to re-submit messages that originally came from remote hosts after
-content scanning, you probably do not want to qualify unqualified addresses in
-header lines. (Such lines will be present only if you have not enabled a header
-syntax check in the appropriate ACL.)
-+
-The %-bnq% option suppresses all qualification of unqualified addresses in
-messages that originate on the local host. When this is used, unqualified
-addresses in the envelope provoke errors (causing message rejection) and
-unqualified addresses in header lines are left alone.
-
-
-*-bP*::
-oindex:[%-bP%]
-cindex:[configuration options, extracting]
-cindex:[options,configuration -- extracting]
-If this option is given with no arguments, it causes the values of all Exim's
-main configuration options to be written to the standard output. The values
-of one or more specific options can be requested by giving their names as
-arguments, for example:
-
- exim -bP qualify_domain hold_domains
-+
-However, any option setting that is preceded by the word ``hide'' in the
-configuration file is not shown in full, except to an admin user. For other
-users, the output is as in this example:
-
- mysql_servers = <value not displayable>
-+
-If %configure_file% is given as an argument, the name of the run time
-configuration file is output.
-If a list of configuration files was supplied, the value that is output here
-is the name of the file that was actually used.
-+
-cindex:[daemon,process id (pid)]
-cindex:[pid (process id),of daemon]
-If %log_file_path% or %pid_file_path% are given, the names of the directories
-where log files and daemon pid files are written are output, respectively. If
-these values are unset, log files are written in a sub-directory of the spool
-directory called %log%, and the pid file is written directly into the spool
-directory.
-+
-If %-bP% is followed by a name preceded by `+`, for example,
-
- exim -bP +local_domains
-+
-it searches for a matching named list of any type (domain, host, address, or
-local part) and outputs what it finds.
-+
-If
-cindex:[options,router -- extracting]
-cindex:[options,transport -- extracting]
-one of the words %router%, %transport%, or %authenticator% is given,
-followed by the name of an appropriate driver instance, the option settings for
-that driver are output. For example:
-
- exim -bP transport local_delivery
-+
-The generic driver options are output first, followed by the driver's private
-options. A list of the names of drivers of a particular type can be obtained by
-using one of the words %router_list%, %transport_list%, or
-%authenticator_list%, and a complete list of all drivers with their option
-settings can be obtained by using %routers%, %transports%, or %authenticators%.
-
-
-*-bp*::
-oindex:[%-bp%]
-cindex:[queue,listing messages on]
-cindex:[listing,messages on the queue]
-This option requests a listing of the contents of the mail queue on the
-standard output. If the %-bp% option is followed by a list of message ids,
-just those messages are listed. By default, this option can be used only by an
-admin user. However, the %queue_list_requires_admin% option can be set false
-to allow any user to see the queue.
-+
-Each message on the queue is displayed as in the following example:
-
- 25m 2.9K 0t5C6f-0000c8-00 <alice@wonderland.fict.example>
- red.king@looking-glass.fict.example
- <other addresses>
-+
-The
-cindex:[message,size in queue listing]
-cindex:[size,of message]
-first line contains the length of time the message has been on the queue
-(in this case 25 minutes), the size of the message (2.9K), the unique local
-identifier for the message, and the message sender, as contained in the
-envelope. For bounce messages, the sender address is empty, and appears as
-``<>''. If the message was submitted locally by an untrusted user who overrode
-the default sender address, the user's login name is shown in parentheses
-before the sender address.
-+
-If
-cindex:[frozen messages,in queue listing]
-the message is frozen (attempts to deliver it are suspended) then the text
-``\*\*\* frozen \*\*\*'' is displayed at the end of this line.
-+
-The recipients of the message (taken from the envelope, not the headers) are
-displayed on subsequent lines. Those addresses to which the message has already
-been delivered are marked with the letter D. If an original address gets
-expanded into several addresses via an alias or forward file, the original is
-displayed with a D only when deliveries for all of its child addresses are
-complete.
-
-
-*-bpa*::
-oindex:[%-bpa%]
-This option operates like %-bp%, but in addition it shows delivered addresses
-that were generated from the original top level address(es) in each message by
-alias or forwarding operations. These addresses are flagged with ``+D'' instead
-of just ``D''.
-
-
-*-bpc*::
-oindex:[%-bpc%]
-cindex:[queue,count of messages on]
-This option counts the number of messages on the queue, and writes the total
-to the standard output. It is restricted to admin users, unless
-%queue_list_requires_admin% is set false.
-
-
-*-bpr*::
-oindex:[%-bpr%]
-This option operates like %-bp%, but the output is not sorted into
-chronological order of message arrival. This can speed it up when there are
-lots of messages on the queue, and is particularly useful if the output is
-going to be post-processed in a way that doesn't need the sorting.
-
-*-bpra*::
-oindex:[%-bpra%]
-This option is a combination of %-bpr% and %-bpa%.
-
-*-bpru*::
-oindex:[%-bpru%]
-This option is a combination of %-bpr% and %-bpu%.
-
-
-*-bpu*::
-oindex:[%-bpu%]
-This option operates like %-bp% but shows only undelivered top-level addresses
-for each message displayed. Addresses generated by aliasing or forwarding are
-not shown, unless the message was deferred after processing by a router with
-the %one_time% option set.
-
-
-*-brt*::
-oindex:[%-brt%]
-cindex:[testing,retry configuration]
-cindex:[retry,configuration testing]
-This option is for testing retry rules, and it must be followed by up to three
-arguments. It causes Exim to look for a retry rule that matches the values
-and to write it to the standard output. For example:
-
- exim -brt bach.comp.mus.example
- Retry rule: *.comp.mus.example F,2h,15m; F,4d,30m;
-+
-See chapter <<CHAPretry>> for a description of Exim's retry rules. The first
-argument, which is required, can be a complete address in the form
-'local_part@domain', or it can be just a domain name. The second argument is
-an optional second domain name; if no retry rule is found for the first
-argument, the second is tried. This ties in with Exim's behaviour when looking
-for retry rules for remote hosts -- if no rule is found that matches the host,
-one that matches the mail domain is sought. The final argument is the name of a
-specific delivery error, as used in setting up retry rules, for example
-``quota_3d''.
-
-*-brw*::
-oindex:[%-brw%]
-cindex:[testing,rewriting]
-cindex:[rewriting,testing]
-This option is for testing address rewriting rules, and it must be followed by
-a single argument, consisting of either a local part without a domain, or a
-complete address with a fully qualified domain. Exim outputs how this address
-would be rewritten for each possible place it might appear. See chapter
-<<CHAPrewrite>> for further details.
-
-*-bS*::
-oindex:[%-bS%]
-cindex:[SMTP,batched incoming]
-cindex:[batched SMTP input]
-This option is used for batched SMTP input, which is an alternative interface
-for non-interactive local message submission. A number of messages can be
-submitted in a single run. However, despite its name, this is not really SMTP
-input. Exim reads each message's envelope from SMTP commands on the standard
-input, but generates no responses. If the caller is trusted, or
-%untrusted_set_sender% is set, the senders in the SMTP MAIL commands are
-believed; otherwise the sender is always the caller of Exim.
-+
-The message itself is read from the standard input, in SMTP format (leading
-dots doubled), terminated by a line containing just a single dot. An error is
-provoked if the terminating dot is missing. A further message may then follow.
-+
-As for other local message submissions, the contents of incoming batch SMTP
-messages can be checked using the non-SMTP ACL (see chapter <<CHAPACL>>).
-Unqualified addresses are automatically qualified using %qualify_domain% and
-%qualify_recipient%, as appropriate, unless the %-bnq% option is used.
-+
-Some other SMTP commands are recognized in the input. HELO and EHLO act
-as RSET; VRFY, EXPN, ETRN, and HELP act as NOOP;
-QUIT quits, ignoring the rest of the standard input.
-+
-cindex:[return code,for %-bS%]
-If any error is encountered, reports are written to the standard output and
-error streams, and Exim gives up immediately. The return code is 0 if no error
-was detected; it is 1 if one or more messages were accepted before the error
-was detected; otherwise it is 2.
-+
-More details of input using batched SMTP are given in section
-<<SECTincomingbatchedSMTP>>.
-
-*-bs*::
-oindex:[%-bs%]
-cindex:[SMTP,local input]
-cindex:[local SMTP input]
-This option causes Exim to accept one or more messages by reading SMTP commands
-on the standard input, and producing SMTP replies on the standard output. SMTP
-policy controls, as defined in ACLs (see chapter <<CHAPACL>>) are applied.
-Some user agents use this interface as a way of passing locally-generated
-messages to the MTA.
-+
-In
-cindex:[sender,source of]
-this usage, if the caller of Exim is trusted, or %untrusted_set_sender% is
-set, the senders of messages are taken from the SMTP MAIL commands.
-Otherwise the content of these commands is ignored and the sender is set up as
-the calling user. Unqualified addresses are automatically qualified using
-%qualify_domain% and %qualify_recipient%, as appropriate, unless the %-bnq%
-option is used.
-+
-cindex:[inetd]
-The
-%-bs% option is also used to run Exim from 'inetd', as an alternative to using
-a listening daemon. Exim can distinguish the two cases by checking whether the
-standard input is a TCP/IP socket. When Exim is called from 'inetd', the source
-of the mail is assumed to be remote, and the comments above concerning senders
-and qualification do not apply. In this situation, Exim behaves in exactly the
-same way as it does when receiving a message via the listening daemon.
-
-*-bt*::
-oindex:[%-bt%]
-cindex:[testing,addresses]
-cindex:[address,testing]
-This option runs Exim in address testing mode, in which each argument is taken
-as an address to be tested for deliverability. The results are written to the
-standard output. If a test fails, and the caller is not an admin user, no
-details of the failure are output, because these might contain sensitive
-information such as usernames and passwords for database lookups.
-+
-If no arguments are given, Exim runs in an interactive manner, prompting with a
-right angle bracket for addresses to be tested.
-+
-Unlike the %-be% test option, you cannot arrange for Exim to use the
-'readline()' function, because it is running as 'root' and there are
-security issues.
-+
-Each address is handled as if it were the recipient address of a message
-(compare the %-bv% option). It is passed to the routers and the result is
-written to the standard output. However, any router that has
-%no_address_test% set is bypassed. This can make %-bt% easier to use for
-genuine routing tests if your first router passes everything to a scanner
-program.
-+
-The
-cindex:[return code,for %-bt%]
-return code is 2 if any address failed outright; it is 1 if no address
-failed outright but at least one could not be resolved for some reason. Return
-code 0 is given only when all addresses succeed.
-+
-*Warning*: %-bt% can only do relatively simple testing. If any of the
-routers in the configuration makes any tests on the sender address of a
-message,
-cindex:[%-f% option,for address testing]
-you can use the %-f% option to set an appropriate sender when running
-%-bt% tests. Without it, the sender is assumed to be the calling user at the
-default qualifying domain. However, if you have set up (for example) routers
-whose behaviour depends on the contents of an incoming message, you cannot test
-those conditions using %-bt%. The %-N% option provides a possible way of
-doing such tests.
-
-*-bV*::
-oindex:[%-bV%]
-cindex:[version number of Exim, verifying]
-This option causes Exim to write the current version number, compilation
-number, and compilation date of the 'exim' binary to the standard output.
-It also lists the DBM library this is being used, the optional modules (such as
-specific lookup types), the drivers that are included in the binary, and the
-name of the run time configuration file that is in use.
-+
-As part of its operation, %-bV% causes Exim to read and syntax check its
-configuration file. However, this is a static check only. It cannot check
-values that are to be expanded. For example, although a misspelt ACL verb is
-detected, an error in the verb's arguments is not. You cannot rely on %-bV%
-alone to discover (for example) all the typos in the configuration; some
-realistic testing is needed. The %-bh% and %-N% options provide more dynamic
-testing facilities.
-
-*-bv*::
-oindex:[%-bv%]
-cindex:[verifying address, using %-bv%]
-cindex:[address,verification]
-This option runs Exim in address verification mode, in which each argument is
-taken as an address to be verified. During normal operation, verification
-happens mostly as a consequence processing a %verify% condition in an ACL (see
-chapter <<CHAPACL>>). If you want to test an entire ACL, see the %-bh% option.
-+
-If verification fails, and the caller is not an admin user, no details of the
-failure are output, because these might contain sensitive information such as
-usernames and passwords for database lookups.
-+
-If no arguments are given, Exim runs in an interactive manner, prompting with a
-right angle bracket for addresses to be verified.
-+
-Unlike the %-be% test option, you cannot arrange for Exim to use the
-'readline()' function, because it is running as 'exim' and there are
-security issues.
-+
-Verification differs from address testing (the %-bt% option) in that routers
-that have %no_verify% set are skipped, and if the address is accepted by a
-router that has %fail_verify% set, verification fails. The address is verified
-as a recipient if %-bv% is used; to test verification for a sender address,
-%-bvs% should be used.
-+
-If the %-v% option is not set, the output consists of a single line for each
-address, stating whether it was verified or not, and giving a reason in the
-latter case. Otherwise, more details are given of how the address has been
-handled, and in the case of address redirection, all the generated addresses
-are also considered. Without %-v%, generating more than one address by
-redirection causes verification to end sucessfully.
-+
-The
-cindex:[return code,for %-bv%]
-return code is 2 if any address failed outright; it is 1 if no address
-failed outright but at least one could not be resolved for some reason. Return
-code 0 is given only when all addresses succeed.
-+
-If any of the routers in the configuration makes any tests on the sender
-address of a message, you should use the %-f% option to set an appropriate
-sender when running %-bv% tests. Without it, the sender is assumed to be the
-calling user at the default qualifying domain.
-
-*-bvs*::
-oindex:[%-bvs%]
-This option acts like %-bv%, but verifies the address as a sender rather
-than a recipient address. This affects any rewriting and qualification that
-might happen.
-
-*-C*~<'filelist'>::
-oindex:[%-C%]
-cindex:[configuration file,alternate]
-cindex:[CONFIGURE_FILE]
-cindex:[alternate configuration file]
-This option causes Exim to find the run time configuration file from the given
-list instead of from the list specified by the CONFIGURE_FILE
-compile-time setting. Usually, the list will consist of just a single file
-name, but it can be a colon-separated list of names. In this case, the first
-file that exists is used. Failure to open an existing file stops Exim from
-proceeding any further along the list, and an error is generated.
-+
-When this option is used by a caller other than root or the Exim user, and the
-list is different from the compiled-in list, Exim gives up its root privilege
-immediately, and runs with the real and effective uid and gid set to those of
-the caller. However, if ALT_CONFIG_ROOT_ONLY is defined in
-_Local/Makefile_, root privilege is retained for %-C% only if the caller of
-Exim is root.
-+
-That is, the Exim user is no longer privileged in this regard. This build-time
-option is not set by default in the Exim source distribution tarbundle.
-However, if you are using a ``packaged'' version of Exim (source or binary), the
-packagers might have enabled it.
-+
-Setting ALT_CONFIG_ROOT_ONLY locks out the possibility of testing a
-configuration using %-C% right through message reception and delivery, even if
-the caller is root. The reception works, but by that time, Exim is running as
-the Exim user, so when it re-execs to regain privilege for the delivery, the
-use of %-C% causes privilege to be lost. However, root can test reception and
-delivery using two separate commands (one to put a message on the queue, using
-%-odq%, and another to do the delivery, using %-M%).
-+
-If ALT_CONFIG_PREFIX is defined _in Local/Makefile_, it specifies a
-prefix string with which any file named in a %-C% command line option
-must start. In addition, the file name must not contain the sequence `/../`.
-However, if the value of the %-C% option is identical to the value of
-CONFIGURE_FILE in _Local/Makefile_, Exim ignores %-C% and proceeds as
-usual. There is no default setting for ALT_CONFIG_PREFIX; when it is
-unset, any file name can be used with %-C%.
-+
-ALT_CONFIG_PREFIX can be used to confine alternative configuration files
-to a directory to which only root has access. This prevents someone who has
-broken into the Exim account from running a privileged Exim with an arbitrary
-configuration file.
-+
-The %-C% facility is useful for ensuring that configuration files are
-syntactically correct, but cannot be used for test deliveries, unless the
-caller is privileged, or unless it is an exotic configuration that does not
-require privilege. No check is made on the owner or group of the files
-specified by this option.
-
-*-D*<'macro'>=<'value'>::
-oindex:[%-D%]
-cindex:[macro,setting on command line]
-This option can be used to override macro definitions in the configuration file
-(see section <<SECTmacrodefs>>). However, like %-C%, if it is used by an
-unprivileged caller, it causes Exim to give up its root privilege.
-If DISABLE_D_OPTION is defined in _Local/Makefile_, the use of %-D% is
-completely disabled, and its use causes an immediate error exit.
-+
-The entire option (including equals sign if present) must all be within one
-command line item. %-D% can be used to set the value of a macro to the empty
-string, in which case the equals sign is optional. These two commands are
-synonymous:
-
- exim -DABC ...
- exim -DABC= ...
-+
-To include spaces in a macro definition item, quotes must be used. If you use
-quotes, spaces are permitted around the macro name and the equals sign. For
-example:
-
- exim '-D ABC = something' ...
-+
-%-D% may be repeated up to 10 times on a command line.
-
-*-d*<'debug~options'>::
-oindex:[%-d%]
-cindex:[debugging,list of selectors]
-cindex:[debugging,%-d% option]
-This option causes debugging information to be written to the standard
-error stream. It is restricted to admin users because debugging output may show
-database queries that contain password information. Also, the details of users'
-filter files should be protected. When %-d% is used, %-v% is assumed. If %-d%
-is given on its own, a lot of standard debugging data is output. This can be
-reduced, or increased to include some more rarely needed information, by
-directly following %-d% with a string made up of names preceded by plus or
-minus characters. These add or remove sets of debugging data, respectively. For
-example, %-d+filter% adds filter debugging, whereas %-d-all+filter% selects
-only filter debugging. Note that no spaces are allowed in the debug setting.
-The available debugging categories are:
-+
-&&&
-`acl ` ACL interpretation
-`auth ` authenticators
-`deliver ` general delivery logic
-`dns ` DNS lookups (see also resolver)
-`dnsbl ` DNS black list (aka RBL) code
-`exec ` arguments for ^^execv()^^ calls
-`expand ` detailed debugging for string expansions
-`filter ` filter handling
-`hints_lookup ` hints data lookups
-`host_lookup ` all types of name-to-IP address handling
-`ident ` ident lookup
-`interface ` lists of local interfaces
-`lists ` matching things in lists
-`load ` system load checks
-`local_scan ` can be used by ^^local_scan()^^ (see chapter <<CHAPlocalscan>>)
-`lookup ` general lookup code and all lookups
-`memory ` memory handling
-`pid ` add pid to debug output lines
-`process_info ` setting info for the process log
-`queue_run ` queue runs
-`receive ` general message reception logic
-`resolver ` turn on the DNS resolver's debugging output
-`retry ` retry handling
-`rewrite ` address rewriting
-`route ` address routing
-`timestamp ` add timestamp to debug output lines
-`tls ` TLS logic
-`transport ` transports
-`uid ` changes of uid/gid and looking up uid/gid
-`verify ` address verification logic
-`all ` almost all of the above (see below), and also %-v%
-&&&
-+
-[revisionflag="changed"]
-The `all` option excludes `memory` when used as `+all`, but includes it for
-`-all`. The reason for this is that `+all` is something that people tend to use
-when generating debug output for Exim maintainers. If `+memory` is included, an
-awful lot of output that is very rarely of interest is generated, so it now has
-to be explicitly requested. However, `-all` does turn everything off.
-+
-The
-cindex:[resolver, debugging output]
-cindex:[DNS resolver, debugging output]
-`resolver` option produces output only if the DNS resolver was compiled
-with DEBUG enabled. This is not the case in some operating systems. Also,
-unfortunately, debugging output from the DNS resolver is written to stdout
-rather than stderr.
-+
-The default (%-d% with no argument) omits `expand`, `filter`,
-`interface`, `load`, `memory`, `pid`, `resolver`, and `timestamp`.
-However, the `pid` selector is forced when debugging is turned on for a
-daemon, which then passes it on to any re-executed Exims. Exim also
-automatically adds the pid to debug lines when several remote deliveries are
-run in parallel.
-+
-The `timestamp` selector causes the current time to be inserted at the start
-of all debug output lines. This can be useful when trying to track down delays
-in processing.
-+
-If the %debug_print% option is set in any driver, it produces output whenever
-any debugging is selected, or if %-v% is used.
-
-*-dd*<'debug~options'>::
-oindex:[%-dd%]
-This option behaves exactly like %-d% except when used on a command that
-starts a daemon process. In that case, debugging is turned off for the
-subprocesses that the daemon creates. Thus, it is useful for monitoring the
-behaviour of the daemon without creating as much output as full debugging does.
-
-*-dropcr*::
-oindex:[%-dropcr%]
-This is an obsolete option that is now a no-op. It used to affect the way Exim
-handled CR and LF characters in incoming messages. What happens now is
-described in section <<SECTlineendings>>.
-
-*-E*::
-oindex:[%-E%]
-cindex:[bounce message,generating]
-This option specifies that an incoming message is a locally-generated delivery
-failure report. It is used internally by Exim when handling delivery failures
-and is not intended for external use. Its only effect is to stop Exim
-generating certain messages to the postmaster, as otherwise message cascades
-could occur in some situations. As part of the same option, a message id may
-follow the characters %-E%. If it does, the log entry for the receipt of the
-new message contains the id, following ``R='', as a cross-reference.
-
-*-e*'x'::
-oindex:[%-e'x'%]
-There are a number of Sendmail options starting with %-oe% which seem to be
-called by various programs without the leading %o% in the option. For example,
-the %vacation% program uses %-eq%. Exim treats all options of the form
-%-e'x'% as synonymous with the corresponding %-oe'x'% options.
-
-*-F*~<'string'>::
-oindex:[%-F%]
-cindex:[sender,name]
-cindex:[name,of sender]
-This option sets the sender's full name for use when a locally-generated
-message is being accepted. In the absence of this option, the user's 'gecos'
-entry from the password data is used. As users are generally permitted to alter
-their 'gecos' entries, no security considerations are involved. White space
-between %-F% and the <'string'> is optional.
-
-*-f*~<'address'>::
-oindex:[%-f%]
-cindex:[sender,address]
-cindex:[address,sender]
-cindex:[trusted user]
-cindex:[envelope sender]
-cindex:[user,trusted]
-This option sets the address of the envelope sender of a locally-generated
-message (also known as the return path). The option can normally be used only
-by a trusted user, but %untrusted_set_sender% can be set to allow untrusted
-users to use it.
-+
-Processes running as root or the Exim user are always trusted. Other
-trusted users are defined by the %trusted_users% or %trusted_groups% options.
-In the absence of %-f%, or if the caller is not trusted, the sender of a local
-message is set to the caller's login name at the default qualify domain.
-+
-There is one exception to the restriction on the use of %-f%: an empty sender
-can be specified by any user, trusted or not, to create a message that can
-never provoke a bounce. An empty sender can be specified either as an empty
-string, or as a pair of angle brackets with nothing between them, as in these
-examples of shell commands:
-
- exim -f '<>' user@domain
- exim -f "" user@domain
-+
-In addition, the use of %-f% is not restricted when testing a filter file with
-%-bf% or when testing or verifying addresses using the %-bt% or %-bv%
-options.
-+
-Allowing untrusted users to change the sender address does not of itself make
-it possible to send anonymous mail. Exim still checks that the 'From:' header
-refers to the local user, and if it does not, it adds a 'Sender:' header,
-though this can be overridden by setting %no_local_from_check%.
-+
-White
-cindex:[``From'' line]
-space between %-f% and the <'address'> is optional (that is, they can be given
-as two arguments or one combined argument). The sender of a locally-generated
-message can also be set (when permitted) by an initial ``From '' line in the
-message -- see the description of %-bm% above -- but if %-f% is also present,
-it overrides ``From''.
-
-*-G*::
-oindex:[%-G%]
-cindex:[Sendmail compatibility,%-G% option ignored]
-This is a Sendmail option which is ignored by Exim.
-
-*-h*~<'number'>::
-oindex:[%-h%]
-cindex:[Sendmail compatibility,%-h% option ignored]
-This option is accepted for compatibility with Sendmail, but has no effect. (In
-Sendmail it overrides the ``hop count'' obtained by counting 'Received:'
-headers.)
-
-*-i*::
-oindex:[%-i%]
-cindex:[Solaris,'mail' command]
-cindex:[dot in incoming, non-SMTP message]
-This option, which has the same effect as %-oi%, specifies that a dot on a line
-by itself should not terminate an incoming, non-SMTP message. I can find no
-documentation for this option in Solaris 2.4 Sendmail, but the 'mailx' command
-in Solaris 2.4 uses it. See also %-ti%.
-
-*-M*~<'message~id'>~<'message~id'>~...::
-oindex:[%-M%]
-cindex:[forcing delivery]
-cindex:[delivery,forcing attempt]
-cindex:[frozen messages,forcing delivery]
-This option requests Exim to run a delivery attempt on each message in turn. If
-any of the messages are frozen, they are automatically thawed before the
-delivery attempt. The settings of %queue_domains%, %queue_smtp_domains%, and
-%hold_domains% are ignored.
-+
-Retry
-cindex:[hints database,overriding retry hints]
-hints for any of the addresses are overridden -- Exim tries to deliver even if
-the normal retry time has not yet been reached. This option requires the caller
-to be an admin user. However, there is an option called %prod_requires_admin%
-which can be set false to relax this restriction (and also the same requirement
-for the %-q%, %-R%, and %-S% options).
-+
-[revisionflag="changed"]
-The deliveries happen synchronously, that is, the original Exim process does
-not terminate until all the delivery attempts have finished. No output is
-produced unless there is a serious error. If you want to see what is happening,
-use the %-v% option as well, or inspect Exim's main log.
-
-*-Mar*~<'message~id'>~<'address'>~<'address'>~...::
-oindex:[%-Mar%]
-cindex:[message,adding recipients]
-cindex:[recipient,adding]
-This option requests Exim to add the addresses to the list of recipients of the
-message (``ar'' for ``add recipients''). The first argument must be a message id,
-and the remaining ones must be email addresses. However, if the message is
-active (in the middle of a delivery attempt), it is not altered. This option
-can be used only by an admin user.
-
-*-MC*~<'transport'>~<'hostname'>~<'sequence~number'>~<'message~id'>::
-oindex:[%-MC%]
-cindex:[SMTP,passed connection]
-cindex:[SMTP,multiple deliveries]
-cindex:[multiple SMTP deliveries]
-This option is not intended for use by external callers. It is used internally
-by Exim to invoke another instance of itself to deliver a waiting message using
-an existing SMTP connection, which is passed as the standard input. Details are
-given in chapter <<CHAPSMTP>>. This must be the final option, and the caller must
-be root or the Exim user in order to use it.
-
-*-MCA*::
-oindex:[%-MCA%]
-This option is not intended for use by external callers. It is used internally
-by Exim in conjunction with the %-MC% option. It signifies that the connection
-to the remote host has been authenticated.
-
-*-MCP*::
-oindex:[%-MCP%]
-This option is not intended for use by external callers. It is used internally
-by Exim in conjunction with the %-MC% option. It signifies that the server to
-which Exim is connected supports pipelining.
-
-*-MCQ*~<'process~id'>~<'pipe~fd'>::
-oindex:[%-MCQ%]
-This option is not intended for use by external callers. It is used internally
-by Exim in conjunction with the %-MC% option when the original delivery was
-started by a queue runner. It passes on the process id of the queue runner,
-together with the file descriptor number of an open pipe. Closure of the pipe
-signals the final completion of the sequence of processes that are passing
-messages through the same SMTP connection.
-
-*-MCS*::
-oindex:[%-MCS%]
-This option is not intended for use by external callers. It is used internally
-by Exim in conjunction with the %-MC% option, and passes on the fact that the
-SMTP SIZE option should be used on messages delivered down the existing
-connection.
-
-*-MCT*::
-oindex:[%-MCT%]
-This option is not intended for use by external callers. It is used internally
-by Exim in conjunction with the %-MC% option, and passes on the fact that the
-host to which Exim is connected supports TLS encryption.
-
-*-Mc*~<'message~id'>~<'message~id'>~...::
-oindex:[%-Mc%]
-cindex:[hints database,not overridden by %-Mc%]
-cindex:[delivery,manually started -- not forced]
-This option requests Exim to run a delivery attempt on each message in turn,
-but unlike the %-M% option, it does check for retry hints, and respects any
-that are found. This option is not very useful to external callers. It is
-provided mainly for internal use by Exim when it needs to re-invoke itself in
-order to regain root privilege for a delivery (see chapter <<CHAPsecurity>>).
-However, %-Mc% can be useful when testing, in order to run a delivery that
-respects retry times and other options such as %hold_domains% that are
-overridden when %-M% is used. Such a delivery does not count as a queue run.
-If you want to run a specific delivery as if in a queue run, you should use
-%-q% with a message id argument. A distinction between queue run deliveries
-and other deliveries is made in one or two places.
-
-*-Mes*~<'message~id'>~<'address'>::
-oindex:[%-Mes%]
-cindex:[message,changing sender]
-cindex:[sender,changing]
-This option requests Exim to change the sender address in the message to the
-given address, which must be a fully qualified address or ``<>'' (``es'' for ``edit
-sender''). There must be exactly two arguments. The first argument must be a
-message id, and the second one an email address. However, if the message is
-active (in the middle of a delivery attempt), its status is not altered. This
-option can be used only by an admin user.
-
-*-Mf*~<'message~id'>~<'message~id'>~...::
-oindex:[%-Mf%]
-cindex:[freezing messages]
-cindex:[message,manually freezing]
-This option requests Exim to mark each listed message as ``frozen''. This
-prevents any delivery attempts taking place until the message is ``thawed'',
-either manually or as a result of the %auto_thaw% configuration option.
-However, if any of the messages are active (in the middle of a delivery
-attempt), their status is not altered. This option can be used only by an admin
-user.
-
-*-Mg*~<'message~id'>~<'message~id'>~...::
-oindex:[%-Mg%]
-cindex:[giving up on messages]
-cindex:[message,abandoning delivery attempts]
-cindex:[delivery,abandoning further attempts]
-This option requests Exim to give up trying to deliver the listed messages,
-including any that are frozen. However, if any of the messages are active,
-their status is not altered. For non-bounce messages, a delivery error message
-is sent to the sender, containing the text ``cancelled by administrator''.
-Bounce messages are just discarded. This option can be used only by an admin
-user.
-
-*-Mmad*~<'message~id'>~<'message~id'>~...::
-oindex:[%-Mmad%]
-cindex:[delivery,cancelling all]
-This option requests Exim to mark all the recipient addresses in the messages
-as already delivered (``mad'' for ``mark all delivered''). However, if any
-message is active (in the middle of a delivery attempt), its status is not
-altered. This option can be used only by an admin user.
-
-*-Mmd*~<'message~id'>~<'address'>~<'address'>~...::
-oindex:[%-Mmd%]
-cindex:[delivery,cancelling by address]
-cindex:[recipient,removing]
-cindex:[removing recipients]
-This option requests Exim to mark the given addresses as already delivered
-(``md'' for ``mark delivered''). The first argument must be a message id, and
-the remaining ones must be email addresses. These are matched to recipient
-addresses in the message in a case-sensitive manner. If the message is active
-(in the middle of a delivery attempt), its status is not altered. This option
-can be used only by an admin user.
-
-*-Mrm*~<'message~id'>~<'message~id'>~...::
-oindex:[%-Mrm%]
-cindex:[removing messages]
-cindex:[abandoning mail]
-cindex:[message,manually discarding]
-This option requests Exim to remove the given messages from the queue. No
-bounce messages are sent; each message is simply forgotten. However, if any of
-the messages are active, their status is not altered. This option can be used
-only by an admin user or by the user who originally caused the message to be
-placed on the queue.
-
-*-Mt*~<'message~id'>~<'message~id'>~...::
-oindex:[%-Mt%]
-cindex:[thawing messages]
-cindex:[unfreezing messages]
-cindex:[frozen messages,thawing]
-cindex:[message,thawing frozen]
-This option requests Exim to ``thaw'' any of the listed messages that are
-``frozen'', so that delivery attempts can resume. However, if any of the messages
-are active, their status is not altered. This option can be used only by an
-admin user.
-
-*-Mvb*~<'message~id'>::
-oindex:[%-Mvb%]
-cindex:[listing,message body]
-cindex:[message,listing body of]
-This option causes the contents of the message body (-D) spool file to be
-written to the standard output. This option can be used only by an admin user.
-
-*-Mvh*~<'message~id'>::
-oindex:[%-Mvh%]
-cindex:[listing,message headers]
-cindex:[header lines,listing]
-cindex:[message,listing header lines]
-This option causes the contents of the message headers (-H) spool file to be
-written to the standard output. This option can be used only by an admin user.
-
-*-Mvl*~<'message~id'>::
-oindex:[%-Mvl%]
-cindex:[listing,message log]
-cindex:[message,listing message log]
-This option causes the contents of the message log spool file to be written to
-the standard output. This option can be used only by an admin user.
-
-*-m*::
-oindex:[%-m%]
-This is apparently a synonym for %-om% that is accepted by Sendmail, so Exim
-treats it that way too.
-
-*-N*::
-oindex:[%-N%]
-cindex:[debugging,%-N% option]
-cindex:[debugging,suppressing delivery]
-This is a debugging option that inhibits delivery of a message at the transport
-level. It implies %-v%. Exim goes through many of the motions of delivery --
-it just doesn't actually transport the message, but instead behaves as if it
-had successfully done so. However, it does not make any updates to the retry
-database, and the log entries for deliveries are flagged with ``\*>'' rather
-than ``=>''.
-+
-Because %-N% discards any message to which it applies, only root or the Exim
-user are allowed to use it with %-bd%, %-q%, %-R% or %-M%. In other words,
-an ordinary user can use it only when supplying an incoming message to which it
-will apply. Although transportation never fails when %-N% is set, an address
-may be deferred because of a configuration problem on a transport, or a routing
-problem. Once %-N% has been used for a delivery attempt, it sticks to the
-message, and applies to any subsequent delivery attempts that may happen for
-that message.
-
-*-n*::
-oindex:[%-n%]
-cindex:[Sendmail compatibility,%-n% option ignored]
-This option is interpreted by Sendmail to mean ``no aliasing''. It is ignored by
-Exim.
-
-*-O*~<'data'>::
-oindex:[%-O%]
-This option is interpreted by Sendmail to mean `set option`. It is ignored by
-Exim.
-
-*-oA*~<'file~name'>::
-oindex:[%-oA%]
-cindex:[Sendmail compatibility,%-oA% option]
-This option is used by Sendmail in conjunction with %-bi% to specify an
-alternative alias file name. Exim handles %-bi% differently; see the
-description above.
-
-*-oB*~<'n'>::
-oindex:[%-oB%]
-cindex:[SMTP,passed connection]
-cindex:[SMTP,multiple deliveries]
-cindex:[multiple SMTP deliveries]
-This is a debugging option which limits the maximum number of messages that can
-be delivered down one SMTP connection, overriding the value set in any ^smtp^
-transport. If <'n'> is omitted, the limit is set to 1.
-
-*-odb*::
-oindex:[%-odb%]
-cindex:[background delivery]
-cindex:[delivery,in the background]
-This option applies to all modes in which Exim accepts incoming messages,
-including the listening daemon. It requests ``background'' delivery of such
-messages, which means that the accepting process automatically starts a
-delivery process for each message received, but does not wait for the delivery
-processes to finish.
-+
-When all the messages have been received, the reception process exits,
-leaving the delivery processes to finish in their own time. The standard output
-and error streams are closed at the start of each delivery process.
-This is the default action if none of the %-od% options are present.
-+
-If one of the queueing options in the configuration file
-(%queue_only% or %queue_only_file%, for example) is in effect, %-odb%
-overrides it if %queue_only_override% is set true, which is the default
-setting. If %queue_only_override% is set false, %-odb% has no effect.
-
-*-odf*::
-oindex:[%-odf%]
-cindex:[foreground delivery]
-cindex:[delivery,in the foreground]
-This option requests ``foreground'' (synchronous) delivery when Exim has accepted
-a locally-generated message. (For the daemon it is exactly the same as
-%-odb%.) A delivery process is automatically started to deliver the
-message, and Exim waits for it to complete before proceeding.
-+
-The original Exim reception process does not finish until the delivery
-process for the final message has ended. The standard error stream is left open
-during deliveries.
-+
-However, like %-odb%, this option has no effect if %queue_only_override% is
-false and one of the queueing options in the configuration file is in effect.
-+
-If there is a temporary delivery error during foreground delivery, the
-message is left on the queue for later delivery, and the original reception
-process exits. See chapter <<CHAPnonqueueing>> for a way of setting up a
-restricted configuration that never queues messages.
-
-
-*-odi*::
-oindex:[%-odi%]
-This option is synonymous with %-odf%. It is provided for compatibility with
-Sendmail.
-
-*-odq*::
-oindex:[%-odq%]
-cindex:[non-immediate delivery]
-cindex:[delivery,suppressing immediate]
-cindex:[queueing incoming messages]
-This option applies to all modes in which Exim accepts incoming messages,
-including the listening daemon. It specifies that the accepting process should
-not automatically start a delivery process for each message received. Messages
-are placed on the queue, and remain there until a subsequent queue runner
-process encounters them. There are several configuration options (such as
-%queue_only%) that can be used to queue incoming messages under certain
-conditions. This option overrides all of them and also %-odqs%. It always
-forces queueing.
-
-*-odqs*::
-oindex:[%-odqs%]
-cindex:[SMTP,delaying delivery]
-This option is a hybrid between %-odb%/%-odi% and %-odq%.
-However, like %-odb% and %-odi%, this option has no effect if
-%queue_only_override% is false and one of the queueing options in the
-configuration file is in effect.
-+
-When %-odqs% does operate, a delivery process is started for each incoming
-message, in the background by default, but in the foreground if %-odi% is also
-present. The recipient addresses are routed, and local deliveries are done in
-the normal way. However, if any SMTP deliveries are required, they are not done
-at this time, so the message remains on the queue until a subsequent queue
-runner process encounters it. Because routing was done, Exim knows which
-messages are waiting for which hosts, and so a number of messages for the same
-host can be sent in a single SMTP connection. The %queue_smtp_domains%
-configuration option has the same effect for specific domains. See also the
-%-qq% option.
-
-*-oee*::
-oindex:[%-oee%]
-cindex:[error,reporting]
-If an error is detected while a non-SMTP message is being received (for
-example, a malformed address), the error is reported to the sender in a mail
-message.
-+
-Provided
-cindex:[return code,for %-oee%]
-this error message is successfully sent, the Exim receiving process
-exits with a return code of zero. If not, the return code is 2 if the problem
-is that the original message has no recipients, or 1 any other error. This is
-the default %-oe'x'% option if Exim is called as 'rmail'.
-
-*-oem*::
-oindex:[%-oem%]
-cindex:[error,reporting]
-cindex:[return code,for %-oem%]
-This is the same as %-oee%, except that Exim always exits with a non-zero
-return code, whether or not the error message was successfully sent.
-This is the default %-oe'x'% option, unless Exim is called as 'rmail'.
-
-*-oep*::
-oindex:[%-oep%]
-cindex:[error,reporting]
-If an error is detected while a non-SMTP message is being received, the
-error is reported by writing a message to the standard error file (stderr).
-cindex:[return code,for %-oep%]
-The return code is 1 for all errors.
-
-*-oeq*::
-oindex:[%-oeq%]
-cindex:[error,reporting]
-This option is supported for compatibility with Sendmail, but has the same
-effect as %-oep%.
-
-*-oew*::
-oindex:[%-oew%]
-cindex:[error,reporting]
-This option is supported for compatibility with Sendmail, but has the same
-effect as %-oem%.
-
-*-oi*::
-oindex:[%-oi%]
-cindex:[dot in incoming, non-SMTP message]
-This option, which has the same effect as %-i%, specifies that a dot on a line
-by itself should not terminate an incoming, non-SMTP message.
-Otherwise, a single dot does terminate, though Exim does no special processing
-for other lines that start with a dot.
-This option is set by default if Exim is called as 'rmail'. See also %-ti%.
-
-*-oitrue*::
-oindex:[%-oitrue%]
-This option is treated as synonymous with %-oi%.
-
-*-oMa*~<'host~address'>::
-oindex:[%-oMa%]
-cindex:[sender host address, specifying for local message]
-A number of options starting with %-oM% can be used to set values associated
-with remote hosts on locally-submitted messages (that is, messages not received
-over TCP/IP). These options can be used by any caller in conjunction with the
-%-bh%, %-be%, %-bf%, %-bF%, %-bt%, or %-bv% testing options. In other
-circumstances, they are ignored unless the caller is trusted.
-+
-The %-oMa% option sets the sender host address. This may include a port number
-at the end, after a full stop (period). For example:
-
- exim -bs -oMa 10.9.8.7.1234
-+
-An alternative syntax is to enclose the IP address in square brackets,
-followed by a colon and the port number:
-
- exim -bs -oMa [10.9.8.7]:1234
-+
-The IP address is placed in the $sender_host_address$ variable, and the
-port, if present, in $sender_host_port$.
-
-*-oMaa*~<'name'>::
-oindex:[%-oMaa%]
-cindex:[authentication name, specifying for local message]
-See %-oMa% above for general remarks about the %-oM% options. The %-oMaa%
-option sets the value of $sender_host_authenticated$ (the authenticator
-name). See chapter <<CHAPSMTPAUTH>> for a discussion of SMTP authentication.
-
-*-oMai*~<'string'>::
-oindex:[%-oMai%]
-cindex:[authentication id, specifying for local message]
-See %-oMa% above for general remarks about the %-oM% options. The %-oMai%
-option sets the value of $authenticated_id$ (the id that was authenticated).
-This overrides the default value (the caller's login id) for messages from
-local sources. See chapter <<CHAPSMTPAUTH>> for a discussion of authenticated
-ids.
-
-*-oMas*~<'address'>::
-oindex:[%-oMas%]
-cindex:[authentication sender, specifying for local message]
-See %-oMa% above for general remarks about the %-oM% options. The %-oMas%
-option sets the authenticated sender value in $authenticated_sender$. It
-overrides the sender address that is created from the caller's login id for
-messages from local sources. See chapter <<CHAPSMTPAUTH>> for a discussion of
-authenticated senders.
-
-*-oMi*~<'interface~address'>::
-oindex:[%-oMi%]
-cindex:[interface address, specifying for local message]
-See %-oMa% above for general remarks about the %-oM% options. The %-oMi% option
-sets the IP interface address value. A port number may be included, using the
-same syntax as for %-oMa%. The interface address is placed in
-$interface_address$ and the port number, if present, in $interface_port$.
-
-*-oMr*~<'protocol~name'>::
-oindex:[%-oMr%]
-cindex:[protocol,incoming -- specifying for local message]
-cindex:[$received_protocol$]
-See %-oMa% above for general remarks about the %-oM% options. The %-oMr% option
-sets the received protocol value that is stored in $received_protocol$.
-However, this applies only when %-bs% is not used. For interactive SMTP input
-(%-bs%), the protocol is always ``local-'' followed by one of the standard SMTP
-protocol names (see the description of $received_protocol$ in section
-<<SECTexpvar>>). For %-bS% (batch SMTP) however, the protocol can be set by
-<<%-oMr%.
-
-*-oMs*~<'host~name'>::
-oindex:[%-oMs%]
-cindex:[sender host name, specifying for local message]
-See %-oMa% above for general remarks about the %-oM% options. The %-oMs% option
-sets the sender host name in $sender_host_name$. When this option is present,
-Exim does not attempt to look up a host name from an IP address; it uses the
-name it is given.
-
-*-oMt*~<'ident~string'>::
-oindex:[%-oMt%]
-cindex:[sender ident string, specifying for local message]
-See %-oMa% above for general remarks about the %-oM% options. The %-oMt% option
-sets the sender ident value in $sender_ident$. The default setting for local
-callers is the login id of the calling process.
-
-*-om*::
-oindex:[%-om%]
-cindex:[Sendmail compatibility,%-om% option ignored]
-In Sendmail, this option means ``me too'', indicating that the sender of a
-message should receive a copy of the message if the sender appears in an alias
-expansion. Exim always does this, so the option does nothing.
-
-*-oo*::
-oindex:[%-oo%]
-cindex:[Sendmail compatibility,%-oo% option ignored]
-This option is ignored. In Sendmail it specifies ``old style headers'', whatever
-that means.
-
-*-oP*~<'path'>::
-oindex:[%-oP%]
-cindex:[pid (process id),of daemon]
-cindex:[daemon,process id (pid)]
-This option is useful only in conjunction with %-bd% or %-q% with a time
-value. The option specifies the file to which the process id of the daemon is
-written. When %-oX% is used with %-bd%, or when %-q% with a time is used
-without %-bd%, this is the only way of causing Exim to write a pid file,
-because in those cases, the normal pid file is not used.
-
-*-or*~<'time'>::
-oindex:[%-or%]
-cindex:[timeout,for non-SMTP input]
-This option sets a timeout value for incoming non-SMTP messages. If it is not
-set, Exim will wait forever for the standard input. The value can also be set
-by the %receive_timeout% option. The format used for specifying times is
-described in section <<SECTtimeformat>>.
-
-*-os*~<'time'>::
-oindex:[%-os%]
-cindex:[timeout,for SMTP input]
-cindex:[SMTP timeout, input]
-This option sets a timeout value for incoming SMTP messages. The timeout
-applies to each SMTP command and block of data. The value can also be set by
-the %smtp_receive_timeout% option; it defaults to 5 minutes. The format used
-for specifying times is described in section <<SECTtimeformat>>.
-
-*-ov*::
-oindex:[%-ov%]
-This option has exactly the same effect as %-v%.
-
-*-oX*~<'number~or~string'>::
-oindex:[%-oX%]
-cindex:[TCP/IP,setting listening ports]
-cindex:[TCP/IP,setting listening interfaces]
-cindex:[port,receiving TCP/IP]
-This option is relevant only when the %-bd% (start listening daemon) option is
-also given. It controls which ports and interfaces the daemon uses. Details of
-the syntax, and how it interacts with configuration file options, are given in
-chapter <<CHAPinterfaces>>. When %-oX% is used to start a daemon, no pid file is
-written unless %-oP% is also present to specify a pid file name.
-
-*-pd*::
-oindex:[%-pd%]
-cindex:[Perl,starting the interpreter]
-This option applies when an embedded Perl interpreter is linked with Exim (see
-chapter <<CHAPperl>>). It overrides the setting of the %perl_at_start% option,
-forcing the starting of the interpreter to be delayed until it is needed.
-
-*-ps*::
-oindex:[%-ps%]
-cindex:[Perl,starting the interpreter]
-This option applies when an embedded Perl interpreter is linked with Exim (see
-chapter <<CHAPperl>>). It overrides the setting of the %perl_at_start% option,
-forcing the starting of the interpreter to occur as soon as Exim is started.
-
-*-p*<'rval'>:<'sval'>::
-oindex:[%-p%]
-For compatibility with Sendmail, this option is equivalent to
-
- -oMr <rval> -oMs <sval>
-+
-It sets the incoming protocol and host name (for trusted callers). The
-host name and its colon can be omitted when only the protocol is to be set.
-Note the Exim already has two private options, %-pd% and %-ps%, that refer to
-embedded Perl. It is therefore impossible to set a protocol value of `p` or
-`s` using this option (but that does not seem a real limitation).
-
-*-q*::
-oindex:[%-q%]
-cindex:[queue runner,starting manually]
-This option is normally restricted to admin users. However, there is a
-configuration option called %prod_requires_admin% which can be set false to
-relax this restriction (and also the same requirement for the %-M%, %-R%, and
-%-S% options).
-+
-The
-cindex:[queue runner,description of operation]
-%-q% option starts one queue runner process. This scans the queue of
-waiting messages, and runs a delivery process for each one in turn. It waits
-for each delivery process to finish before starting the next one. A delivery
-process may not actually do any deliveries if the retry times for the addresses
-have not been reached. Use %-qf% (see below) if you want to override this.
-+
-If
-cindex:[SMTP,passed connection]
-cindex:[SMTP,multiple deliveries]
-cindex:[multiple SMTP deliveries]
-the delivery process spawns other processes to deliver other messages down
-passed SMTP connections, the queue runner waits for these to finish before
-proceeding.
-+
-When all the queued messages have been considered, the original queue runner
-process terminates. In other words, a single pass is made over the waiting
-mail, one message at a time. Use %-q% with a time (see below) if you want this
-to be repeated periodically.
-+
-Exim processes the waiting messages in an unpredictable order. It isn't very
-random, but it is likely to be different each time, which is all that matters.
-If one particular message screws up a remote MTA, other messages to the same
-MTA have a chance of getting through if they get tried first.
-+
-It is possible to cause the messages to be processed in lexical message id
-order, which is essentially the order in which they arrived, by setting the
-%queue_run_in_order% option, but this is not recommended for normal use.
-
-*-q*<'qflags'>::
-The %-q% option may be followed by one or more flag letters that change its
-behaviour. They are all optional, but if more than one is present, they must
-appear in the correct order. Each flag is described in a separate item below.
-
-*-qq...*::
-oindex:[%-qq%]
-cindex:[queue,double scanning]
-cindex:[queue,routing]
-cindex:[routing,whole queue before delivery]
-An option starting with %-qq% requests a two-stage queue run. In the first
-stage, the queue is scanned as if the %queue_smtp_domains% option matched
-every domain. Addresses are routed, local deliveries happen, but no remote
-transports are run.
-+
-The
-cindex:[hints database,remembering routing]
-hints database that remembers which messages are waiting for specific hosts is
-updated, as if delivery to those hosts had been deferred. After this is
-complete, a second, normal queue scan happens, with routing and delivery taking
-place as normal. Messages that are routed to the same host should mostly be
-delivered down a single SMTP
-cindex:[SMTP,passed connection]
-cindex:[SMTP,multiple deliveries]
-cindex:[multiple SMTP deliveries]
-connection because of the hints that were set up during the first queue scan.
-This option may be useful for hosts that are connected to the Internet
-intermittently.
-
-*-q[q]i...*::
-oindex:[%-qi%]
-cindex:[queue,initial delivery]
-If the 'i' flag is present, the queue runner runs delivery processes only for
-those messages that haven't previously been tried. ('i' stands for ``initial
-delivery''.) This can be helpful if you are putting messages on the queue using
-%-odq% and want a queue runner just to process the new messages.
-
-*-q[q][i]f...*::
-oindex:[%-qf%]
-cindex:[queue,forcing delivery]
-cindex:[delivery,forcing in queue run]
-If one 'f' flag is present, a delivery attempt is forced for each non-frozen
-message, whereas without %f% only those non-frozen addresses that have passed
-their retry times are tried.
-
-*-q[q][i]ff...*::
-oindex:[%-qff%]
-cindex:[frozen messages,forcing delivery]
-If 'ff' is present, a delivery attempt is forced for every message, whether
-frozen or not.
-
-*-q[q][i][f[f]]l*::
-oindex:[%-ql%]
-cindex:[queue,local deliveries only]
-The 'l' (the letter ``ell'') flag specifies that only local deliveries are to be
-done. If a message requires any remote deliveries, it remains on the queue for
-later delivery.
-
-*-q*<'qflags'>~<'start~id'>~<'end~id'>::
-cindex:[queue,delivering specific messages]
-When scanning the queue, Exim can be made to skip over messages whose ids are
-lexically less than a given value by following the %-q% option with a starting
-message id. For example:
-
- exim -q 0t5C6f-0000c8-00
-+
-Messages that arrived earlier than `0t5C6f-0000c8-00` are not inspected. If a
-second message id is given, messages whose ids are lexically greater than it
-are also skipped. If the same id is given twice, for example,
-
- exim -q 0t5C6f-0000c8-00 0t5C6f-0000c8-00
-+
-just one delivery process is started, for that message. This differs from %-M%
-in that retry data is respected, and it also differs from %-Mc% in that it
-counts as a delivery from a queue run. Note that the selection mechanism does
-not affect the order in which the messages are scanned. There are also other
-ways of selecting specific sets of messages for delivery in a queue run -- see
-%-R% and %-S%.
-
-*-q*<'qflags'><'time'>::
-cindex:[queue runner,starting periodically]
-cindex:[periodic queue running]
-When a time value is present, the %-q% option causes Exim to run as a daemon,
-starting a queue runner process at intervals specified by the given time value
-(whose format is described in section <<SECTtimeformat>>). This form of the %-q%
-option is commonly combined with the %-bd% option, in which case a single
-daemon process handles both functions. A common way of starting up a combined
-daemon at system boot time is to use a command such as
-
- /usr/exim/bin/exim -bd -q30m
-+
-Such a daemon listens for incoming SMTP calls, and also starts a queue runner
-process every 30 minutes.
-+
-When a daemon is started by %-q% with a time value, but without %-bd%, no pid
-file is written unless one is explicitly requested by the %-oP% option.
-
-*-qR*<'rsflags'>~<'string'>::
-oindex:[%-qR%]
-This option is synonymous with %-R%. It is provided for Sendmail compatibility.
-
-*-qS*<'rsflags'>~<'string'>::
-oindex:[%-qS%]
-This option is synonymous with %-S%.
-
-*-R*<'rsflags'>~<'string'>::
-oindex:[%-R%]
-cindex:[queue runner,for specific recipients]
-cindex:[delivery,to given domain]
-cindex:[domain,delivery to]
-The <'rsflags'> may be empty, in which case the white space before the string
-is optional, unless the string is 'f', 'ff', 'r', 'rf', or 'rff', which are the
-possible values for <'rsflags'>. White space is required if <'rsflags'> is not
-empty.
-+
-This option is similar to %-q% with no time value, that is, it causes Exim to
-perform a single queue run, except that, when scanning the messages on the
-queue, Exim processes only those that have at least one undelivered recipient
-address containing the given string, which is checked in a case-independent
-way. If the <'rsflags'> start with 'r', <'string'> is interpreted as a regular
-expression; otherwise it is a literal string.
-+
-Once a message is selected, all its addresses are processed. For the first
-selected message, Exim overrides any retry information and forces a delivery
-attempt for each undelivered address. This means that if delivery of any
-address in the first message is successful, any existing retry information is
-deleted, and so delivery attempts for that address in subsequently selected
-messages (which are processed without forcing) will run. However, if delivery
-of any address does not succeed, the retry information is updated, and in
-subsequently selected messages, the failing address will be skipped.
-+
-If the <'rsflags'> contain 'f' or 'ff', the delivery forcing applies to all
-selected messages, not just the first;
-cindex:[frozen messages,forcing delivery]
-frozen messages are included when 'ff' is present.
-+
-The %-R% option makes it straightforward to initiate delivery of all messages
-to a given domain after a host has been down for some time. When the SMTP
-command ETRN is accepted by its ACL (see chapter <<CHAPACL>>), its default
-effect is to run Exim with the %-R% option, but it can be configured to run an
-arbitrary command instead.
-
-*-r*::
-oindex:[%-r%]
-This is a documented (for Sendmail) obsolete alternative name for %-f%.
-
-*-S*<'rsflags'>~<'string'>::
-oindex:[%-S%]
-cindex:[delivery,from given sender]
-cindex:[queue runner,for specific senders]
-This option acts like %-R% except that it checks the string against each
-message's sender instead of against the recipients. If %-R% is also set, both
-conditions must be met for a message to be selected. If either of the options
-has 'f' or 'ff' in its flags, the associated action is taken.
-
-*-Tqt*~<'times'>::
-oindex:[%-Tqt%]
-This an option that is exclusively for use by the Exim testing suite. It is not
-recognized when Exim is run normally. It allows for the setting up of explicit
-``queue times'' so that various warning/retry features can be tested.
-
-*-t*::
-oindex:[%-t%]
-cindex:[recipient,extracting from header lines]
-cindex:['Bcc:' header line]
-cindex:['Cc:' header line]
-cindex:['To:' header line]
-When Exim is receiving a locally-generated, non-SMTP message on its standard
-input, the %-t% option causes the recipients of the message to be obtained
-from the 'To:', 'Cc:', and 'Bcc:' header lines in the message instead of from
-the command arguments. The addresses are extracted before any rewriting takes
-place.
-+
-If
-cindex:[Sendmail compatibility,%-t% option]
-the command has any arguments, they specify addresses to which the message
-is 'not' to be delivered. That is, the argument addresses are removed from
-the recipients list obtained from the headers. This is compatible with Smail 3
-and in accordance with the documented behaviour of several versions of
-Sendmail, as described in man pages on a number of operating systems (e.g.
-Solaris 8, IRIX 6.5, HP-UX 11). However, some versions of Sendmail 'add'
-argument addresses to those obtained from the headers, and the O'Reilly
-Sendmail book documents it that way. Exim can be made to add argument addresses
-instead of subtracting them by setting the option
-%extract_addresses_remove_arguments% false.
-+
-If a 'Bcc:' header line is present, it is removed from the message unless
-there is no 'To:' or 'Cc:', in which case a 'Bcc:' line with no data is
-created. This is necessary for conformity with the original RFC 822 standard;
-the requirement has been removed in RFC 2822, but that is still very new.
-+
-If
-cindex:[%Resent-% header lines,with %-t%]
-there are any %Resent-% header lines in the message, Exim extracts
-recipients from all 'Resent-To:', 'Resent-Cc:', and 'Resent-Bcc:' header
-lines instead of from 'To:', 'Cc:', and 'Bcc:'. This is for compatibility
-with Sendmail and other MTAs. (Prior to release 4.20, Exim gave an error if
-%-t% was used in conjunction with %Resent-% header lines.)
-+
-RFC 2822 talks about different sets of %Resent-% header lines (for when a
-message is resent several times). The RFC also specifies that they should be
-added at the front of the message, and separated by 'Received:' lines. It is
-not at all clear how %-t% should operate in the present of multiple sets,
-nor indeed exactly what constitutes a ``set''.
-In practice, it seems that MUAs do not follow the RFC. The %Resent-% lines are
-often added at the end of the header, and if a message is resent more than
-once, it is common for the original set of %Resent-% headers to be renamed as
-%X-Resent-% when a new set is added. This removes any possible ambiguity.
-
-*-ti*::
-oindex:[%-ti%]
-This option is exactly equivalent to %-t% %-i%. It is provided for
-compatibility with Sendmail.
-
-*-tls-on-connect*::
-oindex:[%-tls-on-connect%]
-cindex:[TLS,use without STARTTLS]
-cindex:[TLS,automatic start]
-This option is available when Exim is compiled with TLS support. It forces all
-incoming SMTP connections to behave as if the incoming port is listed in the
-%tls_on_connect_ports% option. See section <<SECTsupobssmt>> and chapter
-<<CHAPTLS>> for further details.
-
-
-*-U*::
-oindex:[%-U%]
-cindex:[Sendmail compatibility,%-U% option ignored]
-Sendmail uses this option for ``initial message submission'', and its
-documentation states that in future releases, it may complain about
-syntactically invalid messages rather than fixing them when this flag is not
-set. Exim ignores this option.
-
-*-v*::
-oindex:[%-v%]
-This option causes Exim to write information to the standard error stream,
-describing what it is doing. In particular, it shows the log lines for
-receiving and delivering a message, and if an SMTP connection is made, the SMTP
-dialogue is shown. Some of the log lines shown may not actually be written to
-the log if the setting of %log_selector% discards them. Any relevant selectors
-are shown with each log line. If none are shown, the logging is unconditional.
-
-*-x*::
-oindex:[%-x%]
-AIX uses %-x% for a private purpose (``mail from a local mail program has
-National Language Support extended characters in the body of the mail item'').
-It sets %-x% when calling the MTA from its %mail% command. Exim ignores this
-option.
-
-///
-We insert a stylized DocBook comment here, to identify the end of the command
-line options. This is for the benefit of the Perl script that automatically
-creates a man page for the options.
-///
-
-++++
-<!-- === End of command line options === -->
-++++
-
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-
-[[CHAPconf]]
-[titleabbrev="The runtime configuration file"]
-The Exim run time configuration file
-------------------------------------
-
-cindex:[run time configuration]
-cindex:[configuration file,general description]
-cindex:[CONFIGURE_FILE]
-cindex:[configuration file,errors in]
-cindex:[error,in configuration file]
-cindex:[return code,for bad configuration]
-Exim uses a single run time configuration file that is read whenever an Exim
-binary is executed. Note that in normal operation, this happens frequently,
-because Exim is designed to operate in a distributed manner, without central
-control.
-
-If a syntax error is detected while reading the configuration file, Exim
-writes a message on the standard error, and exits with a non-zero return code.
-The message is also written to the panic log. *Note*: only simple syntax
-errors can be detected at this time. The values of any expanded options are
-not checked until the expansion happens, even when the expansion does not
-actually alter the string.
-
-
-
-The name of the configuration file is compiled into the binary for security
-reasons, and is specified by the CONFIGURE_FILE compilation option. In
-most configurations, this specifies a single file. However, it is permitted to
-give a colon-separated list of file names, in which case Exim uses the first
-existing file in the list.
-
-cindex:[EXIM_USER]
-cindex:[EXIM_GROUP]
-cindex:[CONFIGURE_OWNER]
-cindex:[CONFIGURE_GROUP]
-cindex:[configuration file,ownership]
-cindex:[ownership,configuration file]
-The run time configuration file must be owned by root or by the user that is
-specified at compile time by the EXIM_USER option, or by the user that is
-specified at compile time by the CONFIGURE_OWNER option (if set). The
-configuration file must not be world-writeable or group-writeable, unless its
-group is the one specified at compile time by the EXIM_GROUP option
-
-or by the CONFIGURE_GROUP option.
-
-
-*Warning*: In a conventional configuration, where the Exim binary is setuid
-to root, anybody who is able to edit the run time configuration file has an
-easy way to run commands as root. If you make your mail administrators members
-of the Exim group, but do not trust them with root, make sure that the run time
-configuration is not group writeable.
-
-A default configuration file, which will work correctly in simple situations,
-is provided in the file _src/configure.default_. If CONFIGURE_FILE
-defines just one file name, the installation process copies the default
-configuration to a new file of that name if it did not previously exist. If
-CONFIGURE_FILE is a list, no default is automatically installed. Chapter
-<<CHAPdefconfil>> is a ``walk-through'' discussion of the default configuration.
-
-
-
-Using a different configuration file
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[configuration file,alternate]
-A one-off alternate configuration can be specified by the %-C% command line
-option, which may specify a single file or a list of files. However, when %-C%
-is used, Exim gives up its root privilege, unless called by root or the Exim
-user (or unless the argument for %-C% is identical to the built-in value from
-CONFIGURE_FILE). %-C% is useful mainly for checking the syntax of
-configuration files before installing them. No owner or group checks are done
-on a configuration file specified by %-C%.
-
-The privileged use of %-C% by the Exim user can be locked out by setting
-ALT_CONFIG_ROOT_ONLY in _Local/Makefile_ when building Exim. However,
-if you do this, you also lock out the possibility of testing a
-configuration using %-C% right through message reception and delivery, even if
-the caller is root. The reception works, but by that time, Exim is running as
-the Exim user, so when it re-execs to regain privilege for the delivery, the
-use of %-C% causes privilege to be lost. However, root can test reception and
-delivery using two separate commands (one to put a message on the queue, using
-%-odq%, and another to do the delivery, using %-M%).
-
-If ALT_CONFIG_PREFIX is defined _in Local/Makefile_, it specifies a
-prefix string with which any file named in a %-C% command line option must
-start. In addition, the file name must not contain the sequence ``##`/../`##''.
-There is no default setting for ALT_CONFIG_PREFIX; when it is unset, any file
-name can be used with %-C%.
-
-One-off changes to a configuration can be specified by the %-D% command line
-option, which defines and overrides values for macros used inside the
-configuration file. However, like %-C%, the use of this option by a
-non-privileged user causes Exim to discard its root privilege.
-If DISABLE_D_OPTION is defined in _Local/Makefile_, the use of %-D% is
-completely disabled, and its use causes an immediate error exit.
-
-Some sites may wish to use the same Exim binary on different machines that
-share a file system, but to use different configuration files on each machine.
-If CONFIGURE_FILE_USE_NODE is defined in _Local/Makefile_, Exim first
-looks for a file whose name is the configuration file name followed by a dot
-and the machine's node name, as obtained from the 'uname()' function. If this
-file does not exist, the standard name is tried. This processing occurs for
-each file name in the list given by CONFIGURE_FILE or %-C%.
-
-In some esoteric situations different versions of Exim may be run under
-different effective uids and the CONFIGURE_FILE_USE_EUID is defined to
-help with this. See the comments in _src/EDITME_ for details.
-
-
-
-[[SECTconffilfor]]
-Configuration file format
-~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[configuration file,format of]
-cindex:[format,configuration file]
-Exim's configuration file is divided into a number of different parts. General
-option settings must always appear at the start of the file. The other parts
-are all optional, and may appear in any order. Each part other than the first
-is introduced by the word ``begin'' followed by the name of the part. The
-optional parts are:
-
-- 'ACL': Access control lists for controlling incoming SMTP mail.
-
-- cindex:[AUTH,configuration]
-'authenticators': Configuration settings for the authenticator drivers. These
-are concerned with the SMTP AUTH command (see chapter <<CHAPSMTPAUTH>>).
-
-- 'routers': Configuration settings for the router drivers. Routers process
-addresses and determine how the message is to be delivered.
-
-- 'transports': Configuration settings for the transport drivers. Transports
-define mechanisms for copying messages to destinations.
-
-- 'retry': Retry rules, for use when a message cannot be immediately delivered.
-
-- 'rewrite': Global address rewriting rules, for use when a message arrives and
-when new addresses are generated during delivery.
-
-- 'local_scan': Private options for the 'local_scan()' function. If you
-want to use this feature, you must set
-
- LOCAL_SCAN_HAS_OPTIONS=yes
-+
-in _Local/Makefile_ before building Exim. Full details of the
-'local_scan()' facility are given in chapter <<CHAPlocalscan>>.
-
-cindex:[configuration file,leading white space in]
-cindex:[configuration file,trailing white space in]
-cindex:[white space,in configuration file]
-Leading and trailing white space in configuration lines is always ignored.
-
-Blank lines in the file, and lines starting with a # character (ignoring
-leading white space) are treated as comments and are ignored. *Note*: a
-# character other than at the beginning of a line is not treated specially,
-and does not introduce a comment.
-
-Any non-comment line can be continued by ending it with a backslash. Note that
-the general rule for white space means that trailing white space after the
-backslash and leading white space at the start of continuation
-lines is ignored. Comment lines beginning with # (but not empty lines) may
-appear in the middle of a sequence of continuation lines.
-
-A convenient way to create a configuration file is to start from the
-default, which is supplied in _src/configure.default_, and add, delete, or
-change settings as required.
-
-The ACLs, retry rules, and rewriting rules have their own syntax which is
-described in chapters <<CHAPACL>>, <<CHAPretry>>, and <<CHAPrewrite>>,
-respectively. The other parts of the configuration file have some syntactic
-items in common, and these are described below, from section <<SECTcos>>
-onwards. Before that, the inclusion, macro, and conditional facilities are
-described.
-
-
-
-File inclusions in the configuration file
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[inclusions in configuration file]
-cindex:[configuration file,including other files]
-cindex:[.include in configuration file]
-cindex:[.include_if_exists in configuration file]
-You can include other files inside Exim's run time configuration file by
-using this syntax:
-
- .include <file name>
-
-or
-
- .include_if_exists <file name>
-
-on a line by itself. Double quotes round the file name are optional. If you use
-the first form, a configuration error occurs if the file does not exist; the
-second form does nothing for non-existent files.
-
-Includes may be nested to any depth, but remember that Exim reads its
-configuration file often, so it is a good idea to keep them to a minimum.
-If you change the contents of an included file, you must HUP the daemon,
-because an included file is read only when the configuration itself is read.
-
-The processing of inclusions happens early, at a physical line level, so, like
-comment lines, an inclusion can be used in the middle of an option setting,
-for example:
-
-....
-hosts_lookup = a.b.c \
- .include /some/file
-....
-
-Include processing happens after macro processing (see below). Its effect is to
-process the lines of the file as if they occurred inline where the inclusion
-appears.
-
-
-
-[[SECTmacrodefs]]
-Macros in the configuration file
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[macro,description of]
-cindex:[configuration file,macros]
-If a line in the main part of the configuration (that is, before the first
-``begin'' line) begins with an upper case letter, it is taken as a macro
-definition, and must be of the form
-
-&&&
-<'name'> = <'rest of line'>
-&&&
-
-The name must consist of letters, digits, and underscores, and need not all be
-in upper case, though that is recommended. The rest of the line, including any
-continuations, is the replacement text, and has leading and trailing white
-space removed. Quotes are not removed. The replacement text can never end with
-a backslash character, but this doesn't seem to be a serious limitation.
-
-[revisionflag="changed"]
-Macros may also be defined between router, transport, authenticator, or ACL
-definitions. They may not, however, be defined within an individual driver or
-ACL, or in the %local_scan%, retry, or rewrite sections of the configuration.
-
-
-Macro substitution
-~~~~~~~~~~~~~~~~~~
-Once a macro is defined, all subsequent lines in the file (and any included
-files) are scanned for the macro name; if there are several macros, the line is
-scanned for each in turn, in the order in which the macros are defined. The
-replacement text is not re-scanned for the current macro, though it is scanned
-for subsequently defined macros. For this reason, a macro name may not contain
-the name of a previously defined macro as a substring. You could, for example,
-define
-
-&&&
-`ABCD_XYZ = `<'something'>
-`ABCD = `<'something else'>
-&&&
-
-but putting the definitions in the opposite order would provoke a configuration
-error. Macro expansion is applied to individual physical lines from the file,
-before checking for line continuation or file inclusion (see above). If a line
-consists solely of a macro name, and the expansion of the macro is empty, the
-line is ignored. A macro at the start of a line may turn the line into a
-comment line or a `.include` line.
-
-
-Redefining macros
-~~~~~~~~~~~~~~~~~
-[revisionflag="changed"]
-Once defined, the value of a macro can be redefined later in the configuration
-(or in an included file). Redefinition is specified by using '==' instead of
-'='. For example:
-
- MAC = initial value
- ...
- MAC == updated value
-
-Redefinition does not alter the order in which the macros are applied to
-the subsequent lines of the configuration file. It is still the same
-order in which the macros were originally defined. All that changes is
-the macro's value. Redefinition makes it possible to accumulate values.
-For example:
-
- MAC = initial value
- ...
- MAC == MAC and something added
-
-This can be helpful in situations where the configuration file is built
-from a number of other files.
-
-
-Overriding macro values
-~~~~~~~~~~~~~~~~~~~~~~~
-The values set for macros in the configuration file can be overridden by the
-%-D% command line option, but Exim gives up its root privilege when %-D% is
-used, unless called by root or the Exim user. A definition on the command line
-using the %-D% option causes all definitions and redefinitions within the file
-to be ignored.
-
-
-
-Example of macro usage
-~~~~~~~~~~~~~~~~~~~~~~
-As an example of macro usage, consider a configuration where aliases are looked
-up in a MySQL database. It helps to keep the file less cluttered if long
-strings such as SQL statements are defined separately as macros, for example:
-
-....
-ALIAS_QUERY = select mailbox from user where \
- login=${quote_mysql:$local_part};
-....
-
-This can then be used in a ^redirect^ router setting like this:
-
- data = ${lookup mysql{ALIAS_QUERY}}
-
-In earlier versions of Exim macros were sometimes used for domain, host, or
-address lists. In Exim 4 these are handled better by named lists -- see section
-<<SECTnamedlists>>.
-
-
-Conditional skips in the configuration file
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[configuration file,conditional skips]
-cindex:[.ifdef]
-You can use the directives `.ifdef`, `.ifndef`, `.elifdef`,
-`.elifndef`, `.else`, and `.endif` to dynamically include or exclude
-portions of the configuration file. The processing happens whenever the file is
-read (that is, when an Exim binary starts to run).
-
-The implementation is very simple. Instances of the first four directives must
-be followed by text that includes the names of one or macros. The condition
-that is tested is whether or not any macro substitution has taken place in the
-line. Thus:
-
- .ifdef AAA
- message_size_limit = 50M
- .else
- message_size_limit = 100M
- .endif
-
-sets a message size limit of 50M if the macro `AAA` is defined, and 100M
-otherwise. If there is more than one macro named on the line, the condition
-is true if any of them are defined. That is, it is an ``or'' condition. To
-obtain an ``and'' condition, you need to use nested `.ifdef`##s.
-
-Although you can use a macro expansion to generate one of these directives,
-it is not very useful, because the condition ``there was a macro substitution
-in this line'' will always be true.
-
-Text following `.else` and `.endif` is ignored, and can be used as comment
-to clarify complicated nestings.
-
-
-
-[[SECTcos]]
-Common option syntax
-~~~~~~~~~~~~~~~~~~~~
-cindex:[common option syntax]
-cindex:[syntax of common options]
-cindex:[configuration file,common option syntax]
-For the main set of options, driver options, and 'local_scan()' options,
-each setting is on a line by itself, and starts with a name consisting of
-lower-case letters and underscores. Many options require a data value, and in
-these cases the name must be followed by an equals sign (with optional white
-space) and then the value. For example:
-
- qualify_domain = mydomain.example.com
-
-Some option settings may contain sensitive data, for example, passwords for
-accessing databases. To stop non-admin users from using the %-bP% command line
-option to read these values, you can precede the option settings with the word
-``hide''. For example:
-
- hide mysql_servers = localhost/users/admin/secret-password
-
-For non-admin users, such options are displayed like this:
-
- mysql_servers = <value not displayable>
-
-If ``hide'' is used on a driver option, it hides the value of that option on all
-instances of the same driver.
-
-The following sections describe the syntax used for the different data types
-that are found in option settings.
-
-
-Boolean options
-~~~~~~~~~~~~~~~
-cindex:[format,boolean]
-cindex:[boolean configuration values]
-oindex:[%no_%'xxx']
-oindex:[%not_%'xxx']
-Options whose type is given as boolean are on/off switches. There are two
-different ways of specifying such options: with and without a data value. If
-the option name is specified on its own without data, the switch is turned on;
-if it is preceded by ``no_'' or ``not_'' the switch is turned off. However,
-boolean options may be followed by an equals sign and one of the words
-``true'', ``false'', ``yes'', or ``no'', as an alternative syntax. For example,
-the following two settings have exactly the same effect:
-
- queue_only
- queue_only = true
-
-The following two lines also have the same (opposite) effect:
-
- no_queue_only
- queue_only = false
-
-You can use whichever syntax you prefer.
-
-
-
-
-Integer values
-~~~~~~~~~~~~~~
-cindex:[integer configuration values]
-cindex:[format,integer]
-If an integer data item starts with the characters ``0x'', the remainder of it
-is interpreted as a hexadecimal number. Otherwise, it is treated as octal if it
-starts with the digit 0, and decimal if not. If an integer value is followed by
-the letter K, it is multiplied by 1024; if it is followed by the letter M, it
-is multiplied by 1024x1024.
-
-When the values of integer option settings are output, values which are an
-exact multiple of 1024 or 1024x1024 are
-sometimes, but not always,
-printed using the letters K and M. The printing style is independent of the
-actual input format that was used.
-
-
-Octal integer values
-~~~~~~~~~~~~~~~~~~~~
-cindex:[integer format]
-cindex:[format,octal integer]
-The value of an option specified as an octal integer is always interpreted in
-octal, whether or not it starts with the digit zero. Such options are always
-output in octal.
-
-
-
-Fixed point number values
-~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[fixed point configuration values]
-cindex:[format,fixed point]
-A fixed point number consists of a decimal integer, optionally followed by a
-decimal point and up to three further digits.
-
-
-
-[[SECTtimeformat]]
-Time interval values
-~~~~~~~~~~~~~~~~~~~~
-cindex:[time interval,specifying in configuration]
-cindex:[format,time interval]
-A time interval is specified as a sequence of numbers, each followed by one of
-the following letters, with no intervening white space:
-
-[frame="none"]
-`-`-----`--------
- %s% seconds
- %m% minutes
- %h% hours
- %d% days
- %w% weeks
------------------
-
-For example, ``3h50m'' specifies 3 hours and 50 minutes. The values of time
-intervals are output in the same format. Exim does not restrict the values; it
-is perfectly acceptable, for example, to specify ``90m'' instead of ``1h30m''.
-
-
-
-[[SECTstrings]]
-String values
-~~~~~~~~~~~~~
-cindex:[string,format of configuration values]
-cindex:[format,string]
-If a string data item does not start with a double-quote character, it is taken
-as consisting of the remainder of the line plus any continuation lines,
-starting at the first character after any leading white space, with trailing
-white space characters removed, and with no interpretation of the characters in
-the string. Because Exim removes comment lines (those beginning with #) at an
-early stage, they can appear in the middle of a multi-line string. The
-following settings are therefore equivalent:
-
-....
-trusted_users = uucp:mail
-
-trusted_users = uucp:\
- # This comment line is ignored
- mail
-....
-
-cindex:[string,quoted]
-cindex:[escape characters in quoted strings]
-If a string does start with a double-quote, it must end with a closing
-double-quote, and any backslash characters other than those used for line
-continuation are interpreted as escape characters, as follows:
-
-[frame="none"]
-`-`----------------------`--------------------------------------------------
- `\\` single backslash
- `\n` newline
- `\r` carriage return
- `\t` tab
- `\`<'octal digits'> up to 3 octal digits specify one character
- `\x`<'hex digits'> up to 2 hexadecimal digits specify one character
-----------------------------------------------------------------------------
-
-If a backslash is followed by some other character, including a double-quote
-character, that character replaces the pair.
-
-Quoting is necessary only if you want to make use of the backslash escapes to
-insert special characters, or if you need to specify a value with leading or
-trailing spaces. These cases are rare, so quoting is almost never needed in
-current versions of Exim. In versions of Exim before 3.14, quoting was required
-in order to continue lines, so you may come across older configuration files
-and examples that apparently quote unnecessarily.
-
-
-Expanded strings
-~~~~~~~~~~~~~~~~
-cindex:[string expansion, definition of]
-cindex:[expansion,definition of]
-Some strings in the configuration file are subjected to 'string expansion',
-by which means various parts of the string may be changed according to the
-circumstances (see chapter <<CHAPexpand>>). The input syntax for such strings is
-as just described; in particular, the handling of backslashes in quoted strings
-is done as part of the input process, before expansion takes place. However,
-backslash is also an escape character for the expander, so any backslashes that
-are required for that reason must be doubled if they are within a quoted
-configuration string.
-
-
-User and group names
-~~~~~~~~~~~~~~~~~~~~
-cindex:[user name,format of]
-cindex:[format,user name]
-cindex:[group,name format]
-cindex:[format,group name]
-User and group names are specified as strings, using the syntax described
-above, but the strings are interpreted specially. A user or group name must
-either consist entirely of digits, or be a name that can be looked up using the
-'getpwnam()' or 'getgrnam()' function, as appropriate.
-
-
-[[SECTlistconstruct]]
-List construction
-~~~~~~~~~~~~~~~~~
-cindex:[list,syntax of in configuration]
-cindex:[format,list item in configuration]
-cindex:[string list, definition]
-The data for some configuration options is a list of items, with colon as the
-default separator. Many of these options are shown with type ``string list'' in
-the descriptions later in this document. Others are listed as ``domain list'',
-``host list'', ``address list'', or ``local part list''. Syntactically, they
-are all the same; however, those other than ``string list'' are subject to
-particular kinds of interpretation, as described in chapter
-<<CHAPdomhosaddlists>>.
-
-In all these cases, the entire list is treated as a single string as far as the
-input syntax is concerned. The %trusted_users% setting in section
-<<SECTstrings>> above is an example. If a colon is actually needed in an item in
-a list, it must be entered as two colons. Leading and trailing white space on
-each item in a list is ignored. This makes it possible to include items that
-start with a colon, and in particular, certain forms of IPv6 address. For
-example, the list
-
- local_interfaces = 127.0.0.1 : ::::1
-
-contains two IP addresses, the IPv4 address 127.0.0.1 and the IPv6 address ::1.
-
-[revisionflag="changed"]
-*Note*: Although leading and trailing white space is ignored in individual list
-items, it is not ignored when parsing the list. The space after the first colon
-in the example above is necessary. If it were not there, the list would be
-interpreted as the two items 127.0.0.1:: and 1.
-
-cindex:[list separator, changing]
-cindex:[IPv6,addresses in lists]
-Doubling colons in IPv6 addresses is an unwelcome chore, so a mechanism was
-introduced to allow the separator character to be changed. If a list begins
-with a left angle bracket, followed by any punctuation character, that
-character is used instead of colon as the list separator. For example, the list
-above can be rewritten to use a semicolon separator like this:
-
- local_interfaces = <; 127.0.0.1 ; ::1
-
-This facility applies to all lists, with the exception of the list in
-%log_file_path%. It is recommended that the use of non-colon separators be
-confined to circumstances where they really are needed.
-
-
-
-[[SECTempitelis]]
-Empty items in lists
-~~~~~~~~~~~~~~~~~~~~
-cindex:[list,empty item in]
-An empty item at the end of a list is always ignored. In other words, trailing
-separator characters are ignored. Thus, the list in
-
- senders = user@domain :
-
-contains only a single item. If you want to include an empty string as one item
-in a list, it must not be the last item. For example, this list contains three
-items, the second of which is empty:
-
- senders = user1@domain : : user2@domain
-
-*Note*: there must be white space between the two colons, as otherwise they
-are interpreted as representing a single colon data character (and the list
-would then contain just one item). If you want to specify a list that contains
-just one, empty item, you can do it as in this example:
-
- senders = :
-
-In this case, the first item is empty, and the second is discarded because it
-is at the end of the list.
-
-
-
-
-[[SECTfordricon]]
-Format of driver configurations
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[drivers,configuration format]
-There are separate parts in the configuration for defining routers, transports,
-and authenticators. In each part, you are defining a number of driver
-instances, each with its own set of options. Each driver instance is defined by
-a sequence of lines like this:
-
-&&&
-<'instance name'>:
- <'option'>
- ...
- <'option'>
-&&&
-
-In the following example, the instance name is ^localuser^, and it is
-followed by three options settings:
-
- localuser:
- driver = accept
- check_local_user
- transport = local_delivery
-
-For each driver instance, you specify which Exim code module it uses -- by the
-setting of the %driver% option -- and (optionally) some configuration settings.
-For example, in the case of transports, if you want a transport to deliver with
-SMTP you would use the ^smtp^ driver; if you want to deliver to a local file
-you would use the ^appendfile^ driver. Each of the drivers is described in
-detail in its own separate chapter later in this manual.
-
-You can have several routers, transports, or authenticators that are based on
-the same underlying driver (each must have a different instance name).
-
-The order in which routers are defined is important, because addresses are
-passed to individual routers one by one, in order. The order in which
-transports are defined does not matter at all. The order in which
-authenticators are defined is used only when Exim, as a client, is searching
-them to find one that matches an authentication mechanism offered by the
-server.
-
-cindex:[generic options]
-cindex:[options, generic -- definition of]
-Within a driver instance definition, there are two kinds of option:
-'generic' and 'private'. The generic options are those that apply to all
-drivers of the same type (that is, all routers, all transports or all
-authenticators).
-The %driver% option is a generic option that must appear in every definition.
-
-cindex:[private options]
-The private options are special for each driver, and none need appear, because
-they all have default values.
-
-The options may appear in any order, except that the %driver% option must
-precede any private options, since these depend on the particular driver. For
-this reason, it is recommended that %driver% always be the first option.
-
-Driver instance names, which are used for reference in log entries and
-elsewhere, can be any sequence of letters, digits, and underscores (starting
-with a letter) and must be unique among drivers of the same type. A router and
-a transport (for example) can each have the same name, but no two router
-instances can have the same name. The name of a driver instance should not be
-confused with the name of the underlying driver module. For example, the
-configuration lines:
-
- remote_smtp:
- driver = smtp
-
-create an instance of the ^smtp^ transport driver whose name is
-^remote_smtp^. The same driver code can be used more than once, with
-different instance names and different option settings each time. A second
-instance of the ^smtp^ transport, with different options, might be defined
-thus:
-
- special_smtp:
- driver = smtp
- port = 1234
- command_timeout = 10s
-
-The names ^remote_smtp^ and ^special_smtp^ would be used to reference
-these transport instances from routers, and these names would appear in log
-lines.
-
-Comment lines may be present in the middle of driver specifications. The full
-list of option settings for any particular driver instance, including all the
-defaulted values, can be extracted by making use of the %-bP% command line
-option.
-
-
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPdefconfil]]
-The default configuration file
-------------------------------
-cindex:[configuration file,default ``walk through'']
-cindex:[default,configuration file ``walk through'']
-The default configuration file supplied with Exim as _src/configure.default_
-is sufficient for a host with simple mail requirements. As an introduction to
-the way Exim is configured, this chapter ``walks through'' the default
-configuration, giving brief explanations of the settings. Detailed descriptions
-of the options are given in subsequent chapters. The default configuration file
-itself contains extensive comments about ways you might want to modify the
-initial settings. However, note that there are many options that are not
-mentioned at all in the default configuration.
-
-
-
-Main configuration settings
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The main (global) configuration option settings must always come first in the
-file. The first thing you'll see in the file, after some initial comments, is
-the line
-
- # primary_hostname =
-
-This is a commented-out setting of the %primary_hostname% option. Exim needs
-to know the official, fully qualified name of your host, and this is where you
-can specify it. However, in most cases you do not need to set this option. When
-it is unset, Exim uses the 'uname()' system function to obtain the host name.
-
-The first three non-comment configuration lines are as follows:
-
- domainlist local_domains = @
- domainlist relay_to_domains =
- hostlist relay_from_hosts = 127.0.0.1
-
-These are not, in fact, option settings. They are definitions of two named
-domain lists and one named host list. Exim allows you to give names to lists of
-domains, hosts, and email addresses, in order to make it easier to manage the
-configuration file (see section <<SECTnamedlists>>).
-
-The first line defines a domain list called 'local_domains'; this is used
-later in the configuration to identify domains that are to be delivered
-on the local host.
-
-cindex:[@ in a domain list]
-There is just one item in this list, the string ``@''. This is a special form of
-entry which means ``the name of the local host''. Thus, if the local host is
-called 'a.host.example', mail to 'any.user@a.host.example' is expected to
-be delivered locally. Because the local host's name is referenced indirectly,
-the same configuration file can be used on different hosts.
-
-The second line defines a domain list called 'relay_to_domains', but the
-list itself is empty. Later in the configuration we will come to the part that
-controls mail relaying through the local host; it allows relaying to any
-domains in this list. By default, therefore, no relaying on the basis of a mail
-domain is permitted.
-
-The third line defines a host list called 'relay_from_hosts'. This list is
-used later in the configuration to permit relaying from any host or IP address
-that matches the list. The default contains just the IP address of the IPv4
-loopback interface, which means that processes on the local host are able to
-submit mail for relaying by sending it over TCP/IP to that interface. No other
-hosts are permitted to submit messages for relaying.
-
-Just to be sure there's no misunderstanding: at this point in the configuration
-we aren't actually setting up any controls. We are just defining some domains
-and hosts that will be used in the controls that are specified later.
-
-The next two configuration lines are genuine option settings:
-
- acl_smtp_rcpt = acl_check_rcpt
- acl_smtp_data = acl_check_data
-
-[revisionflag="changed"]
-These options specify 'Access Control Lists' (ACLs) that are to be used during
-an incoming SMTP session for every recipient of a message (every RCPT command),
-and after the contents of the message have been received, respectively. The
-names of the lists are 'acl_check_rcpt' and 'acl_check_data', and we will come
-to their definitions below, in the ACL section of the configuration. The RCPT
-ACL controls which recipients are accepted for an incoming message -- if a
-configuration does not provide an ACL to check recipients, no SMTP mail can be
-accepted. The DATA ACL allows the contents of a message to be checked.
-
-[revisionflag="changed"]
-Two commented-out option settings are next:
-
-[revisionflag="changed"]
-....
-# av_scanner = clamd:/tmp/clamd
-# spamd_address = 127.0.0.1 783
-....
-
-[revisionflag="changed"]
-These are example settings that can be used when Exim is compiled with the
-content-scanning extension. The first specifies the interface to the virus
-scanner, and the second specifies the interface to SpamAssassin. Further
-details are given in chapter <<CHAPexiscan>>.
-
-Two more commented-out options settings follow:
-
- # qualify_domain =
- # qualify_recipient =
-
-The first of these specifies a domain that Exim uses when it constructs a
-complete email address from a local login name. This is often needed when Exim
-receives a message from a local process. If you do not set %qualify_domain%,
-the value of %primary_hostname% is used. If you set both of these options, you
-can have different qualification domains for sender and recipient addresses. If
-you set only the first one, its value is used in both cases.
-
-cindex:[domain literal,recognizing format]
-The following line must be uncommented if you want Exim to recognize
-addresses of the form 'user@[10.11.12.13]' that is, with a ``domain literal''
-(an IP address within square brackets) instead of a named domain.
-
- # allow_domain_literals
-
-The RFCs still require this form, but many people think that in the modern
-Internet it makes little sense to permit mail to be sent to specific hosts by
-quoting their IP addresses. This ancient format has been used by people who
-try to abuse hosts by using them for unwanted relaying. However, some
-people believe there are circumstances (for example, messages addressed to
-'postmaster') where domain literals are still useful.
-
-The next configuration line is a kind of trigger guard:
-
- never_users = root
-
-It specifies that no delivery must ever be run as the root user. The normal
-convention is to set up 'root' as an alias for the system administrator. This
-setting is a guard against slips in the configuration.
-The list of users specified by %never_users% is not, however, the complete
-list; the build-time configuration in _Local/Makefile_ has an option called
-FIXED_NEVER_USERS specifying a list that cannot be overridden. The
-contents of %never_users% are added to this list. By default
-FIXED_NEVER_USERS also specifies root.
-
-When a remote host connects to Exim in order to send mail, the only information
-Exim has about the host's identity is its IP address. The next configuration
-line,
-
- host_lookup = *
-
-specifies that Exim should do a reverse DNS lookup on all incoming connections,
-in order to get a host name. This improves the quality of the logging
-information, but if you feel it is too expensive, you can remove it entirely,
-or restrict the lookup to hosts on ``nearby'' networks.
-Note that it is not always possible to find a host name from an IP address,
-because not all DNS reverse zones are maintained, and sometimes DNS servers are
-unreachable.
-
-The next two lines are concerned with 'ident' callbacks, as defined by RFC
-1413 (hence their names):
-
- rfc1413_hosts = *
- rfc1413_query_timeout = 30s
-
-These settings cause Exim to make ident callbacks for all incoming SMTP calls.
-You can limit the hosts to which these calls are made, or change the timeout
-that is used. If you set the timeout to zero, all ident calls are disabled.
-Although they are cheap and can provide useful information for tracing problem
-messages, some hosts and firewalls have problems with ident calls. This can
-result in a timeout instead of an immediate refused connection, leading to
-delays on starting up an incoming SMTP session.
-
-When Exim receives messages over SMTP connections, it expects all addresses to
-be fully qualified with a domain, as required by the SMTP definition. However,
-if you are running a server to which simple clients submit messages, you may
-find that they send unqualified addresses. The two commented-out options:
-
- # sender_unqualified_hosts =
- # recipient_unqualified_hosts =
-
-show how you can specify hosts that are permitted to send unqualified sender
-and recipient addresses, respectively.
-
-The %percent_hack_domains% option is also commented out:
-
- # percent_hack_domains =
-
-It provides a list of domains for which the ``percent hack'' is to operate. This
-is an almost obsolete form of explicit email routing. If you do not know
-anything about it, you can safely ignore this topic.
-
-The last two settings in the main part of the default configuration are
-concerned with messages that have been ``frozen'' on Exim's queue. When a message
-is frozen, Exim no longer continues to try to deliver it. Freezing occurs when
-a bounce message encounters a permanent failure because the sender address of
-the original message that caused the bounce is invalid, so the bounce cannot be
-delivered. This is probably the most common case, but there are also other
-conditions that cause freezing, and frozen messages are not always bounce
-messages.
-
- ignore_bounce_errors_after = 2d
- timeout_frozen_after = 7d
-
-The first of these options specifies that failing bounce messages are to be
-discarded after 2 days on the queue. The second specifies that any frozen
-message (whether a bounce message or not) is to be timed out (and discarded)
-after a week. In this configuration, the first setting ensures that no failing
-bounce message ever lasts a week.
-
-
-
-ACL configuration
-~~~~~~~~~~~~~~~~~
-cindex:[default,ACLs]
-cindex:[{ACL},default configuration]
-In the default configuration, the ACL section follows the main configuration.
-It starts with the line
-
- begin acl
-
-and it contains the definitions of two ACLs, called 'acl_check_rcpt' and
-'acl_check_data', that were referenced in the settings of %acl_smtp_rcpt% and
-%acl_smtp_data% above.
-
-cindex:[RCPT,ACL for]
-The first ACL is used for every RCPT command in an incoming SMTP message. Each
-RCPT command specifies one of the message's recipients. The ACL statements
-are considered in order, until the recipient address is either accepted or
-rejected. The RCPT command is then accepted or rejected, according to the
-result of the ACL processing.
-
- acl_check_rcpt:
-
-This line, consisting of a name terminated by a colon, marks the start of the
-ACL, and names it.
-
- accept hosts = :
-
-This ACL statement accepts the recipient if the sending host matches the list.
-But what does that strange list mean? It doesn't actually contain any host
-names or IP addresses. The presence of the colon puts an empty item in the
-list; Exim matches this only if the incoming message did not come from a remote
-host, because in that case, the remote hostname is empty. The colon is
-important. Without it, the list itself is empty, and can never match anything.
-
-What this statement is doing is to accept unconditionally all recipients in
-messages that are submitted by SMTP from local processes using the standard
-input and output (that is, not using TCP/IP). A number of MUAs operate in this
-manner.
-
- deny message = Restricted characters in address
- domains = +local_domains
- local_parts = ^[.] : ^.*[@%!/|]
-
- deny message = Restricted characters in address
- domains = !+local_domains
- local_parts = ^[./|] : ^.*[@%!] : ^.*/\\.\\./
-
-These statements are concerned with local parts that contain any of the
-characters ``@'', ``%'', ``!'', ``/'', ``|'', or dots in unusual places. Although these
-characters are entirely legal in local parts (in the case of ``@'' and leading
-dots, only if correctly quoted), they do not commonly occur in Internet mail
-addresses.
-
-The first three have in the past been associated with explicitly routed
-addresses (percent is still sometimes used -- see the %percent_hack_domains%
-option). Addresses containing these characters are regularly tried by spammers
-in an attempt to bypass relaying restrictions, and also by open relay testing
-programs. Unless you really need them it is safest to reject these characters
-at this early stage. This configuration is heavy-handed in rejecting these
-characters for all messages it accepts from remote hosts. This is a deliberate
-policy of being as safe as possible.
-
-The first rule above is stricter, and is applied to messages that are addressed
-to one of the local domains handled by this host. This is implemented by the
-first condition, which restricts it to domains that are listed in the
-'local_domains' domain list. The ``+'' character is used to indicate a
-reference to a named list. In this configuration, there is just one domain in
-'local_domains', but in general there may be many.
-
-The second condition on the first statement uses two regular expressions to
-block local parts that begin with a dot or contain ``@'', ``%'', ``!'', ``/'', or ``|''.
-If you have local accounts that include these characters, you will have to
-modify this rule.
-
-Empty components (two dots in a row) are not valid in RFC 2822, but Exim
-allows them because they have been encountered in practice. (Consider local
-parts constructed as ``first-initial.second-initial.family-name'' when applied to
-someone like the author of Exim, who has no second initial.) However, a local
-part starting with a dot or containing ``/../'' can cause trouble if it is used
-as part of a file name (for example, for a mailing list). This is also true for
-local parts that contain slashes. A pipe symbol can also be troublesome if the
-local part is incorporated unthinkingly into a shell command line.
-
-The second rule above applies to all other domains, and is less strict. This
-allows your own users to send outgoing messages to sites that use slashes
-and vertical bars in their local parts. It blocks local parts that begin
-with a dot, slash, or vertical bar, but allows these characters within the
-local part. However, the sequence ``/../'' is barred. The use of ``@'', ``%'', and
-``!'' is blocked, as before. The motivation here is to prevent your users (or
-your users' viruses) from mounting certain kinds of attack on remote sites.
-
- accept local_parts = postmaster
- domains = +local_domains
-
-This statement, which has two conditions, accepts an incoming address if the
-local part is 'postmaster' and the domain is one of those listed in the
-'local_domains' domain list. The ``+'' character is used to indicate a
-reference to a named list. In this configuration, there is just one domain in
-'local_domains', but in general there may be many.
-
-The presence of this statement means that mail to postmaster is never blocked
-by any of the subsequent tests. This can be helpful while sorting out problems
-in cases where the subsequent tests are incorrectly denying access.
-
- require verify = sender
-
-This statement requires the sender address to be verified before any subsequent
-ACL statement can be used. If verification fails, the incoming recipient
-address is refused. Verification consists of trying to route the address, to
-see if a bounce message could be delivered to it. In the case of remote
-addresses, basic verification checks only the domain, but 'callouts' can be
-used for more verification if required. Section <<SECTaddressverification>>
-discusses the details of address verification.
-
- accept hosts = +relay_from_hosts
- control = submission
-
-[revisionflag="changed"]
-This statement accepts the address if the message is coming from one of the
-hosts that are defined as being allowed to relay through this host. Recipient
-verification is omitted here, because in many cases the clients are dumb MUAs
-that do not cope well with SMTP error responses. For the same reason, the
-second line specifies ``submission mode'' for messages that are accepted. This
-is described in detail in section <<SECTsubmodnon>>; it causes Exim to fix
-messages that are deficient in some way, for example, because they lack a
-'Date:' header line. If you are actually relaying out from MTAs, you should
-probably add recipient verification here, and disable submission mode.
-
- accept authenticated = *
- control = submission
-
-[revisionflag="changed"]
-This statement accepts the address if the client host has authenticated itself.
-Submission mode is again specified, on the grounds that such messages are most
-likely to come from MUAs. The default configuration does not define any
-authenticators, which means that no client can in fact authenticate. You will
-need to add authenticator definitions if you want to make use of this ACL
-statement.
-
-....
-# deny message = rejected because $sender_host_address is \
-# in a black list at $dnslist_domain\n\
-# $dnslist_text
-# dnslists = black.list.example
-#
-# warn message = X-Warning: $sender_host_address is \
-# in a black list at $dnslist_domain
-# log_message = found in $dnslist_domain
-# dnslists = black.list.example
-....
-
-These commented-out lines are examples of how you could configure Exim to check
-sending hosts against a DNS black list. The first statement rejects messages
-from blacklisted hosts, whereas the second merely inserts a warning header
-line.
-
- accept domains = +local_domains
- endpass
- verify = recipient
-
-This statement accepts the incoming recipient address if its domain is one of
-the local domains, but only if the address can be verified. Verification of
-local addresses normally checks both the local part and the domain. The
-%endpass% line needs some explanation: if the condition above %endpass% fails,
-that is, if the address is not in a local domain, control is passed to the next
-ACL statement. However, if the condition below %endpass% fails, that is, if a
-recipient in a local domain cannot be verified, access is denied and the
-recipient is rejected.
-
- accept domains = +relay_to_domains
- endpass
- verify = recipient
-
-This statement accepts the incoming recipient address if its domain is one of
-the domains for which this host is a relay, but again, only if the address can
-be verified.
-
- deny message = relay not permitted
-
-The final statement denies access, giving a specific error message. Reaching
-the end of the ACL also causes access to be denied, but with the generic
-message ``administrative prohibition''.
-
- acl_check_data:
-
-[revisionflag="changed"]
-This line marks the start of the second ACL, and names it. Most of the contents
-of this ACL are commented out:
-
-[revisionflag="changed"]
-....
-# deny malware = *
-# message = This message contains a virus \
-# ($malware_name).
-....
-
-[revisionflag="changed"]
-These lines are examples of how to arrange for messages to be scanned for
-viruses when Exim has been compiled with the content-scanning extension, and a
-suitable virus scanner is installed. If the message is found to contain a
-virus, it is rejected with the given custom error message.
-
-[revisionflag="changed"]
-....
-# warn spam = nobody
-# message = X-Spam_score: $spam_score\n\
-# X-Spam_score_int: $spam_score_int\n\
-# X-Spam_bar: $spam_bar\n\
-# X-Spam_report: $spam_report
-....
-
-[revisionflag="changed"]
-These lines are an example of how to arrange for messages to be scanned by
-SpamAssassin when Exim has been compiled with the content-scanning extension,
-and SpamAssassin has been installed. The SpamAssassin check is run with
-`nobody` as its user parameter, and the results are added to the message as a
-series of extra header line. In this case, the message is not rejected,
-whatever the spam score.
-
- accept
-
-[revisionflag="changed"]
-This final line in the DATA ACL accepts the message unconditionally.
-
-
-
-Router configuration
-~~~~~~~~~~~~~~~~~~~~
-cindex:[default,routers]
-cindex:[routers,default]
-The router configuration comes next in the default configuration, introduced
-by the line
-
- begin routers
-
-Routers are the modules in Exim that make decisions about where to send
-messages. An address is passed to each router in turn, until it is either
-accepted, or failed. This means that the order in which you define the routers
-matters. Each router is fully described in its own chapter later in this
-manual. Here we give only brief overviews.
-
- # domain_literal:
- # driver = ipliteral
- # domains = !+local_domains
- # transport = remote_smtp
-
-cindex:[domain literal,default router]
-This router is commented out because the majority of sites do not want to
-support domain literal addresses (those of the form 'user@[10.9.8.7]'). If
-you uncomment this router, you also need to uncomment the setting of
-%allow_domain_literals% in the main part of the configuration.
-
- dnslookup:
- driver = dnslookup
- domains = ! +local_domains
- transport = remote_smtp
- ignore_target_hosts = 0.0.0.0 : 127.0.0.0/8
- no_more
-
-The first uncommented router handles addresses that do not involve any local
-domains. This is specified by the line
-
- domains = ! +local_domains
-
-The %domains% option lists the domains to which this router applies, but the
-exclamation mark is a negation sign, so the router is used only for domains
-that are not in the domain list called 'local_domains' (which was defined at
-the start of the configuration). The plus sign before 'local_domains'
-indicates that it is referring to a named list. Addresses in other domains are
-passed on to the following routers.
-
-The name of the router driver is ^dnslookup^,
-and is specified by the %driver% option. Do not be confused by the fact that
-the name of this router instance is the same as the name of the driver. The
-instance name is arbitrary, but the name set in the %driver% option must be one
-of the driver modules that is in the Exim binary.
-
-The ^dnslookup^ router routes addresses by looking up their domains in the
-DNS in order to obtain a list of hosts to which the address is routed. If the
-router succeeds, the address is queued for the ^remote_smtp^ transport, as
-specified by the %transport% option. If the router does not find the domain in
-the DNS, no further routers are tried because of the %no_more% setting, so the
-address fails and is bounced.
-
-The %ignore_target_hosts% option specifies a list of IP addresses that are to
-be entirely ignored. This option is present because a number of cases have been
-encountered where MX records in the DNS point to host names
-whose IP addresses are 0.0.0.0 or are in the 127 subnet (typically 127.0.0.1).
-Completely ignoring these IP addresses causes Exim to fail to route the
-email address, so it bounces. Otherwise, Exim would log a routing problem, and
-continue to try to deliver the message periodically until the address timed
-out.
-
- system_aliases:
- driver = redirect
- allow_fail
- allow_defer
- data = ${lookup{$local_part}lsearch{/etc/aliases}}
- # user = exim
- file_transport = address_file
- pipe_transport = address_pipe
-
-Control reaches this and subsequent routers only for addresses in the local
-domains. This router checks to see whether the local part is defined as an
-alias in the _/etc/aliases_ file, and if so, redirects it according to the
-data that it looks up from that file. If no data is found for the local part,
-the value of the %data% option is empty, causing the address to be passed to
-the next router.
-
-_/etc/aliases_ is a conventional name for the system aliases file that is
-often used. That is why it is referenced by from the default configuration
-file. However, you can change this by setting SYSTEM_ALIASES_FILE in
-_Local/Makefile_ before building Exim.
-
- userforward:
- driver = redirect
- check_local_user
- # local_part_suffix = +* : -*
- # local_part_suffix_optional
- file = $home/.forward
- # allow_filter
- no_verify
- no_expn
- check_ancestor
- file_transport = address_file
- pipe_transport = address_pipe
- reply_transport = address_reply
-
-[revisionflag="changed"]
-This is the most complicated router in the default configuration. It is another
-redirection router, but this time it is looking for forwarding data set up by
-individual users. The %check_local_user% setting specifies a check that the
-local part of the address is the login name of a local user. If it is not, the
-router is skipped. The two commented options that follow %check_local_user%,
-namely:
-
-[revisionflag="changed"]
-....
-# local_part_suffix = +* : -*
-# local_part_suffix_optional
-....
-
-[revisionflag="changed"]
-cindex:[$local_part_suffix$]
-show how you can specify the recognition of local part suffixes. If the first
-is uncommented, a suffix beginning with either a plus or a minus sign, followed
-by any sequence of characters, is removed from the local part and placed in the
-variable $local_part_suffix$. The second suffix option specifies that the
-presence of a suffix in the local part is optional. When a suffix is present,
-the check for a local login uses the local part with the suffix removed.
-
-When a local user account is found, the file called _.forward_ in the user's
-home directory is consulted. If it does not exist, or is empty, the router
-declines. Otherwise, the contents of _.forward_ are interpreted as redirection
-data (see chapter <<CHAPredirect>> for more details).
-
-cindex:[Sieve filter,enabling in default router]
-Traditional _.forward_ files contain just a list of addresses, pipes, or
-files. Exim supports this by default. However, if %allow_filter% is set (it is
-commented out by default), the contents of the file are interpreted as a set of
-Exim or Sieve filtering instructions, provided the file begins with ``#Exim
-filter'' or ``#Sieve filter'', respectively. User filtering is discussed in the
-separate document entitled 'Exim's interfaces to mail filtering'.
-
-The %no_verify% and %no_expn% options mean that this router is skipped when
-verifying addresses, or when running as a consequence of an SMTP EXPN command.
-There are two reasons for doing this:
-
-. Whether or not a local user has a _.forward_ file is not really relevant when
-checking an address for validity; it makes sense not to waste resources doing
-unnecessary work.
-
-. More importantly, when Exim is verifying addresses or handling an EXPN
-command during an SMTP session, it is running as the Exim user, not as root.
-The group is the Exim group, and no additional groups are set up.
-It may therefore not be possible for Exim to read users' _.forward_ files at
-this time.
-
-The setting of %check_ancestor% prevents the router from generating a new
-address that is the same as any previous address that was redirected. (This
-works round a problem concerning a bad interaction between aliasing and
-forwarding -- see section <<SECTredlocmai>>).
-
-The final three option settings specify the transports that are to be used when
-forwarding generates a direct delivery to a file, or to a pipe, or sets up an
-auto-reply, respectively. For example, if a _.forward_ file contains
-
- a.nother@elsewhere.example, /home/spqr/archive
-
-the delivery to _/home/spqr/archive_ is done by running the %address_file%
-transport.
-
- localuser:
- driver = accept
- check_local_user
- # local_part_suffix = +* : -*
- # local_part_suffix_optional
- transport = local_delivery
-
-[revisionflag="changed"]
-The final router sets up delivery into local mailboxes, provided that the local
-part is the name of a local login, by accepting the address and assigning it to
-the ^local_delivery^ transport. Otherwise, we have reached the end of the
-routers, so the address is bounced. The commented suffix settings fulfil the
-same purpose as they do for the ^userforward^ router.
-
-
-
-Transport configuration
-~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[default,transports]
-cindex:[transports,default]
-Transports define mechanisms for actually delivering messages. They operate
-only when referenced from routers, so the order in which they are defined does
-not matter. The transports section of the configuration starts with
-
- begin transports
-
-One remote transport and four local transports are defined.
-
- remote_smtp:
- driver = smtp
-
-This transport is used for delivering messages over SMTP connections. All its
-options are defaulted. The list of remote hosts comes from the router.
-
- local_delivery:
- driver = appendfile
- file = /var/mail/$local_part
- delivery_date_add
- envelope_to_add
- return_path_add
- # group = mail
- # mode = 0660
-
-This ^appendfile^ transport is used for local delivery to user mailboxes in
-traditional BSD mailbox format. By default it runs under the uid and gid of the
-local user, which requires the sticky bit to be set on the _/var/mail_
-directory. Some systems use the alternative approach of running mail deliveries
-under a particular group instead of using the sticky bit. The commented options
-show how this can be done.
-
-Exim adds three headers to the message as it delivers it: 'Delivery-date:',
-'Envelope-to:' and 'Return-path:'. This action is requested by the three
-similarly-named options above.
-
- address_pipe:
- driver = pipe
- return_output
-
-This transport is used for handling deliveries to pipes that are generated by
-redirection (aliasing or users' _.forward_ files). The %return_output%
-option specifies that any output generated by the pipe is to be returned to the
-sender.
-
- address_file:
- driver = appendfile
- delivery_date_add
- envelope_to_add
- return_path_add
-
-This transport is used for handling deliveries to files that are generated by
-redirection. The name of the file is not specified in this instance of
-^appendfile^, because it comes from the ^redirect^ router.
-
- address_reply:
- driver = autoreply
-
-This transport is used for handling automatic replies generated by users'
-filter files.
-
-
-
-Default retry rule
-~~~~~~~~~~~~~~~~~~
-cindex:[retry,default rule]
-cindex:[default,retry rule]
-The retry section of the configuration file contains rules which affect the way
-Exim retries deliveries that cannot be completed at the first attempt. It is
-introduced by the line
-
- begin retry
-
-In the default configuration, there is just one rule, which applies to all
-errors:
-
-&&&
-`\* \* F,2h,15m; G,16h,1h,1.5; F,4d,6h`
-&&&
-
-This causes any temporarily failing address to be retried every 15 minutes for
-2 hours, then at intervals starting at one hour and increasing by a factor of
-1.5 until 16 hours have passed, then every 6 hours up to 4 days. If an address
-is not delivered after 4 days of failure, it is bounced.
-
-
-
-Rewriting configuration
-~~~~~~~~~~~~~~~~~~~~~~~
-The rewriting section of the configuration, introduced by
-
- begin rewrite
-
-contains rules for rewriting addresses in messages as they arrive. There are no
-rewriting rules in the default configuration file.
-
-
-
-Authenticators configuration
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[AUTH,configuration]
-The authenticators section of the configuration, introduced by
-
- begin authenticators
-
-defines mechanisms for the use of the SMTP AUTH command. No authenticators
-are specified in the default configuration file.
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPregexp]]
-Regular expressions
--------------------
-
-cindex:[regular expressions,library]
-cindex:[PCRE]
-Exim supports the use of regular expressions in many of its options. It
-uses the PCRE regular expression library; this provides regular expression
-matching that is compatible with Perl 5. The syntax and semantics of
-regular expressions is discussed in many Perl reference books, and also in
-Jeffrey Friedl's 'Mastering Regular Expressions', which is published by
-O'Reilly (*http://www.oreilly.com/catalog/regex/[]*).
-
-The documentation for the syntax and semantics of the regular expressions that
-are supported by PCRE is included in plain text in the file
-_doc/pcrepattern.txt_ in the Exim distribution, and also in the HTML tarbundle
-of Exim documentation. It describes in detail the features of the regular
-expressions that PCRE supports, so no further description is included here. The
-PCRE functions are called from Exim using the default option settings (that is,
-with no PCRE options set), except that the PCRE_CASELESS option is set when the
-matching is required to be case-insensitive.
-
-In most cases, when a regular expression is required in an Exim configuration,
-it has to start with a circumflex, in order to distinguish it from plain text
-or an ``ends with'' wildcard. In this example of a configuration setting, the
-second item in the colon-separated list is a regular expression.
-
- domains = a.b.c : ^\\d{3} : *.y.z : ...
-
-The doubling of the backslash is required because of string expansion that
-precedes interpretation -- see section <<SECTlittext>> for more discussion of
-this issue, and a way of avoiding the need for doubling backslashes. The
-regular expression that is eventually used in this example contains just one
-backslash. The circumflex is included in the regular expression, and has the
-normal effect of ``anchoring'' it to the start of the string that is being
-matched.
-
-There are, however, two cases where a circumflex is not required for the
-recognition of a regular expression: these are the %match% condition in a
-string expansion, and the %matches% condition in an Exim filter file. In these
-cases, the relevant string is always treated as a regular expression; if it
-does not start with a circumflex, the expression is not anchored, and can match
-anywhere in the subject string.
-
-In all cases, if you want a regular expression to match at the end of a string,
-you must code the \$ metacharacter to indicate this. For example:
-
- domains = ^\\d{3}\\.example
-
-matches the domain '123.example', but it also matches '123.example.com'.
-You need to use:
-
- domains = ^\\d{3}\\.example\$
-
-if you want 'example' to be the top-level domain. The backslash before the
-\$ is needed because string expansion also interprets dollar characters.
-
-
-
-Testing regular expressions
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[testing,regular expressions]
-cindex:[regular expressions,testing]
-cindex:['pcretest']
-A program called 'pcretest' forms part of the PCRE distribution and is built
-with PCRE during the process of building Exim. It is primarily intended for
-testing PCRE itself, but it can also be used for experimenting with regular
-expressions. After building Exim, the binary can be found in the build
-directory (it is not installed anywhere automatically). There is documentation
-of various options in _doc/pcretest.txt_, but for simple testing, none are
-needed. This is the output of a sample run of 'pcretest':
-
-&&&
-` re> `*`/^([^@]+)@.+\.(ac|edu)\.(?!kr)[a-z]{2}$/`*
-`data> `*`x@y.ac.uk`*
-` 0: x@y.ac.uk`
-` 1: x`
-` 2: ac`
-`data> `*`x@y.ac.kr`*
-`No match`
-`data> `*`x@y.edu.com`*
-`No match`
-`data> `*`x@y.edu.co`*
-` 0: x@y.edu.co`
-` 1: x`
-` 2: edu`
-&&&
-
-Input typed by the user is shown in bold face. After the ``re>'' prompt, a
-regular expression enclosed in delimiters is expected. If this compiles without
-error, ``data>'' prompts are given for strings against which the expression is
-matched. An empty data line causes a new regular expression to be read. If the
-match is successful, the captured substring values (that is, what would be in
-the variables $0$, $1$, $2$, etc.) are shown. The above example tests for an
-email address whose domain ends with either ``ac'' or ``edu'' followed by a
-two-character top-level domain that is not ``kr''. The local part is captured
-in $1$ and the ``ac'' or ``edu'' in $2$.
-
-
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPfdlookup]]
-File and database lookups
--------------------------
-cindex:[file,lookup]
-cindex:[database lookups]
-cindex:[lookup,description of]
-Exim can be configured to look up data in files or databases as it processes
-messages. Two different kinds of syntax are used:
-
-. A string that is to be expanded may contain explicit lookup requests. These
-cause parts of the string to be replaced by data that is obtained from the
-lookup. String expansions are described in detail in chapter <<CHAPexpand>>.
-
-. Lists of domains, hosts, and email addresses can contain lookup requests as a
-way of avoiding excessively long linear lists. In this case, the data that is
-returned by the lookup is often (but not always) discarded; whether the lookup
-succeeds or fails is what really counts. These kinds of list are described in
-chapter <<CHAPdomhosaddlists>>.
-
-[revisionflag="changed"]
-String expansions, lists, and lookups interact with each other in such a way
-that there is no order in which to describe any one of them that does not
-involve references to the others. Each of these three chapters makes more sense
-if you have read the other two first. If you are reading this for the first
-time, be aware that some of it will make a lot more sense after you have read
-chapters <<CHAPdomhosaddlists>> and <<CHAPexpand>>.
-
-
-Examples of different lookup syntax
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-It is easy to confuse the two different kinds of lookup, especially as the
-lists that may contain the second kind are always expanded before being
-processed as lists. Therefore, they may also contain lookups of the first kind.
-Be careful to distinguish between the following two examples:
-
- domains = ${lookup{$sender_host_address}lsearch{/some/file}}
- domains = lsearch;/some/file
-
-The first uses a string expansion, the result of which must be a domain list.
-The expansion takes place before the string is processed as a list, and the
-file that is searched could contain lines like this:
-
- 192.168.3.4: domain1:domain2:...
- 192.168.1.9: domain3:domain4:...
-
-The result of the expansion (assuming the lookup succeeds) is a list of domains
-(and possibly other types of item that are allowed in domain lists).
-
-In the second example, the lookup is a single item in a domain list. It causes
-Exim to use a lookup to see if the domain that is being processed can be found
-in the file. The file could contains lines like this:
-
- domain1:
- domain2:
-
-Any data that follows the keys is not relevant when checking that the domain
-matches the list item.
-
-It is possible, though no doubt confusing, to use both kinds of lookup at once.
-Consider a file containing lines like this:
-
- 192.168.5.6: lsearch;/another/file
-
-If the value of $sender_host_address$ is 192.168.5.6, expansion of the
-first %domains% setting above generates the second setting, which therefore
-causes a second lookup to occur.
-
-The rest of this chapter describes the different lookup types that are
-available. Any of them can be used in any part of the configuration where a
-lookup is permitted.
-
-
-Lookup types
-~~~~~~~~~~~~
-cindex:[lookup,types of]
-cindex:[single-key lookup,definition of]
-Two different types of data lookup are implemented:
-
-- The 'single-key' type requires the specification of a file in which to look,
-and a single key to search for. The key must be a non-empty string for the
-lookup to succeed. The lookup type determines how the file is searched.
-
-- cindex:[query-style lookup,definition of]
-The 'query-style' type accepts a generalized database query. No particular key
-value is assumed by Exim for query-style lookups. You can use whichever Exim
-variables you need to construct the database query.
-
-The code for each lookup type is in a separate source file that is included in
-the binary of Exim only if the corresponding compile-time option is set. The
-default settings in _src/EDITME_ are:
-
- LOOKUP_DBM=yes
- LOOKUP_LSEARCH=yes
-
-which means that only linear searching and DBM lookups are included by default.
-For some types of lookup (e.g. SQL databases), you need to install appropriate
-libraries and header files before building Exim.
-
-
-
-
-[[SECTsinglekeylookups]]
-Single-key lookup types
-~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[lookup,single-key types]
-cindex:[single-key lookup,list of types]
-The following single-key lookup types are implemented:
-
-- cindex:[cdb,description of]
-cindex:[lookup,cdb]
-cindex:[binary zero,in lookup key]
-^cdb^: The given file is searched as a Constant DataBase file, using the key
-string without a terminating binary zero. The cdb format is designed for
-indexed files that are read frequently and never updated, except by total
-re-creation. As such, it is particulary suitable for large files containing
-aliases or other indexed data referenced by an MTA. Information about cdb can
-be found in several places:
-+
-&&&
-*http://www.pobox.com/~djb/cdb.html[]*
-*ftp://ftp.corpit.ru/pub/tinycdb/[]*
-*http://packages.debian.org/stable/utils/freecdb.html[]*
-&&&
-+
-A cdb distribution is not needed in order to build Exim with cdb support,
-because the code for reading cdb files is included directly in Exim itself.
-However, no means of building or testing cdb files is provided with Exim, so
-you need to obtain a cdb distribution in order to do this.
-
-- cindex:[DBM,lookup type]
-cindex:[lookup,dbm]
-cindex:[binary zero,in lookup key]
-^dbm^: Calls to DBM library functions are used to extract data from the given
-DBM file by looking up the record with the given key. A terminating binary
-zero is included in the key that is passed to the DBM library. See section
-<<SECTdb>> for a discussion of DBM libraries.
-+
-cindex:[Berkeley DB library,file format]
-For all versions of Berkeley DB, Exim uses the DB_HASH style of database
-when building DBM files using the %exim_dbmbuild% utility. However, when using
-Berkeley DB versions 3 or 4, it opens existing databases for reading with the
-DB_UNKNOWN option. This enables it to handle any of the types of database
-that the library supports, and can be useful for accessing DBM files created by
-other applications. (For earlier DB versions, DB_HASH is always used.)
-
-- cindex:[lookup,dbmnz]
-cindex:[lookup,dbm -- terminating zero]
-cindex:[binary zero,in lookup key]
-cindex:[Courier]
-cindex:[_/etc/userdbshadow.dat_]
-cindex:[dmbnz lookup type]
-^dbmnz^: This is the same as ^dbm^, except that a terminating binary zero
-is not included in the key that is passed to the DBM library. You may need this
-if you want to look up data in files that are created by or shared with some
-other application that does not use terminating zeros. For example, you need to
-use ^dbmnz^ rather than ^dbm^ if you want to authenticate incoming SMTP
-calls using the passwords from Courier's _/etc/userdbshadow.dat_ file. Exim's
-utility program for creating DBM files ('exim_dbmbuild') includes the zeros
-by default, but has an option to omit them (see section <<SECTdbmbuild>>).
-
-- cindex:[lookup,dsearch]
-cindex:[dsearch lookup type]
-^dsearch^: The given file must be a directory; this is searched for a file
-whose name is the key. The key may not contain any forward slash characters.
-The result of a successful lookup is the name of the file. An example of how
-this lookup can be used to support virtual domains is given in section
-<<SECTvirtualdomains>>.
-
-- cindex:[lookup,iplsearch]
-cindex:[iplsearch lookup type]
-^iplsearch^: The given file is a text file containing keys and data. A key is
-terminated by a colon or white space or the end of the line. The keys in the
-file must be IP addresses, or IP addresses with CIDR masks. Keys that involve
-IPv6 addresses must be enclosed in quotes to prevent the first internal colon
-being interpreted as a key terminator. For example:
-
- 1.2.3.4: data for 1.2.3.4
- 192.168.0.0/16 data for 192.168.0.0/16
- "abcd::cdab": data for abcd::cdab
- "abcd:abcd::/32" data for abcd:abcd::/32
-+
-The key for an ^iplsearch^ lookup must be an IP address (without a mask). The
-file is searched linearly, using the CIDR masks where present, until a matching
-key is found. The first key that matches is used; there is no attempt to find a
-``best'' match. Apart from the way the keys are matched, the processing for
-^iplsearch^ is the same as for ^lsearch^.
-+
-*Warning 1*: Unlike most other single-key lookup types, a file of data for
-^iplsearch^ can 'not' be turned into a DBM or cdb file, because those
-lookup types support only literal keys.
-+
-*Warning 2*: In a host list, you must always use ^net-iplsearch^ so that
-the implicit key is the host's IP address rather than its name (see section
-<<SECThoslispatsikey>>).
-
-- cindex:[linear search]
-cindex:[lookup,lsearch]
-cindex:[lsearch lookup type]
-^lsearch^: The given file is a text file that is searched linearly for a
-line beginning with the search key, terminated by a colon or white space or the
-end of the line. The first occurrence that is found in the file is used. White
-space between the key and the colon is permitted. The remainder of the line,
-with leading and trailing white space removed, is the data. This can be
-continued onto subsequent lines by starting them with any amount of white
-space, but only a single space character is included in the data at such a
-junction. If the data begins with a colon, the key must be terminated by a
-colon, for example:
-
- baduser: :fail:
-+
-Empty lines and lines beginning with # are ignored, even if they occur in the
-middle of an item. This is the traditional textual format of alias files. Note
-that the keys in an ^lsearch^ file are literal strings. There is no
-wildcarding of any kind.
-+
-cindex:[lookup,lsearch -- colons in keys]
-cindex:[white space,in lsearch key]
-In most ^lsearch^ files, keys are not required to contain colons or #
-characters, or white space. However, if you need this feature, it is available.
-If a key begins with a doublequote character, it is terminated only by a
-matching quote (or end of line), and the normal escaping rules apply to its
-contents (see section <<SECTstrings>>). An optional colon is permitted after
-quoted keys (exactly as for unquoted keys). There is no special handling of
-quotes for the data part of an ^lsearch^ line.
-
-- cindex:[NIS lookup type]
-cindex:[lookup,NIS]
-cindex:[binary zero,in lookup key]
-^nis^: The given file is the name of a NIS map, and a NIS lookup is done with
-the given key, without a terminating binary zero. There is a variant called
-^nis0^ which does include the terminating binary zero in the key. This is
-reportedly needed for Sun-style alias files. Exim does not recognize NIS
-aliases; the full map names must be used.
-
-- cindex:[wildlsearch lookup type]
-cindex:[lookup,wildlsearch]
-cindex:[nwildlsearch lookup type]
-cindex:[lookup,nwildlsearch]
-^wildlsearch^ or ^nwildlsearch^: These search a file linearly, like ^lsearch^,
-but instead of being interpreted as a literal string, each key in the file may
-be wildcarded. The difference between these two lookup types is that for
-^wildlsearch^, each key in the file is string-expanded before being used,
-whereas for ^nwildlsearch^, no expansion takes place.
-+
-Like ^lsearch^, the testing is done case-insensitively. The following forms
-of wildcard are recognized:
-+
---
-.. The string may begin with an asterisk to mean ``ends with''. For example:
-
- *.a.b.c data for anything.a.b.c
- *fish data for anythingfish
-
-.. The string may begin with a circumflex to indicate a regular expression. For
-example, for ^wildlsearch^:
-
- ^\N\d+\.a\.b\N data for <digits>.a.b
-
-Note the use of `\N` to disable expansion of the contents of the regular
-expression. If you are using ^nwildlsearch^, where the keys are not
-string-expanded, the equivalent entry is:
-
- ^\d+\.a\.b data for <digits>.a.b
-
-If the regular expression contains white space or colon characters, you must
-either quote it (see ^lsearch^ above), or represent these characters in other
-ways. For example, `\s` can be used for white space and `\x3A` for a
-colon. This may be easier than quoting, because if you quote, you have to
-escape all the backslashes inside the quotes.
-
-*Note*: It is not possible to capture substrings in a regular expression match
-for later use, because the results of all lookups are cached. If a lookup is
-repeated, the result is taken from the cache, and no actual pattern matching
-takes place. The values of all the numeric variables are unset after a
-^(n)wildlsearch^ match.
-
-.. Although I cannot see it being of much use, the general matching function
-that is used to implement ^(n)wildlsearch^ means that the string may begin with
-a lookup name terminated by a semicolon, and followed by lookup data. For
-example:
-
- cdb;/some/file data for keys that match the file
-
-The data that is obtained from the nested lookup is discarded.
---
-+
-Keys that do not match any of these patterns are interpreted literally. The
-continuation rules for the data are the same as for ^lsearch^, and keys may
-be followed by optional colons.
-+
-*Warning*: Unlike most other single-key lookup types, a file of data for
-^(n)wildlsearch^ can 'not' be turned into a DBM or cdb file, because those
-lookup types support only literal keys.
-
-
-
-Query-style lookup types
-~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[lookup,query-style types]
-cindex:[query-style lookup,list of types]
-The supported query-style lookup types are listed below. Further details about
-many of them are given in later sections.
-
-- cindex:[DNS,as a lookup type]
-cindex:[lookup,DNS]
-^dnsdb^: This does a DNS search for one or more records whose domain names are
-given in the supplied query. The resulting data is the contents of the records.
-See section <<SECTdnsdb>>.
-
-- cindex:[Interbase lookup type]
-cindex:[lookup,Interbase]
-^ibase^: This does a lookup in an Interbase database.
-
-- cindex:[LDAP,lookup type]
-cindex:[lookup,LDAP]
-^ldap^: This does an LDAP lookup using a query in the form of a URL, and
-returns attributes from a single entry. There is a variant called ^ldapm^
-that permits values from multiple entries to be returned. A third variant
-called ^ldapdn^ returns the Distinguished Name of a single entry instead of
-any attribute values. See section <<SECTldap>>.
-
-- cindex:[MySQL,lookup type]
-cindex:[lookup,MySQL]
-^mysql^: The format of the query is an SQL statement that is passed to a MySQL
-database. See section <<SECTsql>>.
-
-- cindex:[NIS+ lookup type]
-cindex:[lookup,NIS+]
-^nisplus^: This does a NIS+ lookup using a query that can specify the name of
-the field to be returned. See section <<SECTnisplus>>.
-
-- cindex:[Oracle,lookup type]
-cindex:[lookup,Oracle]
-^oracle^: The format of the query is an SQL statement that is passed to an
-Oracle database. See section <<SECTsql>>.
-
-- cindex:[lookup,passwd]
-cindex:[passwd lookup type]
-cindex:[_/etc/passwd_]
-^passwd^ is a query-style lookup with queries that are just user names. The
-lookup calls 'getpwnam()' to interrogate the system password data, and on
-success, the result string is the same as you would get from an ^lsearch^
-lookup on a traditional _/etc/passwd file_, though with `*` for the
-password value. For example:
-
- *:42:42:King Rat:/home/kr:/bin/bash
-
-- cindex:[PostgreSQL lookup type]
-cindex:[lookup,PostgreSQL]
-^pgsql^: The format of the query is an SQL statement that is passed to a
-PostgreSQL database. See section <<SECTsql>>.
-
-[revisionflag="changed"]
-- cindex:[sqlite lookup type]
-cindex:[lookup,sqlite]
-^sqlite^: The format of the query is a file name followed by an SQL statement
-that is passed to an SQLite database. See section <<SECTsqlite>>.
-
-- ^testdb^: This is a lookup type that is used for testing Exim. It is
-not likely to be useful in normal operation.
-
-- cindex:[whoson lookup type]
-cindex:[lookup,whoson]
-^whoson^: 'Whoson' (*http://whoson.sourceforge.net[]*) is a proposed
-Internet protocol that allows Internet server programs to check whether a
-particular (dynamically allocated) IP address is currently allocated to a known
-(trusted) user and, optionally, to obtain the identity of the said user. In
-Exim, this can be used to implement ``POP before SMTP'' checking using ACL
-statements such as
-+
-....
-require condition = \
- ${lookup whoson {$sender_host_address}{yes}{no}}
-....
-+
-The query consists of a single IP address. The value returned is the name of
-the authenticated user.
-
-
-
-Temporary errors in lookups
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[lookup,temporary error in]
-Lookup functions can return temporary error codes if the lookup cannot be
-completed. For example, an SQL or LDAP database might be unavailable. For this
-reason, it is not advisable to use a lookup that might do this for critical
-options such as a list of local domains.
-
-When a lookup cannot be completed in a router or transport, delivery
-of the message (to the relevant address) is deferred, as for any other
-temporary error. In other circumstances Exim may assume the lookup has failed,
-or may give up altogether.
-
-
-
-[[SECTdefaultvaluelookups]]
-Default values in single-key lookups
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[wildcard lookups]
-cindex:[lookup,default values]
-cindex:[lookup,wildcard]
-cindex:[lookup,\* added to type]
-cindex:[default,in single-key lookups]
-In this context, a ``default value'' is a value specified by the administrator
-that is to be used if a lookup fails.
-
-If ``\*'' is added to a single-key lookup type (for example, %lsearch\*%) and
-the initial lookup fails, the key ``\*'' is looked up in the file to provide
-a default value. See also the section on partial matching below.
-
-cindex:[\*@ with single-key lookup]
-cindex:[lookup,\*@ added to type]
-cindex:[alias file,per-domain default]
-Alternatively, if ``\*@'' is added to a single-key lookup type (for example
-\dbm\*\) then, if the initial lookup fails and the key contains an @
-character, a second lookup is done with everything before the last @ replaced
-by \*. This makes it possible to provide per-domain defaults in alias files
-that include the domains in the keys. If the second lookup fails (or doesn't
-take place because there is no @ in the key), ``\*'' is looked up.
-For example, a ^redirect^ router might contain:
-
- data = ${lookup{$local_part@$domain}lsearch*@{/etc/mixed-aliases}}
-
-Suppose the address that is being processed is 'jane@eyre.example'. Exim
-looks up these keys, in this order:
-
- jane@eyre.example
- *@eyre.example
- *
-
-The data is taken from whichever key it finds first. *Note*: in an
-^lsearch^ file, this does not mean the first of these keys in the file. A
-complete scan is done for each key, and only if it is not found at all does
-Exim move on to try the next key.
-
-
-
-[[SECTpartiallookup]]
-Partial matching in single-key lookups
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[partial matching]
-cindex:[wildcard lookups]
-cindex:[lookup,partial matching]
-cindex:[lookup,wildcard]
-cindex:[asterisk,in search type]
-The normal operation of a single-key lookup is to search the file for an exact
-match with the given key. However, in a number of situations where domains are
-being looked up, it is useful to be able to do partial matching. In this case,
-information in the file that has a key starting with ``\*.'' is matched by any
-domain that ends with the components that follow the full stop. For example, if
-a key in a DBM file is
-
- *.dates.fict.example
-
-then when partial matching is enabled this is matched by (amongst others)
-'2001.dates.fict.example' and '1984.dates.fict.example'. It is also matched
-by 'dates.fict.example', if that does not appear as a separate key in the
-file.
-
-*Note*: Partial matching is not available for query-style lookups. It is
-also not available for any lookup items in address lists (see section
-<<SECTaddresslist>>).
-
-Partial matching is implemented by doing a series of separate lookups using
-keys constructed by modifying the original subject key. This means that it can
-be used with any of the single-key lookup types, provided that
-partial matching keys
-beginning with a special prefix (default ``\*.'') are included in the data file.
-Keys in the file that do not begin with the prefix are matched only by
-unmodified subject keys when partial matching is in use.
-
-Partial matching is requested by adding the string ``partial-'' to the front of
-the name of a single-key lookup type, for example, %partial-dbm%. When this is
-done, the subject key is first looked up unmodified; if that fails, ``\*.''
-is added at the start of the subject key, and it is looked up again. If that
-fails, further lookups are tried with dot-separated components removed
-from the start of the subject key, one-by-one, and ``\*.'' added on the front of
-what remains.
-
-A minimum number of two non-\* components are required. This can be adjusted
-by including a number before the hyphen in the search type. For example,
-%partial3-lsearch% specifies a minimum of three non-\* components in the
-modified keys. Omitting the number is equivalent to ``partial2-''. If the subject
-key is '2250.dates.fict.example' then the following keys are looked up when
-the minimum number of non-\* components is two:
-
- 2250.dates.fict.example
- *.2250.dates.fict.example
- *.dates.fict.example
- *.fict.example
-
-As soon as one key in the sequence is successfully looked up, the lookup
-finishes.
-
-cindex:[lookup,partial matching -- changing prefix]
-cindex:[prefix,for partial matching]
-The use of ``\*.'' as the partial matching prefix is a default that can be
-changed. The motivation for this feature is to allow Exim to operate with file
-formats that are used by other MTAs. A different prefix can be supplied in
-parentheses instead of the hyphen after ``partial''. For example:
-
- domains = partial(.)lsearch;/some/file
-
-In this example, if the domain is 'a.b.c', the sequence of lookups is
-`a.b.c`, `.a.b.c`, and `.b.c` (the default minimum of 2 non-wild
-components is unchanged). The prefix may consist of any punctuation characters
-other than a closing parenthesis. It may be empty, for example:
-
- domains = partial1()cdb;/some/file
-
-For this example, if the domain is 'a.b.c', the sequence of lookups is
-`a.b.c`, `b.c`, and `c`.
-
-If ``partial0'' is specified, what happens at the end (when the lookup with just
-one non-wild component has failed, and the original key is shortened right down
-to the null string) depends on the prefix:
-
-- If the prefix has zero length, the whole lookup fails.
-
-- If the prefix has length 1, a lookup for just the prefix is done. For
-example, the final lookup for ``partial0(.)'' is for `.` alone.
-
-- Otherwise, if the prefix ends in a dot, the dot is removed, and the
-remainder is looked up. With the default prefix, therefore, the final lookup is
-for ``\*'' on its own.
-
-- Otherwise, the whole prefix is looked up.
-
-
-If the search type ends in ``\*'' or ``\*@'' (see section
-<<SECTdefaultvaluelookups>> above), the search for an ultimate default that this
-implies happens after all partial lookups have failed. If ``partial0'' is
-specified, adding ``\*'' to the search type has no effect with the default
-prefix, because the ``\*'' key is already included in the sequence of partial
-lookups. However, there might be a use for lookup types such as
-``partial0(.)lsearch\*''.
-
-The use of ``\*'' in lookup partial matching differs from its use as a wildcard
-in domain lists and the like. Partial matching works only in terms of
-dot-separated components; a key such as `*fict.example`
-in a database file is useless, because the asterisk in a partial matching
-subject key is always followed by a dot.
-
-
-
-
-Lookup caching
-~~~~~~~~~~~~~~
-cindex:[lookup,caching]
-cindex:[caching,lookup data]
-Exim caches all lookup results in order to avoid needless repetition of
-lookups. However, because (apart from the daemon) Exim operates as a collection
-of independent, short-lived processes, this caching applies only within a
-single Exim process. There is no inter-process caching facility.
-
-For single-key lookups, Exim keeps the relevant files open in case there is
-another lookup that needs them. In some types of configuration this can lead to
-many files being kept open for messages with many recipients. To avoid hitting
-the operating system limit on the number of simultaneously open files, Exim
-closes the least recently used file when it needs to open more files than its
-own internal limit, which can be changed via the %lookup_open_max% option.
-
-The single-key lookup files are closed and the lookup caches are flushed at
-strategic points during delivery -- for example, after all routing is complete.
-
-
-
-
-Quoting lookup data
-~~~~~~~~~~~~~~~~~~~
-cindex:[lookup,quoting]
-cindex:[quoting,in lookups]
-When data from an incoming message is included in a query-style lookup, there
-is the possibility of special characters in the data messing up the syntax of
-the query. For example, a NIS+ query that contains
-
- [name=$local_part]
-
-will be broken if the local part happens to contain a closing square bracket.
-For NIS+, data can be enclosed in double quotes like this:
-
- [name="$local_part"]
-
-but this still leaves the problem of a double quote in the data. The rule for
-NIS+ is that double quotes must be doubled. Other lookup types have different
-rules, and to cope with the differing requirements, an expansion operator
-of the following form is provided:
-
- \$\{quote_<lookup-type>:<string>\}
-
-For example, the safest way to write the NIS+ query is
-
- [name="${quote_nisplus:$local_part}"]
-
-See chapter <<CHAPexpand>> for full coverage of string expansions. The quote
-operator can be used for all lookup types, but has no effect for single-key
-lookups, since no quoting is ever needed in their key strings.
-
-
-
-
-[[SECTdnsdb]]
-More about dnsdb
-~~~~~~~~~~~~~~~~
-cindex:[dnsdb lookup]
-cindex:[lookup,dnsdb]
-cindex:[DNS,as a lookup type]
-The ^dnsdb^ lookup type uses the DNS as its database. A simple query consists
-of a record type and a domain name, separated by an equals sign. For example,
-an expansion string could contain:
-
- ${lookup dnsdb{mx=a.b.example}{$value}fail}
-
-The supported DNS record types are A, CNAME, MX, NS, PTR, SRV, and TXT, and,
-when Exim is compiled with IPv6 support, AAAA (and A6 if that is also
-configured). If no type is given, TXT is assumed. When the type is PTR,
-the data can be an IP address, written as normal; inversion and the addition of
-%in-addr.arpa% or %ip6.arpa% happens automatically. For example:
-
- ${lookup dnsdb{ptr=192.168.4.5}{$value}fail}
-
-If the data for a PTR record is not a syntactically valid IP address, it is not
-altered and nothing is added.
-
-cindex:[MX record,in ^dnsdb^ lookup]
-cindex:[SRV record,in ^dnsdb^ lookup]
-For an MX lookup, both the preference value and the host name are returned for
-each record, separated by a space. For an SRV lookup, the priority, weight,
-port, and host name are returned for each record, separated by spaces.
-
-For any record type, if multiple records are found (or, for A6 lookups, if a
-single record leads to multiple addresses), the data is returned as a
-concatenation, with newline as the default separator. The order, of course,
-depends on the DNS resolver. You can specify a different separator character
-between multiple records by putting a right angle-bracket followed immediately
-by the new separator at the start of the query. For example:
-
- ${lookup dnsdb{>: a=host1.example}}
-
-It is permitted to specify a space as the separator character. Further
-white space is ignored.
-
-Pseudo dnsdb record types
-~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[MX record,in ^dnsdb^ lookup]
-By default, both the preference value and the host name are returned for
-each MX record, separated by a space. If you want only host names, you can use
-the pseudo-type MXH:
-
- ${lookup dnsdb{mxh=a.b.example}}
-
-In this case, the preference values are omitted, and just the host names are
-returned.
-
-cindex:[name server,for enclosing domain]
-Another pseudo-type is ZNS (for ``zone NS''). It performs a lookup for NS
-records on the given domain, but if none are found, it removes the first
-component of the domain name, and tries again. This process continues until NS
-records are found or there are no more components left (or there is a DNS
-error). In other words, it may return the name servers for a top-level domain,
-but it never returns the root name servers. If there are no NS records for the
-top-level domain, the lookup fails. Consider these examples:
-
- ${lookup dnsdb{zns=xxx.quercite.com}}
- ${lookup dnsdb{zns=xxx.edu}}
-
-Assuming that in each case there are no NS records for the full domain name,
-the first returns the name servers for %quercite.com%, and the second returns
-the name servers for %edu%.
-
-You should be careful about how you use this lookup because, unless the
-top-level domain does not exist, the lookup always returns some host names. The
-sort of use to which this might be put is for seeing if the name servers for a
-given domain are on a blacklist. You can probably assume that the name servers
-for the high-level domains such as %com% or %co.uk% are not going to be on such
-a list.
-
-[revisionflag="changed"]
-cindex:[CSA,in ^dnsdb^ lookup]
-A third pseudo-type is CSA (Client SMTP Authorization), which looks up SRV
-records according to the CSA rules, which are described in section
-<<SECTverifyCSA>>. Although ^dnsdb^ supports SRV lookups directly, this is not
-sufficient because of the extra parent domain search behaviour of CSA. The
-result of a successful lookup such as:
-
-[revisionflag="changed"]
-....
-${lookup dnsdb {csa=$sender_helo_name}}
-....
-
-[revisionflag="changed"]
-has two space-separated fields: an authorization code and a target host name.
-The authorization code can be ``Y'' for yes, ``N'' for no, ``X'' for explicit
-authorization required but absent, or ``?'' for unknown.
-
-
-
-Multiple dnsdb lookups
-~~~~~~~~~~~~~~~~~~~~~~
-In the previous sections, ^dnsdb^ lookups for a single domain are described.
-However, you can specify a list of domains or IP addresses in a single
-^dnsdb^ lookup. The list is specified in the normal Exim way, with colon as
-the default separator, but with the ability to change this. For example:
-
- ${lookup dnsdb{one.domain.com:two.domain.com}}
- ${lookup dnsdb{a=one.host.com:two.host.com}}
- ${lookup dnsdb{ptr = <; 1.2.3.4 ; 4.5.6.8}}
-
-In order to retain backwards compatibility, there is one special case: if
-the lookup type is PTR and no change of separator is specified, Exim looks
-to see if the rest of the string is precisely one IPv6 address. In this
-case, it does not treat it as a list.
-
-The data from each lookup is concatenated, with newline separators by default,
-in the same way that multiple DNS records for a single item are handled. A
-different separator can be specified, as described above.
-
-The ^dnsdb^ lookup fails only if all the DNS lookups fail. If there is a
-temporary DNS error for any of them, the behaviour is controlled by
-an optional keyword followed by a comma that may appear before the record
-type. The possible keywords are ``defer_strict'', ``defer_never'', and
-``defer_lax''. With ``strict'' behaviour, any temporary DNS error causes the
-whole lookup to defer. With ``never'' behaviour, a temporary DNS error is
-ignored, and the behaviour is as if the DNS lookup failed to find anything.
-With ``lax'' behaviour, all the queries are attempted, but a temporary DNS
-error causes the whole lookup to defer only if none of the other lookups
-succeed. The default is ``lax'', so the following lookups are equivalent:
-
- ${lookup dnsdb{defer_lax,a=one.host.com:two.host.com}}
- ${lookup dnsdb{a=one.host.com:two.host.com}}
-
-Thus, in the default case, as long as at least one of the DNS lookups
-yields some data, the lookup succeeds.
-
-
-
-
-[[SECTldap]]
-More about LDAP
-~~~~~~~~~~~~~~~
-cindex:[LDAP lookup]
-cindex:[lookup,LDAP]
-cindex:[Solaris,LDAP]
-The original LDAP implementation came from the University of Michigan; this has
-become ``Open LDAP'', and there are now two different releases. Another
-implementation comes from Netscape, and Solaris 7 and subsequent releases
-contain inbuilt LDAP support. Unfortunately, though these are all compatible at
-the lookup function level, their error handling is different. For this reason
-it is necessary to set a compile-time variable when building Exim with LDAP, to
-indicate which LDAP library is in use. One of the following should appear in
-your _Local/Makefile_:
-
- LDAP_LIB_TYPE=UMICHIGAN
- LDAP_LIB_TYPE=OPENLDAP1
- LDAP_LIB_TYPE=OPENLDAP2
- LDAP_LIB_TYPE=NETSCAPE
- LDAP_LIB_TYPE=SOLARIS
-
-If LDAP_LIB_TYPE is not set, Exim assumes `OPENLDAP1`, which has the
-same interface as the University of Michigan version.
-
-There are three LDAP lookup types in Exim. These behave slightly differently in
-the way they handle the results of a query:
-
-- ^ldap^ requires the result to contain just one entry; if there are more, it
-gives an error.
-
-- ^ldapdn^ also requires the result to contain just one entry, but it is the
-Distinguished Name that is returned rather than any attribute values.
-
-- ^ldapm^ permits the result to contain more than one entry; the attributes from
-all of them are returned.
-
-
-For ^ldap^ and ^ldapm^, if a query finds only entries with no attributes,
-Exim behaves as if the entry did not exist, and the lookup fails. The format of
-the data returned by a successful lookup is described in the next section.
-First we explain how LDAP queries are coded.
-
-
-[[SECTforldaque]]
-Format of LDAP queries
-~~~~~~~~~~~~~~~~~~~~~~
-cindex:[LDAP,query format]
-An LDAP query takes the form of a URL as defined in RFC 2255. For example, in
-the configuration of a ^redirect^ router one might have this setting:
-
-....
-data = ${lookup ldap \
- {ldap:///cn=$local_part,o=University%20of%20Cambridge,\
- c=UK?mailbox?base?}}
-....
-
-cindex:[LDAP,with TLS]
-The URL may begin with `ldap` or `ldaps` if your LDAP library supports
-secure (encrypted) LDAP connections. The second of these ensures that an
-encrypted TLS connection is used.
-
-
-LDAP quoting
-~~~~~~~~~~~~
-cindex:[LDAP,quoting]
-Two levels of quoting are required in LDAP queries, the first for LDAP itself
-and the second because the LDAP query is represented as a URL. Furthermore,
-within an LDAP query, two different kinds of quoting are required. For this
-reason, there are two different LDAP-specific quoting operators.
-
-The %quote_ldap% operator is designed for use on strings that are part of
-filter specifications. Conceptually, it first does the following conversions on
-the string:
-
-....
-* => \2A
-( => \28
-) => \29
-\ => \5C
-....
-
-in accordance with RFC 2254. The resulting string is then quoted according
-to the rules for URLs, that is, all characters except
-
- ! $ ' - . _ ( ) * +
-
-are converted to their hex values, preceded by a percent sign. For example:
-
- ${quote_ldap: a(bc)*, a<yz>; }
-
-yields
-
- %20a%5C28bc%5C29%5C2A%2C%20a%3Cyz%3E%3B%20
-
-Removing the URL quoting, this is (with a leading and a trailing space):
-
- a\28bc\29\2A, a<yz>;
-
-
-The %quote_ldap_dn% operator is designed for use on strings that are part of
-base DN specifications in queries. Conceptually, it first converts the string
-by inserting a backslash in front of any of the following characters:
-
- , + " \ < > ;
-
-It also inserts a backslash before any leading spaces or # characters, and
-before any trailing spaces. (These rules are in RFC 2253.) The resulting string
-is then quoted according to the rules for URLs. For example:
-
- ${quote_ldap_dn: a(bc)*, a<yz>; }
-
-yields
-
- %5C%20a(bc)*%5C%2C%20a%5C%3Cyz%5C%3E%5C%3B%5C%20
-
-Removing the URL quoting, this is (with a trailing space):
-
-....
-\ a(bc)*\, a\<yz\>\;\
-....
-
-There are some further comments about quoting in the section on LDAP
-authentication below.
-
-
-LDAP connections
-~~~~~~~~~~~~~~~~
-cindex:[LDAP,connections]
-The connection to an LDAP server may either be over TCP/IP, or, when OpenLDAP
-is in use, via a Unix domain socket. The example given above does not specify
-an LDAP server. A server that is reached by TCP/IP can be specified in a query
-by starting it with
-
- ldap://<hostname>:<port>/...
-
-If the port (and preceding colon) are omitted, the standard LDAP port (389) is
-used. When no server is specified in a query, a list of default servers is
-taken from the %ldap_default_servers% configuration option. This supplies a
-colon-separated list of servers which are tried in turn until one successfully
-handles a query, or there is a serious error. Successful handling either
-returns the requested data, or indicates that it does not exist. Serious errors
-are syntactical, or multiple values when only a single value is expected.
-Errors which cause the next server to be tried are connection failures, bind
-failures, and timeouts.
-
-For each server name in the list, a port number can be given. The standard way
-of specifing a host and port is to use a colon separator (RFC 1738). Because
-%ldap_default_servers% is a colon-separated list, such colons have to be
-doubled. For example
-
- ldap_default_servers = ldap1.example.com::145:ldap2.example.com
-
-If %ldap_default_servers% is unset, a URL with no server name is passed
-to the LDAP library with no server name, and the library's default (normally
-the local host) is used.
-
-If you are using the OpenLDAP library, you can connect to an LDAP server using
-a Unix domain socket instead of a TCP/IP connection. This is specified by using
-`ldapi` instead of `ldap` in LDAP queries. What follows here applies only
-to OpenLDAP. If Exim is compiled with a different LDAP library, this feature is
-not available.
-
-For this type of connection, instead of a host name for the server, a pathname
-for the socket is required, and the port number is not relevant. The pathname
-can be specified either as an item in %ldap_default_servers%, or inline in
-the query. In the former case, you can have settings such as
-
- ldap_default_servers = /tmp/ldap.sock : backup.ldap.your.domain
-
-When the pathname is given in the query, you have to escape the slashes as
-`%2F` to fit in with the LDAP URL syntax. For example:
-
- ${lookup ldap {ldapi://%2Ftmp%2Fldap.sock/o=...
-
-When Exim processes an LDAP lookup and finds that the ``hostname'' is really
-a pathname, it uses the Unix domain socket code, even if the query actually
-specifies `ldap` or `ldaps`. In particular, no encryption is used for a
-socket connection. This behaviour means that you can use a setting of
-%ldap_default_servers% such as in the example above with traditional `ldap`
-or `ldaps` queries, and it will work. First, Exim tries a connection via
-the Unix domain socket; if that fails, it tries a TCP/IP connection to the
-backup host.
-
-If an explicit `ldapi` type is given in a query when a host name is
-specified, an error is diagnosed. However, if there are more items in
-%ldap_default_servers%, they are tried. In other words:
-
-- Using a pathname with `ldap` or `ldaps` forces the use of the Unix domain
-interface.
-
-- Using `ldapi` with a host name causes an error.
-
-
-Using `ldapi` with no host or path in the query, and no setting of
-%ldap_default_servers%, does whatever the library does by default.
-
-
-
-LDAP authentication and control information
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[LDAP,authentication]
-The LDAP URL syntax provides no way of passing authentication and other control
-information to the server. To make this possible, the URL in an LDAP query may
-be preceded by any number of ``<''name'>=<'value'>' settings, separated by
-spaces. If a value contains spaces it must be enclosed in double quotes, and
-when double quotes are used, backslash is interpreted in the usual way inside
-them. The following names are recognized:
-
-&&&
-`DEREFERENCE` set the dereferencing parameter
-`NETTIME ` set a timeout for a network operation
-`USER ` set the DN, for authenticating the LDAP bind
-`PASS ` set the password, likewise
-`SIZE ` set the limit for the number of entries returned
-`TIME ` set the maximum waiting time for a query
-&&&
-
-The value of the DEREFERENCE parameter must be one of the words ``never'',
-``searching'', ``finding'', or ``always''.
-
-The name CONNECT is an obsolete name for NETTIME, retained for
-backwards compatibility. This timeout (specified as a number of seconds) is
-enforced from the client end for operations that can be carried out over a
-network. Specifically, it applies to network connections and calls to the
-'ldap_result()' function. If the value is greater than zero, it is used if
-LDAP_OPT_NETWORK_TIMEOUT is defined in the LDAP headers (OpenLDAP), or
-if LDAP_X_OPT_CONNECT_TIMEOUT is defined in the LDAP headers (Netscape
-SDK 4.1). A value of zero forces an explicit setting of ``no timeout'' for
-Netscape SDK; for OpenLDAP no action is taken.
-
-The TIME parameter (also a number of seconds) is passed to the server to
-set a server-side limit on the time taken to complete a search.
-
-
-Here is an example of an LDAP query in an Exim lookup that uses some of these
-values. This is a single line, folded for ease of reading:
-
- ${lookup ldap
- {user="cn=manager,o=University of Cambridge,c=UK" pass=secret
- ldap:///o=University%20of%20Cambridge,c=UK?sn?sub?(cn=foo)}
- {$value}fail}
-
-The encoding of spaces as {pc}20 is a URL thing which should not be done for any
-of the auxiliary data. Exim configuration settings that include lookups which
-contain password information should be preceded by ``hide'' to prevent non-admin
-users from using the %-bP% option to see their values.
-
-The auxiliary data items may be given in any order. The default is no
-connection timeout (the system timeout is used), no user or password, no limit
-on the number of entries returned, and no time limit on queries.
-
-When a DN is quoted in the USER= setting for LDAP authentication, Exim
-removes any URL quoting that it may contain before passing it LDAP. Apparently
-some libraries do this for themselves, but some do not. Removing the URL
-quoting has two advantages:
-
-- It makes it possible to use the same %quote_ldap_dn% expansion for USER=
-DNs as with DNs inside actual queries.
-
-- It permits spaces inside USER= DNs.
-
-For example, a setting such as
-
- USER=cn=${quote_ldap_dn:$1}
-
-should work even if $1$ contains spaces.
-
-Expanded data for the PASS= value should be quoted using the %quote%
-expansion operator, rather than the LDAP quote operators. The only reason this
-field needs quoting is to ensure that it conforms to the Exim syntax, which
-does not allow unquoted spaces. For example:
-
- PASS=${quote:$3}
-
-
-The LDAP authentication mechanism can be used to check passwords as part of
-SMTP authentication. See the %ldapauth% expansion string condition in chapter
-<<CHAPexpand>>.
-
-
-
-Format of data returned by LDAP
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[LDAP,returned data formats]
-The ^ldapdn^ lookup type returns the Distinguished Name from a single entry as
-a sequence of values, for example
-
- cn=manager, o=University of Cambridge, c=UK
-
-
-The ^ldap^ lookup type generates an error if more than one entry matches the
-search filter, whereas ^ldapm^ permits this case, and inserts a newline in
-the result between the data from different entries. It is possible for multiple
-values to be returned for both ^ldap^ and ^ldapm^, but in the former case
-you know that whatever values are returned all came from a single entry in the
-directory.
-
-In the common case where you specify a single attribute in your LDAP query, the
-result is not quoted, and does not contain the attribute name. If the attribute
-has multiple values, they are separated by commas.
-
-If you specify multiple attributes, the result contains space-separated, quoted
-strings, each preceded by the attribute name and an equals sign. Within the
-quotes, the quote character, backslash, and newline are escaped with
-backslashes, and commas are used to separate multiple values for the attribute.
-Apart from the escaping, the string within quotes takes the same form as the
-output when a single attribute is requested. Specifying no attributes is the
-same as specifying all of an entry's attributes.
-
-Here are some examples of the output format. The first line of each pair is an
-LDAP query, and the second is the data that is returned. The attribute called
-%attr1% has two values, whereas %attr2% has only one value:
-
- ldap:///o=base?attr1?sub?(uid=fred)
- value1.1, value1.2
-
- ldap:///o=base?attr2?sub?(uid=fred)
- value two
-
- ldap:///o=base?attr1,attr2?sub?(uid=fred)
- attr1="value1.1, value1.2" attr2="value two"
-
- ldap:///o=base??sub?(uid=fred)
- objectClass="top" attr1="value1.1, value1.2" attr2="value two"
-
-The %extract% operator in string expansions can be used to pick out individual
-fields from data that consists of 'key'='value' pairs. You can make use
-of Exim's %-be% option to run expansion tests and thereby check the results of
-LDAP lookups.
-
-
-
-
-[[SECTnisplus]]
-More about NIS+
-~~~~~~~~~~~~~~~
-cindex:[NIS+ lookup type]
-cindex:[lookup,NIS+]
-NIS+ queries consist of a NIS+ 'indexed name' followed by an optional colon
-and field name. If this is given, the result of a successful query is the
-contents of the named field; otherwise the result consists of a concatenation
-of 'field-name=field-value' pairs, separated by spaces. Empty values and
-values containing spaces are quoted. For example, the query
-
- [name=mg1456],passwd.org_dir
-
-might return the string
-
- name=mg1456 passwd="" uid=999 gid=999 gcos="Martin Guerre"
- home=/home/mg1456 shell=/bin/bash shadow=""
-
-(split over two lines here to fit on the page), whereas
-
- [name=mg1456],passwd.org_dir:gcos
-
-would just return
-
- Martin Guerre
-
-with no quotes. A NIS+ lookup fails if NIS+ returns more than one table entry
-for the given indexed key. The effect of the %quote_nisplus% expansion
-operator is to double any quote characters within the text.
-
-
-
-[[SECTsql]]
-SQL lookups
-~~~~~~~~~~~
-[revisionflag="changed"]
-cindex:[SQL lookup types]
-Exim can support lookups in Interbase, MySQL, Oracle, PostgreSQL, and SQLite
-databases. Queries for these databases contain SQL statements, so an example
-might be
-
-....
-${lookup mysql{select mailbox from users where id='userx'}\
- {$value}fail}
-....
-
-If the result of the query contains more than one field, the data for each
-field in the row is returned, preceded by its name, so the result of
-
-....
-${lookup pgsql{select home,name from users where id='userx'}\
- {$value}}
-....
-
-might be
-
- home=/home/userx name="Mister X"
-
-Empty values and values containing spaces are double quoted, with embedded
-quotes escaped by a backslash. If the result of the query contains just one
-field, the value is passed back verbatim, without a field name, for example:
-
- Mister X
-
-If the result of the query yields more than one row, it is all concatenated,
-with a newline between the data for each row.
-
-
-More about MySQL, PostgreSQL, Oracle, and Interbase
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[MySQL,lookup type]
-cindex:[PostgreSQL lookup type]
-cindex:[lookup,MySQL]
-cindex:[lookup,PostgreSQL]
-cindex:[Oracle,lookup type]
-cindex:[lookup,Oracle]
-cindex:[Interbase lookup type]
-cindex:[lookup,Interbase]
-If any MySQL, PostgreSQL, Oracle, or Interbase lookups are used, the
-%mysql_servers%, %pgsql_servers%, %oracle_servers%, or %ibase_servers% option
-(as appropriate) must be set to a colon-separated list of server information.
-Each item in the list is a slash-separated list of four items: host name,
-database name, user name, and password. In the case of Oracle, the host name
-field is used for the ``service name'', and the database name field is not used
-and should be empty. For example:
-
- hide oracle_servers = oracle.plc.example//userx/abcdwxyz
-
-Because password data is sensitive, you should always precede the setting with
-``hide'', to prevent non-admin users from obtaining the setting via the %-bP%
-option. Here is an example where two MySQL servers are listed:
-
-....
-hide mysql_servers = localhost/users/root/secret:\
- otherhost/users/root/othersecret
-....
-
-For MySQL and PostgreSQL, a host may be specified as <'name'>:<'port'> but
-because this is a colon-separated list, the colon has to be doubled. For each
-query, these parameter groups are tried in order until a connection and a query
-succeeds.
-
-The %quote_mysql%, %quote_pgsql%, and %quote_oracle% expansion operators
-convert newline, tab, carriage return, and backspace to \n, \t, \r, and \b
-respectively, and the characters single-quote, double-quote, and backslash
-itself are escaped with backslashes. The %quote_pgsql% expansion operator, in
-addition, escapes the percent and underscore characters. This cannot be done
-for MySQL because these escapes are not recognized in contexts where these
-characters are not special.
-
-
-Special MySQL features
-~~~~~~~~~~~~~~~~~~~~~~
-For MySQL, an empty host name or the use of ``localhost'' in %mysql_servers%
-causes a connection to the server on the local host by means of a Unix domain
-socket. An alternate socket can be specified in parentheses. The full syntax of
-each item in %mysql_servers% is:
-
-&&&
-<'hostname'>::<'port'>(<'socket name'>)/<'database'>/<'user'>/<'password'>
-&&&
-
-Any of the three sub-parts of the first field can be omitted. For normal use on
-the local host it can be left blank or set to just ``localhost''.
-
-No database need be supplied -- but if it is absent here, it must be given in
-the queries.
-
-If a MySQL query is issued that does not request any data (an insert, update,
-or delete command), the result of the lookup is the number of rows affected.
-
-*Warning*: this can be misleading. If an update does not actually change
-anything (for example, setting a field to the value it already has), the result
-is zero because no rows are affected.
-
-
-Special PostgreSQL features
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
-PostgreSQL lookups can also use Unix domain socket connections to the database.
-This is usually faster and costs less CPU time than a TCP/IP connection.
-However it can be used only if the mail server runs on the same machine as the
-database server. A configuration line for PostgreSQL via Unix domain sockets
-looks like this:
-
- hide pgsql_servers = (/tmp/.s.PGSQL.5432)/db/user/password : ...
-
-In other words, instead of supplying a host name, a path to the socket is
-given. The path name is enclosed in parentheses so that its slashes aren't
-visually confused with the delimiters for the other server parameters.
-
-If a PostgreSQL query is issued that does not request any data (an insert,
-update, or delete command), the result of the lookup is the number of rows
-affected.
-
-[[SECTsqlite]]
-More about SQLite
-~~~~~~~~~~~~~~~~~
-[revisionflag="changed"]
-cindex:[lookup,SQLite]
-cindex:[SQLite lookup type]
-SQLite is different to the other SQL lookups because a file name is required in
-addition to the SQL query. An SQLite database is a single file, and there is no
-daemon as in the other SQL databases. The interface to Exim requires the name
-of the file, as an absolute path, to be given at the start of the query. It is
-separated from the query by white space. This means that the path name cannot
-contain white space. Here is a lookup expansion example:
-
-....
-${lookup sqlite {/some/thing/sqlitedb \
- select name from aliases where id='userx';}}
-....
-
-[revisionflag="changed"]
-In a list, the syntax is similar. For example:
-
-....
-domainlist relay_domains = sqlite;/some/thing/sqlitedb \
- select * from relays where ip='$sender_host_address';
-....
-
-[revisionflag="changed"]
-The only character affected by the %quote_sqlite% operator is a single
-quote, which it doubles.
-
-[revisionflag="changed"]
-The SQLite library handles multiple simultaneous accesses to the database
-internally. Multiple readers are permitted, but only one process can
-update at once. Attempts to access the database while it is being updated
-are rejected after a timeout period, during which the SQLite library
-waits for the lock to be released. In Exim, the default timeout is set
-to 5 seconds, but it can be changed by means of the %sqlite_lock_timeout%
-option.
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPdomhosaddlists]]
-[titleabbrev="Domain, host, and address lists"]
-Domain, host, address, and local part lists
--------------------------------------------
-cindex:[list of domains; hosts; etc.]
-A number of Exim configuration options contain lists of domains, hosts,
-email addresses, or local parts. For example, the %hold_domains% option
-contains a list of domains whose delivery is currently suspended. These lists
-are also used as data in ACL statements (see chapter <<CHAPACL>>), and as
-arguments to expansion conditions such as %match_domain%.
-
-Each item in one of these lists is a pattern to be matched against a domain,
-host, email address, or local part, respectively. In the sections below, the
-different types of pattern for each case are described, but first we cover some
-general facilities that apply to all four kinds of list.
-
-
-
-Expansion of lists
-~~~~~~~~~~~~~~~~~~
-cindex:[expansion,of lists]
-Each list is expanded as a single string before it is used. The result of
-expansion must be a list, possibly containing empty items, which is split up
-into separate items for matching. By default, colon is the separator character,
-but this can be varied if necessary. See sections <<SECTlistconstruct>> and
-<<SECTempitelis>> for details of the list syntax; the second of these discusses
-the way to specify empty list items.
-
-
-If the string expansion is forced to fail, Exim behaves as if the item it is
-testing (domain, host, address, or local part) is not in the list. Other
-expansion failures cause temporary errors.
-
-If an item in a list is a regular expression, backslashes, dollars and possibly
-other special characters in the expression must be protected against
-misinterpretation by the string expander. The easiest way to do this is to use
-the `\N` expansion feature to indicate that the contents of the regular
-expression should not be expanded. For example, in an ACL you might have:
-
-....
-deny senders = \N^\d{8}\w@.*\.baddomain\.example$\N : \
- ${lookup{$domain}lsearch{/badsenders/bydomain}}
-....
-
-The first item is a regular expression that is protected from expansion by
-`\N`, whereas the second uses the expansion to obtain a list of unwanted
-senders based on the receiving domain.
-
-
-
-
-Negated items in lists
-~~~~~~~~~~~~~~~~~~~~~~
-cindex:[list,negation]
-cindex:[negation in lists]
-Items in a list may be positive or negative. Negative items are indicated by a
-leading exclamation mark, which may be followed by optional white space. A list
-defines a set of items (domains, etc). When Exim processes one of these lists,
-it is trying to find out whether a domain, host, address, or local part
-(respectively) is in the set that is defined by the list. It works like this:
-
-The list is scanned from left to right. If a positive item is matched, the
-subject that is being checked is in the set; if a negative item is matched, the
-subject is not in the set. If the end of the list is reached without the
-subject having matched any of the patterns, it is in the set if the last item
-was a negative one, but not if it was a positive one. For example, the list in
-
- domainlist relay_domains = !a.b.c : *.b.c
-
-matches any domain ending in '.b.c' except for 'a.b.c'. Domains that match
-neither 'a.b.c' nor '*.b.c' do not match, because the last item in the
-list is positive. However, if the setting were
-
- domainlist relay_domains = !a.b.c
-
-then all domains other than 'a.b.c' would match because the last item in the
-list is negative. In other words, a list that ends with a negative item behaves
-as if it had an extra item `:*` on the end.
-
-Another way of thinking about positive and negative items in lists is to read
-the connector as ``or'' after a positive item and as ``and'' after a negative
-item.
-
-
-
-[[SECTfilnamlis]]
-File names in lists
-~~~~~~~~~~~~~~~~~~~
-cindex:[list,file name in]
-If an item in a domain, host, address, or local part list is an absolute file
-name (beginning with a slash character), each line of the file is read and
-processed as if it were an independent item in the list, except that further
-file names are not allowed,
-and no expansion of the data from the file takes place.
-Empty lines in the file are ignored, and the file may also contain comment
-lines:
-
-- For domain and host lists, if a # character appears anywhere in a line of the
-file, it and all following characters are ignored.
-
-- Because local parts may legitimately contain # characters, a comment in an
-address list or local part list file is recognized only if # is preceded by
-white space or the start of the line. For example:
-
- not#comment@x.y.z # but this is a comment
-
-Putting a file name in a list has the same effect as inserting each line of the
-file as an item in the list (blank lines and comments excepted). However, there
-is one important difference: the file is read each time the list is processed,
-so if its contents vary over time, Exim's behaviour changes.
-
-If a file name is preceded by an exclamation mark, the sense of any match
-within the file is inverted. For example, if
-
- hold_domains = !/etc/nohold-domains
-
-and the file contains the lines
-
- !a.b.c
- *.b.c
-
-then 'a.b.c' is in the set of domains defined by %hold_domains%, whereas any
-domain matching `*.b.c` is not.
-
-
-
-An lsearch file is not an out-of-line list
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-As will be described in the sections that follow, lookups can be used in lists
-to provide indexed methods of checking list membership. There has been some
-confusion about the way ^lsearch^ lookups work in lists. Because
-an ^lsearch^ file contains plain text and is scanned sequentially, it is
-sometimes thought that it is allowed to contain wild cards and other kinds of
-non-constant pattern. This is not the case. The keys in an ^lsearch^ file are
-always fixed strings, just as for any other single-key lookup type.
-
-If you want to use a file to contain wild-card patterns that form part of a
-list, just give the file name on its own, without a search type, as described
-in the previous section.
-
-
-
-
-[[SECTnamedlists]]
-Named lists
-~~~~~~~~~~~
-cindex:[named lists]
-cindex:[list,named]
-A list of domains, hosts, email addresses, or local parts can be given a name
-which is then used to refer to the list elsewhere in the configuration. This is
-particularly convenient if the same list is required in several different
-places. It also allows lists to be given meaningful names, which can improve
-the readability of the configuration. For example, it is conventional to define
-a domain list called 'local_domains' for all the domains that are handled
-locally on a host, using a configuration line such as
-
- domainlist local_domains = localhost:my.dom.example
-
-Named lists are referenced by giving their name preceded by a plus sign, so,
-for example, a router that is intended to handle local domains would be
-configured with the line
-
- domains = +local_domains
-
-The first router in a configuration is often one that handles all domains
-except the local ones, using a configuration with a negated item like this:
-
- dnslookup:
- driver = dnslookup
- domains = ! +local_domains
- transport = remote_smtp
- no_more
-
-The four kinds of named list are created by configuration lines starting with
-the words %domainlist%, %hostlist%, %addresslist%, or %localpartlist%,
-respectively. Then there follows the name that you are defining, followed by an
-equals sign and the list itself. For example:
-
- hostlist relay_hosts = 192.168.23.0/24 : my.friend.example
- addresslist bad_senders = cdb;/etc/badsenders
-
-A named list may refer to other named lists:
-
- domainlist dom1 = first.example : second.example
- domainlist dom2 = +dom1 : third.example
- domainlist dom3 = fourth.example : +dom2 : fifth.example
-
-
-*Warning*: If the last item in a referenced list is a negative one, the
-effect may not be what you intended, because the negation does not propagate
-out to the higher level. For example, consider:
-
- domainlist dom1 = !a.b
- domainlist dom2 = +dom1 : *.b
-
-The second list specifies ``either in the %dom1% list or '*.b'##''. The first
-list specifies just ``not 'a.b'##'', so the domain 'x.y' matches it. That means
-it matches the second list as well. The effect is not the same as
-
- domainlist dom2 = !a.b : *.b
-
-where 'x.y' does not match. It's best to avoid negation altogether in
-referenced lists if you can.
-
-Named lists may have a performance advantage. When Exim is routing an
-address or checking an incoming message, it caches the result of tests on named
-lists. So, if you have a setting such as
-
- domains = +local_domains
-
-on several of your routers
-or in several ACL statements,
-the actual test is done only for the first one. However, the caching works only
-if there are no expansions within the list itself or any sublists that it
-references. In other words, caching happens only for lists that are known to be
-the same each time they are referenced.
-
-By default, there may be up to 16 named lists of each type. This limit can be
-extended by changing a compile-time variable. The use of domain and host lists
-is recommended for concepts such as local domains, relay domains, and relay
-hosts. The default configuration is set up like this.
-
-
-
-Named lists compared with macros
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[list,named compared with macro]
-cindex:[macro,compared with named list]
-At first sight, named lists might seem to be no different from macros in the
-configuration file. However, macros are just textual substitutions. If you
-write
-
- ALIST = host1 : host2
- auth_advertise_hosts = !ALIST
-
-it probably won't do what you want, because that is exactly the same as
-
- auth_advertise_hosts = !host1 : host2
-
-Notice that the second host name is not negated. However, if you use a host
-list, and write
-
- hostlist alist = host1 : host2
- auth_advertise_hosts = ! +alist
-
-the negation applies to the whole list, and so that is equivalent to
-
- auth_advertise_hosts = !host1 : !host2
-
-
-
-
-Named list caching
-~~~~~~~~~~~~~~~~~~
-cindex:[list,caching of named]
-cindex:[caching,named lists]
-While processing a message, Exim caches the result of checking a named list if
-it is sure that the list is the same each time. In practice, this means that
-the cache operates only if the list contains no \$ characters, which guarantees
-that it will not change when it is expanded. Sometimes, however, you may have
-an expanded list that you know will be the same each time within a given
-message. For example:
-
-....
-domainlist special_domains = \
- ${lookup{$sender_host_address}cdb{/some/file}}
-....
-
-This provides a list of domains that depends only on the sending host's IP
-address. If this domain list is referenced a number of times (for example,
-in several ACL lines, or in several routers) the result of the check is not
-cached by default, because Exim does not know that it is going to be the
-same list each time.
-
-By appending `_cache` to `domainlist` you can tell Exim to go ahead and
-cache the result anyway. For example:
-
- domainlist_cache special_domains = ${lookup{...
-
-If you do this, you should be absolutely sure that caching is going to do
-the right thing in all cases. When in doubt, leave it out.
-
-
-
-[[SECTdomainlist]]
-Domain lists
-~~~~~~~~~~~~
-cindex:[domain list,patterns for]
-cindex:[list,domain list]
-Domain lists contain patterns that are to be matched against a mail domain.
-The following types of item may appear in domain lists:
-
-- cindex:[primary host name]
-cindex:[host name, matched in domain list]
-cindex:[%primary_hostname%]
-cindex:[domain list,matching primary host name]
-cindex:[@ in a domain list]
-If a pattern consists of a single @ character, it matches the local host name,
-as set by the %primary_hostname% option (or defaulted). This makes it possible
-to use the same configuration file on several different hosts that differ only
-in their names.
-
-- cindex:[@{bk} in a domain list]
-cindex:[domain list,matching local IP interfaces]
-cindex:[domain literal]
-If a pattern consists of the string `@[]` it matches any local IP interface
-address, enclosed in square brackets, as in an email address that contains a
-domain literal.
-In today's Internet, the use of domain literals is controversial.
-
-- cindex:[@mx_any]
-cindex:[@mx_primary]
-cindex:[@mx_secondary]
-cindex:[domain list,matching MX pointers to local host]
-If a pattern consists of the string `@mx_any` it matches any domain that
-has an MX record pointing to the local host or to any host that is listed in
-cindex:[%hosts_treat_as_local%]
-%hosts_treat_as_local%. The items `@mx_primary` and `@mx_secondary`
-are similar, except that the first matches only when a primary MX target is the
-local host, and the second only when no primary MX target is the local host,
-but a secondary MX target is. ``Primary'' means an MX record with the lowest
-preference value -- there may of course be more than one of them.
-+
-The MX lookup that takes place when matching a pattern of this type is
-performed with the resolver options for widening names turned off. Thus, for
-example, a single-component domain will 'not' be expanded by adding the
-resolver's default domain. See the %qualify_single% and %search_parents%
-options of the ^dnslookup^ router for a discussion of domain widening.
-+
-Sometimes you may want to ignore certain IP addresses when using one of these
-patterns. You can specify this by following the pattern with `/ignore=`<'ip
-list'>, where <'ip list'> is a list of IP addresses. These addresses are
-ignored when processing the pattern (compare the %ignore_target_hosts% option
-on a router). For example:
-
- domains = @mx_any/ignore=127.0.0.1
-+
-This example matches any domain that has an MX record pointing to one of
-the local host's IP addresses other than 127.0.0.1.
-+
-The list of IP addresses is in fact processed by the same code that processes
-host lists, so it may contain CIDR-coded network specifications and it may also
-contain negative items.
-+
-Because the list of IP addresses is a sublist within a domain list, you have to
-be careful about delimiters if there is more than one address. Like any other
-list, the default delimiter can be changed. Thus, you might have:
-+
-....
-domains = @mx_any/ignore=<;127.0.0.1;0.0.0.0 : \
- an.other.domain : ...
-....
-+
-so that the sublist uses semicolons for delimiters. When IPv6 addresses are
-involved, it is easiest to change the delimiter for the main list as well:
-+
-....
-domains = <? @mx_any/ignore=<;127.0.0.1;::1 ? \
- an.other.domain ? ...
-....
-
-- cindex:[asterisk,in domain list]
-cindex:[domain list,asterisk in]
-cindex:[domain list,matching ``ends with'']
-If a pattern starts with an asterisk, the remaining characters of the pattern
-are compared with the terminating characters of the domain. The use of ``\*'' in
-domain lists differs from its use in partial matching lookups. In a domain
-list, the character following the asterisk need not be a dot, whereas partial
-matching works only in terms of dot-separated components. For example, a domain
-list item such as `*key.ex` matches 'donkey.ex' as well as
-'cipher.key.ex'.
-
-- cindex:[regular expressions,in domain list]
-cindex:[domain list,matching regular expression]
-If a pattern starts with a circumflex character, it is treated as a regular
-expression, and matched against the domain using a regular expression matching
-function. The circumflex is treated as part of the regular expression.
-References to descriptions of the syntax of regular expressions are given in
-chapter <<CHAPregexp>>.
-+
-*Warning*: Because domain lists are expanded before being processed, you
-must escape any backslash and dollar characters in the regular expression, or
-use the special `\N` sequence (see chapter <<CHAPexpand>>) to specify that it
-is not to be expanded (unless you really do want to build a regular expression
-by expansion, of course).
-
-- cindex:[lookup,in domain list]
-cindex:[domain list,matching by lookup]
-If a pattern starts with the name of a single-key lookup type followed by a
-semicolon (for example, ``dbm;'' or ``lsearch;''), the remainder of the pattern
-must be a file name in a suitable format for the lookup type. For example, for
-``cdb;'' it must be an absolute path:
-
- domains = cdb;/etc/mail/local_domains.cdb
-+
-The appropriate type of lookup is done on the file using the domain name as the
-key. In most cases, the data that is looked up is not used; Exim is interested
-only in whether or not the key is present in the file. However, when a lookup
-is used for the %domains% option on a router
-or a %domains% condition in an ACL statement, the data is preserved in the
-$domain_data$ variable and can be referred to in other router options or
-other statements in the same ACL.
-
-- Any of the single-key lookup type names may be preceded by ``partial<''n'>-',
-where the <'n'> is optional, for example,
-
- domains = partial-dbm;/partial/domains
-+
-This causes partial matching logic to be invoked; a description of how this
-works is given in section <<SECTpartiallookup>>.
-
-- cindex:[asterisk,in lookup type]
-Any of the single-key lookup types may be followed by an asterisk. This causes
-a default lookup for a key consisting of a single asterisk to be done if the
-original lookup fails. This is not a useful feature when using a domain list to
-select particular domains (because any domain would match), but it might have
-value if the result of the lookup is being used via the $domain_data$
-expansion variable.
-
-- If the pattern starts with the name of a query-style lookup type followed by a
-semicolon (for example, ``nisplus;'' or ``ldap;''), the remainder of the pattern
-must be an appropriate query for the lookup type, as described in chapter
-<<CHAPfdlookup>>. For example:
-+
-....
-hold_domains = mysql;select domain from holdlist \
- where domain = '$domain';
-....
-+
-In most cases, the data that is looked up is not used (so for an SQL query, for
-example, it doesn't matter what field you select). Exim is interested only in
-whether or not the query succeeds. However, when a lookup is used for the
-%domains% option on a router, the data is preserved in the $domain_data$
-variable and can be referred to in other options.
-
-- cindex:[domain list,matching literal domain name]
-If none of the above cases apply, a caseless textual comparison is made
-between the pattern and the domain.
-
-
-Here is an example that uses several different kinds of pattern:
-
-....
-domainlist funny_domains = \
- @ : \
- lib.unseen.edu : \
- *.foundation.fict.example : \
- \N^[1-2]\d{3}\.fict\.example$\N : \
- partial-dbm;/opt/data/penguin/book : \
- nis;domains.byname : \
- nisplus;[name=$domain,status=local],domains.org_dir
-....
-
-There are obvious processing trade-offs among the various matching modes. Using
-an asterisk is faster than a regular expression, and listing a few names
-explicitly probably is too. The use of a file or database lookup is expensive,
-but may be the only option if hundreds of names are required. Because the
-patterns are tested in order, it makes sense to put the most commonly matched
-patterns earlier.
-
-
-
-[[SECThostlist]]
-Host lists
-~~~~~~~~~~
-cindex:[host list,patterns in]
-cindex:[list,host list]
-Host lists are used to control what remote hosts are allowed to do. For
-example, some hosts may be allowed to use the local host as a relay, and some
-may be permitted to use the SMTP ETRN command. Hosts can be identified in
-two different ways, by name or by IP address. In a host list, some types of
-pattern are matched to a host name, and some are matched to an IP address.
-You need to be particularly careful with this when single-key lookups are
-involved, to ensure that the right value is being used as the key.
-
-
-Special host list patterns
-~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[empty item in hosts list]
-cindex:[host list,empty string in]
-If a host list item is the empty string, it matches only when no remote host is
-involved. This is the case when a message is being received from a local
-process using SMTP on the standard input, that is, when a TCP/IP connection is
-not used.
-
-cindex:[asterisk,in host list]
-The special pattern ``\*'' in a host list matches any host or no host. Neither
-the IP address nor the name is actually inspected.
-
-
-
-[[SECThoslispatip]]
-Host list patterns that match by IP address
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[host list,matching IP addresses]
-If an IPv4 host calls an IPv6 host and the call is accepted on an IPv6 socket,
-the incoming address actually appears in the IPv6 host as
-``::`ffff`:<''v4address'>'. When such an address is tested against a host
-list, it is converted into a traditional IPv4 address first. (Not all operating
-systems accept IPv4 calls on IPv6 sockets, as there have been some security
-concerns.)
-
-The following types of pattern in a host list check the remote host by
-inspecting its IP address:
-
-- If the pattern is a plain domain name (not a regular expression, not starting
-with \*, not a lookup of any kind), Exim calls the operating system function
-to find the associated IP address(es). Exim uses the newer
-'getipnodebyname()' function when available, otherwise 'gethostbyname()'.
-This typically causes a forward DNS lookup of the name. The result is compared
-with the IP address of the subject host.
-+
-If there is a temporary problem (such as a DNS timeout) with the host name
-lookup, a temporary error occurs. For example, if the list is being used in an
-ACL condition, the ACL gives a ``defer'' response, usually leading to a temporary
-SMTP error code. If no IP address can be found for the host name, what happens
-is described in section <<SECTbehipnot>> below.
-
-- cindex:[@ in a host list]
-If the pattern is ``@'', the primary host name is substituted and used as a
-domain name, as just described.
-
-- If the pattern is an IP address, it is matched against the IP address of the
-subject host. IPv4 addresses are given in the normal ``dotted-quad'' notation.
-IPv6 addresses can be given in colon-separated format, but the colons have to
-be doubled so as not to be taken as item separators when the default list
-separator is used. IPv6 addresses are recognized even when Exim is compiled
-without IPv6 support. This means that if they appear in a host list on an
-IPv4-only host, Exim will not treat them as host names. They are just addresses
-that can never match a client host.
-
-- cindex:[@{bk} in a host list]
-If the pattern is ``@[]'', it matches the IP address of any IP interface on
-the local host. For example, if the local host is an IPv4 host with one
-interface address 10.45.23.56, these two ACL statements have the same effect:
-
- accept hosts = 127.0.0.1 : 10.45.23.56
- accept hosts = @[]
-
-- cindex:[CIDR notation]
-If the pattern is an IP address followed by a slash and a mask length (for
-example 10.11.42.0/24), it is matched against the IP address of the subject
-host under the given mask. This allows, an entire network of hosts to be
-included (or excluded) by a single item. The mask uses CIDR notation; it
-specifies the number of address bits that must match, starting from the most
-significant end of the address.
-+
-*Note*: the mask is 'not' a count of addresses, nor is it the high number
-of a range of addresses. It is the number of bits in the network portion of the
-address. The above example specifies a 24-bit netmask, so it matches all 256
-addresses in the 10.11.42.0 network. An item such as
-
- 192.168.23.236/31
-+
-matches just two addresses, 192.168.23.236 and 192.168.23.237. A mask value of
-32 for an IPv4 address is the same as no mask at all; just a single address
-matches.
-+
-Here is another example which shows an IPv4 and an IPv6 network:
-+
-....
-recipient_unqualified_hosts = 192.168.0.0/16: \
- 3ffe::ffff::836f::::/48
-....
-+
-The doubling of list separator characters applies only when these items
-appear inline in a host list. It is not required when indirecting via a file.
-For example,
-
- recipient_unqualified_hosts = /opt/exim/unqualnets
-+
-could make use of a file containing
-
- 172.16.0.0/12
- 3ffe:ffff:836f::/48
-+
-to have exactly the same effect as the previous example. When listing IPv6
-addresses inline, it is usually more convenient to use the facility for
-changing separator characters. This list contains the same two networks:
-+
-....
-recipient_unqualified_hosts = <; 172.16.0.0/12; \
- 3ffe:ffff:836f::/48
-....
-+
-The separator is changed to semicolon by the leading ``<;'' at the start of the
-list.
-
-
-
-
-[[SECThoslispatsikey]]
-Host list patterns for single-key lookups by host address
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[host list,lookup of IP address]
-When a host is to be identified by a single-key lookup of its complete IP
-address, the pattern takes this form:
-
- net-<single-key-search-type>;<search-data>
-
-For example:
-
- hosts_lookup = net-cdb;/hosts-by-ip.db
-
-The text form of the IP address of the subject host is used as the lookup key.
-IPv6 addresses are converted to an unabbreviated form, using lower case
-letters, with dots as separators because colon is the key terminator in
-^lsearch^ files. [Colons can in fact be used in keys in ^lsearch^ files by
-quoting the keys, but this is a facility that was added later.] The data
-returned by the lookup is not used.
-
-cindex:[IP address,masking]
-cindex:[host list,masked IP address]
-Single-key lookups can also be performed using masked IP addresses, using
-patterns of this form:
-
- net<number>-<single-key-search-type>;<search-data>
-
-For example:
-
- net24-dbm;/networks.db
-
-The IP address of the subject host is masked using <'number'> as the mask
-length. A textual string is constructed from the masked value, followed by the
-mask, and this is used as the lookup key. For example, if the host's IP address
-is 192.168.34.6, the key that is looked up for the above example is
-``192.168.34.0/24''. IPv6 addresses are converted to a text value using lower
-case letters and dots as separators instead of the more usual colon, because
-colon is the key terminator in ^lsearch^ files. Full, unabbreviated IPv6
-addresses are always used.
-
-*Warning*: Specifing %net32-% (for an IPv4 address) or %net128-% (for an
-IPv6 address) is not the same as specifing just %net-% without a number. In
-the former case the key strings include the mask value, whereas in the latter
-case the IP address is used on its own.
-
-
-
-[[SECThoslispatnam]]
-Host list patterns that match by host name
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[host,lookup failures]
-cindex:[unknown host name]
-cindex:[host list,matching host name]
-There are several types of pattern that require Exim to know the name of the
-remote host. These are either wildcard patterns or lookups by name. (If a
-complete hostname is given without any wildcarding, it is used to find an IP
-address to match against, as described in the section <<SECThoslispatip>> above.)
-
-If the remote host name is not already known when Exim encounters one of these
-patterns, it has to be found from the IP address.
-Although many sites on the Internet are conscientious about maintaining reverse
-DNS data for their hosts, there are also many that do not do this.
-Consequently, a name cannot always be found, and this may lead to unwanted
-effects. Take care when configuring host lists with wildcarded name patterns.
-Consider what will happen if a name cannot be found.
-
-Because of the problems of determining host names from IP addresses, matching
-against host names is not as common as matching against IP addresses.
-
-By default, in order to find a host name, Exim first does a reverse DNS lookup;
-if no name is found in the DNS, the system function ('gethostbyaddr()' or
-'getipnodebyaddr()' if available) is tried. The order in which these lookups
-are done can be changed by setting the %host_lookup_order% option.
-
-There are some options that control what happens if a host name cannot be
-found. These are described in section <<SECTbehipnot>> below.
-
-cindex:[host,alias for]
-cindex:[alias for host]
-As a result of aliasing, hosts may have more than one name. When processing any
-of the following types of pattern, all the host's names are checked:
-
-- cindex:[asterisk,in host list]
-If a pattern starts with ``\*'' the remainder of the item must match the end of
-the host name. For example, `*.b.c` matches all hosts whose names end in
-'.b.c'. This special simple form is provided because this is a very common
-requirement. Other kinds of wildcarding require the use of a regular
-expression.
-
-- cindex:[regular expressions,in host list]
-cindex:[host list,regular expression in]
-If the item starts with ``^'' it is taken to be a regular expression which is
-matched against the host name. For example,
-
- ^(a|b)\.c\.d$
-+
-is a regular expression that matches either of the two hosts 'a.c.d' or
-'b.c.d'. When a regular expression is used in a host list, you must take care
-that backslash and dollar characters are not misinterpreted as part of the
-string expansion. The simplest way to do this is to use `\N` to mark that
-part of the string as non-expandable. For example:
-
- sender_unqualified_hosts = \N^(a|b)\.c\.d$\N : ....
-+
-*Warning*: If you want to match a complete host name, you must include the
-`\$` terminating metacharacter in the regular expression, as in the above
-example. Without it, a match at the start of the host name is all that is
-required.
-
-
-
-
-[[SECTbehipnot]]
-Behaviour when an IP address or name cannot be found
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[host,lookup failures]
-While processing a host list, Exim may need to look up an IP address from a
-name (see section <<SECThoslispatip>>), or it may need to look up a host name
-from an IP address (see section <<SECThoslispatnam>>). In either case, the
-behaviour when it fails to find the information it is seeking is the same.
-
-cindex:[`+include_unknown`]
-cindex:[`+ignore_unknown`]
-By default, Exim behaves as if the host does not match the list. This may not
-always be what you want to happen. To change Exim's behaviour, the special
-items `+include_unknown` or `+ignore_unknown` may appear in the list (at
-top level -- they are not recognized in an indirected file).
-
-- If any item that follows `+include_unknown` requires information that
-cannot found, Exim behaves as if the host does match the list. For example,
-
- host_reject_connection = +include_unknown:*.enemy.ex
-+
-rejects connections from any host whose name matches `*.enemy.ex`, and also
-any hosts whose name it cannot find.
-
-- If any item that follows `+ignore_unknown` requires information that cannot
-be found, Exim ignores that item and proceeds to the rest of the list. For
-example:
-+
-....
-accept hosts = +ignore_unknown : friend.example : \
- 192.168.4.5
-....
-+
-accepts from any host whose name is 'friend.example' and from 192.168.4.5,
-whether or not its host name can be found. Without `+ignore_unknown`, if no
-name can be found for 192.168.4.5, it is rejected.
-
-Both `+include_unknown` and `+ignore_unknown` may appear in the same
-list. The effect of each one lasts until the next, or until the end of the
-list.
-
-*Note*: This section applies to permanent lookup failures. It does 'not'
-apply to temporary DNS errors. They always cause a defer action.
-
-
-
-[[SECThoslispatnamsk]]
-Host list patterns for single-key lookups by host name
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[host,lookup failures]
-cindex:[unknown host name]
-cindex:[host list,matching host name]
-If a pattern is of the form
-
- <single-key-search-type>;<search-data>
-
-for example
-
- dbm;/host/accept/list
-
-a single-key lookup is performend, using the host name as its key. If the
-lookup succeeds, the host matches the item. The actual data that is looked up
-is not used.
-
-*Reminder*: With this kind of pattern, you must have host 'names' as
-keys in the file, not IP addresses. If you want to do lookups based on IP
-addresses, you must precede the search type with ``net-'' (see section
-<<SECThoslispatsikey>>). There is, however, no reason why you could not use two
-items in the same list, one doing an address lookup and one doing a name
-lookup, both using the same file.
-
-
-
-Host list patterns for query-style lookups
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-If a pattern is of the form
-
- <query-style-search-type>;<query>
-
-the query is obeyed, and if it succeeds, the host matches the item. The actual
-data that is looked up is not used. The variables $sender_host_address$ and
-$sender_host_name$ can be used in the query. For example:
-
-....
-hosts_lookup = pgsql;\
- select ip from hostlist where ip='$sender_host_address'
-....
-
-The value of $sender_host_address$ for an IPv6 address contains colons. You
-can use the %sg% expansion item to change this if you need to. If you want to
-use masked IP addresses in database queries, you can use the %mask% expansion
-operator.
-
-If the query contains a reference to $sender_host_name$, Exim automatically
-looks up the host name if has not already done so. (See section
-<<SECThoslispatnam>> for comments on finding host names.)
-
-Historical note: prior to release 4.30, Exim would always attempt to find a
-host name before running the query, unless the search type was preceded by
-`net-`. This is no longer the case. For backwards compatibility, `net-` is
-still recognized for query-style lookups, but its presence or absence has no
-effect. (Of course, for single-key lookups, `net-` 'is' important.
-See section <<SECThoslispatsikey>>.)
-
-
-
-[[SECTmixwilhos]]
-Mixing wildcarded host names and addresses in host lists
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[host list,mixing names and addresses in]
-If you have name lookups or wildcarded host names and IP addresses in the same
-host list, you should normally put the IP addresses first. For example, in an
-ACL you could have:
-
- accept hosts = 10.9.8.7 : *.friend.example
-
-The reason for this lies in the left-to-right way that Exim processes lists.
-It can test IP addresses without doing any DNS lookups, but when it reaches an
-item that requires a host name, it fails if it cannot find a host name to
-compare with the pattern. If the above list is given in the opposite order, the
-%accept% statement fails for a host whose name cannot be found, even if its
-IP address is 10.9.8.7.
-
-If you really do want to do the name check first, and still recognize the IP
-address, you can rewrite the ACL like this:
-
- accept hosts = *.friend.example
- accept hosts = 10.9.8.7
-
-If the first %accept% fails, Exim goes on to try the second one. See chapter
-<<CHAPACL>> for details of ACLs.
-
-
-
-
-
-[[SECTaddresslist]]
-Address lists
-~~~~~~~~~~~~~
-cindex:[list,address list]
-cindex:[address list,empty item]
-cindex:[address list,patterns]
-Address lists contain patterns that are matched against mail addresses. There
-is one special case to be considered: the sender address of a bounce message is
-always empty. You can test for this by providing an empty item in an address
-list. For example, you can set up a router to process bounce messages by
-using this option setting:
-
- senders = :
-
-The presence of the colon creates an empty item. If you do not provide any
-data, the list is empty and matches nothing. The empty sender can also be
-detected by a regular expression that matches an empty string,
-
-and by a query-style lookup that succeeds when $sender_address$ is empty.
-
-The following kinds of address list pattern can match any address, including
-the empty address that is characteristic of bounce message senders:
-
-- As explained above, if a pattern item is empty, it matches the empty address
-(and no others).
-
-- cindex:[regular expressions,in address list]
-cindex:[address list,regular expression in]
-If (after expansion) a pattern starts with ``^'', a regular expression match is
-done against the complete address, with the pattern as the regular expression.
-You must take care that backslash and dollar characters are not misinterpreted
-as part of the string expansion. The simplest way to do this is to use `\N`
-to mark that part of the string as non-expandable. For example:
-
- deny senders = \N^\d{8}.+@spamhaus.example$\N : ...
-+
-The `\N` sequences are removed by the expansion, so the item does start
-with ``^'' by the time it is being interpreted as an address pattern.
-
-- cindex:[address list,lookup for complete address]
-Complete addresses can be looked up by using a pattern that starts with a
-lookup type terminated by a semicolon, followed by the data for the lookup. For
-example:
-+
-....
-deny senders = cdb;/etc/blocked.senders : \
- mysql;select address from blocked where \
- address='${quote_mysql:$sender_address}'
-....
-+
-Both query-style and single-key lookup types can be used. For a single-key
-lookup type, Exim uses the complete address as the key. However, empty keys are
-not supported for single-key lookups, so a match against the empty address
-always fails. This restriction does not apply to query-style lookups.
-+
-Partial matching for single-key lookups (section <<SECTpartiallookup>>) cannot
-be used, and is ignored if specified, with an entry being written to the panic
-log.
-+
-cindex:[\*@ with single-key lookup]
-However, you can configure lookup defaults, as described in section
-<<SECTdefaultvaluelookups>>, but this is useful only for the ``\*@'' type of
-default. For example, with this lookup:
-
- accept senders = lsearch*@;/some/file
-+
-the file could contains lines like this:
-
- user1@domain1.example
- *@domain2.example
-+
-and for the sender address 'nimrod@jaeger.example', the sequence of keys
-that are tried is:
-
- nimrod@jaeger.example
- *@jaeger.example
- *
-+
-*Warning 1*: Do not include a line keyed by ``\*'' in the file, because that
-would mean that every address matches, thus rendering the test useless.
-+
-*Warning 2*: Do not confuse these two kinds of item:
-
- deny recipients = dbm*@;/some/file
- deny recipients = *@dbm;/some/file
-+
-The first does a whole address lookup, with defaulting, as just described,
-because it starts with a lookup type. The second matches the local part and
-domain independently, as described in a bullet point below.
-
-
-
-The following kinds of address list pattern can match only non-empty addresses.
-If the subject address is empty, a match against any of these pattern types
-always fails.
-
-
-- cindex:[@@ with single-key lookup]
-cindex:[address list,@@ lookup type]
-cindex:[address list,split local part and domain]
-If a pattern starts with ``@@'' followed by a single-key lookup item
-(for example, `@@lsearch;/some/file`), the address that is being checked is
-split into a local part and a domain. The domain is looked up in the file. If
-it is not found, there is no match. If it is found, the data that is looked up
-from the file is treated as a colon-separated list of local part patterns, each
-of which is matched against the subject local part in turn.
-+
-cindex:[asterisk,in address list]
-The lookup may be a partial one, and/or one involving a search for a default
-keyed by ``\*'' (see section <<SECTdefaultvaluelookups>>). The local part patterns
-that are looked up can be regular expressions or begin with ``\*'', or even be
-further lookups. They may also be independently negated. For example, with
-
- deny senders = @@dbm;/etc/reject-by-domain
-+
-the data from which the DBM file is built could contain lines like
-
- baddomain.com: !postmaster : *
-+
-to reject all senders except %postmaster% from that domain.
-+
-cindex:[local part,starting with !]
-If a local part that actually begins with an exclamation mark is required, it
-has to be specified using a regular expression. In ^lsearch^ files, an entry
-may be split over several lines by indenting the second and subsequent lines,
-but the separating colon must still be included at line breaks. White space
-surrounding the colons is ignored. For example:
-
- aol.com: spammer1 : spammer2 : ^[0-9]+$ :
- spammer3 : spammer4
-+
-As in all colon-separated lists in Exim, a colon can be included in an item by
-doubling.
-+
-If the last item in the list starts with a right angle-bracket, the remainder
-of the item is taken as a new key to look up in order to obtain a continuation
-list of local parts. The new key can be any sequence of characters. Thus one
-might have entries like
-
- aol.com: spammer1 : spammer 2 : >*
- xyz.com: spammer3 : >*
- *: ^\d{8}$
-+
-in a file that was searched with %@@dbm\*%, to specify a match for 8-digit
-local parts for all domains, in addition to the specific local parts listed for
-each domain. Of course, using this feature costs another lookup each time a
-chain is followed, but the effort needed to maintain the data is reduced.
-+
-cindex:[loop,in lookups]
-It is possible to construct loops using this facility, and in order to catch
-them, the chains may be no more than fifty items long.
-
-- The @@<'lookup'> style of item can also be used with a query-style
-lookup, but in this case, the chaining facility is not available. The lookup
-can only return a single list of local parts.
-
-- If a pattern contains an @ character, but is not a regular expression and does
-not begin with a lookup type as described above, the local part of the subject
-address is compared with the local part of the pattern, which may start with an
-asterisk. If the local parts match, the domain is checked in exactly the same
-way as for a pattern in a domain list. For example, the domain can be
-wildcarded, refer to a named list, or be a lookup:
-+
-....
-deny senders = *@*.spamming.site:\
- *@+hostile_domains:\
- bozo@partial-lsearch;/list/of/dodgy/sites:\
- *@dbm;/bad/domains.db
-....
-+
-cindex:[local part,starting with !]
-cindex:[address list,local part starting with !]
-If a local part that begins with an exclamation mark is required, it has to be
-specified using a regular expression, because otherwise the exclamation mark is
-treated as a sign of negation.
-
-- If a pattern is not one of the above syntax forms, that is, if a
-non-empty pattern that is not a regular expression or a lookup does not contain
-an @ character, it is matched against the domain part of the subject address.
-The only two formats that are recognized this way are a literal domain, or a
-domain pattern that starts with \*. In both these cases, the effect is the same
-as if `*@` preceded the pattern.
-
-*Warning*: there is an important difference between the address list items
-in these two examples:
-
- senders = +my_list
- senders = *@+my_list
-
-In the first one, `my_list` is a named address list, whereas in the second
-example it is a named domain list.
-
-
-
-
-[[SECTcasletadd]]
-Case of letters in address lists
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[case of local parts]
-cindex:[address list,case forcing]
-cindex:[case forcing in address lists]
-Domains in email addresses are always handled caselessly, but for local parts
-case may be significant on some systems (see %caseful_local_part% for how
-Exim deals with this when routing addresses). However, RFC 2505 ('Anti-Spam
-Recommendations for SMTP MTAs') suggests that matching of addresses to blocking
-lists should be done in a case-independent manner. Since most address lists in
-Exim are used for this kind of control, Exim attempts to do this by default.
-
-The domain portion of an address is always lowercased before matching it to an
-address list. The local part is lowercased by default, and any string
-comparisons that take place are done caselessly. This means that the data in
-the address list itself, in files included as plain file names, and in any file
-that is looked up using the ``@@'' mechanism, can be in any case. However, the
-keys in files that are looked up by a search type other than ^lsearch^ (which
-works caselessly) must be in lower case, because these lookups are not
-case-independent.
-
-cindex:[`+caseful`]
-To allow for the possibility of caseful address list matching, if an item in
-an address list is the string ``+caseful'', the original case of the local
-part is restored for any comparisons that follow, and string comparisons are no
-longer case-independent. This does not affect the domain, which remains in
-lower case. However, although independent matches on the domain alone are still
-performed caselessly, regular expressions that match against an entire address
-become case-sensitive after ``+caseful'' has been seen.
-
-
-
-[[SECTlocparlis]]
-Local part lists
-~~~~~~~~~~~~~~~~
-cindex:[list,local part list]
-cindex:[local part,list]
-Case-sensitivity in local part lists is handled in the same way as for address
-lists, as just described. The ``+caseful'' item can be used if required. In a
-setting of the %local_parts% option in a router with %caseful_local_part%
-set false, the subject is lowercased and the matching is initially
-case-insensitive. In this case, ``+caseful'' will restore case-sensitive matching
-in the local part list, but not elsewhere in the router. If
-%caseful_local_part% is set true in a router, matching in the %local_parts%
-option is case-sensitive from the start.
-
-If a local part list is indirected to a file (see section <<SECTfilnamlis>>),
-comments are handled in the same way as address lists -- they are recognized
-only if the # is preceded by white space or the start of the line.
-Otherwise, local part lists are matched in the same way as domain lists, except
-that the special items that refer to the local host (`@`, `@[]`,
-`@mx_any`, `@mx_primary`, and `@mx_secondary`) are not recognized.
-Refer to section <<SECTdomainlist>> for details of the other available item
-types.
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPexpand]]
-String expansions
------------------
-cindex:[expansion,of strings]
-Many strings in Exim's run time configuration are expanded before use. Some of
-them are expanded every time they are used; others are expanded only once.
-
-When a string is being expanded it is copied verbatim from left to right except
-when a dollar or backslash character is encountered. A dollar specifies the
-start of a portion of the string that is interpreted and replaced as described
-below in section <<SECTexpansionitems>> onwards. Backslash is used as an escape
-character, as described in the following section.
-
-
-
-[[SECTlittext]]
-Literal text in expanded strings
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[expansion,including literal text]
-An uninterpreted dollar can be included in an expanded string by putting a
-backslash in front of it. A backslash can be used to prevent any special
-character being treated specially in an expansion, including backslash itself.
-If the string appears in quotes in the configuration file, two backslashes are
-required because the quotes themselves cause interpretation of backslashes when
-the string is read in (see section <<SECTstrings>>).
-
-cindex:[expansion,non-expandable substrings]
-A portion of the string can specified as non-expandable by placing it between
-two occurrences of `\N`. This is particularly useful for protecting regular
-expressions, which often contain backslashes and dollar signs. For example:
-
- deny senders = \N^\d{8}[a-z]@some\.site\.example$\N
-
-On encountering the first `\N`, the expander copies subsequent characters
-without interpretation until it reaches the next `\N` or the end of the
-string.
-
-
-
-Character escape sequences in expanded strings
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[expansion,escape sequences]
-A backslash followed by one of the letters ``n'', ``r'', or ``t'' in an expanded
-string is recognized as an escape sequence for the character newline, carriage
-return, or tab, respectively. A backslash followed by up to three octal digits
-is recognized as an octal encoding for a single character, and a backslash
-followed by ``x'' and up to two hexadecimal digits is a hexadecimal encoding.
-
-These escape sequences are also recognized in quoted strings when they are read
-in. Their interpretation in expansions as well is useful for unquoted strings,
-and for other cases such as looked-up strings that are then expanded.
-
-
-Testing string expansions
-~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[expansion,testing]
-cindex:[testing,string expansion]
-cindex:[%-be% option]
-Many expansions can be tested by calling Exim with the %-be% option. This takes
-the command arguments, or lines from the standard input if there are no
-arguments, runs them through the string expansion code, and writes the results
-to the standard output. Variables based on configuration values are set up, but
-since no message is being processed, variables such as $local_part$ have no
-value. Nevertheless the %-be% option can be useful for checking out file and
-database lookups, and the use of expansion operators such as %sg%, %substr% and
-%nhash%.
-
-Exim gives up its root privilege when it is called with the %-be% option, and
-instead runs under the uid and gid it was called with, to prevent users from
-using %-be% for reading files to which they do not have access.
-
-
-
-[[SECTforexpfai]]
-Forced expansion failure
-~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[expansion,forced failure]
-A number of expansions that are described in the following section have
-alternative ``true'' and ``false'' substrings, enclosed in brace characters
-(which are sometimes called ``curly brackets''). Which of the two strings is
-used depends on some condition that is evaluated as part of the expansion. If,
-instead of a ``false'' substring, the word ``fail'' is used (not in braces),
-the entire string expansion fails in a way that can be detected by the code
-that requested the expansion. This is called ``forced expansion failure'', and
-its consequences depend on the circumstances. In some cases it is no different
-from any other expansion failure, but in others a different action may be
-taken. Such variations are mentioned in the documentation of the option that is
-being expanded.
-
-
-
-
-[[SECTexpansionitems]]
-Expansion items
-~~~~~~~~~~~~~~~
-The following items are recognized in expanded strings. White space may be used
-between sub-items that are keywords or substrings enclosed in braces inside an
-outer set of braces, to improve readability. *Warning*: Within braces,
-white space is significant.
-
-*\$*<'variable~name'>~or~*\$\{*<'variable~name'>*\}*::
-cindex:[expansion,variables]
-Substitute the contents of the named variable, for example
-
- $local_part
- ${domain}
-+
-The second form can be used to separate the name from subsequent alphanumeric
-characters. This form (using braces) is available only for variables; it does
-'not' apply to message headers. The names of the variables are given in section
-<<SECTexpvar>> below. If the name of a non-existent variable is given, the
-expansion fails.
-
-*\$\{*<'op'>*:*<'string'>*\}*::
-cindex:[expansion,operators]
-The string is first itself expanded, and then the operation specified by <'op'>
-is applied to it. For example,
-
- ${lc:$local_part}
-+
-The string starts with the first character after the colon, which may be
-leading white space. A list of operators is given in section <<SECTexpop>>
-below. The operator notation is used for simple expansion items that have just
-one argument, because it reduces the number of braces and therefore makes the
-string easier to understand.
-
-*\$\{dlfunc\{*<'file'>*\}\{*<'function'>*\}\{*<'arg'>*\}\{*<'arg'>*\}...\}*::
-+
-[revisionflag="changed"]
-This expansion dynamically loads and then calls a locally-written C function.
-This functionality is available only if Exim is compiled with
-+
-[revisionflag="changed"]
-....
- EXPAND_DLFUNC=yes
-....
-+
-[revisionflag="changed"]
-set in _Local/Makefile_. Once loaded, Exim remembers the dynamically loaded
-object so that it doesn't reload the same object file in the same Exim process
-(but of course Exim does start new processes frequently).
-+
-[revisionflag="changed"]
-There may be from zero to eight arguments to the function. When compiling
-a local function that is to be called in this way, _local_scan.h_ should be
-included. The Exim variables and functions that are defined by that API
-are also available for dynamically loaded functions. The function itself
-must have the following type:
-+
-[revisionflag="changed"]
-....
-int dlfunction(uschar **yield, int argc, uschar *argv[])
-....
-+
-[revisionflag="changed"]
-Where `uschar` is a typedef for `unsigned char` in _local_scan.h_. The
-function should return one of the following values:
-+
-[revisionflag="changed"]
-`OK`: Success. The string that is placed in the variable 'yield' is put into
-the expanded string that is being built.
-+
-[revisionflag="changed"]
-`FAIL`: A non-forced expansion failure occurs, with the error message taken
-from 'yield', if it is set.
-+
-[revisionflag="changed"]
-`FAIL_FORCED`: A forced expansion failure occurs, with the error message
-taken from 'yield' if it is set.
-+
-[revisionflag="changed"]
-`ERROR`: Same as `FAIL`, except that a panic log entry is written.
-+
-[revisionflag="changed"]
-When compiling a function that is to be used in this way with gcc,
-you need to add %-shared% to the gcc command. Also, in the Exim build-time
-configuration, you must add %-export-dynamic% to EXTRALIBS.
-
-
-*\$\{extract\{*<'key'>*\}\{*<'string1'>*\}\{*<'string2'>*\}\{*<'string3'>*\}\}*::
-cindex:[expansion,extracting substrings by key]
-The key and <'string1'> are first expanded separately. Leading and trailing
-white space is removed from the key (but not from any of the strings). The key
-must not consist entirely of digits. The expanded <'string1'> must be of the
-form:
-
- <key1> = <value1> <key2> = <value2> ...
-+
-cindex:[$value$]
-where the equals signs and spaces (but not both) are optional. If any of the
-values contain white space, they must be enclosed in double quotes, and any
-values that are enclosed in double quotes are subject to escape processing as
-described in section <<SECTstrings>>. The expanded <'string1'> is searched for
-the value that corresponds to the key. The search is case-insensitive. If the
-key is found, <'string2'> is expanded, and replaces the whole item; otherwise
-<'string3'> is used. During the expansion of <'string2'> the variable $value$
-contains the value that has been extracted. Afterwards, it is restored to any
-previous value it might have had.
-+
-If \{<'string3'>\} is omitted, the item is replaced by an empty string if the
-key is not found. If \{<'string2'>\} is also omitted, the value that was
-extracted is used. Thus, for example, these two expansions are identical, and
-yield ``2001'':
-
- ${extract{gid}{uid=1984 gid=2001}}
- ${extract{gid}{uid=1984 gid=2001}{$value}}
-+
-Instead of \{<'string3'>\} the word ``fail'' (not in curly brackets) can
-appear, for example:
-
- ${extract{Z}{A=... B=...}{$value} fail }
-+
-This forces an expansion failure (see section <<SECTforexpfai>>);
-{<'string2'>\} must be present for ``fail'' to be recognized.
-
-
-*\$\{extract\{*<'number'>*\}\{*<'separators'>*\}\{*<'string1'>*\}\{*<'string2'>*\}\{*<'string3'>*\}\}*::
-cindex:[expansion,extracting substrings by number]
-The <'number'> argument must consist entirely of decimal digits,
-apart from leading and trailing white space, which is ignored.
-This is what distinguishes this form of %extract% from the previous kind. It
-behaves in the same way, except that, instead of extracting a named field, it
-extracts from <'string1'> the field whose number is given as the first
-argument. You can use $value$ in <'string2'> or `fail` instead of
-<'string3'> as before.
-+
-The fields in the string are separated by any one of the characters in the
-separator string. These may include space or tab characters.
-The first field is numbered one. If the number is negative, the fields are
-counted from the end of the string, with the rightmost one numbered -1. If the
-number given is zero, the entire string is returned. If the modulus of the
-number is greater than the number of fields in the string, the result is the
-expansion of <'string3'>, or the empty string if <'string3'> is not provided.
-For example:
-
- ${extract{2}{:}{x:42:99:& Mailer::/bin/bash}}
-+
-yields ``42'', and
-
- ${extract{-4}{:}{x:42:99:& Mailer::/bin/bash}}
-+
-yields ``99''. Two successive separators mean that the field between them is
-empty (for example, the fifth field above).
-
-
-*\$\{hash\{*<'string1'>*\}\{*<'string2'>*\}\{*<'string3'>*\}\}*::
-cindex:[hash function,textual]
-cindex:[expansion,textual hash]
-This is a textual hashing function, and was the first to be implemented in
-early versions of Exim. In current releases, there are other hashing functions
-(numeric, MD5, and SHA-1), which are described below.
-+
-The first two strings, after expansion, must be numbers. Call them <'m'> and
-<'n'>. If you are using fixed values for these numbers, that is, if <'string1'>
-and <'string2'> do not change when they are expanded, you can use the
-simpler operator notation that avoids some of the braces:
-
- ${hash_<n>_<m>:<string>}
-+
-The second number is optional (in both notations).
-+
-If <'n'> is greater than or equal to the length of the string, the expansion
-item returns the string. Otherwise it computes a new string of length <'n'> by
-applying a hashing function to the string. The new string consists of
-characters taken from the first <'m'> characters of the string
-
- abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQWRSTUVWXYZ0123456789
-+
-If <'m'> is not present the value 26 is used, so that only lower case
-letters appear. For example:
-+
-&&&
-`\${hash{3}{monty}} ` yields `jmg`
-`\${hash{5}{monty}} ` yields `monty`
-`\${hash{4}{62}{monty python}}` yields `fbWx`
-&&&
-
-
-*\$header_*<'header~name'>*:*~or~*\$h_*<'header~name'>*:*::
-See *\$rheader* below.
-
-*\$bheader_*<'header~name'>*:*~or~*\$bh_*<'header~name'>*:*::
-See *\$rheader* below.
-
-*\$rheader_*<'header~name'>*:*~or~*\$rh_*<'header~name'>*:*::
-cindex:[expansion,header insertion]
-cindex:[$header_$]
-cindex:[$bheader_$]
-cindex:[$rheader_$]
-cindex:[header lines,in expansion strings]
-cindex:[header lines,character sets]
-cindex:[header lines,decoding]
-Substitute the contents of the named message header line, for example
-
- $header_reply-to:
-+
-The newline that terminates a header line is not included in the expansion, but
-internal newlines (caused by splitting the header line over several physical
-lines) may be present.
-+
-The difference between %rheader%, %bheader%, and %header% is in the way the
-data in the header line is interpreted.
-+
---
-- cindex:[white space,in header lines]
-%rheader% gives the original ``raw'' content of the header line, with no
-processing at all, and without the removal of leading and trailing white space.
-
-- cindex:[base64 encoding,in header lines]
-%bheader% removes leading and trailing white space, and then decodes base64 or
-quoted-printable MIME ``words'' within the header text, but does no character
-set translation. If decoding of what looks superficially like a MIME ``word''
-fails, the raw string is returned. If decoding
-cindex:[binary zero,in header line]
-produces a binary zero character, it is replaced by a question mark -- this is
-what Exim does for binary zeros that are actually received in header lines.
-
-- %header% tries to translate the string as decoded by %bheader% to a standard
-character set. This is an attempt to produce the same string as would be
-displayed on a user's MUA. If translation fails, the %bheader% string is
-returned. Translation is attempted only on operating systems that support the
-'iconv()' function. This is indicated by the compile-time macro
-HAVE_ICONV in a system Makefile or in _Local/Makefile_.
---
-+
-In a filter file, the target character set for %header% can be specified by a
-command of the following form:
-
- headers charset "UTF-8"
-+
-This command affects all references to $h_$ (or $header_$) expansions in
-subsequently obeyed filter commands. In the absence of this command, the target
-character set in a filter is taken from the setting of the %headers_charset%
-option in the runtime configuration. The value of this option defaults to the
-value of HEADERS_CHARSET in _Local/Makefile_. The ultimate default is
-ISO-8859-1.
-+
-Header names follow the syntax of RFC 2822, which states that they may contain
-any printing characters except space and colon. Consequently, curly brackets
-'do not' terminate header names, and should not be used to enclose them as
-if they were variables. Attempting to do so causes a syntax error.
-+
-Only header lines that are common to all copies of a message are visible to
-this mechanism. These are the original header lines that are received with the
-message, and any that are added by an ACL %warn% statement or by a system
-filter. Header lines that are added to a particular copy of a message by a
-router or transport are not accessible.
-+
-For incoming SMTP messages, no header lines are visible in ACLs that are obeyed
-before the DATA ACL, because the header structure is not set up until the
-message is received. Header lines that are added by %warn% statements in a
-RCPT ACL (for example) are saved until the message's incoming header lines
-are available, at which point they are added. When a DATA ACL is running,
-however, header lines added by earlier ACLs are visible.
-+
-Upper case and lower case letters are synonymous in header names. If the
-following character is white space, the terminating colon may be omitted, but
-this is not recommended, because you may then forget it when it is needed. When
-white space terminates the header name, it is included in the expanded string.
-If the message does not contain the given header, the expansion item is
-replaced by an empty string. (See the %def% condition in section <<SECTexpcond>>
-for a means of testing for the existence of a header.)
-+
-If there is more than one header with the same name, they are all
-concatenated to form the substitution string, up to a maximum length of 64K. A
-newline character is inserted between each line. For the %header% expansion,
-for those headers that contain lists of addresses, a comma is also inserted at
-the junctions between lines. This does not happen for the %rheader% expansion.
-
-
-
-*\$\{hmac\{*<'hashname'>*\}\{*<'secret'>*\}\{*<'string'>*\}\}*::
-cindex:[expansion,hmac hashing]
-This function uses cryptographic hashing (either MD5 or SHA-1) to convert a
-shared secret and some text into a message authentication code, as specified in
-RFC 2104. This differs from `\$\{md5:secret_text...\}` or
-`\$\{sha1:secret_text...\}` in that the hmac step adds a signature to the
-cryptographic hash, allowing for authentication that is not possible with MD5
-or SHA-1 alone. The hash name must expand to either `md5` or `sha1` at present.
-For example:
-
- ${hmac{md5}{somesecret}{$primary_hostname $tod_log}}
-+
-For the hostname 'mail.example.com' and time 2002-10-17 11:30:59, this
-produces:
-
- dd97e3ba5d1a61b5006108f8c8252953
-+
-As an example of how this might be used, you might put in the main part of
-an Exim configuration:
-
- SPAMSCAN_SECRET=cohgheeLei2thahw
-+
-In a router or a transport you could then have:
-+
-....
-headers_add = \
- X-Spam-Scanned: ${primary_hostname} ${message_exim_id} \
- ${hmac{md5}{SPAMSCAN_SECRET}\
- {${primary_hostname},${message_exim_id},$h_message-id:}}
-....
-+
-Then given a message, you can check where it was scanned by looking at the
-'X-Spam-Scanned:' header line. If you know the secret, you can check that this
-header line is authentic by recomputing the authentication code from the host
-name, message ID and the 'Message-id:' header line. This can be done using
-Exim's %-be% option, or by other means, for example by using the
-'hmac_md5_hex()' function in Perl.
-
-
-*\$\{if~*<'condition'>*~\{*<'string1'>*\}\{*<'string2'>*\}\}*::
-cindex:[expansion,conditional]
-If <'condition'> is true, <'string1'> is expanded and replaces the whole item;
-otherwise <'string2'> is used. The available conditions are described in
-section <<SECTexpcond>> below. For example:
-
- ${if eq {$local_part}{postmaster} {yes}{no} }
-+
-The second string need not be present; if it is not and the condition is not
-true, the item is replaced with nothing. Alternatively, the word ``fail'' may be
-present instead of the second string (without any curly brackets). In this
-case, the expansion is forced to fail if the condition is not true (see section
-<<SECTforexpfai>>).
-+
-If both strings are omitted, the result is the string `true` if the condition
-is true, and the empty string if the condition is false. This makes it less
-cumbersome to write custom ACL and router conditions. For example, instead of
-
- condition = ${if >{$acl_m4}{3}{true}{false}}
-+
-you can use
-
- condition = ${if >{$acl_m4}{3}}
-
-
-
-*\$\{length\{*<'string1'>*\}\{*<'string2'>*\}\}*::
-cindex:[expansion,string truncation]
-The %length% item is used to extract the initial portion of a string. Both
-strings are expanded, and the first one must yield a number, <'n'>, say. If you
-are using a fixed value for the number, that is, if <'string1'> does not change
-when expanded, you can use the simpler operator notation that avoids some of
-the braces:
-
- ${length_<n>:<string>}
-+
-The result of this item is either the first <'n'> characters or the whole
-of <'string2'>, whichever is the shorter. Do not confuse %length% with
-%strlen%, which gives the length of a string.
-
-
-*\$\{lookup\{*<'key'>*\}~*<'search~type'>*~\{*<'file'>*\}~\{*<'string1'>*\}~\{*<'string2'>*\}\}*::
-This is the first of one of two different types of lookup item, which are both
-described in the next item.
-
-*\$\{lookup~*<'search~type'>*~\{*<'query'>*\}~\{*<'string1'>*\}~\{*<'string2'>*\}\}*::
-cindex:[expansion,lookup in]
-cindex:[file,lookup]
-cindex:[lookup,in expanded string]
-The two forms of lookup item specify data lookups in files and databases, as
-discussed in chapter <<CHAPfdlookup>>. The first form is used for single-key
-lookups, and the second is used for query-style lookups. The <'key'>, <'file'>,
-and <'query'> strings are expanded before use.
-+
-If there is any white space in a lookup item which is part of a filter command,
-a retry or rewrite rule, a routing rule for the ^manualroute^ router, or any
-other place where white space is significant, the lookup item must be enclosed
-in double quotes. The use of data lookups in users' filter files may be locked
-out by the system administrator.
-+
-cindex:[$value$]
-If the lookup succeeds, <'string1'> is expanded and replaces the entire item.
-During its expansion, the variable $value$ contains the data returned by the
-lookup. Afterwards it reverts to the value it had previously (at the outer
-level it is empty). If the lookup fails, <'string2'> is expanded and replaces
-the entire item. If \{<'string2'>\} is omitted, the replacement is the empty
-string on failure. If <'string2'> is provided, it can itself be a nested
-lookup, thus providing a mechanism for looking up a default value when the
-original lookup fails.
-+
-If a nested lookup is used as part of <'string1'>, $value$ contains the data
-for the outer lookup while the parameters of the second lookup are expanded,
-and also while <'string2'> of the second lookup is expanded, should the second
-lookup fail. + Instead of \{<'string2'>\} the word ``fail'' can appear, and in
-this case, if the lookup fails, the entire expansion is forced to fail (see
-section <<SECTforexpfai>>). If both \{<'string1'>\} and \{<'string2'>\} are
-omitted, the result is the looked up value in the case of a successful lookup,
-and nothing in the case of failure.
-+
-For single-key lookups, the string ``partial'' is permitted to precede the
-search type in order to do partial matching, and \* or \*@ may follow a search
-type to request default lookups if the key does not match (see sections
-<<SECTdefaultvaluelookups>> and <<SECTpartiallookup>> for details).
-+
-cindex:[numerical variables ($1$ $2$ etc),in lookup expansion]
-If a partial search is used, the variables $1$ and $2$ contain the wild
-and non-wild parts of the key during the expansion of the replacement text.
-They return to their previous values at the end of the lookup item.
-+
-This example looks up the postmaster alias in the conventional alias file:
-
- ${lookup {postmaster} lsearch {/etc/aliases} {$value}}
-+
-This example uses NIS+ to look up the full name of the user corresponding to
-the local part of an address, forcing the expansion to fail if it is not found:
-+
-....
-${lookup nisplus {[name=$local_part],passwd.org_dir:gcos} \
- {$value}fail}
-....
-
-
-*\$\{nhash\{*<'string1'>*\}\{*<'string2'>*\}\{*<'string3'>*\}\}*::
-cindex:[expansion,numeric hash]
-cindex:[hash function,numeric]
-The three strings are expanded; the first two must yield numbers. Call them
-<'n'> and <'m'>. If you are using fixed values for these numbers, that is, if
-<'string1'> and <'string2'> do not change when they are expanded, you can use
-the simpler operator notation that avoids some of the braces:
-
- ${nhash_<n>_<m>:<string>}
-+
-The second number is optional (in both notations). If there is only one number,
-the result is a number in the range 0--<'n'>-1. Otherwise, the string is
-processed by a div/mod hash function that returns two numbers, separated by a
-slash, in the ranges 0 to <'n'>-1 and 0 to <'m'>-1, respectively. For example,
-
- ${nhash{8}{64}{supercalifragilisticexpialidocious}}
-+
-returns the string ``6/33''.
-
-
-
-*\$\{perl\{*<'subroutine'>*\}\{*<'arg'>*\}\{*<'arg'>*\}...\}*::
-cindex:[Perl,use in expanded string]
-cindex:[expansion,calling Perl from]
-This item is available only if Exim has been built to include an embedded Perl
-interpreter. The subroutine name and the arguments are first separately
-expanded, and then the Perl subroutine is called with those arguments. No
-additional arguments need be given; the maximum number permitted, including the
-name of the subroutine, is nine.
-+
-The return value of the subroutine is inserted into the expanded string, unless
-the return value is %undef%. In that case, the expansion fails in the same way
-as an explicit ``fail'' on a lookup item.
-The return value is a scalar. Whatever you return is evaluated in a scalar
-context. For example, if you return the name of a Perl vector, the
-return value is the size of the vector, not its contents.
-+
-If the subroutine exits by calling Perl's %die% function, the expansion fails
-with the error message that was passed to %die%. More details of the embedded
-Perl facility are given in chapter <<CHAPperl>>.
-+
-The ^redirect^ router has an option called %forbid_filter_perl% which locks
-out the use of this expansion item in filter files.
-
-
-*\$\{prvs\{*<'address'>*\}\{*<'secret'>*\}\{*<'keynumber'>*\}\}*::
-+
-[revisionflag="changed"]
-cindex:[prvs,expansion item]
-The first argument is a complete email address and the second is secret
-keystring. The third argument, specifying a key number, is optional. If absent,
-it defaults to 0. The result of the expansion is a prvs-signed email address,
-to be typically used with the %return_path% option on an ^smtp^ transport as
-part of a bounce address tag validation (BATV) scheme. For more discussion and
-an example, see section <<SECTverifyPRVS>>.
-
-
-*\$\{prvscheck\{*<'address'>*\}\{*<'secret'>*\}\{*<'string'>*\}\}*::
-+
-[revisionflag="changed"]
-cindex:[prvscheck,expansion item]
-This expansion item is the complement of the %prvs% item. It is used for
-checking prvs-signed addresses. If the expansion of the first argument does not
-yield a syntactically valid prvs-signed address, the whole item expands to the
-empty string. When the first argument does expand to a syntactically valid
-prvs-signed address, the second argument is expanded, with the prvs-decoded
-version of the address and the key number extracted from the address in the
-variables $prvscheck_address$ and $prvscheck_keynum$, respectively.
-+
-[revisionflag="changed"]
-These two variables can be used in the expansion of the second argument to
-retrieve the secret. The validity of the prvs-signed address is then checked
-against the secret. The result is stored in the variable $prvscheck_result$,
-which is empty for failure or ``1'' for success.
-+
-[revisionflag="changed"]
-The third argument is optional; if it is missing, it defaults to an empty
-string. This argument is now expanded. If the result is an empty string, the
-result of the expansion is the decoded version of the address. This is the case
-whether or not the signature was valid. Otherwise, the result of the expansion
-is the expansion of the third argument.
-+
-[revisionflag="changed"]
-All three variables can be used in the expansion of the third argument.
-However, once the expansion is complete, only $prvscheck_result$ remains set.
-For more discussion and an example, see section <<SECTverifyPRVS>>.
-
-
-*\$\{readfile\{*<'file~name'>*\}\{*<'eol~string'>*\}\}*::
-cindex:[expansion,inserting an entire file]
-cindex:[file,inserting into expansion]
-The file name and end-of-line string are first expanded separately. The file is
-then read, and its contents replace the entire item. All newline characters in
-the file are replaced by the end-of-line string if it is present. Otherwise,
-newlines are left in the string.
-String expansion is not applied to the contents of the file. If you want this,
-you must wrap the item in an %expand% operator. If the file cannot be read, the
-string expansion fails.
-+
-The ^redirect^ router has an option called %forbid_filter_readfile% which
-locks out the use of this expansion item in filter files.
-
-
-
-*\$\{readsocket\{*<'name'>*\}\{*<'request'>*\}\{*<'timeout'>*\}\{*<'eol~string'>*\}\{*<'fail~string'>*\}\}*::
-cindex:[expansion,inserting from a socket]
-cindex:[socket, use of in expansion]
-This item inserts data that is read from a Unix domain socket into the expanded
-string. The minimal way of using it uses just two arguments:
-
- ${readsocket{/socket/name}{request string}}
-+
-Exim connects to the socket, writes the request string (unless it is an
-empty string) and reads from the socket until an end-of-file is read. A timeout
-of 5 seconds is applied. Additional, optional arguments extend what can be
-done. Firstly, you can vary the timeout. For example:
-
- ${readsocket{/socket/name}{request-string}{3s}}
-+
-A fourth argument allows you to change any newlines that are in the data
-that is read, in the same way as for %readfile% (see above). This example turns
-them into spaces:
-
- ${readsocket{/socket/name}{request-string}{3s}{ }}
-+
-As with all expansions, the substrings are expanded before the processing
-happens. Errors in these sub-expansions cause the expansion to fail. In
-addition, the following errors can occur:
-+
---
-- Failure to create a socket file descriptor;
-
-- Failure to connect the socket;
-
-- Failure to write the request-string;
-
-- Timeout on reading from the socket.
---
-+
-By default, any of these errors causes the expansion to fail. However, if
-you supply a fifth substring, it is expanded and used when any of the above
-errors occurs. For example:
-+
-....
- ${readsocket{/socket/name}{request-string}{3s}{\n}\
- {socket failure}}
-....
-+
-You can test for the existence of the socket by wrapping this expansion in
-`\$\{if exists`, but there is a race condition between that test and the
-actual opening of the socket, so it is safer to use the fifth argument if you
-want to be absolutely sure of avoiding an expansion error for a non-existent
-socket.
-+
-The ^redirect^ router has an option called %forbid_filter_readsocket% which
-locks out the use of this expansion item in filter files.
-
-*\$rheader_*<'header~name'>*:~or~\$rh_*<'header~name'>*:*::
-This item inserts ``raw'' header lines. It is described with the %header%
-expansion item above.
-
-
-
-*\$\{run\{*<'command'>*~*<'args'>*\}\{*<'string1'>*\}\{*<'string2'>*\}\}*::
-cindex:[expansion,running a command]
-The command and its arguments are first expanded separately, and then the
-command is run in a separate process, but under the same uid and gid. As in
-other command executions from Exim, a shell is not used by default. If you want
-a shell, you must explicitly code it.
-+
-[revisionflag="changed"]
-cindex:[return code,from %run% expansion]
-cindex:[$value$]
-If the command succeeds (gives a zero return code) <'string1'> is expanded and
-replaces the entire item; during this expansion, the standard output from the
-command is in the variable $value$. If the command fails, <'string2'>, if
-present, is expanded and used. Once again, during the expansion, the standard
-output from the command is in the variable $value$. If <'string2'> is absent,
-the result is empty. Alternatively, <'string2'> can be the word ``fail'' (not
-in braces) to force expansion failure if the command does not succeed. If both
-strings are omitted, the result is contents of the standard output on success,
-and nothing on failure.
-+
-cindex:[$runrc$]
-The return code from the command is put in the variable $runrc$, and this
-remains set afterwards, so in a filter file you can do things like this:
-
- if "${run{x y z}{}}$runrc" is 1 then ...
- elif $runrc is 2 then ...
- ...
- endif
-+
-If execution of the command fails (for example, the command does not exist),
-the return code is 127 -- the same code that shells use for non-existent
-commands.
-+
-*Warning*: In a router or transport, you cannot assume the order in which
-option values are expanded, except for those pre-conditions whose order of
-testing is documented. Therefore, you cannot reliably expect to set $runrc$
-by the expansion of one option, and use it in another.
-+
-The ^redirect^ router has an option called %forbid_filter_run% which locks
-out the use of this expansion item in filter files.
-
-
-*\$\{sg\{*<'subject'>*\}\{*<'regex'>*\}\{*<'replacement'>*\}\}*::
-cindex:[expansion,string substitution]
-This item works like Perl's substitution operator (s) with the global (/g)
-option; hence its name. However, unlike the Perl equivalent, Exim does not
-modify the subject string; instead it returns the modified string for insertion
-into the overall expansion. The item takes three arguments: the subject string,
-a regular expression, and a substitution string. For example
-
- ${sg{abcdefabcdef}{abc}{xyz}}
-+
-yields ``xyzdefxyzdef''. Because all three arguments are expanded before use, if
-any \$ or \ characters are required in the regular expression or in the
-substitution string, they have to be escaped. For example
-
- ${sg{abcdef}{^(...)(...)\$}{\$2\$1}}
-+
-yields ``defabc'', and
-
- ${sg{1=A 4=D 3=C}{\N(\d+)=\N}{K\$1=}}
-+
-yields ``K1=A K4=D K3=C''. Note the use of `\N` to protect the contents of
-the regular expression from string expansion.
-
-
-
-*\$\{substr\{*<'string1'>*\}\{*<'string2'>*\}\{*<'string3'>*\}\}*::
-cindex:[%substr%]
-cindex:[substring extraction]
-cindex:[expansion,substring extraction]
-The three strings are expanded; the first two must yield numbers. Call them
-<'n'> and <'m'>. If you are using fixed values for these numbers, that is, if
-<'string1'> and <'string2'> do not change when they are expanded, you can use
-the simpler operator notation that avoids some of the braces:
-
- ${substr_<n>_<m>:<string>}
-+
-The second number is optional (in both notations).
-If it is absent in the simpler format, the preceding underscore must also be
-omitted.
-+
-The %substr% item can be used to extract more general substrings than
-%length%. The first number, <'n'>, is a starting offset, and <'m'> is the
-length required. For example
-
- ${substr{3}{2}{$local_part}}
-+
-If the starting offset is greater than the string length the result is the
-null string; if the length plus starting offset is greater than the string
-length, the result is the right-hand part of the string, starting from the
-given offset. The first character in the string has offset zero.
-+
-The %substr% expansion item can take negative offset values to count
-from the right-hand end of its operand. The last character is offset -1, the
-second-last is offset -2, and so on. Thus, for example,
-
- ${substr{-5}{2}{1234567}}
-+
-yields ``34''. If the absolute value of a negative offset is greater than the
-length of the string, the substring starts at the beginning of the string, and
-the length is reduced by the amount of overshoot. Thus, for example,
-
- ${substr{-5}{2}{12}}
-+
-yields an empty string, but
-
- ${substr{-3}{2}{12}}
-+
-yields ``1''.
-+
-When the second number is omitted from %substr%, the remainder of the string
-is taken if the offset is positive. If it is negative, all characters in the
-string preceding the offset point are taken. For example, an offset of -1 and
-no length, as in these semantically identical examples:
-
- ${substr_-1:abcde}
- ${substr{-1}{abcde}}
-+
-yields all but the last character of the string, that is, ``abcd''.
-
-
-
-*\$\{tr\{*<'subject'>*\}\{*<'characters'>*\}\{*<'replacements'>*\}\}*::
-cindex:[expansion,character translation]
-This item does single-character translation on its subject string. The second
-argument is a list of characters to be translated in the subject string. Each
-matching character is replaced by the corresponding character from the
-replacement list. For example
-
- ${tr{abcdea}{ac}{13}}
-+
-yields `1b3de1`. If there are duplicates in the second character string, the
-last occurrence is used. If the third string is shorter than the second, its
-last character is replicated. However, if it is empty, no translation takes
-place.
-
-
-
-[[SECTexpop]]
-Expansion operators
-~~~~~~~~~~~~~~~~~~~
-cindex:[expansion,operators]
-For expansion items that perform transformations on a single argument string,
-the ``operator'' notation is used because it is simpler and uses fewer braces.
-The substring is first expanded before the operation is applied to it. The
-following operations can be performed:
-
-*\$\{address:*<'string'>*\}*::
-cindex:[expansion,RFC 2822 address handling]
-The string is interpreted as an RFC 2822 address, as it might appear in a
-header line, and the effective address is extracted from it. If the string does
-not parse successfully, the result is empty.
-
-
-*\$\{base62:*<'digits'>*\}*::
-+
-[revisionflag="changed"]
-cindex:[base62]
-cindex:[expansion,conversion to base 62]
-The string must consist entirely of decimal digits. The number is converted to
-base 62 and output as a string of six characters, including leading zeros. In
-the few operating environments where Exim uses base 36 instead of base 62 for
-its message identifiers (because those systems do not have case-sensitive file
-names), base 36 is used by this operator, despite its name. *Note*: Just to be
-absolutely clear: this is 'not' base64 encoding.
-
-*\$\{base62d:*<'base-62~digits'>*\}*::
-+
-[revisionflag="changed"]
-cindex:[base62]
-cindex:[expansion,conversion to base 62]
-The string must consist entirely of base-62 digits, or, in operating
-environments where Exim uses base 36 instead of base 62 for its message
-identifiers, base-36 digits. The number is converted to decimal and output as a
-string.
-
-
-*\$\{domain:*<'string'>*\}*::
-cindex:[domain,extraction]
-cindex:[expansion,domain extraction]
-The string is interpreted as an RFC 2822 address and the domain is extracted
-from it. If the string does not parse successfully, the result is empty.
-
-
-*\$\{escape:*<'string'>*\}*::
-cindex:[expansion,escaping non-printing characters]
-If the string contains any non-printing characters, they are converted to
-escape sequences starting with a backslash. Whether characters with the most
-significant bit set (so-called ``8-bit characters'') count as printing or not is
-controlled by the %print_topbitchars% option.
-
-
-*\$\{eval:*<'string'>*\}*::
-*\$\{eval10:*<'string'>*\}*::
-+
-[revisionflag="changed"]
-cindex:[expansion,expression evaluation]
-cindex:[expansion,arithmetic expression]
-These items supports simple arithmetic in expansion strings. The string (after
-expansion) must be a conventional arithmetic expression, but it is limited to
-five basic operators (plus, minus, times, divide, remainder) and parentheses.
-All operations are carried out using integer arithmetic. Plus and minus have a
-lower priority than times, divide, and remainder; operators with the same
-priority are evaluated from left to right.
-+
-For %eval%, numbers may be decimal, octal (starting with ``0'') or hexadecimal
-(starting with ``0x''). For %eval10%, all numbers are taken as decimal, even if
-they start with a leading zero. This can be useful when processing numbers
-extracted from dates or times, which often do have leading zeros.
-+
-A number may be followed by ``K'' or ``M'' to multiply it by 1024 or 1024\*1024,
-respectively. Negative numbers are supported. The result of the computation is
-a decimal representation of the answer (without ``K'' or ``M''). For example:
-+
-[revisionflag="changed"]
-&&&
-`\${eval:1+1} ` yields 2
-`\${eval:1+2*3} ` yields 7
-`\${eval:(1+2)*3} ` yields 9
-`\${eval:2+42%5} ` yields 4
-&&&
-+
-As a more realistic example, in an ACL you might have
-+
-....
-deny message = Too many bad recipients
- condition = \
- ${if and { \
- {>{$rcpt_count}{10}} \
- { \
- < \
- {$recipients_count} \
- {${eval:$rcpt_count/2}} \
- } \
- }{yes}{no}}
-....
-+
-The condition is true if there have been more than 10 RCPT commands and
-fewer than half of them have resulted in a valid recipient.
-
-
-*\$\{expand:*<'string'>*\}*::
-cindex:[expansion,re-expansion of substring]
-The %expand% operator causes a string to be expanded for a second time. For
-example,
-
- ${expand:${lookup{$domain}dbm{/some/file}{$value}}}
-+
-first looks up a string in a file while expanding the operand for %expand%, and
-then re-expands what it has found.
-
-
-*\$\{from_utf8:*<'string'>*\}*::
-cindex:[Unicode]
-cindex:[UTF-8,conversion from]
-cindex:[expansion,UTF-8 conversion]
-The world is slowly moving towards Unicode, although there are no standards for
-email yet. However, other applications (including some databases) are starting
-to store data in Unicode, using UTF-8 encoding. This operator converts from a
-UTF-8 string to an ISO-8859-1 string. UTF-8 code values greater than 255 are
-converted to underscores. The input must be a valid UTF-8 string. If it is not,
-the result is an undefined sequence of bytes.
-+
-Unicode code points with values less than 256 are compatible with ASCII and
-ISO-8859-1 (also known as Latin-1).
-For example, character 169 is the copyright symbol in both cases, though the
-way it is encoded is different. In UTF-8, more than one byte is needed for
-characters with code values greater than 127, whereas ISO-8859-1 is a
-single-byte encoding (but thereby limited to 256 characters). This makes
-translation from UTF-8 to ISO-8859-1 straightforward.
-
-
-*\$\{hash_*<'n'>*_*<'m'>*:*<'string'>*\}*::
-cindex:[hash function,textual]
-cindex:[expansion,textual hash]
-The %hash% operator is a simpler interface to the hashing function that can be
-used when the two parameters are fixed numbers (as opposed to strings that
-change when expanded). The effect is the same as
-
- ${hash{<n>}{<m>}{<string>}}
-+
-See the description of the general %hash% item above for details. The
-abbreviation %h% can be used when %hash% is used as an operator.
-
-
-
-*\$\{hex2b64:*<'hexstring'>*\}*::
-cindex:[base64 encoding,conversion from hex]
-cindex:[expansion,hex to base64]
-This operator converts a hex string into one that is base64 encoded. This can
-be useful for processing the output of the MD5 and SHA-1 hashing functions.
-
-
-*\$\{lc:*<'string'>*\}*::
-cindex:[case forcing in strings]
-cindex:[string,case forcing]
-cindex:[lower casing]
-cindex:[expansion,case forcing]
-This forces the letters in the string into lower-case, for example:
-
- ${lc:$local_part}
-
-
-
-*\$\{length_*<'number'>*:*<'string'>*\}*::
-cindex:[expansion,string truncation]
-The %length% operator is a simpler interface to the %length% function that can
-be used when the parameter is a fixed number (as opposed to a string that
-changes when expanded). The effect is the same as
-
- ${length{<number>}{<string>}}
-+
-See the description of the general %length% item above for details. Note that
-%length% is not the same as %strlen%. The abbreviation %l% can be used when
-%length% is used as an operator.
-
-
-*\$\{local_part:*<'string'>*\}*::
-cindex:[expansion,local part extraction]
-The string is interpreted as an RFC 2822 address and the local part is
-extracted from it. If the string does not parse successfully, the result is
-empty.
-
-
-*\$\{mask:*<'IP~address'>*/*<'bit~count'>*\}*::
-cindex:[masked IP address]
-cindex:[IP address,masking]
-cindex:[CIDR notation]
-cindex:[expansion,IP address masking]
-If the form of the string to be operated on is not an IP address followed by a
-slash and an integer (that is, a network address in CIDR notation), the
-expansion fails. Otherwise, this operator converts the IP address to binary,
-masks off the least significant bits according to the bit count, and converts
-the result back to text, with mask appended. For example,
-
- ${mask:10.111.131.206/28}
-+
-returns the string ``10.111.131.192/28''. Since this operation is expected to be
-mostly used for looking up masked addresses in files, the result for an IPv6
-address uses dots to separate components instead of colons, because colon
-terminates a key string in lsearch files. So, for example,
-
- ${mask:3ffe:ffff:836f:0a00:000a:0800:200a:c031/99}
-+
-returns the string
-
- 3ffe.ffff.836f.0a00.000a.0800.2000.0000/99
-+
-Letters in IPv6 addresses are always output in lower case.
-
-
-*\$\{md5:*<'string'>*\}*::
-cindex:[MD5 hash]
-cindex:[expansion,MD5 hash]
-The %md5% operator computes the MD5 hash value of the string, and returns it as
-a 32-digit hexadecimal number,
-in which any letters are in lower case.
-
-
-*\$\{nhash_*<'n'>*_*<'m'>*:*<'string'>*\}*::
-cindex:[expansion,numeric hash]
-cindex:[hash function,numeric]
-The %nhash% operator is a simpler interface to the numeric hashing function
-that can be used when the two parameters are fixed numbers (as opposed to
-strings that change when expanded). The effect is the same as
-
- ${nhash{<n>}{<m>}{<string>}}
-+
-See the description of the general %nhash% item above for details.
-
-
-*\$\{quote:*<'string'>*\}*::
-cindex:[quoting,in string expansions]
-cindex:[expansion,quoting]
-The %quote% operator puts its argument into double quotes if it
-is an empty string or
-contains anything other than letters, digits, underscores, dots, and hyphens.
-Any occurrences of double quotes and backslashes are escaped with a backslash.
-Newlines and carriage returns are converted to `\n` and `\r`,
-respectively For example,
-
- ${quote:ab"*"cd}
-+
-becomes
-
- "ab\"*\"cd"
-+
-The place where this is useful is when the argument is a substitution from a
-variable or a message header.
-
-*\$\{quote_local_part:*<'string'>*\}*::
-This operator is like %quote%, except that it quotes the string only if
-required to do so by the rules of RFC 2822 for quoting local parts. For
-example, a plus sign would not cause quoting (but it would for %quote%).
-If you are creating a new email address from the contents of $local_part$
-(or any other unknown data), you should always use this operator.
-
-
-*\$\{quote_*<'lookup-type'>*:*<'string'>*\}*::
-cindex:[quoting,lookup-specific]
-This operator applies lookup-specific quoting rules to the string. Each
-query-style lookup type has its own quoting rules which are described with
-the lookups in chapter <<CHAPfdlookup>>. For example,
-
- ${quote_ldap:two * two}
-+
-returns
-
- two%20%5C2A%20two
-+
-For single-key lookup types, no quoting is ever necessary and this operator
-yields an unchanged string.
-
-
-*\$\{rxquote:*<'string'>*\}*::
-cindex:[quoting,in regular expressions]
-cindex:[regular expressions,quoting]
-The %rxquote% operator inserts a backslash before any non-alphanumeric
-characters in its argument. This is useful when substituting the values of
-variables or headers inside regular expressions.
-
-
-*\$\{rfc2047:*<'string'>*\}*::
-cindex:[expansion,RFC 2047]
-cindex:[RFC 2047,expansion operator]
-This operator encodes text according to the rules of RFC 2047. This is an
-encoding that is used in header lines to encode non-ASCII characters. It is
-assumed that the input string is in the encoding specified by the
-%headers_charset% option, which defaults to ISO-8859-1. If the string contains
-only characters in the range 33--126, and no instances of the characters
-
- ? = ( ) < > @ , ; : \ " . [ ] _
-+
-it is not modified. Otherwise, the result is the RFC 2047 encoding of the
-string, using as many ``encoded words'' as necessary to encode all the
-characters.
-
-
-
-*\$\{sha1:*<'string'>*\}*::
-cindex:[SHA-1 hash]
-cindex:[expansion,SHA-1 hashing]
-The %sha1% operator computes the SHA-1 hash value of the string, and returns it
-as a 40-digit hexadecimal number, in which any letters are in upper case.
-
-
-*\$\{stat:*<'string'>*\}*::
-cindex:[expansion,statting a file]
-cindex:[file,extracting characteristics]
-The string, after expansion, must be a file path. A call to the 'stat()'
-function is made for this path. If 'stat()' fails, an error occurs and the
-expansion fails. If it succeeds, the data from the stat replaces the item, as a
-series of <'name'>=<'value'> pairs, where the values are all numerical, except
-for the value of ``smode''. The names are: ``mode'' (giving the mode as a
-4-digit octal number), ``smode'' (giving the mode in symbolic format as a
-10-character string, as for the 'ls' command), ``inode'', ``device'',
-``links'', ``uid'', ``gid'', ``size'', ``atime'', ``mtime'', and ``ctime''. You
-can extract individual fields using the %extract% expansion item.
-+
-[revisionflag="changed"]
-The use of the %stat% expansion in users' filter files can be locked out by the
-system administrator. *Warning*: The file size may be incorrect on 32-bit
-systems for files larger than 2GB.
-
-
-*\$\{str2b64:*<'string'>*\}*::
-cindex:[expansion,base64 encoding]
-cindex:[base64 encoding,in string expansion]
-This operator converts a string into one that is base64 encoded.
-
-
-
-*\$\{strlen:*<'string'>*\}*::
-cindex:[expansion,string length]
-cindex:[string,length in expansion]
-The item is replace by the length of the expanded string, expressed as a
-decimal number. *Note*: Do not confuse %strlen% with %length%.
-
-
-*\$\{substr_*<'start'>*_*<'length'>*:*<'string'>*\}*::
-cindex:[%substr%]
-cindex:[substring extraction]
-cindex:[expansion,substring expansion]
-The %substr% operator is a simpler interface to the %substr% function that can
-be used when the two parameters are fixed numbers (as opposed to strings that
-change when expanded). The effect is the same as
-
- ${substr{<start>}{<length>}{<string>}}
-+
-See the description of the general %substr% item above for details. The
-abbreviation %s% can be used when %substr% is used as an operator.
-
-*\$\{time_interval:*<'string'>*\}*::
-cindex:[%time_interval%]
-cindex:[time interval,formatting]
-The argument (after sub-expansion) must be a sequence of decimal digits that
-represents an interval of time as a number of seconds. It is converted into a
-number of larger units and output in Exim's normal time format, for example,
-`1w3d4h2m6s`.
-
-*\$\{uc:*<'string'>*\}*::
-cindex:[case forcing in strings]
-cindex:[string,case forcing]
-cindex:[upper casing]
-cindex:[expansion,case forcing]
-This forces the letters in the string into upper-case.
-
-
-
-
-
-
-[[SECTexpcond]]
-Expansion conditions
-~~~~~~~~~~~~~~~~~~~~
-cindex:[expansion,conditions]
-The following conditions are available for testing by the %\$\{if% construct
-while expanding strings:
-
-*!*<'condition'>::
-cindex:[expansion,negating a condition]
-Preceding any condition with an exclamation mark negates the result of the
-condition.
-
-<'symbolic~operator'>~*\{*<'string1'>*\}\{*<'string2'>*\}*::
-cindex:[numeric comparison]
-cindex:[expansion,numeric comparison]
-There are a number of symbolic operators for doing numeric comparisons. They
-are:
-+
-&&&
-`= ` equal
-`== ` equal
-`> ` greater
-`>= ` greater or equal
-`< ` less
-`<= ` less or equal
-&&&
-+
-For example,
-
- ${if >{$message_size}{10M} ...
-+
-Note that the general negation operator provides for inequality testing. The
-two strings must take the form of optionally signed decimal integers,
-optionally followed by one of the letters ``K'' or ``M'' (in either upper or
-lower case), signifying multiplication by 1024 or 1024\*1024, respectively.
-
-*crypteq~\{*<'string1'>*\}\{*<'string2'>*\}*::
-cindex:[expansion,encrypted comparison]
-cindex:[encrypted strings, comparing]
-This condition is included in the Exim binary if it is built to support any
-authentication mechanisms (see chapter <<CHAPSMTPAUTH>>). Otherwise, it is
-necessary to define SUPPORT_CRYPTEQ in _Local/Makefile_ to get %crypteq%
-included in the binary.
-+
-The %crypteq% condition has two arguments. The first is encrypted and compared
-against the second, which is already encrypted. The second string may be in the
-LDAP form for storing encrypted strings, which starts with the encryption type
-in curly brackets, followed by the data. If the second string does not begin
-with ``\{'' it is assumed to be encrypted with 'crypt()' or 'crypt16()' (see
-below), since such strings cannot begin with ``\{''. Typically this will be a
-field from a password file.
-+
-An example of an encrypted string in LDAP form is:
-
- {md5}CY9rzUYh03PK3k6DJie09g==
-+
-If such a string appears directly in an expansion, the curly brackets have to
-be quoted, because they are part of the expansion syntax. For example:
-
- ${if crypteq {test}{\{md5\}CY9rzUYh03PK3k6DJie09g==}{yes}{no}}
-+
-The following encryption types (whose names are matched case-independently) are
-supported:
-+
---
-- cindex:[MD5 hash]
-cindex:[base64 encoding,in encrypted password]
-%\{md5\}% computes the MD5 digest of the first string, and expresses this as
-printable characters to compare with the remainder of the second string. If the
-length of the comparison string is 24, Exim assumes that it is base64 encoded
-(as in the above example). If the length is 32, Exim assumes that it is a
-hexadecimal encoding of the MD5 digest. If the length not 24 or 32, the
-comparison fails.
-
-- cindex:[SHA-1 hash]
-%\{sha1\}% computes the SHA-1 digest of the first string, and expresses this as
-printable characters to compare with the remainder of the second string. If the
-length of the comparison string is 28, Exim assumes that it is base64 encoded.
-If the length is 40, Exim assumes that it is a hexadecimal encoding of the
-SHA-1 digest. If the length is not 28 or 40, the comparison fails.
-
-- cindex:['crypt()']
-%\{crypt\}% calls the 'crypt()' function, which traditionally used to use only
-the first eight characters of the password. However, in modern operating
-systems this is no longer true, and in many cases the entire password is used,
-whatever its length.
-
-- cindex:['crypt16()']
-%\{crypt16\}% calls the 'crypt16()' function (also known as 'bigcrypt()'),
-which was orginally created to use up to 16 characters of the password. Again,
-in modern operating systems, more characters may be used.
---
-+
-Exim has its own version of 'crypt16()' (which is just a double call to
-'crypt()'). For operating systems that have their own version, setting
-HAVE_CRYPT16 in _Local/Makefile_ when building Exim causes it to use the
-operating system version instead of its own. This option is set by default in
-the OS-dependent _Makefile_ for those operating systems that are known to
-support 'crypt16()'.
-+
-If you do not put any curly bracket encryption type in a %crypteq% comparison,
-the default is either `\{crypt\}` or `\{crypt16\}`, as determined by the
-setting of DEFAULT_CRYPT in _Local/Makefile_. The default default is
-`\{crypt\}`. Whatever the default, you can always use either function by
-specifying it explicitly in curly brackets.
-+
-Note that if a password is no longer than 8 characters, the results of
-encrypting it with 'crypt()' and 'crypt16()' are identical. That means that
-'crypt16()' is backwards compatible, as long as nobody feeds it a password
-longer than 8 characters.
-
-
-*def:*<'variable~name'>*::
-cindex:[expansion,checking for empty variable]
-The %def% condition must be followed by the name of one of the expansion
-variables defined in section <<SECTexpvar>>. The condition is true if the named
-expansion variable does not contain the empty string, for example
-
- ${if def:sender_ident {from $sender_ident}}
-+
-Note that the variable name is given without a leading %\$% character. If the
-variable does not exist, the expansion fails.
-
-*def:header_*<'header~name'>*:*~~or~~*def:h_*<'header~name'>*:*::
-cindex:[expansion,checking header line existence]
-This condition is true if a message is being processed and the named header
-exists in the message. For example,
-
- ${if def:header_reply-to:{$h_reply-to:}{$h_from:}}
-+
-*Note*: no %\$% appears before %header_% or %h_% in the condition, and the
-header name must be terminated by a colon if white space does not follow.
-
-*eq~\{*<'string1'>*\}\{*<'string2'>*\}*::
-cindex:[string,comparison]
-cindex:[expansion,string comparison]
-The two substrings are first expanded. The condition is true if the two
-resulting strings are identical, including the case of letters.
-
-*eqi~\{*<'string1'>*\}\{*<'string2'>*\}*::
-cindex:[string,comparison]
-cindex:[expansion,string comparison]
-The two substrings are first expanded. The condition is true if the two
-resulting strings are identical when compared in a case-independent way.
-
-*exists~\{*<'file~name'>*\}*::
-cindex:[expansion,file existence test]
-cindex:[file,existence test]
-The substring is first expanded and then interpreted as an absolute path. The
-condition is true if the named file (or directory) exists. The existence test
-is done by calling the 'stat()' function. The use of the %exists% test in
-users' filter files may be locked out by the system administrator.
-
-*first_delivery*::
-cindex:[delivery,first]
-cindex:[first delivery]
-cindex:[expansion,first delivery test]
-This condition, which has no data, is true during a message's first delivery
-attempt. It is false during any subsequent delivery attempts.
-
-*ge~\{*<'string1'>*\}\{*<'string2'>*\}*::
-See *gei*.
-
-*gei~\{*<'string1'>*\}\{*<'string2'>*\}*::
-cindex:[string,comparison]
-cindex:[expansion,string comparison]
-The two substrings are first expanded. The condition is true if the first
-string is lexically greater than or equal to the second string: for %ge% the
-comparison includes the case of letters, whereas for %gei% the comparison is
-case-independent.
-
-*gt~\{*<'string1'>*\}\{*<'string2'>*\}*::
-See *gti*.
-
-*gti~\{*<'string1'>*\}\{*<'string2'>*\}*::
-cindex:[string,comparison]
-cindex:[expansion,string comparison]
-The two substrings are first expanded. The condition is true if the first
-string is lexically greater than the second string: for %gt% the comparison
-includes the case of letters, whereas for %gti% the comparison is
-case-independent.
-
-*isip~\{*<'string'>*\}*::
-See *isip6*.
-
-*isip4~\{*<'string'>*\}*::
-See *isip6*.
-
-*isip6~\{*<'string'>*\}*::
-cindex:[IP address,testing string format]
-cindex:[string,testing for IP address]
-The substring is first expanded, and then tested to see if it has the form of
-an IP address. Both IPv4 and IPv6 addresses are valid for %isip%, whereas
-%isip4% and %isip6% test just for IPv4 or IPv6 addresses, respectively. For
-example, you could use
-
- ${if isip4{$sender_host_address}...
-+
-to test which version of IP an incoming SMTP connection is using.
-
-
-*ldapauth~\{*<'ldap~query'>*\}*::
-cindex:[LDAP,use for authentication]
-cindex:[expansion,LDAP authentication test]
-This condition supports user authentication using LDAP. See section
-<<SECTldap>> for details of how to use LDAP in lookups and the syntax of
-queries. For this use, the query must contain a user name and password. The
-query itself is not used, and can be empty. The condition is true if the
-password is not empty, and the user name and password are accepted by the LDAP
-server. An empty password is rejected without calling LDAP because LDAP binds
-with an empty password are considered anonymous regardless of the username, and
-will succeed in most configurations. See chapter <<CHAPSMTPAUTH>> for details
-of SMTP authentication, and chapter <<CHAPplaintext>> for an example of how
-this can be used.
-
-
-*le~\{*<'string1'>*\}\{*<'string2'>*\}*::
-See *lei*.
-
-*lei~\{*<'string1'>*\}\{*<'string2'>*\}*::
-cindex:[string,comparison]
-cindex:[expansion,string comparison]
-The two substrings are first expanded. The condition is true if the first
-string is lexically less than or equal to the second string: for %le% the
-comparison includes the case of letters, whereas for %lei% the comparison is
-case-independent.
-
-*lt~\{*<'string1'>*\}\{*<'string2'>*\}*::
-See *lti*.
-
-*lti~\{*<'string1'>*\}\{*<'string2'>*\}*::
-cindex:[string,comparison]
-cindex:[expansion,string comparison]
-The two substrings are first expanded. The condition is true if the first
-string is lexically less than the second string: for %lt% the comparison
-includes the case of letters, whereas for %lti% the comparison is
-case-independent.
-
-
-*match~\{*<'string1'>*\}\{*<'string2'>*\}*::
-cindex:[expansion,regular expression comparison]
-cindex:[regular expressions,match in expanded string]
-The two substrings are first expanded. The second is then treated as a regular
-expression and applied to the first. Because of the pre-expansion, if the
-regular expression contains dollar, or backslash characters, they must be
-escaped. Care must also be taken if the regular expression contains braces
-(curly brackets). A closing brace must be escaped so that it is not taken as a
-premature termination of <'string2'>. The easiest approach is to use the
-`\N` feature to disable expansion of the regular expression.
-For example,
-
- ${if match {$local_part}{\N^\d{3}\N} ...
-+
-If the whole expansion string is in double quotes, further escaping of
-backslashes is also required.
-+
-The condition is true if the regular expression match succeeds.
-The regular expression is not required to begin with a circumflex
-metacharacter, but if there is no circumflex, the expression is not anchored,
-and it may match anywhere in the subject, not just at the start. If you want
-the pattern to match at the end of the subject, you must include the `\$`
-metacharacter at an appropriate point.
-+
-cindex:[numerical variables ($1$ $2$ etc),in %if% expansion]
-At the start of an %if% expansion the values of the numeric variable
-substitutions $1$ etc. are remembered. Obeying a %match% condition that
-succeeds causes them to be reset to the substrings of that condition and they
-will have these values during the expansion of the success string. At the end
-of the %if% expansion, the previous values are restored. After testing a
-combination of conditions using %or%, the subsequent values of the numeric
-variables are those of the condition that succeeded.
-
-*match_address~\{*<'string1'>*\}\{*<'string2'>*\}*::
-See *match_local_part*.
-
-*match_domain~\{*<'string1'>*\}\{*<'string2'>*\}*::
-See *match_local_part*.
-
-*match_ip~\{*<'string1'>*\}\{*<'string2'>*\}*::
-+
-[revisionflag="changed"]
-This condition matches an IP address to a list of IP address patterns. It must
-be followed by two argument strings. The first (after expansion) must be an IP
-address or an empty string. The second (after expansion) is a restricted host
-list that can match only an IP address, not a host name. For example:
-+
-[revisionflag="changed"]
-....
-${if match_ip{$sender_host_address}{1.2.3.4:5.6.7.8}{...}{...}}
-....
-+
-[revisionflag="changed"]
-The specific types of host list item that are permitted in the list are:
-+
---
-- An IP address, optionally with a CIDR mask.
-
-- A single asterisk, which matches any IP address.
-
-- An empty item, which matches only if the IP address is empty. This could be
-useful for testing for a locally submitted message or one from specific hosts
-in a single test such as
-
-....
- ${if match_ip{$sender_host_address}{:4.3.2.1:...}{...}{...}}
-....
-
-where the first item in the list is the empty string.
-
-- The item @[] matches any of the local host's interface addresses.
-
-- Lookups are assumed to be ``net-'' style lookups, even if `net-` is not
-specified. Thus, the following are equivalent:
-
-....
- ${if match_ip{$sender_host_address}{lsearch;/some/file}...
- ${if match_ip{$sender_host_address}{net-lsearch;/some/file}...
-....
-
-You do need to specify the `net-` prefix if you want to specify a
-specific address mask, for example, by using `net24-`.
---
-+
-[revisionflag="changed"]
-Consult section <<SECThoslispatip>> for further details of these patterns.
-
-
-
-*match_local_part~\{*<'string1'>*\}\{*<'string2'>*\}*::
-cindex:[domain list,in expansion condition]
-cindex:[address list,in expansion condition]
-cindex:[local part list,in expansion condition]
-This condition, together with %match_address% and %match_domain%, make it
-possible to test domain, address, and local part lists within expansions. Each
-condition requires two arguments: an item and a list to match. A trivial
-example is:
-
- ${if match_domain{a.b.c}{x.y.z:a.b.c:p.q.r}{yes}{no}}
-+
-In each case, the second argument may contain any of the allowable items for a
-list of the appropriate type. Also, because the second argument (after
-expansion) is a standard form of list, it is possible to refer to a named list.
-Thus, you can use conditions like this:
-
- ${if match_domain{$domain}{+local_domains}{...
-+
-cindex:[`+caseful`]
-For address lists, the matching starts off caselessly, but the `+caseful`
-item can be used, as in all address lists, to cause subsequent items to
-have their local parts matched casefully. Domains are always matched
-caselessly.
-+
-*Note*: Host lists are 'not' supported in this way. This is because
-hosts have two identities: a name and an IP address, and it is not clear
-how to specify cleanly how such a test would work. However, IP addresses can be
-matched using %match_ip%.
-
-*pam~\{*<'string1'>*:*<'string2'>*:...\}*::
-cindex:[PAM authentication]
-cindex:[AUTH,with PAM]
-cindex:[Solaris,PAM support]
-cindex:[expansion,PAM authentication test]
-'Pluggable Authentication Modules'
-(*http://www.kernel.org/pub/linux/libs/pam/[]*)
-are a facility that is available in the latest releases of Solaris and in some
-GNU/Linux distributions. The Exim support, which is intended for use in
-conjunction with the SMTP AUTH command, is available only if Exim is
-compiled with
-
- SUPPORT_PAM=yes
-+
-in _Local/Makefile_. You probably need to add %-lpam% to EXTRALIBS, and
-in some releases of GNU/Linux %-ldl% is also needed.
-+
-The argument string is first expanded, and the result must be a
-colon-separated list of strings. Leading and trailing white space is ignored.
-The PAM module is initialized with the service name ``exim'' and the user name
-taken from the first item in the colon-separated data string (<'string1'>). The
-remaining items in the data string are passed over in response to requests from
-the authentication function. In the simple case there will only be one request,
-for a password, so the data consists of just two strings.
-+
-There can be problems if any of the strings are permitted to contain colon
-characters. In the usual way, these have to be doubled to avoid being taken as
-separators. If the data is being inserted from a variable, the %sg% expansion
-item can be used to double any existing colons. For example, the configuration
-of a LOGIN authenticator might contain this setting:
-
- server_condition = ${if pam{$1:${sg{$2}{:}{::}}}{yes}{no}}
-+
-For a PLAIN authenticator you could use:
-
- server_condition = ${if pam{$2:${sg{$3}{:}{::}}}{yes}{no}}
-+
-In some operating systems, PAM authentication can be done only from a process
-running as root. Since Exim is running as the Exim user when receiving
-messages, this means that PAM cannot be used directly in those systems.
-A patched version of the 'pam_unix' module that comes with the
-Linux PAM package is available from *http://www.e-admin.de/pam_exim/[]*.
-The patched module allows one special uid/gid combination, in addition to root,
-to authenticate. If you build the patched module to allow the Exim user and
-group, PAM can then be used from an Exim authenticator.
-
-
-*pwcheck~\{*<'string1'>*:*<'string2'>*\}*::
-cindex:['pwcheck' daemon]
-cindex:[Cyrus]
-cindex:[expansion,'pwcheck' authentication test]
-This condition supports user authentication using the Cyrus 'pwcheck' daemon.
-This is one way of making it possible for passwords to be checked by a process
-that is not running as root. *Note:* The use of 'pwcheck' is now deprecated.
-Its replacement is 'saslauthd' (see below).
-+
-The pwcheck support is not included in Exim by default. You need to specify
-the location of the pwcheck daemon's socket in _Local/Makefile_ before
-building Exim. For example:
-
- CYRUS_PWCHECK_SOCKET=/var/pwcheck/pwcheck
-+
-You do not need to install the full Cyrus software suite in order to use
-the pwcheck daemon. You can compile and install just the daemon alone
-from the Cyrus SASL library. Ensure that 'exim' is the only user that has
-access to the _/var/pwcheck_ directory.
-+
-The %pwcheck% condition takes one argument, which must be the user name and
-password, separated by a colon. For example, in a LOGIN authenticator
-configuration, you might have this:
-
- server_condition = ${if pwcheck{$1:$2}{1}{0}}
-
-
-*queue_running*::
-cindex:[queue runner,detecting when delivering from]
-cindex:[expansion,queue runner test]
-This condition, which has no data, is true during delivery attempts that are
-initiated by queue runner processes, and false otherwise.
-
-
-*radius~\{*<'authentication~string'>*\}*::
-cindex:[Radius]
-cindex:[expansion,Radius authentication]
-Radius authentication (RFC 2865) is supported in a similar way to PAM. You must
-set RADIUS_CONFIG_FILE in _Local/Makefile_ to specify the location of
-the Radius client configuration file in order to build Exim with Radius
-support.
-+
-[revisionflag="changed"]
-With just that one setting, Exim expects to be linked with the %radiusclient%
-library, using the original API. If you are using release 0.4.0 or later of
-this library, you need to set
-+
-[revisionflag="changed"]
-....
-RADIUS_LIB_TYPE=RADIUSCLIENTNEW
-....
-+
-[revisionflag="changed"]
-in _Local/Makefile_ when building Exim. You can also link Exim with the
-%libradius% library that comes with FreeBSD. To do this, set
-
- RADIUS_LIB_TYPE=RADLIB
-+
-in _Local/Makefile_, in addition to setting RADIUS_CONFIGURE_FILE.
-You may also have to supply a suitable setting in EXTRALIBS so that the
-Radius library can be found when Exim is linked.
-+
-The string specified by RADIUS_CONFIG_FILE is expanded and passed to the
-Radius client library, which calls the Radius server. The condition is true if
-the authentication is successful. For example
-
- server_condition = \$\{if radius\{<arguments>\}\{yes\}\{no\}\}
-
-
-
-
-*saslauthd~\{\{*<'user'>*\}\{*<'password'>*\}\{*<'service'>*\}\{*<'realm'>*\}\}*::
-cindex:['saslauthd' daemon]
-cindex:[Cyrus]
-cindex:[expansion,'saslauthd' authentication test]
-This condition supports user authentication using the Cyrus 'saslauthd'
-daemon. This replaces the older 'pwcheck' daemon, which is now deprecated.
-Using this daemon is one way of making it possible for passwords to be checked
-by a process that is not running as root.
-+
-The saslauthd support is not included in Exim by default. You need to specify
-the location of the saslauthd daemon's socket in _Local/Makefile_ before
-building Exim. For example:
-
- CYRUS_SASLAUTHD_SOCKET=/var/state/saslauthd/mux
-+
-You do not need to install the full Cyrus software suite in order to use
-the saslauthd daemon. You can compile and install just the daemon alone
-from the Cyrus SASL library.
-+
-Up to four arguments can be supplied to the %saslauthd% condition, but only two
-are mandatory. For example:
-
- server_condition = ${if saslauthd{{$1}{$2}}{1}{0}}
-+
-The service and the realm are optional (which is why the arguments are enclosed
-in their own set of braces). For details of the meaning of the service and
-realm, and how to run the daemon, consult the Cyrus documentation.
-
-
-
-Combining expansion conditions
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[expansion,combining conditions]
-Several conditions can be tested at once by combining them using the %and% and
-%or% combination conditions. Note that %and% and %or% are complete conditions
-on their own, and precede their lists of sub-conditions. Each sub-condition
-must be enclosed in braces within the overall braces that contain the list. No
-repetition of %if% is used.
-
-
-*or~\{\{*<'cond1'>*\}\{*<'cond2'>*\}...\}*::
-cindex:[``or'' expansion condition]
-cindex:[expansion,``or'' of conditions]
-The sub-conditions are evaluated from left to right. The condition is true if
-any one of the sub-conditions is true.
-For example,
-
- ${if or {{eq{$local_part}{spqr}}{eq{$domain}{testing.com}}}...
-+
-When a true sub-condition is found, the following ones are parsed but not
-evaluated. If there are several ``match'' sub-conditions the values of the
-numeric variables afterwards are taken from the first one that succeeds.
-
-*and~\{\{*<'cond1'>*\}\{*<'cond2'>*\}...\}*::
-cindex:[``and'' expansion condition]
-cindex:[expansion,``and'' of conditions]
-The sub-conditions are evaluated from left to right. The condition is true if
-all of the sub-conditions are true. If there are several ``match''
-sub-conditions, the values of the numeric variables afterwards are taken from
-the last one. When a false sub-condition is found, the following ones are
-parsed but not evaluated.
-
-
-
-
-[[SECTexpvar]]
-Expansion variables
-~~~~~~~~~~~~~~~~~~~
-cindex:[expansion variables, list of]
-This section contains an alphabetical list of all the expansion variables. Some
-of them are available only when Exim is compiled with specific options such as
-support for TLS or the content scanning extension.
-
-$0$, $1$, etc::
-cindex:[numerical variables ($1$ $2$ etc)]
-When a %match% expansion condition succeeds, these variables contain the
-captured substrings identified by the regular expression during subsequent
-processing of the success string of the containing %if% expansion item. They
-may also be set externally by some other matching process which precedes the
-expansion of the string. For example, the commands available in Exim filter
-files include an %if% command with its own regular expression matching
-condition.
-
-$acl_c0$ -- $acl_c9$::
-Values can be placed in these variables by the %set% modifier in an ACL. The
-values persist throughout the lifetime of an SMTP connection. They can be used
-to pass information between ACLs and different invocations of the same ACL.
-When a message is received, the values of these variables are saved with the
-message, and can be accessed by filters, routers, and transports during
-subsequent delivery.
-
-$acl_m0$ -- $acl_m9$::
-Values can be placed in these variables by the %set% modifier in an ACL. They
-retain their values while a message is being received, but are reset
-afterwards. They are also reset by MAIL, RSET, EHLO, HELO, and after starting a
-TLS session. When a message is received, the values of these variables are
-saved with the message, and can be accessed by filters, routers, and transports
-during subsequent delivery.
-
-$acl_verify_message$::
-+
-[revisionflag="changed"]
-cindex:[$acl_verify_message$]
-After an address verification has failed, this variable contains the failure
-message. It retains its value for use in subsequent modifiers. The message can
-be preserved by coding like this:
-+
-[revisionflag="changed"]
-....
-warn !verify = sender
- set acl_m0 = $acl_verify_message
-....
-+
-[revisionflag="changed"]
-You can use $acl_verify_message$ during the expansion of the %message% or
-%log_message% modifiers, to include information about the verification failure.
-
-
-$address_data$::
-cindex:[$address_data$]
-This variable is set by means of the %address_data% option in routers. The
-value then remains with the address while it is processed by subsequent routers
-and eventually a transport. If the transport is handling multiple addresses,
-the value from the first address is used. See chapter <<CHAProutergeneric>> for
-more details. *Note*: the contents of $address_data$ are visible in user filter
-files.
-+
-If $address_data$ is set when the routers are called from an ACL to verify
-a recipient address, the final value is still in the variable for subsequent
-conditions and modifiers of the ACL statement. If routing the address caused it
-to be redirected to just one address, the child address is also routed as part
-of the verification, and in this case the final value of $address_data$ is
-from the child's routing.
-+
-If $address_data$ is set when the routers are called from an ACL to verify a
-sender address, the final value is also preserved, but this time in
-$sender_address_data$, to distinguish it from data from a recipient
-address.
-+
-In both cases (recipient and sender verification), the value does not persist
-after the end of the current ACL statement. If you want to preserve
-these values for longer, you can save them in ACL variables.
-
-$address_file$::
-cindex:[$address_file$]
-When, as a result of aliasing, forwarding, or filtering, a message is directed
-to a specific file, this variable holds the name of the file when the transport
-is running. At other times, the variable is empty. For example, using the
-default configuration, if user %r2d2% has a _.forward_ file containing
-
- /home/r2d2/savemail
-+
-then when the ^address_file^ transport is running, $address_file$
-contains ``/home/r2d2/savemail''.
-+
-cindex:[Sieve filter,value of $address_file$]
-For Sieve filters, the value may be ``inbox'' or a relative folder name. It is
-then up to the transport configuration to generate an appropriate absolute path
-to the relevant file.
-
-$address_pipe$::
-cindex:[$address_pipe$]
-When, as a result of aliasing or forwarding, a message is directed to a pipe,
-this variable holds the pipe command when the transport is running.
-
-$authenticated_id$::
-cindex:[authentication,id]
-cindex:[$authenticated_id$]
-When a server successfully authenticates a client it may be configured to
-preserve some of the authentication information in the variable
-$authenticated_id$ (see chapter <<CHAPSMTPAUTH>>). For example, a user/password
-authenticator configuration might preserve the user name for use in the
-routers. Note that this is not the same information that is saved in
-$sender_host_authenticated$. When a message is submitted locally (that is, not
-over a TCP connection), the value of $authenticated_id$ is the login name of
-the calling process.
-
-$authenticated_sender$::
-cindex:[sender,authenticated]
-cindex:[authentication,sender]
-cindex:[AUTH,on MAIL command]
-cindex:[$authenticated_sender$]
-When acting as a server, Exim takes note of the AUTH= parameter on an incoming
-SMTP MAIL command if it believes the sender is sufficiently trusted, as
-described in section <<SECTauthparamail>>. Unless the data is the string
-``<>'', it is set as the authenticated sender of the message, and the value is
-available during delivery in the $authenticated_sender$ variable. If the sender
-is not trusted, Exim accepts the syntax of AUTH=, but ignores the data.
-+
-cindex:[$qualify_domain$]
-When a message is submitted locally (that is, not over a TCP connection), the
-value of $authenticated_sender$ is an address constructed from the login
-name of the calling process and $qualify_domain$.
-
-
-$authentication_failed$::
-cindex:[authentication,failure]
-cindex:[$authentication_failed$]
-This variable is set to ``1'' in an Exim server if a client issues an AUTH
-command that does not succeed. Otherwise it is set to ``0''. This makes it
-possible to distinguish between ``did not try to authenticate''
-($sender_host_authenticated$ is empty and $authentication_failed$ is set to
-``0'') and ``tried to authenticate but failed'' ($sender_host_authenticated$ is
-empty and $authentication_failed$ is set to ``1''). Failure includes any
-negative response to an AUTH command, including (for example) an attempt to use
-an undefined mechanism.
-
-$body_linecount$::
-cindex:[message body, line count]
-cindex:[body of message,line count]
-cindex:[$body_linecount$]
-When a message is being received or delivered, this variable contains the
-number of lines in the message's body. See also $message_linecount$.
-
-$body_zerocount$::
-cindex:[message body, binary zero count]
-cindex:[body of message,binary zero count]
-cindex:[binary zero,in message body]
-cindex:[$body_zerocount$]
-When a message is being received or delivered, this variable contains the
-number of binary zero bytes in the message's body.
-
-$bounce_recipient$::
-cindex:[$bounce_recipient$]
-This is set to the recipient address of a bounce message while Exim is creating
-it. It is useful if a customized bounce message text file is in use (see
-chapter <<CHAPemsgcust>>).
-
-$bounce_return_size_limit$::
-cindex:[$bounce_return_size_limit$]
-This contains the value set in the %bounce_return_size_limit% option, rounded
-up to a multiple of 1000. It is useful when a customized error message text
-file is in use (see chapter <<CHAPemsgcust>>).
-
-$caller_gid$::
-cindex:[gid (group id),caller]
-cindex:[$caller_gid$]
-The real group id under which the process that called Exim was running. This is
-not the same as the group id of the originator of a message (see
-$originator_gid$). If Exim re-execs itself, this variable in the new
-incarnation normally contains the Exim gid.
-
-$caller_uid$::
-cindex:[uid (user id),caller]
-cindex:[$caller_uid$]
-The real user id under which the process that called Exim was running. This is
-not the same as the user id of the originator of a message (see
-$originator_uid$). If Exim re-execs itself, this variable in the new
-incarnation normally contains the Exim uid.
-
-$compile_date$::
-cindex:[$compile_date$]
-The date on which the Exim binary was compiled.
-
-$compile_number$::
-cindex:[$compile_number$]
-The building process for Exim keeps a count of the number
-of times it has been compiled. This serves to distinguish different
-compilations of the same version of the program.
-
-$demime_errorlevel$::
-cindex:[$demime_errorlevel$]
-This variable is available when Exim is compiled with
-the content-scanning extension and the obsolete %demime% condition. For
-details, see section <<SECTdemimecond>>.
-
-$demime_reason$::
-cindex:[$demime_reason$]
-This variable is available when Exim is compiled with the
-content-scanning extension and the obsolete %demime% condition. For details,
-see section <<SECTdemimecond>>.
-
-
-$dnslist_domain$::
-cindex:[black list (DNS)]
-cindex:[$dnslist_domain$]
-When a client host is found to be on a DNS (black) list,
-the list's domain name is put into this variable so that it can be included in
-the rejection message.
-
-$dnslist_text$::
-cindex:[$dnslist_text$]
-When a client host is found to be on a DNS (black) list, the
-contents of any associated TXT record are placed in this variable.
-
-$dnslist_value$::
-cindex:[$dnslist_value$]
-When a client host is found to be on a DNS (black) list,
-the IP address from the resource record is placed in this variable.
-If there are multiple records, all the addresses are included, comma-space
-separated.
-
-$domain$::
-cindex:[$domain$]
-When an address is being routed, or delivered on its own, this variable
-contains the domain. Global address rewriting happens when a message is
-received, so the value of $domain$ during routing and delivery is the value
-after rewriting. $domain$ is set during user filtering, but not during system
-filtering, because a message may have many recipients and the system filter is
-called just once.
-+
-When more than one address is being delivered at once (for example, several
-RCPT commands in one SMTP delivery), $domain$ is set only if they all
-have the same domain. Transports can be restricted to handling only one domain
-at a time if the value of $domain$ is required at transport time -- this is
-the default for local transports. For further details of the environment in
-which local transports are run, see chapter <<CHAPenvironment>>.
-+
-cindex:[%delay_warning_condition%]
-At the end of a delivery, if all deferred addresses have the same domain, it is
-set in $domain$ during the expansion of %delay_warning_condition%.
-+
-The $domain$ variable is also used in some other circumstances:
-+
---
-- When an ACL is running for a RCPT command, $domain$ contains the domain of
-the recipient address. The domain of the 'sender' address is in
-$sender_address_domain$ at both MAIL time and at RCPT time. $domain$ is not
-normally set during the running of the MAIL ACL. However, if the sender address
-is verified with a callout during the MAIL ACL, the sender domain is placed in
-$domain$ during the expansions of %hosts%, %interface%, and %port% in the
-^smtp^ transport.
-
-- When a rewrite item is being processed (see chapter <<CHAPrewrite>>), $domain$
-contains the domain portion of the address that is being rewritten; it can be
-used in the expansion of the replacement address, for example, to rewrite
-domains by file lookup.
-
-- With one important exception, whenever a domain list is being scanned,
-$domain$ contains the subject domain. *Exception*: When a domain list in
-a %sender_domains% condition in an ACL is being processed, the subject domain
-is in $sender_address_domain$ and not in $domain$. It works this way so
-that, in a RCPT ACL, the sender domain list can be dependent on the
-recipient domain (which is what is in $domain$ at this time).
-
-- cindex:[ETRN,value of $domain$]
-cindex:[%smtp_etrn_command%]
-When the %smtp_etrn_command% option is being expanded, $domain$ contains
-the complete argument of the ETRN command (see section <<SECTETRN>>).
---
-
-
-$domain_data$::
-cindex:[$domain_data$]
-When the %domains% option on a router matches a domain by
-means of a lookup, the data read by the lookup is available during the running
-of the router as $domain_data$. In addition, if the driver routes the
-address to a transport, the value is available in that transport. If the
-transport is handling multiple addresses, the value from the first address is
-used.
-+
-$domain_data$ is also set when the %domains% condition in an ACL matches a
-domain by means of a lookup. The data read by the lookup is available during
-the rest of the ACL statement. In all other situations, this variable expands
-to nothing.
-
-$exim_gid$::
-cindex:[$exim_gid$]
-This variable contains the numerical value of the Exim group id.
-
-$exim_path$::
-cindex:[$exim_path$]
-This variable contains the path to the Exim binary.
-
-$exim_uid$::
-cindex:[$exim_uid$]
-This variable contains the numerical value of the Exim user id.
-
-$found_extension$::
-cindex:[$found_extension$]
-This variable is available when Exim is compiled with the
-content-scanning extension and the obsolete %demime% condition. For details,
-see section <<SECTdemimecond>>.
-
-$header_$<'name'>::
-This is not strictly an expansion variable. It is expansion syntax for
-inserting the message header line with the given name. Note that the name must
-be terminated by colon or white space, because it may contain a wide variety of
-characters. Note also that braces must 'not' be used.
-
-$home$::
-cindex:[$home$]
-When the %check_local_user% option is set for a router, the user's home
-directory is placed in $home$ when the check succeeds. In particular, this
-means it is set during the running of users' filter files. A router may also
-explicitly set a home directory for use by a transport; this can be overridden
-by a setting on the transport itself.
-+
-When running a filter test via the %-bf% option, $home$ is set to the value
-of the environment variable HOME.
-
-$host$::
-cindex:[$host$]
-When the ^smtp^ transport is expanding its options for encryption using TLS,
-$host$ contains the name of the host to which it is connected. Likewise, when
-used in the client part of an authenticator configuration (see chapter
-<<CHAPSMTPAUTH>>), $host$ contains the name of the server to which the client
-is connected.
-+
-cindex:[transport,filter]
-cindex:[filter,transport filter]
-When used in a transport filter (see chapter <<CHAPtransportgeneric>>) $host$
-refers to the host involved in the current connection. When a local transport
-is run as a result of a router that sets up a host list, $host$ contains the
-name of the first host.
-
-$host_address$::
-cindex:[$host_address$]
-This variable is set to the remote host's IP address whenever $host$ is set for
-a remote connection. It is also set to the IP address that is being checked
-when the %ignore_target_hosts% option is being processed.
-
-$host_data$::
-cindex:[$host_data$]
-If a %hosts% condition in an ACL is satisfied by means of a lookup, the result
-of the lookup is made available in the $host_data$ variable. This
-allows you, for example, to do things like this:
-
- deny hosts = net-lsearch;/some/file
- message = $host_data
-
-
-$host_lookup_deferred$::
-cindex:[host name lookup, failure of]
-cindex:[$host_lookup_deferred$]
-This variable normally contains ``0'', as does $host_lookup_failed$. When a
-message comes from a remote host and there is an attempt to look up the host's
-name from its IP address, and the attempt is not successful, one of these
-variables is set to ``1''.
-+
---
-- If the lookup receives a definite negative response (for example, a DNS lookup
-succeeded, but no records were found), $host_lookup_failed$ is set to ``1''.
-
-- If there is any kind of problem during the lookup, such that Exim cannot
-tell whether or not the host name is defined (for example, a timeout for a DNS
-lookup), $host_lookup_deferred$ is set to ``1''.
---
-+
-Looking up a host's name from its IP address consists of more than just a
-single reverse lookup. Exim checks that a forward lookup of at least one of the
-names it receives from a reverse lookup yields the original IP address. If this
-is not the case, Exim does not accept the looked up name(s), and
-$host_lookup_failed$ is set to ``1''. Thus, being able to find a name from an
-IP address (for example, the existence of a PTR record in the DNS) is not
-sufficient on its own for the success of a host name lookup. If the reverse
-lookup succeeds, but there is a lookup problem such as a timeout when checking
-the result, the name is not accepted, and $host_lookup_deferred$ is set to
-``1''. See also $sender_host_name$.
-
-$host_lookup_failed$::
-cindex:[$host_lookup_failed$]
-See $host_lookup_deferred$.
-
-
-$inode$::
-cindex:[$inode$]
-The only time this variable is set is while expanding the %directory_file%
-option in the ^appendfile^ transport. The variable contains the inode number
-of the temporary file which is about to be renamed. It can be used to construct
-a unique name for the file.
-
-$interface_address$::
-+
-[revisionflag="changed"]
-cindex:[$interface_address$]
-As soon as a server starts processing a TCP/IP connection, this variable is set
-to the address of the local IP interface, and $interface_port$ is set to the
-port number. These values are therefore available for use in the ``connect''
-ACL. See also the %-oMi% command line option. As well as being used in ACLs,
-these variable could be used, for example, to make the file name for a TLS
-certificate depend on which interface and/or port is being used.
-
-$interface_port$::
-cindex:[$interface_port$]
-See $interface_address$.
-
-$ldap_dn$::
-cindex:[$ldap_dn$]
-This variable, which is available only when Exim is compiled with LDAP support,
-contains the DN from the last entry in the most recently successful LDAP
-lookup.
-
-$load_average$::
-cindex:[$load_average$]
-This variable contains the system load average, multiplied by 1000 to that it
-is an integer. For example, if the load average is 0.21, the value of the
-variable is 210. The value is recomputed every time the variable is referenced.
-
-$local_part$::
-cindex:[$local_part$]
-When an address is being routed, or delivered on its own, this
-variable contains the local part. When a number of addresses are being
-delivered together (for example, multiple RCPT commands in an SMTP
-session), $local_part$ is not set.
-+
-Global address rewriting happens when a message is received, so the value of
-$local_part$ during routing and delivery is the value after rewriting.
-$local_part$ is set during user filtering, but not during system filtering,
-because a message may have many recipients and the system filter is called just
-once.
-+
-cindex:[$local_part_prefix$]
-cindex:[$local_part_suffix$]
-If a local part prefix or suffix has been recognized, it is not included in the
-value of $local_part$ during routing and subsequent delivery. The values of
-any prefix or suffix are in $local_part_prefix$ and
-$local_part_suffix$, respectively.
-+
-When a message is being delivered to a file, pipe, or autoreply transport as a
-result of aliasing or forwarding, $local_part$ is set to the local part of
-the parent address, not to the file name or command (see $address_file$ and
-$address_pipe$).
-+
-When an ACL is running for a RCPT command, $local_part$ contains the
-local part of the recipient address.
-+
-When a rewrite item is being processed (see chapter <<CHAPrewrite>>),
-$local_part$ contains the local part of the address that is being rewritten;
-it can be used in the expansion of the replacement address, for example.
-+
-In all cases, all quoting is removed from the local part. For example, for both
-the addresses
-
- "abc:xyz"@test.example
- abc\:xyz@test.example
-+
-the value of $local_part$ is
-
- abc:xyz
-+
-If you use $local_part$ to create another address, you should always wrap it
-inside a quoting operator. For example, in a ^redirect^ router you could have:
-
- data = ${quote_local_part:$local_part}@new.domain.example
-+
-*Note*: The value of $local_part$ is normally lower cased. If you want
-to process local parts in a case-dependent manner in a router, you can set the
-%caseful_local_part% option (see chapter <<CHAProutergeneric>>).
-
-$local_part_data$::
-cindex:[$local_part_data$]
-When the %local_parts% option on a router matches a local part by means of a
-lookup, the data read by the lookup is available during the running of the
-router as $local_part_data$. In addition, if the driver routes the address
-to a transport, the value is available in that transport. If the transport is
-handling multiple addresses, the value from the first address is used.
-+
-$local_part_data$ is also set when the %local_parts% condition in an ACL
-matches a local part by means of a lookup. The data read by the lookup is
-available during the rest of the ACL statement. In all other situations, this
-variable expands to nothing.
-
-$local_part_prefix$::
-cindex:[$local_part_prefix$]
-When an address is being routed or delivered, and a
-specific prefix for the local part was recognized, it is available in this
-variable, having been removed from $local_part$.
-
-$local_part_suffix$::
-cindex:[$local_part_suffix$]
-When an address is being routed or delivered, and a
-specific suffix for the local part was recognized, it is available in this
-variable, having been removed from $local_part$.
-
-$local_scan_data$::
-cindex:[$local_scan_data$]
-This variable contains the text returned by the 'local_scan()' function when a
-message is received. See chapter <<CHAPlocalscan>> for more details.
-
-$local_user_gid$::
-cindex:[$local_user_gid$]
-See $local_user_uid$.
-
-$local_user_uid$::
-cindex:[$local_user_uid$]
-This variable and $local_user_gid$ are set to the uid and gid after the
-%check_local_user% router precondition succeeds. This means that their values
-are available for the remaining preconditions (%senders%, %require_files%, and
-%condition%), for the %address_data% expansion, and for any router-specific
-expansions. At all other times, the values in these variables are `(uid_t)(-1)`
-and `(gid_t)(-1)`, respectively.
-
-$localhost_number$::
-cindex:[$localhost_number$]
-This contains the expanded value of the
-%localhost_number% option. The expansion happens after the main options have
-been read.
-
-$log_inodes$::
-cindex:[$log_inodes$]
-The number of free inodes in the disk partition where Exim's
-log files are being written. The value is recalculated whenever the variable is
-referenced. If the relevant file system does not have the concept of inodes,
-the value of is -1. See also the %check_log_inodes% option.
-
-$log_space$::
-cindex:[$log_space$]
-The amount of free space (as a number of kilobytes) in the disk
-partition where Exim's log files are being written. The value is recalculated
-whenever the variable is referenced. If the operating system does not have the
-ability to find the amount of free space (only true for experimental systems),
-the space value is -1. See also the %check_log_space% option.
-
-
-$mailstore_basename$::
-cindex:[$mailstore_basename$]
-This variable is set only when doing deliveries in ``mailstore'' format in the
-^appendfile^ transport. During the expansion of the %mailstore_prefix%,
-%mailstore_suffix%, %message_prefix%, and %message_suffix% options, it contains
-the basename of the files that are being written, that is, the name without the
-``.tmp'', ``.env'', or ``.msg'' suffix. At all other times, this variable is
-empty.
-
-$malware_name$::
-cindex:[$malware_name$]
-This variable is available when Exim is compiled with the
-content-scanning extension. It is set to the name of the virus that was found
-when the ACL %malware% condition is true (see section <<SECTscanvirus>>).
-
-
-$message_age$::
-cindex:[message,age of]
-cindex:[$message_age$]
-This variable is set at the start of a delivery attempt to contain the number
-of seconds since the message was received. It does not change during a single
-delivery attempt.
-
-$message_body$::
-cindex:[body of message,expansion variable]
-cindex:[message body, in expansion]
-cindex:[binary zero,in message body]
-cindex:[$message_body$]
-This variable contains the initial portion of a message's
-body while it is being delivered, and is intended mainly for use in filter
-files. The maximum number of characters of the body that are put into the
-variable is set by the %message_body_visible% configuration option; the
-default is 500. Newlines are converted into spaces to make it easier to search
-for phrases that might be split over a line break.
-Binary zeros are also converted into spaces.
-
-$message_body_end$::
-cindex:[body of message,expansion variable]
-cindex:[message body, in expansion]
-cindex:[$message_body_end$]
-This variable contains the final portion of a message's
-body while it is being delivered. The format and maximum size are as for
-$message_body$.
-
-$message_body_size$::
-cindex:[body of message,size]
-cindex:[message body, size]
-cindex:[$message_body_size$]
-When a message is being delivered, this variable contains the size of the body
-in bytes. The count starts from the character after the blank line that
-separates the body from the header. Newlines are included in the count. See
-also $message_size$, $body_linecount$, and $body_zerocount$.
-
-$message_exim_id$::
-+
-[revisionflag="changed"]
-cindex:[$message_exim_id$]
-When a message is being received or delivered, this variable contains the
-unique message id that is generated and used by Exim to identify the message.
-An id is not created for a message until after its header has been successfully
-received. *Note*: This is 'not' the contents of the 'Message-ID:' header line;
-it is the local id that Exim assigns to the message, for example:
-`1BXTIK-0001yO-VA`.
-
-$message_headers$::
-This variable contains a concatenation of all the header lines when a message
-is being processed, except for lines added by routers or transports. The header
-lines are separated by newline characters.
-
-$message_id$::
-+
-[revisionflag="changed"]
-This is an old name for $message_exim_id$, which is now deprecated.
-
-$message_linecount$::
-+
-[revisionflag="changed"]
-cindex:[$message_linecount$]
-This variable contains the total number of lines in the header and body of the
-message. Compare $body_linecount$, which is the count for the body only. During
-the DATA and content-scanning ACLs, $message_linecount$ contains the number of
-lines received. Before delivery happens (that is, before filters, routers, and
-transports run) the count is increased to include the 'Received:' header line
-that Exim standardly adds, and also any other header lines that are added by
-ACLs. The blank line that separates the message header from the body is not
-counted. Here is an example of the use of this variable in a DATA ACL:
-+
-[revisionflag="changed"]
-....
-deny message = Too many lines in message header
- condition = \
- ${if <{250}{${eval: $message_linecount - $body_linecount}}}
-....
-+
-[revisionflag="changed"]
-In the MAIL and RCPT ACLs, the value is zero because at that stage the
-message has not yet been received.
-
-$message_size$::
-cindex:[size,of message]
-cindex:[message,size]
-cindex:[$message_size$]
-When a message is being processed, this variable contains its size in bytes. In
-most cases, the size includes those headers that were received with the
-message, but not those (such as 'Envelope-to:') that are added to individual
-deliveries as they are written. However, there is one special case: during the
-expansion of the %maildir_tag% option in the ^appendfile^ transport while
-doing a delivery in maildir format, the value of $message_size$ is the
-precise size of the file that has been written. See also
-$message_body_size$, $body_linecount$, and $body_zerocount$.
-+
-cindex:[RCPT,value of $message_size$]
-While running an ACL at the time of an SMTP RCPT command, $message_size$
-contains the size supplied on the MAIL command, or -1 if no size was given. The
-value may not, of course, be truthful.
-
-$mime_$'xxx'::
-A number of variables whose names start with $mime$ are
-available when Exim is compiled with the content-scanning extension. For
-details, see section <<SECTscanmimepart>>.
-
-$n0$ -- $n9$::
-These variables are counters that can be incremented by means
-of the %add% command in filter files.
-
-$original_domain$::
-cindex:[$domain$]
-cindex:[$original_domain$]
-When a top-level address is being processed for delivery, this contains the
-same value as $domain$. However, if a ``child'' address (for example, generated
-by an alias, forward, or filter file) is being processed, this variable
-contains the domain of the original address. This differs from $parent_domain$
-only when there is more than one level of aliasing or forwarding. When more
-than one address is being delivered in a single transport run,
-$original_domain$ is not set.
-+
-If new an address is created by means of a %deliver% command in a system
-filter, it is set up with an artificial ``parent'' address. This has the local
-part 'system-filter' and the default qualify domain.
-
-$original_local_part$::
-cindex:[$local_part$]
-cindex:[$original_local_part$]
-When a top-level address is being processed for delivery, this contains the
-same value as $local_part$, unless a prefix or suffix was removed from the
-local part, because $original_local_part$ always contains the full local part.
-When a ``child'' address (for example, generated by an alias, forward, or
-filter file) is being processed, this variable contains the full local part of
-the original address.
-+
-If the router that did the redirection processed the local part
-case-insensitively, the value in $original_local_part$ is in lower case.
-This variable differs from $parent_local_part$ only when there is more than
-one level of aliasing or forwarding. When more than one address is being
-delivered in a single transport run, $original_local_part$ is not set.
-+
-If new an address is created by means of a %deliver% command in a system
-filter, it is set up with an artificial ``parent'' address. This has the local
-part 'system-filter' and the default qualify domain.
-
-$originator_gid$::
-cindex:[gid (group id),of originating user]
-cindex:[sender,gid]
-cindex:[$caller_gid$]
-cindex:[$originator_gid$]
-This variable contains the value of $caller_gid$ that was set when the message
-was received. For messages received via the command line, this is the gid of
-the sending user. For messages received by SMTP over TCP/IP, this is normally
-the gid of the Exim user.
-
-$originator_uid$::
-cindex:[uid (user id),of originating user]
-cindex:[sender,uid]
-cindex:[$caller_uid$]
-cindex:[$originaltor_uid$]
-The value of $caller_uid$ that was set when the message was received. For
-messages received via the command line, this is the uid of the sending user.
-For messages received by SMTP over TCP/IP, this is normally the uid of the Exim
-user.
-
-$parent_domain$::
-cindex:[$parent_domain$]
-This variable is similar to $original_domain$ (see
-above), except that it refers to the immediately preceding parent address.
-
-$parent_local_part$::
-cindex:[$parent_local_part$]
-This variable is similar to $original_local_part$
-(see above), except that it refers to the immediately preceding parent address.
-
-$pid$::
-cindex:[pid (process id),of current process]
-cindex:[$pid$]
-This variable contains the current process id.
-
-$pipe_addresses$::
-cindex:[filter,transport filter]
-cindex:[transport,filter]
-cindex:[$pipe_addresses$]
-This is not an expansion variable, but is mentioned here because the string
-``\$pipe_addresses'' is handled specially in the command specification for the
-^pipe^ transport (chapter <<CHAPpipetransport>>) and in transport filters
-(described under %transport_filter% in chapter <<CHAPtransportgeneric>>). It
-cannot be used in general expansion strings, and provokes an ``unknown
-variable'' error if encountered.
-
-$primary_hostname$::
-cindex:[$primary_hostname$]
-This variable contains the value set by %primary_hostname% in the configuration
-file, or read by the 'uname()' function. If 'uname()' returns a
-single-component name, Exim calls 'gethostbyname()' (or 'getipnodebyname()'
-where available) in an attempt to acquire a fully qualified host name. See also
-$smtp_active_hostname$.
-
-
-$prvscheck_address$::
-+
-[revisionflag="changed"]
-This variable is used in conjunction with the %prvscheck% expansion item, which
-is described in sections <<SECTexpansionitems>> and <<SECTverifyPRVS>>.
-
-$prvscheck_keynum$::
-+
-[revisionflag="changed"]
-This variable is used in conjunction with the %prvscheck% expansion item, which
-is described in sections <<SECTexpansionitems>> and <<SECTverifyPRVS>>.
-
-$prvscheck_result$::
-+
-[revisionflag="changed"]
-This variable is used in conjunction with the %prvscheck% expansion item, which
-is described in sections <<SECTexpansionitems>> and <<SECTverifyPRVS>>.
-
-$qualify_domain$::
-cindex:[$qualify_domain$]
-The value set for the %qualify_domain% option in the configuration file.
-
-$qualify_recipient$::
-cindex:[$qualify_recipient$]
-The value set for the %qualify_recipient% option in the configuration file,
-or if not set, the value of $qualify_domain$.
-
-$rcpt_count$::
-cindex:[$rcpt_count$]
-When a message is being received by SMTP, this variable contains the number of
-RCPT commands received for the current message. If this variable is used in a
-RCPT ACL, its value includes the current command.
-
-$rcpt_defer_count$::
-cindex:[$rcpt_defer_count$]
-When a message is being received by SMTP, this variable contains the number of
-RCPT commands in the current message that have previously been rejected with a
-temporary (4##'xx') response.
-
-$rcpt_fail_count$::
-cindex:[$rcpt_fail_count$]
-When a message is being received by SMTP, this variable contains the number of
-RCPT commands in the current message that have previously been rejected with a
-permanent (5##'xx') response.
-
-$received_count$::
-cindex:[$received_count$]
-This variable contains the number of 'Received:' header lines in the message,
-including the one added by Exim (so its value is always greater than zero). It
-is available in the DATA ACL, the non-SMTP ACL, and while routing and
-delivering.
-
-$received_for$::
-cindex:[$received_for$]
-If there is only a single recipient address in an incoming message, this
-variable contains that address when the 'Received:' header line is being built.
-The value is copied after recipient rewriting has happened, but before the
-'local_scan()' function is run.
-
-$received_protocol$::
-cindex:[$received_protocol$]
-When a message is being processed, this variable contains the name of the
-protocol by which it was received. Most of the names used by Exim are defined
-by RFCs 821, 2821, and 3848. They start with ``smtp'' (the client used HELO) or
-``esmtp'' (the client used EHLO). This can be followed by ``s'' for secure
-(encrypted) and/or ``a'' for authenticated. Thus, for example, if the protocol
-is set to ``esmtpsa'', the message was received over an encrypted SMTP
-connection and the client was successfully authenticated.
-+
-Exim uses the protocol name ``smtps'' for the case when encryption is
-automatically set up on connection without the use of STARTTLS (see
-%tls_on_connect_ports%), and the client uses HELO to initiate the
-encrypted SMTP session. The name ``smtps'' is also used for the rare situation
-where the client initially uses EHLO, sets up an encrypted connection using
-STARTTLS, and then uses HELO afterwards.
-+
-The %-oMr% option provides a way of specifying a custom protocol name for
-messages that are injected locally by trusted callers. This is commonly used to
-identify messages that are being re-injected after some kind of scanning.
-
-$received_time$::
-+
-[revisionflag="changed"]
-cindex:[$received_time$]
-This variable contains the date and time when the current message was received,
-as a number of seconds since the start of the Unix epoch.
-
-$recipient_data$::
-cindex:[$recipient_data$]
-This variable is set after an indexing lookup success in an ACL %recipients%
-condition. It contains the data from the lookup, and the value remains set
-until the next %recipients% test. Thus, you can do things like this:
-+
-&&&
-`require recipients = cdb*@;/some/file`
-`deny `'some further test involving' `\$recipient_data`
-&&&
-+
-*Warning*: This variable is set only when a lookup is used as an indexing
-method in the address list, using the semicolon syntax as in the example above.
-The variable is not set for a lookup that is used as part of the string
-expansion that all such lists undergo before being interpreted.
-
-$recipient_verify_failure$::
-cindex:[$recipient_verify_failure$]
-In an ACL, when a recipient verification fails, this variable contains
-information about the failure. It is set to one of the following words:
-+
---
-- ``qualify'': The address was unqualified (no domain), and the message
-was neither local nor came from an exempted host.
-
-- ``route'': Routing failed.
-
-- ``mail'': Routing succeeded, and a callout was attempted; rejection occurred at
-or before the MAIL command (that is, on initial connection, HELO, or
-MAIL).
-
-- ``recipient'': The RCPT command in a callout was rejected.
-
-- ``postmaster'': The postmaster check in a callout was rejected.
---
-+
-The main use of this variable is expected to be to distinguish between
-rejections of MAIL and rejections of RCPT.
-
-
-$recipients$::
-cindex:[$recipients$]
-This variable contains a list of envelope recipients for a
-message. A comma and a space separate the addresses in the replacement text.
-However, the variable is not generally available, to prevent exposure of Bcc
-recipients in unprivileged users' filter files. You can use $recipients$ only
-in these two cases:
-
-. In a system filter file.
-
-. In the ACLs associated with the DATA command, that is, the ACLs defined by
-%acl_smtp_predata% and %acl_smtp_data%.
-
-
-$recipients_count$::
-cindex:[$recipients_count$]
-When a message is being processed, this variable contains the number of
-envelope recipients that came with the message. Duplicates are not excluded
-from the count. While a message is being received over SMTP, the number
-increases for each accepted recipient. It can be referenced in an ACL.
-
-$reply_address$::
-cindex:[$reply_address$]
-When a message is being processed, this variable contains the contents of the
-'Reply-To:' header line if one exists and it is not empty, or otherwise the
-contents of the 'From:' header line.
-
-$return_path$::
-cindex:[$return_path$]
-When a message is being delivered, this variable contains the return path --
-the sender field that will be sent as part of the envelope. It is not enclosed
-in <> characters. At the start of routing an address, $return_path$ has the
-same value as $sender_address$, but if, for example, an incoming message to a
-mailing list has been expanded by a router which specifies a different address
-for bounce messages, $return_path$ subsequently contains the new bounce
-address, whereas $sender_address$ always contains the original sender address
-that was received with the message. In other words, $sender_address$ contains
-the incoming envelope sender, and $return_path$ contains the outgoing envelope
-sender.
-
-$return_size_limit$::
-cindex:[$return_size_limit$]
-This is an obsolete name for $bounce_return_size_limit$.
-
-$runrc$::
-cindex:[return code,from %run% expansion]
-cindex:[$runrc$]
-This variable contains the return code from a command that is run by the
-%\$\{run...\}% expansion item. *Warning*: In a router or transport, you cannot
-assume the order in which option values are expanded, except for those
-pre-conditions whose order of testing is documented. Therefore, you cannot
-reliably expect to set $runrc$ by the expansion of one option, and use it in
-another.
-
-$self_hostname$::
-cindex:[%self% option,value of host name]
-cindex:[$self_hostname$]
-When an address is routed to a supposedly remote host that turns out to be the
-local host, what happens is controlled by the %self% generic router option. One
-of its values causes the address to be passed to another router. When this
-happens, $self_hostname$ is set to the name of the local host that the original
-router encountered. In other circumstances its contents are null.
-
-$sender_address$::
-cindex:[$sender_address$]
-When a message is being processed, this variable contains the sender's address
-that was received in the message's envelope. For bounce messages, the value of
-this variable is the empty string. See also $return_path$.
-
-$sender_address_data$::
-cindex:[$address_data$]
-cindex:[$sender_address_data$]
-If $address_data$ is set when the routers are called from an ACL to verify a
-sender address, the final value is preserved in $sender_address_data$, to
-distinguish it from data from a recipient address. The value does not persist
-after the end of the current ACL statement. If you want to preserve it for
-longer, you can save it in an ACL variable.
-
-$sender_address_domain$::
-cindex:[$sender_address_domain$]
-The domain portion of $sender_address$.
-
-$sender_address_local_part$::
-cindex:[$sender_address_local_part$]
-The local part portion of $sender_address$.
-
-$sender_data$::
-cindex:[$sender_data$]
-This variable is set after a lookup success in an ACL %senders% condition or in
-a router %senders% option. It contains the data from the lookup, and the value
-remains set until the next %senders% test. Thus, you can do things like this:
-+
-&&&
-`require senders = cdb*@;/some/file`
-`deny `'some further test involving' `\$sender_data`
-&&&
-+
-*Warning*: This variable is set only when a lookup is used as an indexing
-method in the address list, using the semicolon syntax as in the example above.
-The variable is not set for a lookup that is used as part of the string
-expansion that all such lists undergo before being interpreted.
-
-$sender_fullhost$::
-cindex:[$sender_fullhost$]
-When a message is received from a remote host, this variable contains the host
-name and IP address in a single string. It ends with the IP address in square
-brackets, followed by a colon and a port number if the logging of ports is
-enabled. The format of the rest of the string depends on whether the host
-issued a HELO or EHLO SMTP command, and whether the host name was verified by
-looking up its IP address. (Looking up the IP address can be forced by the
-%host_lookup% option, independent of verification.) A plain host name at the
-start of the string is a verified host name; if this is not present,
-verification either failed or was not requested. A host name in parentheses is
-the argument of a HELO or EHLO command. This is omitted if it is identical to
-the verified host name or to the host's IP address in square brackets.
-
-$sender_helo_name$::
-cindex:[$sender_hslo_name$]
-When a message is received from a remote host that has issued a HELO or EHLO
-command, the argument of that command is placed in this variable. It is also
-set if HELO or EHLO is used when a message is received using SMTP locally via
-the %-bs% or %-bS% options.
-
-$sender_host_address$::
-cindex:[$sender_host_address$]
-When a message is received from a remote host, this variable contains that
-host's IP address. For locally submitted messages, it is empty.
-
-$sender_host_authenticated$::
-cindex:[$sender_host_authenticated$]
-This variable contains the name (not the public name) of the authenticator
-driver that successfully authenticated the client from which the message was
-received. It is empty if there was no successful authentication. See also
-$authenticated_id$.
-
-$sender_host_name$::
-cindex:[$sender_host_name$]
-When a message is received from a remote host, this variable contains the
-host's name as obtained by looking up its IP address. For messages received by
-other means, this variable is empty.
-+
-cindex:[$host_lookup_failed$]
-If the host name has not previously been looked up, a reference to
-$sender_host_name$ triggers a lookup (for messages from remote hosts).
-A looked up name is accepted only if it leads back to the original IP address
-via a forward lookup. If either the reverse or the forward lookup fails to find
-any data, or if the forward lookup does not yield the original IP address,
-$sender_host_name$ remains empty, and $host_lookup_failed$ is set to ``1''.
-+
-cindex:[$host_lookup_deferred$]
-However, if either of the lookups cannot be completed (for example, there is a
-DNS timeout), $host_lookup_deferred$ is set to ``1'', and
-$host_lookup_failed$ remains set to ``0''.
-+
-Once $host_lookup_failed$ is set to ``1'', Exim does not try to look up the
-host name again if there is a subsequent reference to $sender_host_name$
-in the same Exim process, but it does try again if $sender_host_deferred$
-is set to ``1''.
-+
-Exim does not automatically look up every calling host's name. If you want
-maximum efficiency, you should arrange your configuration so that it avoids
-these lookups altogether. The lookup happens only if one or more of the
-following are true:
-
-- A string containing $sender_host_name$ is expanded.
-
-- The calling host matches the list in %host_lookup%. In the default
-configuration, this option is set to \*, so it must be changed if lookups are
-to be avoided. (In the code, the default for %host_lookup% is unset.)
-
-- Exim needs the host name in order to test an item in a host list. The items
-that require this are described in sections <<SECThoslispatnam>> and
-<<SECThoslispatnamsk>>.
-
-- The calling host matches %helo_try_verify_hosts% or %helo_verify_hosts%.
-In this case, the host name is required to compare with the name quoted in any
-EHLO or HELO commands that the client issues.
-
-- The remote host issues a EHLO or HELO command that quotes one of the
-domains in %helo_lookup_domains%. The default value of this option is
-+
-....
-helo_lookup_domains = @ : @[]
-....
-+
-which causes a lookup if a remote host (incorrectly) gives the server's name or
-IP address in an EHLO or HELO command.
-
-
-$sender_host_port$::
-cindex:[$sender_host_port$]
-When a message is received from a remote host, this variable contains the port
-number that was used on the remote host.
-
-$sender_ident$::
-cindex:[$sender_ident$]
-When a message is received from a remote host, this variable contains the
-identification received in response to an RFC 1413 request. When a message has
-been received locally, this variable contains the login name of the user that
-called Exim.
-
-$sender_rate_$'xxx'::
-+
-[revisionflag="changed"]
-A number of variables whose names begin $sender_rate_$ are set as part of the
-%ratelimit% ACL condition. Details are given in section <<SECTratelimiting>>.
-
-$sender_rcvhost$::
-cindex:[DNS,reverse lookup]
-cindex:[reverse DNS lookup]
-cindex:[$sender_rcvhost$]
-This is provided specifically for use in 'Received:' headers. It starts with
-either the verified host name (as obtained from a reverse DNS lookup) or, if
-there is no verified host name, the IP address in square brackets. After that
-there may be text in parentheses. When the first item is a verified host name,
-the first thing in the parentheses is the IP address in square brackets,
-followed by a colon and a port number if port logging is enabled. When the
-first item is an IP address, the port is recorded as ``port='xxxx'##'' inside
-the parentheses.
-+
-There may also be items of the form ``helo='xxxx'##'' if HELO or EHLO
-was used and its argument was not identical to the real host name or IP
-address, and ``ident='xxxx'##'' if an RFC 1413 ident string is available. If all
-three items are present in the parentheses, a newline and tab are inserted into
-the string, to improve the formatting of the 'Received:' header.
-
-$sender_verify_failure$::
-cindex:[$sender_verify_failure$]
-In an ACL, when a sender verification fails, this variable contains information
-about the failure. The details are the same as for $recipient_verify_failure$.
-
-$smtp_active_hostname$::
-cindex:[$smtp_active_hostname$]
-During an SMTP session, this variable contains the value of the active host
-name, as specified by the %smtp_active_hostname% option. The value of
-$smtp_active_hostname$ is saved with any message that is received, so its value
-can be consulted during routing and delivery.
-
-$smtp_command$::
-+
-[revisionflag="changed"]
-cindex:[$smtp_command$]
-During the processing of an incoming SMTP command, this variable contains the
-entire command. This makes it possible to distinguish between HELO and EHLO in
-the HELO ACL, and also to distinguish between commands such as these:
-+
-....
-MAIL FROM:<>
-MAIL FROM: <>
-....
-+
-For a MAIL command, extra parameters such as SIZE can be inspected. For a RCPT
-command, the address in $smtp_command$ is the original address before any
-rewriting, whereas the values in $local_part$ and $domain$ are taken from the
-address after SMTP-time rewriting.
-
-
-$smtp_command_argument$::
-+
-[revisionflag="changed"]
-cindex:[SMTP command,argument for]
-cindex:[$smtp_command_argument$]
-While an ACL is running to check an SMTP command, this variable contains the
-argument, that is, the text that follows the command name, with leading white
-space removed. Following the introduction of $smtp_command$, this variable is
-somewhat redundant, but is retained for backwards compatibility.
-
-$sn0$ -- $sn9$::
-These variables are copies of the values of the $n0$ -- $n9$ accumulators that
-were current at the end of the system filter file. This allows a system filter
-file to set values that can be tested in users' filter files. For example, a
-system filter could set a value indicating how likely it is that a message is
-junk mail.
-
-$spam_$'xxx'::
-A number of variables whose names start with $spam$ are available when Exim is
-compiled with the content-scanning extension. For details, see section
-<<SECTscanspamass>>.
-
-
-$spool_directory$::
-cindex:[$spool_directory$]
-The name of Exim's spool directory.
-
-$spool_inodes$::
-cindex:[$spool_inodes$]
-The number of free inodes in the disk partition where Exim's spool files are
-being written. The value is recalculated whenever the variable is referenced.
-If the relevant file system does not have the concept of inodes, the value of
-is -1. See also the %check_spool_inodes% option.
-
-$spool_space$::
-cindex:[$spool_space$]
-The amount of free space (as a number of kilobytes) in the disk partition where
-Exim's spool files are being written. The value is recalculated whenever the
-variable is referenced. If the operating system does not have the ability to
-find the amount of free space (only true for experimental systems), the space
-value is -1. For example, to check in an ACL that there is at least 50
-megabytes free on the spool, you could write:
-
- condition = ${if > {$spool_space}{50000}}
-+
-See also the %check_spool_space% option.
-
-
-$thisaddress$::
-cindex:[$thisaddress$]
-This variable is set only during the processing of the %foranyaddress% command
-in a filter file. Its use is explained in the description of that command,
-which can be found in the separate document entitled 'Exim's interfaces to mail
-filtering'.
-
-$tls_certificate_verified$::
-cindex:[$tls_certificate_verified$]
-This variable is set to ``1'' if a TLS certificate was verified when the
-message was received, and ``0'' otherwise.
-
-$tls_cipher$::
-cindex:[$tls_cipher$]
-When a message is received from a remote host over an encrypted SMTP
-connection, this variable is set to the cipher suite that was negotiated, for
-example DES-CBC3-SHA. In other circumstances, in particular, for message
-received over unencrypted connections, the variable is empty. See chapter
-<<CHAPTLS>> for details of TLS support.
-
-$tls_peerdn$::
-cindex:[$tls_peerdn$]
-When a message is received from a remote host over an encrypted SMTP
-connection, and Exim is configured to request a certificate from the client,
-the value of the Distinguished Name of the certificate is made available in the
-$tls_peerdn$ during subsequent processing.
-
-$tod_bsdinbox$::
-cindex:[$tod_bsdinbox$]
-The time of day and date, in the format required for BSD-style mailbox files,
-for example: Thu Oct 17 17:14:09 1995.
-
-$tod_epoch$::
-cindex:[$tod_epoch$]
-The time and date as a number of seconds since the start of the Unix epoch.
-
-$tod_full$::
-cindex:[$tod_full$]
-A full version of the time and date, for example: Wed, 16 Oct 1995 09:51:40
-+0100. The timezone is always given as a numerical offset from UTC, with
-positive values used for timezones that are ahead (east) of UTC, and negative
-values for those that are behind (west).
-
-$tod_log$::
-cindex:[$tod_log$]
-The time and date in the format used for writing Exim's log files, for example:
-1995-10-12 15:32:29, but without a timezone.
-
-$tod_logfile$::
-cindex:[$tod_logfile$]
-This variable contains the date in the format yyyymmdd. This is the format that
-is used for datestamping log files when %log_file_path% contains the `%D`
-flag.
-
-$tod_zone$::
-cindex:[$tod_zone$]
-This variable contains the numerical value of the local timezone, for example:
--0500.
-
-$tod_zulu$::
-cindex:[$tod_zulu$]
-This variable contains the UTC date and time in ``Zulu'' format, as specified by
-ISO 8601, for example: 20030221154023Z.
-
-$value$::
-cindex:[$value$]
-This variable contains the result of an expansion lookup, extraction operation,
-or external command, as described above.
-
-$version_number$::
-cindex:[$version_number$]
-The version number of Exim.
-
-$warn_message_delay$::
-cindex:[$warn_message_delay$]
-This variable is set only during the creation of a message warning about a
-delivery delay. Details of its use are explained in section <<SECTcustwarn>>.
-
-$warn_message_recipients$::
-cindex:[$warn_message_recipients$]
-This variable is set only during the creation of a message warning about a
-delivery delay. Details of its use are explained in section <<SECTcustwarn>>.
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPperl]]
-Embedded Perl
--------------
-cindex:[Perl,calling from Exim]
-Exim can be built to include an embedded Perl interpreter. When this is done,
-Perl subroutines can be called as part of the string expansion process. To make
-use of the Perl support, you need version 5.004 or later of Perl installed on
-your system. To include the embedded interpreter in the Exim binary, include
-the line
-
- EXIM_PERL = perl.o
-
-in your _Local/Makefile_ and then build Exim in the normal way.
-
-
-Setting up so Perl can be used
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[%perl_startup%]
-Access to Perl subroutines is via a global configuration option called
-%perl_startup% and an expansion string operator %\$\{perl ...\}%. If there is
-no %perl_startup% option in the Exim configuration file then no Perl
-interpreter is started and there is almost no overhead for Exim (since none of
-the Perl library will be paged in unless used). If there is a %perl_startup%
-option then the associated value is taken to be Perl code which is executed in
-a newly created Perl interpreter.
-
-The value of %perl_startup% is not expanded in the Exim sense, so you do not
-need backslashes before any characters to escape special meanings. The option
-should usually be something like
-
- perl_startup = do '/etc/exim.pl'
-
-where _/etc/exim.pl_ is Perl code which defines any subroutines you want to
-use from Exim. Exim can be configured either to start up a Perl interpreter as
-soon as it is entered, or to wait until the first time it is needed. Starting
-the interpreter at the beginning ensures that it is done while Exim still has
-its setuid privilege, but can impose an unnecessary overhead if Perl is not in
-fact used in a particular run. Also, note that this does not mean that Exim is
-necessarily running as root when Perl is called at a later time. By default,
-the interpreter is started only when it is needed, but this can be changed in
-two ways:
-
-- cindex:[%perl_at_start%]
-Setting %perl_at_start% (a boolean option) in the configuration requests
-a startup when Exim is entered.
-
-- The command line option %-ps% also requests a startup when Exim is entered,
-overriding the setting of %perl_at_start%.
-
-There is also a command line option %-pd% (for delay) which suppresses the
-initial startup, even if %perl_at_start% is set.
-
-
-Calling Perl subroutines
-~~~~~~~~~~~~~~~~~~~~~~~~
-When the configuration file includes a %perl_startup% option you can make use
-of the string expansion item to call the Perl subroutines that are defined
-by the %perl_startup% code. The operator is used in any of the following
-forms:
-
- ${perl{foo}}
- ${perl{foo}{argument}}
- ${perl{foo}{argument1}{argument2} ... }
-
-which calls the subroutine %foo% with the given arguments. A maximum of eight
-arguments may be passed. Passing more than this results in an expansion failure
-with an error message of the form
-
- Too many arguments passed to Perl subroutine "foo" (max is 8)
-
-The return value of the Perl subroutine is evaluated in a scalar context before
-it is passed back to Exim to be inserted into the expanded string. If the
-return value is 'undef', the expansion is forced to fail in the same way as
-an explicit ``fail'' on an %\$\{if ...\}% or %\$\{lookup...\}% item. If the
-subroutine aborts by obeying Perl's %die% function, the expansion fails with
-the error message that was passed to %die%.
-
-
-Calling Exim functions from Perl
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Within any Perl code called from Exim, the function 'Exim::expand_string'
-is available to call back into Exim's string expansion function. For example,
-the Perl code
-
- my $lp = Exim::expand_string('$local_part');
-
-makes the current Exim $local_part$ available in the Perl variable $lp$.
-Note those are single quotes and not double quotes to protect against
-$local_part$ being interpolated as a Perl variable.
-
-If the string expansion is forced to fail by a ``fail'' item, the result of
-'Exim::expand_string' is %undef%. If there is a syntax error in the
-expansion string, the Perl call from the original expansion string fails with
-an appropriate error message, in the same way as if %die% were used.
-
-cindex:[debugging,from embedded Perl]
-cindex:[log,writing from embedded Perl]
-Two other Exim functions are available for use from within Perl code.
-'Exim::debug_write(<'string'>)' writes the string to the standard error
-stream if Exim's debugging is enabled. If you want a newline at the end, you
-must supply it. 'Exim::log_write(<'string'>)' writes the string to Exim's
-main log, adding a leading timestamp. In this case, you should not supply a
-terminating newline.
-
-
-Use of standard output and error by Perl
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[Perl,standard output and error]
-You should not write to the standard error or output streams from within your
-Perl code, as it is not defined how these are set up. In versions of Exim
-before 4.50, it is possible for the standard output or error to refer to the
-SMTP connection during message reception via the daemon. Writing to this stream
-is certain to cause chaos. From Exim 4.50 onwards, the standard output and
-error streams are connected to _/dev/null_ in the daemon. The chaos is
-avoided, but the output is lost.
-
-cindex:[Perl,use of %warn%]
-The Perl %warn% statement writes to the standard error stream by default. Calls
-to %warn% may be embedded in Perl modules that you use, but over which you have
-no control. When Exim starts up the Perl interpreter, it arranges for output
-from the %warn% statement to be written to the Exim main log. You can change
-this by including appropriate Perl magic somewhere in your Perl code. For
-example, to discard %warn% output completely, you need this:
-
- $SIG{__WARN__} = sub { };
-
-Whenever a %warn% is obeyed, the anonymous subroutine is called. In this
-example, the code for the subroutine is empty, so it does nothing, but you can
-include any Perl code that you like. The text of the %warn% message is passed
-as the first subroutine argument.
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPinterfaces]]
-[titleabbrev="Starting the daemon"]
-Starting the daemon and the use of network interfaces
------------------------------------------------------
-cindex:[daemon,starting]
-cindex:[interface,listening]
-cindex:[network interface]
-cindex:[interface,network]
-cindex:[IP address,for listening]
-cindex:[daemon,listening IP addresses]
-cindex:[TCP/IP,setting listening interfaces]
-cindex:[TCP/IP,setting listening ports]
-A host that is connected to a TCP/IP network may have one or more physical
-hardware network interfaces. Each of these interfaces may be configured as one
-or more ``logical'' interfaces, which are the entities that a program actually
-works with. Each of these logical interfaces is associated with an IP address.
-In addition, TCP/IP software supports ``loopback'' interfaces (127.0.0.1 in IPv4
-and ::1 in IPv6), which do not use any physical hardware. Exim requires
-knowledge about the host's interfaces for use in three different circumstances:
-
-. When a listening daemon is started, Exim needs to know which interfaces
-and ports to listen on.
-
-. When Exim is routing an address, it needs to know which IP addresses
-are associated with local interfaces. This is required for the correct
-processing of MX lists by removing the local host and others with the
-same or higher priority values. Also, Exim needs to detect cases
-when an address is routed to an IP address that in fact belongs to the
-local host. Unless the %self% router option or the %allow_localhost%
-option of the smtp transport is set (as appropriate), this is treated
-as an error situation.
-
-. When Exim connects to a remote host, it may need to know which interface to use
-for the outgoing connection.
-
-
-Exim's default behaviour is likely to be appropriate in the vast majority
-of cases. If your host has only one interface, and you want all its IP
-addresses to be treated in the same way, and you are using only the
-standard SMTP port, you should not need to take any special action. The
-rest of this chapter does not apply to you.
-
-In a more complicated situation you may want to listen only on certain
-interfaces, or on different ports, and for this reason there are a number of
-options that can be used to influence Exim's behaviour. The rest of this
-chapter describes how they operate.
-
-When a message is received over TCP/IP, the interface and port that were
-actually used are set in $interface_address$ and $interface_port$.
-
-
-
-Starting a listening daemon
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
-When a listening daemon is started (by means of the %-bd% command line
-option), the interfaces and ports on which it listens are controlled by the
-following options:
-
-- %daemon_smtp_ports% contains a list of default ports. (For backward
-compatibility, this option can also be specified in the singular.)
-
-- %local_interfaces% contains list of interface IP addresses on which to
-listen. Each item may optionally also specify a port.
-
-The default list separator in both cases is a colon, but this can be changed as
-described in section <<SECTlistconstruct>>. When IPv6 addresses are involved, it
-is usually best to change the separator to avoid having to double all the
-colons. For example:
-
-....
-local_interfaces = <; 127.0.0.1 ; \
- 192.168.23.65 ; \
- ::1 ; \
- 3ffe:ffff:836f::fe86:a061
-....
-
-There are two different formats for specifying a port along with an IP address
-in %local_interfaces%:
-
-. The port is added onto the address with a dot separator. For example, to listen
-on port 1234 on two different IP addresses:
-+
-....
-local_interfaces = <; 192.168.23.65.1234 ; \
- 3ffe:ffff:836f::fe86:a061.1234
-....
-
-. The IP address is enclosed in square brackets, and the port is added
-with a colon separator, for example:
-+
-....
-local_interfaces = <; [192.168.23.65]:1234 ; \
- [3ffe:ffff:836f::fe86:a061]:1234
-....
-
-When a port is not specified, the value of %daemon_smtp_ports% is used. The
-default setting contains just one port:
-
- daemon_smtp_ports = smtp
-
-If more than one port is listed, each interface that does not have its own port
-specified listens on all of them. Ports that are listed in
-%daemon_smtp_ports% can be identified either by name (defined in
-_/etc/services_) or by number. However, when ports are given with individual
-IP addresses in %local_interfaces%, only numbers (not names) can be used.
-
-
-
-Special IP listening addresses
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The addresses 0.0.0.0 and ::0 are treated specially. They are interpreted
-as ``all IPv4 interfaces'' and ``all IPv6 interfaces'', respectively. In each
-case, Exim tells the TCP/IP stack to ``listen on all IPv##'x' interfaces''
-instead of setting up separate listening sockets for each interface. The
-default value of %local_interfaces% is
-
- local_interfaces = 0.0.0.0
-
-when Exim is built without IPv6 support; otherwise it is:
-
- local_interfaces = <; ::0 ; 0.0.0.0
-
-Thus, by default, Exim listens on all available interfaces, on the SMTP port.
-
-
-
-Overriding local_interfaces and daemon_smtp_ports
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The %-oX% command line option can be used to override the values of
-%daemon_smtp_ports% and/or %local_interfaces% for a particular daemon
-instance. Another way of doing this would be to use macros and the %-D%
-option. However, %-oX% can be used by any admin user, whereas modification of
-the runtime configuration by %-D% is allowed only when the caller is root or
-exim.
-
-The value of %-oX% is a list of items. The default colon separator can be
-changed in the usual way if required. If there are any items that do not
-contain dots or colons (that is, are not IP addresses), the value of
-%daemon_smtp_ports% is replaced by the list of those items. If there are any
-items that do contain dots or colons, the value of %local_interfaces% is
-replaced by those items. Thus, for example,
-
- -oX 1225
-
-overrides %daemon_smtp_ports%, but leaves %local_interfaces% unchanged,
-whereas
-
- -oX 192.168.34.5.1125
-
-overrides %local_interfaces%, leaving %daemon_smtp_ports% unchanged.
-(However, since %local_interfaces% now contains no items without ports, the
-value of %daemon_smtp_ports% is no longer relevant in this example.)
-
-
-
-[[SECTsupobssmt]]
-Support for the obsolete SSMTP (or SMTPS) protocol
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[ssmtp protocol]
-cindex:[smtps protocol]
-cindex:[SMTP,ssmtp protocol]
-cindex:[SMTP,smtps protocol]
-Exim supports the obsolete SSMTP protocol (also known as SMTPS) that was used
-before the STARTTLS command was standardized for SMTP. Some legacy clients
-still use this protocol. If the %tls_on_connect_ports% option is set to a
-list of port numbers, connections to those ports must use SSMTP. The most
-common use of this option is expected to be
-
- tls_on_connect_ports = 465
-
-because 465 is the usual port number used by the legacy clients. There is also
-a command line option %-tls-on-connect%, which forces all ports to behave in
-this way when a daemon is started.
-
-*Warning*: Setting %tls_on_connect_ports% does not of itself cause the
-daemon to listen on those ports. You must still specify them in
-%daemon_smtp_ports%, %local_interfaces%, or the %-oX% option. (This is
-because %tls_on_connect_ports% applies to %inetd% connections as well as to
-connections via the daemon.)
-
-
-
-
-IPv6 address scopes
-~~~~~~~~~~~~~~~~~~~
-IPv6 addresses have ``scopes'', and a host with multiple hardware interfaces
-can, in principle, have the same link-local IPv6 address on different
-interfaces. Thus, additional information is needed, over and above the IP
-address, to distinguish individual interfaces. A convention of using a
-percent sign followed by something (often the interface name) has been
-adopted in some cases, leading to addresses like this:
-
- fe80::202:b3ff:fe03:45c1%eth0
-
-To accommodate this usage, a percent sign followed by an arbitrary string is
-allowed at the end of an IPv6 address. By default, Exim calls 'getaddrinfo()'
-to convert a textual IPv6 address for actual use. This function recognizes the
-percent convention in operating systems that support it, and it processes the
-address appropriately. Unfortunately, some older libraries have problems with
-'getaddrinfo()'. If
-
- IPV6_USE_INET_PTON=yes
-
-is set in _Local/Makefile_ (or an OS-dependent Makefile) when Exim is built,
-Exim uses 'inet_pton()' to convert a textual IPv6 address for actual use,
-instead of 'getaddrinfo()'. (Before version 4.14, it always used this
-function.) Of course, this means that the additional functionality of
-'getaddrinfo()' -- recognizing scoped addresses -- is lost.
-
-
-
-Examples of starting a listening daemon
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The default case in an IPv6 environment is
-
- daemon_smtp_ports = smtp
- local_interfaces = <; ::0 ; 0.0.0.0
-
-This specifies listening on the smtp port on all IPv6 and IPv4 interfaces.
-Either one or two sockets may be used, depending on the characteristics of
-the TCP/IP stack. (This is complicated and messy; for more information,
-read the comments in the _daemon.c_ source file.)
-
-To specify listening on ports 25 and 26 on all interfaces:
-
- daemon_smtp_ports = 25 : 26
-
-(leaving %local_interfaces% at the default setting) or, more explicitly:
-
-....
-local_interfaces = <; ::0.25 ; ::0.26 \
- 0.0.0.0.25 ; 0.0.0.0.26
-....
-
-To listen on the default port on all IPv4 interfaces, and on port 26 on the
-IPv4 loopback address only:
-
- local_interfaces = 0.0.0.0 : 127.0.0.1.26
-
-To specify listening on the default port on specific interfaces only:
-
- local_interfaces = 192.168.34.67 : 192.168.34.67
-
-*Warning*: such a setting excludes listening on the loopback interfaces.
-
-
-
-[[SECTreclocipadd]]
-Recognising the local host
-~~~~~~~~~~~~~~~~~~~~~~~~~~
-The %local_interfaces% option is also used when Exim needs to determine
-whether or not an IP address refers to the local host. That is, the IP
-addresses of all the interfaces on which a daemon is listening are always
-treated as local.
-
-For this usage, port numbers in %local_interfaces% are ignored. If either of
-the items 0.0.0.0 or ::0 are encountered, Exim gets a complete list of
-available interfaces from the operating system, and extracts the relevant
-(that is, IPv4 or IPv6) addresses to use for checking.
-
-Some systems set up large numbers of virtual interfaces in order to provide
-many virtual web servers. In this situation, you may want to listen for
-email on only a few of the available interfaces, but nevertheless treat all
-interfaces as local when routing. You can do this by setting
-%extra_local_interfaces% to a list of IP addresses, possibly including the
-``all'' wildcard values. These addresses are recognized as local, but are not
-used for listening. Consider this example:
-
-....
-local_interfaces = <; 127.0.0.1 ; ::1 ; \
- 192.168.53.235 ; \
- 3ffe:2101:12:1:a00:20ff:fe86:a061
-
-extra_local_interfaces = <; ::0 ; 0.0.0.0
-....
-
-The daemon listens on the loopback interfaces and just one IPv4 and one IPv6
-address, but all available interface addresses are treated as local when
-Exim is routing.
-
-In some environments the local host name may be in an MX list, but with an IP
-address that is not assigned to any local interface. In other cases it may be
-desirable to treat other host names as if they referred to the local host. Both
-these cases can be handled by setting the %hosts_treat_as_local% option.
-This contains host names rather than IP addresses. When a host is referenced
-during routing, either via an MX record or directly, it is treated as the local
-host if its name matches %hosts_treat_as_local%, or if any of its IP
-addresses match %local_interfaces% or %extra_local_interfaces%.
-
-
-
-Delivering to a remote host
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Delivery to a remote host is handled by the smtp transport. By default, it
-allows the system's TCP/IP functions to choose which interface to use (if
-there is more than one) when connecting to a remote host. However, the
-%interface% option can be set to specify which interface is used. See the
-description of the smtp transport in chapter <<CHAPsmtptrans>> for more details.
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPmainconfig]]
-Main configuration
-------------------
-cindex:[configuration file,main section]
-cindex:[main configuration]
-The first part of the run time configuration file contains three types of item:
-
-- Macro definitions: These lines start with an upper case letter. See section
-<<SECTmacrodefs>> for details of macro processing.
-
-- Named list definitions: These lines start with one of the words ``domainlist'',
-``hostlist'', ``addresslist'', or ``localpartlist''. Their use is described in
-section <<SECTnamedlists>>.
-
-- Main configuration settings: Each setting occupies one line of the file
-(with possible continuations). If any setting is preceded by the word
-``hide'', the %-bP% command line option displays its value to admin users only.
-See section <<SECTcos>> for a description of the syntax of these option settings.
-
-This chapter specifies all the main configuration options, along with their
-types and default values. For ease of finding a particular option, they appear
-in alphabetical order in section <<SECTalomo>> below. However, because there are
-now so many options, they are first listed briefly in functional groups, as an
-aid to finding the name of the option you are looking for. Some options are
-listed in more than one group.
-
-Miscellaneous
-~~~~~~~~~~~~~
-[frame="none"]
-`-----------------------------------`-------------------------------------
-%bi_command% to run for %-bi% command line option
-%keep_malformed% for broken files -- should not happen
-%localhost_number% for unique message ids in clusters
-%message_body_visible% how much to show in $message_body$
-%mua_wrapper% run in ``MUA wrapper'' mode
-%print_topbitchars% top-bit characters are printing
-%timezone% force time zone
---------------------------------------------------------------------------
-
-
-Exim parameters
-~~~~~~~~~~~~~~~
-[frame="none"]
-`-----------------------------------`-------------------------------------
-%exim_group% override compiled-in value
-%exim_path% override compiled-in value
-%exim_user% override compiled-in value
-%primary_hostname% default from 'uname()'
-%split_spool_directory% use multiple directories
-%spool_directory% override compiled-in value
---------------------------------------------------------------------------
-
-
-
-Privilege controls
-~~~~~~~~~~~~~~~~~~
-[frame="none"]
-`-----------------------------------`-------------------------------------
-%admin_groups% groups that are Exim admin users
-%deliver_drop_privilege% drop root for delivery processes
-%local_from_check% insert 'Sender:' if necessary
-%local_from_prefix% for testing 'From:' for local sender
-%local_from_suffix% for testing 'From:' for local sender
-%local_sender_retain% keep 'Sender:' from untrusted user
-%never_users% do not run deliveries as these
-%prod_requires_admin% forced delivery requires admin user
-%queue_list_requires_admin% queue listing requires admin user
-%trusted_groups% groups that are trusted
-%trusted_users% users that are trusted
---------------------------------------------------------------------------
-
-
-
-Logging
-~~~~~~~
-[frame="none"]
-`-----------------------------------`-------------------------------------
-%hosts_connection_nolog% exemption from connect logging
-%log_file_path% override compiled-in value
-%log_selector% set/unset optional logging
-%log_timezone% add timezone to log lines
-%message_logs% create per-message logs
-%preserve_message_logs% after message completion
-%process_log_path% for SIGUSR1 and 'exiwhat'
-%syslog_duplication% controls duplicate log lines on syslog
-%syslog_facility% set syslog ``facility'' field
-%syslog_processname% set syslog ``ident'' field
-%syslog_timestamp% timestamp syslog lines
-%write_rejectlog% control use of message log
---------------------------------------------------------------------------
-
-
-
-Frozen messages
-~~~~~~~~~~~~~~~
-[frame="none"]
-`-----------------------------------`-------------------------------------
-%auto_thaw% sets time for retrying frozen messages
-%freeze_tell% send message when freezing
-%move_frozen_messages% to another directory
-%timeout_frozen_after% keep frozen messages only so long
---------------------------------------------------------------------------
-
-
-
-Data lookups
-~~~~~~~~~~~~
-[frame="none"]
-`-----------------------------------`-------------------------------------
-%ldap_default_servers% used if no server in query
-%ldap_version% set protocol version
-%lookup_open_max% lookup files held open
-%mysql_servers% as it says
-%oracle_servers% as it says
-%pgsql_servers% as it says
-%sqlite_lock_timeout% as it says
---------------------------------------------------------------------------
-
-
-
-Message ids
-~~~~~~~~~~~
-[frame="none"]
-`-----------------------------------`-------------------------------------
-%message_id_header_domain% used to build 'Message-ID:' header
-%message_id_header_text% ditto
---------------------------------------------------------------------------
-
-
-
-Embedded Perl Startup
-~~~~~~~~~~~~~~~~~~~~~
-[frame="none"]
-`-----------------------------------`-------------------------------------
-%perl_at_start% always start the interpreter
-%perl_startup% code to obey when starting Perl
---------------------------------------------------------------------------
-
-
-
-Daemon
-~~~~~~
-[frame="none"]
-`-----------------------------------`-------------------------------------
-%daemon_smtp_ports% default ports
-%daemon_startup_retries% number of times to retry
-%daemon_startup_sleep% time to sleep between tries
-%extra_local_interfaces% not necessarily listened on
-%local_interfaces% on which to listen, with optional ports
-%pid_file_path% override compiled-in value
-%queue_run_max% maximum simultaneous queue runners
---------------------------------------------------------------------------
-
-
-
-Resource control
-~~~~~~~~~~~~~~~~
-[frame="none"]
-`-----------------------------------`-------------------------------------
-%check_log_inodes% before accepting a message
-%check_log_space% before accepting a message
-%check_spool_inodes% before accepting a message
-%check_spool_space% before accepting a message
-%deliver_queue_load_max% no queue deliveries if load high
-%queue_only_load% queue incoming if load high
-%queue_run_max% maximum simultaneous queue runners
-%remote_max_parallel% parallel SMTP delivery per message
-%smtp_accept_max% simultaneous incoming connections
-%smtp_accept_max_nommail% non-mail commands
-%smtp_accept_max_nonmail_hosts% hosts to which the limit applies
-%smtp_accept_max_per_connection% messages per connection
-%smtp_accept_max_per_host% connections from one host
-%smtp_accept_queue% queue mail if more connections
-%smtp_accept_queue_per_connection% queue if more messages per connection
-%smtp_accept_reserve% only reserve hosts if more connections
-%smtp_check_spool_space% from SIZE on MAIL command
-%smtp_connect_backlog% passed to TCP/IP stack
-%smtp_load_reserve% SMTP from reserved hosts if load high
-%smtp_reserve_hosts% these are the reserve hosts
---------------------------------------------------------------------------
-
-
-
-Policy controls
-~~~~~~~~~~~~~~~
-[frame="none"]
-`-----------------------------------`-------------------------------------
-%acl_not_smtp% ACL for non-SMTP messages
-%acl_not_smtp_mime% ACL for non-SMTP MIME parts
-%acl_smtp_auth% ACL for AUTH
-%acl_smtp_connect% ACL for connection
-%acl_smtp_data% ACL for DATA
-%acl_smtp_etrn% ACL for ETRN
-%acl_smtp_expn% ACL for EXPN
-%acl_smtp_helo% ACL for EHLO or HELO
-%acl_smtp_mail% ACL for MAIL
-%acl_smtp_mailauth% ACL for AUTH on MAIL command
-%acl_smtp_mime% ACL for MIME parts
-%acl_smtp_predata% ACL for start of data
-%acl_smtp_quit% ACL for QUIT
-%acl_smtp_rcpt% ACL for RCPT
-%acl_smtp_starttls% ACL for STARTTLS
-%acl_smtp_vrfy% ACL for VRFY
-%av_scanner% specify virus scanner
-%check_rfc2047_length% check length of RFC 2047 ``encoded words''
-%dns_csa_search_limit% control CSA parent search depth
-%dns_csa_use_reverse% en/disable CSA IP reverse search
-%header_maxsize% total size of message header
-%header_line_maxsize% individual header line limit
-%helo_accept_junk_hosts% allow syntactic junk from these hosts
-%helo_allow_chars% allow illegal chars in HELO names
-%helo_lookup_domains% lookup hostname for these HELO names
-%helo_try_verify_hosts% HELO soft-checked for these hosts
-%helo_verify_hosts% HELO hard-checked for these hosts
-%host_lookup% host name looked up for these hosts
-%host_lookup_order% order of DNS and local name lookups
-%host_reject_connection% reject connection from these hosts
-%hosts_treat_as_local% useful in some cluster configurations
-%local_scan_timeout% timeout for 'local_scan()'
-%message_size_limit% for all messages
-%percent_hack_domains% recognize %-hack for these domains
-%spamd_address% set interface to SpamAssassin
---------------------------------------------------------------------------
-
-
-
-Callout cache
-~~~~~~~~~~~~~
-[frame="none"]
-`-----------------------------------`-------------------------------------
-%callout_domain_negative_expire% timeout for negative domain cache item
-%callout_domain_positive_expire% timeout for positive domain cache item
-%callout_negative_expire% timeout for negative address cache item
-%callout_positive_expire% timeout for positive address cache item
-%callout_random_local_part% string to use for ``random'' testing
---------------------------------------------------------------------------
-
-
-
-TLS
-~~~
-[frame="none"]
-`-----------------------------------`-------------------------------------
-%tls_advertise_hosts% advertise TLS to these hosts
-%tls_certificate% location of server certificate
-%tls_crl% certificate revocation list
-%tls_dhparam% DH parameters for server
-%tls_on_connect_ports% specify SSMTP (SMTPS) ports
-%tls_privatekey% location of server private key
-%tls_remember_esmtp% don't reset after starting TLS
-%tls_require_ciphers% specify acceptable cipers
-%tls_try_verify_hosts% try to verify client certificate
-%tls_verify_certificates% expected client certificates
-%tls_verify_hosts% insist on client certificate verify
---------------------------------------------------------------------------
-
-
-
-Local user handling
-~~~~~~~~~~~~~~~~~~~
-[frame="none"]
-`-----------------------------------`-------------------------------------
-%finduser_retries% useful in NIS environments
-%gecos_name% used when creating 'Sender:'
-%gecos_pattern% ditto
-%max_username_length% for systems that truncate
-%unknown_login% used when no login name found
-%unknown_username% ditto
-%uucp_from_pattern% for recognizing ``From '' lines
-%uucp_from_sender% ditto
---------------------------------------------------------------------------
-
-
-
-All incoming messages (SMTP and non-SMTP)
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-[frame="none"]
-`-----------------------------------`-------------------------------------
-%header_maxsize% total size of message header
-%header_line_maxsize% individual header line limit
-%message_size_limit% applies to all messages
-%percent_hack_domains% recognize %-hack for these domains
-%received_header_text% expanded to make 'Received:'
-%received_headers_max% for mail loop detection
-%recipients_max% limit per message
-%recipients_max_reject% permanently reject excess
---------------------------------------------------------------------------
-
-
-
-
-Non-SMTP incoming messages
-~~~~~~~~~~~~~~~~~~~~~~~~~~
-[frame="none"]
-`-----------------------------------`-------------------------------------
-%receive_timeout% for non-SMTP messages
---------------------------------------------------------------------------
-
-
-
-
-
-Incoming SMTP messages
-~~~~~~~~~~~~~~~~~~~~~~
-See also the 'Policy controls' section above.
-
-[frame="none"]
-`-----------------------------------`-------------------------------------
-%host_lookup% host name looked up for these hosts
-%host_lookup_order% order of DNS and local name lookups
-%recipient_unqualified_hosts% may send unqualified recipients
-%rfc1413_hosts% make ident calls to these hosts
-%rfc1413_query_timeout% zero disables ident calls
-%sender_unqualified_hosts% may send unqualified senders
-%smtp_accept_keepalive% some TCP/IP magic
-%smtp_accept_max% simultaneous incoming connections
-%smtp_accept_max_nonmail% non-mail commands
-%smtp_accept_max_nonmail_hosts% hosts to which the limit applies
-%smtp_accept_max_per_connection% messages per connection
-%smtp_accept_max_per_host% connections from one host
-%smtp_accept_queue% queue mail if more connections
-%smtp_accept_queue_per_connection% queue if more messages per connection
-%smtp_accept_reserve% only reserve hosts if more connections
-%smtp_active_hostname% host name to use in messages
-%smtp_banner% text for welcome banner
-%smtp_check_spool_space% from SIZE on MAIL command
-%smtp_connect_backlog% passed to TCP/IP stack
-%smtp_enforce_sync% of SMTP command/responses
-%smtp_etrn_command% what to run for ETRN
-%smtp_etrn_serialize% only one at once
-%smtp_load_reserve% only reserve hosts if this load
-%smtp_max_unknown_commands% before dropping connection
-%smtp_ratelimit_hosts% apply ratelimiting to these hosts
-%smtp_ratelimit_mail% ratelimit for MAIL commands
-%smtp_ratelimit_rcpt% ratelimit for RCPT commands
-%smtp_receive_timeout% per command or data line
-%smtp_reserve_hosts% these are the reserve hosts
-%smtp_return_error_details% give detail on rejections
---------------------------------------------------------------------------
-
-
-
-SMTP extensions
-~~~~~~~~~~~~~~~
-[frame="none"]
-`-----------------------------------`-------------------------------------
-%accept_8bitmime% advertise 8BITMIME
-%auth_advertise_hosts% advertise AUTH to these hosts
-%ignore_fromline_hosts% allow ``From '' from these hosts
-%ignore_fromline_local% allow ``From '' from local SMTP
-%pipelining_advertise_hosts% advertise pipelining to these hosts
-%tls_advertise_hosts% advertise TLS to these hosts
---------------------------------------------------------------------------
-
-
-
-Processing messages
-~~~~~~~~~~~~~~~~~~~
-[frame="none"]
-`-----------------------------------`-------------------------------------
-%allow_domain_literals% recognize domain literal syntax
-%allow_mx_to_ip% allow MX to point to IP address
-%allow_utf8_domains% in addresses
-%check_rfc2047_length% check length of RFC 2047 ``encoded words''
-%delivery_date_remove% from incoming messages
-%envelope_to_remote% from incoming messages
-%extract_addresses_remove_arguments% affects %-t% processing
-%headers_charset% default for translations
-%qualify_domain% default for senders
-%qualify_recipient% default for recipients
-%return_path_remove% from incoming messages
-%strip_excess_angle_brackets% in addresses
-%strip_trailing_dot% at end of addresses
-%untrusted_set_sender% untrusted can set envelope sender
---------------------------------------------------------------------------
-
-
-
-System filter
-~~~~~~~~~~~~~
-[frame="none"]
-`-----------------------------------`-------------------------------------
-%system_filter% locate system filter
-%system_filter_directory_transport% transport for delivery to a directory
-%system_filter_file_transport% transport for delivery to a file
-%system_filter_group% group for filter running
-%system_filter_pipe_transport% transport for delivery to a pipe
-%system_filter_reply_transport% transport for autoreply delivery
-%system_filter_user% user for filter running
---------------------------------------------------------------------------
-
-
-
-Routing and delivery
-~~~~~~~~~~~~~~~~~~~~
-[frame="none"]
-`-----------------------------------`-------------------------------------
-%dns_again_means_nonexist% for broken domains
-%dns_check_names_pattern% pre-DNS syntax check
-%dns_ipv4_lookup% only v4 lookup for these domains
-%dns_retrans% parameter for resolver
-%dns_retry% parameter for resolver
-%hold_domains% hold delivery for these domains
-%local_interfaces% for routing checks
-%queue_domains% no immediate delivery for these
-%queue_only% no immediate delivery at all
-%queue_only_file% no immediate delivery if file exists
-%queue_only_load% no immediate delivery if load is high
-%queue_only_override% allow command line to override
-%queue_run_in_order% order of arrival
-%queue_run_max% of simultaneous queue runners
-%queue_smtp_domains% no immediate SMTP delivery for these
-%remote_max_parallel% parallel SMTP delivery per message
-%remote_sort_domains% order of remote deliveries
-%retry_data_expire% timeout for retry data
-%retry_interval_max% safety net for retry rules
---------------------------------------------------------------------------
-
-
-
-Bounce and warning messages
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
-[frame="none"]
-`-----------------------------------`-------------------------------------
-%bounce_message_file% content of bounce
-%bounce_message_text% content of bounce
-%bounce_return_body% include body if returning message
-%bounce_return_message% include original message in bounce
-%bounce_return_size_limit% limit on returned message
-%bounce_sender_authentication% send authenticated sender with bounce
-%errors_copy% copy bounce messages
-%errors_reply_to% 'Reply-to:' in bounces
-%delay_warning% time schedule
-%delay_warning_condition% condition for warning messages
-%ignore_bounce_errors_after% discard undeliverable bounces
-%smtp_return_error_details% give detail on rejections
-%warn_message_file% content of warning message
---------------------------------------------------------------------------
-
-
-
-[[SECTalomo]]
-Alphabetical list of main options
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Those options that undergo string expansion before use are marked with !!.
-
-oindex:[%accept_8bitmime%]
-`..'=
-%accept_8bitmime%, Use: 'main', Type: 'boolean', Default: 'false'
-===
-
-cindex:[8BITMIME]
-cindex:[8-bit characters]
-This option causes Exim to send 8BITMIME in its response to an SMTP
-EHLO command, and to accept the BODY= parameter on MAIL commands.
-However, though Exim is 8-bit clean, it is not a protocol converter, and it
-takes no steps to do anything special with messages received by this route.
-Consequently, this option is turned off by default.
-
-oindex:[%acl_not_smtp%]
-`..'=
-%acl_not_smtp%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[{ACL},for non-SMTP messages]
-cindex:[non-SMTP messages, ACLs for]
-This option defines the ACL that is run when a non-SMTP message is on the point
-of being accepted. See chapter <<CHAPACL>> for further details.
-
-oindex:[%acl_not_smtp_mime%]
-`..'=
-%acl_not_smtp_mime%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-[revisionflag="changed"]
-This option defines the ACL that is run for individual MIME parts of non-SMTP
-messages. It operates in exactly the same way as %acl_smtp_mime% operates for
-SMTP messages.
-
-oindex:[%acl_smtp_auth%]
-`..'=
-%acl_smtp_auth%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[{ACL},setting up for SMTP commands]
-cindex:[AUTH,ACL for]
-This option defines the ACL that is run when an SMTP AUTH command is
-received. See chapter <<CHAPACL>> for further details.
-
-oindex:[%acl_smtp_connect%]
-`..'=
-%acl_smtp_connect%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[{ACL},on SMTP connection]
-This option defines the ACL that is run when an SMTP connection is received.
-See chapter <<CHAPACL>> for further details.
-
-oindex:[%acl_smtp_data%]
-`..'=
-%acl_smtp_data%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[DATA, ACL for]
-This option defines the ACL that is run after an SMTP DATA command has been
-processed and the message itself has been received, but before the final
-acknowledgement is sent. See chapter <<CHAPACL>> for further details.
-
-oindex:[%acl_smtp_etrn%]
-`..'=
-%acl_smtp_etrn%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[ETRN,ACL for]
-This option defines the ACL that is run when an SMTP ETRN command is
-received. See chapter <<CHAPACL>> for further details.
-
-oindex:[%acl_smtp_expn%]
-`..'=
-%acl_smtp_expn%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[EXPN,ACL for]
-This option defines the ACL that is run when an SMTP EXPN command is
-received. See chapter <<CHAPACL>> for further details.
-
-oindex:[%acl_smtp_helo%]
-`..'=
-%acl_smtp_helo%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[EHLO,ACL for]
-cindex:[HELO,ACL for]
-This option defines the ACL that is run when an SMTP EHLO or HELO
-command is received. See chapter <<CHAPACL>> for further details.
-
-
-oindex:[%acl_smtp_mail%]
-`..'=
-%acl_smtp_mail%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[MAIL,ACL for]
-This option defines the ACL that is run when an SMTP MAIL command is
-received. See chapter <<CHAPACL>> for further details.
-
-oindex:[%acl_smtp_mailauth%]
-`..'=
-%acl_smtp_mailauth%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[AUTH,on MAIL command]
-This option defines the ACL that is run when there is an AUTH parameter on
-a MAIL command. See chapter <<CHAPACL>> for details of ACLs, and chapter
-<<CHAPSMTPAUTH>> for details of authentication.
-
-oindex:[%acl_smtp_mime%]
-`..'=
-%acl_smtp_mime%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[MIME content scanning,ACL for]
-This option is available when Exim is built with the content-scanning
-extension. It defines the ACL that is run for each MIME part in a message. See
-section <<SECTscanmimepart>> for details.
-
-oindex:[%acl_smtp_predata%]
-`..'=
-%acl_smtp_predata%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-This option defines the ACL that is run when an SMTP DATA command is
-received, before the message itself is received. See chapter <<CHAPACL>> for
-further details.
-
-oindex:[%acl_smtp_quit%]
-`..'=
-%acl_smtp_quit%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[QUIT,ACL for]
-This option defines the ACL that is run when an SMTP QUIT command is
-received. See chapter <<CHAPACL>> for further details.
-
-oindex:[%acl_smtp_rcpt%]
-`..'=
-%acl_smtp_rcpt%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[RCPT,ACL for]
-This option defines the ACL that is run when an SMTP RCPT command is
-received. See chapter <<CHAPACL>> for further details.
-
-oindex:[%acl_smtp_starttls%]
-`..'=
-%acl_smtp_starttls%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[STARTTLS, ACL for]
-This option defines the ACL that is run when an SMTP STARTTLS command is
-received. See chapter <<CHAPACL>> for further details.
-
-oindex:[%acl_smtp_vrfy%]
-`..'=
-%acl_smtp_vrfy%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[VRFY,ACL for]
-This option defines the ACL that is run when an SMTP VRFY command is
-received. See chapter <<CHAPACL>> for further details.
-
-oindex:[%admin_groups%]
-`..'=
-%admin_groups%, Use: 'main', Type: 'string list'!!, Default: 'unset'
-===
-
-[revisionflag="changed"]
-cindex:[admin user]
-This option is expanded just once, at the start of Exim's processing. If the
-current group or any of the supplementary groups of an Exim caller is in this
-colon-separated list, the caller has admin privileges. If all your system
-programmers are in a specific group, for example, you can give them all Exim
-admin privileges by putting that group in %admin_groups%. However, this does
-not permit them to read Exim's spool files (whose group owner is the Exim gid).
-To permit this, you have to add individuals to the Exim group.
-
-
-oindex:[%allow_domain_literals%]
-`..'=
-%allow_domain_literals%, Use: 'main', Type: 'boolean', Default: 'false'
-===
-
-cindex:[domain literal]
-If this option is set, the RFC 2822 domain literal format is permitted in
-email addresses. The option is not set by default, because the domain literal
-format is not normally required these days, and few people know about it. It
-has, however, been exploited by mail abusers.
-
-Unfortunately, it seems that some DNS black list maintainers are using this
-format to report black listing to postmasters. If you want to accept messages
-addressed to your hosts by IP address, you need to set
-%allow_domain_literals% true, and also to add `@[]` to the list of local
-domains (defined in the named domain list %local_domains% in the default
-configuration). This ``magic string'' matches the domain literal form of all the
-local host's IP addresses.
-
-
-oindex:[%allow_mx_to_ip%]
-`..'=
-%allow_mx_to_ip%, Use: 'main', Type: 'boolean', Default: 'false'
-===
-
-cindex:[MX record,pointing to IP address]
-It appears that more and more DNS zone administrators are breaking the rules
-and putting domain names that look like IP addresses on the right hand side of
-MX records. Exim follows the rules and rejects this, giving an error message
-that explains the mis-configuration. However, some other MTAs support this
-practice, so to avoid ``Why can''t Exim do this?' complaints, %allow_mx_to_ip%
-exists, in order to enable this heinous activity. It is not recommended, except
-when you have no other choice.
-
-oindex:[%allow_utf8_domains%]
-`..'=
-%allow_utf8_domains%, Use: 'main', Type: 'boolean', Default: 'false'
-===
-
-cindex:[domain,UTF-8 characters in]
-cindex:[UTF-8,in domain name]
-Lots of discussion is going on about internationalized domain names. One
-camp is strongly in favour of just using UTF-8 characters, and it seems
-that at least two other MTAs permit this. This option allows Exim users to
-experiment if they wish.
-
-If it is set true, Exim's domain parsing function allows valid
-UTF-8 multicharacters to appear in domain name components, in addition to
-letters, digits, and hyphens. However, just setting this option is not
-enough; if you want to look up these domain names in the DNS, you must also
-adjust the value of %dns_check_names_pattern% to match the extended form. A
-suitable setting is:
-
-....
-dns_check_names_pattern = (?i)^(?>(?(1)\.|())[a-z0-9\xc0-\xff]\
- (?>[-a-z0-9\x80-\xff]*[a-z0-9\x80-\xbf])?)+$
-....
-
-Alternatively, you can just disable this feature by setting
-
- dns_check_names_pattern =
-
-That is, set the option to an empty string so that no check is done.
-
-
-oindex:[%auth_advertise_hosts%]
-`..'=
-%auth_advertise_hosts%, Use: 'main', Type: 'host list'!!, Default: '\*'
-===
-
-cindex:[authentication,advertising]
-cindex:[AUTH,advertising]
-If any server authentication mechanisms are configured, Exim advertises them in
-response to an EHLO command only if the calling host matches this list.
-Otherwise, Exim does not advertise AUTH.
-Exim does not accept AUTH commands from clients to which it has not
-advertised the availability of AUTH. The advertising of individual
-authentication mechanisms can be controlled by the use of the
-%server_advertise_condition% generic authenticator option on the individual
-authenticators. See chapter <<CHAPSMTPAUTH>> for further details.
-
-Certain mail clients (for example, Netscape) require the user to provide a name
-and password for authentication if AUTH is advertised, even though it may
-not be needed (the host may accept messages from hosts on its local LAN without
-authentication, for example). The %auth_advertise_hosts% option can be used
-to make these clients more friendly by excluding them from the set of hosts to
-which Exim advertises AUTH.
-
-cindex:[AUTH,advertising when encrypted]
-If you want to advertise the availability of AUTH only when the connection
-is encrypted using TLS, you can make use of the fact that the value of this
-option is expanded, with a setting like this:
-
- auth_advertise_hosts = ${if eq{$tls_cipher}{}{}{*}}
-
-cindex:[$tls_cipher$]
-If $tls_cipher$ is empty, the session is not encrypted, and the result of
-the expansion is empty, thus matching no hosts. Otherwise, the result of the
-expansion is \*, which matches all hosts.
-
-
-oindex:[%auto_thaw%]
-`..'=
-%auto_thaw%, Use: 'main', Type: 'time', Default: '0s'
-===
-
-[revisionflag="changed"]
-cindex:[thawing messages]
-cindex:[unfreezing messages]
-If this option is set to a time greater than zero, a queue runner will try a
-new delivery attempt on any frozen message, other than a bounce message, if
-this much time has passed since it was frozen. This may result in the message
-being re-frozen if nothing has changed since the last attempt. It is a way of
-saying ``keep on trying, even though there are big problems''.
-
-*Note*: This is an old option, which predates %timeout_frozen_after% and
-%ignore_bounce_errors_after%. It is retained for compatibility, but it is not
-thought to be very useful any more, and its use should probably be avoided.
-
-
-oindex:[%av_scanner%]
-`..'=
-%av_scanner%, Use: 'main', Type: 'string', Default: 'see below'
-===
-
-This option is available if Exim is built with the content-scanning extension.
-It specifies which anti-virus scanner to use. The default value is:
-
- sophie:/var/run/sophie
-
-If the value of %av_scanner% starts with dollar character, it is expanded
-before use. See section <<SECTscanvirus>> for further details.
-
-
-
-oindex:[%bi_command%]
-`..'=
-%bi_command%, Use: 'main', Type: 'string', Default: 'unset'
-===
-
-cindex:[%-bi% option]
-This option supplies the name of a command that is run when Exim is called with
-the %-bi% option (see chapter <<CHAPcommandline>>). The string value is just the
-command name, it is not a complete command line. If an argument is required, it
-must come from the %-oA% command line option.
-
-
-oindex:[%bounce_message_file%]
-`..'=
-%bounce_message_file%, Use: 'main', Type: 'string', Default: 'unset'
-===
-
-cindex:[bounce message,customizing]
-cindex:[customizing,bounce message]
-This option defines a template file containing paragraphs of text to be used
-for constructing bounce messages. Details of the file's contents are given in
-chapter <<CHAPemsgcust>>. See also %warn_message_file%.
-
-
-oindex:[%bounce_message_text%]
-`..'=
-%bounce_message_text%, Use: 'main', Type: 'string', Default: 'unset'
-===
-
-When this option is set, its contents are included in the default bounce
-message immediately after ``This message was created automatically by mail
-delivery software.'' It is not used if %bounce_message_file% is set.
-
-oindex:[%bounce_return_body%]
-`..'=
-%bounce_return_body%, Use: 'main', Type: 'boolean', Default: 'true'
-===
-
-cindex:[bounce message,including body]
-This option controls whether the body of an incoming message is included in a
-bounce message when %bounce_return_message% is true. If it is not set, only
-the message header is included.
-cindex:[bounce message,including original]
-
-oindex:[%bounce_return_message%]
-`..'=
-%bounce_return_message%, Use: 'main', Type: 'boolean', Default: 'true'
-===
-
-If this option is set false, the original message is not included in bounce
-messages generated by Exim. See also %bounce_return_size_limit%.
-
-
-oindex:[%bounce_return_size_limit%]
-`..'=
-%bounce_return_size_limit%, Use: 'main', Type: 'integer', Default: '100K'
-===
-
-cindex:[size limit, of bounce]
-cindex:[bounce message,size limit]
-cindex:[limit,bounce message size]
-This option sets a limit in bytes on the size of messages that are returned to
-senders as part of bounce messages when %bounce_return_message% is true. The
-limit should be less than the value of the global %message_size_limit% and of
-any %message_size_limit% settings on transports, to allow for the bounce text
-that Exim generates. If this option is set to zero there is no limit.
-
-When the body of any message that is to be included in a bounce message is
-greater than the limit, it is truncated, and a comment pointing this out is
-added at the top. The actual cutoff may be greater than the value given, owing
-to the use of buffering for transferring the message in chunks (typically 8K in
-size). The idea is to save bandwidth on those undeliverable 15-megabyte
-messages.
-
-oindex:[%bounce_sender_authentication%]
-`..'=
-%bounce_sender_authentication%, Use: 'main', Type: 'string', Default: 'unset'
-===
-
-cindex:[bounce message,sender authentication]
-cindex:[authentication,bounce message]
-cindex:[AUTH,on bounce message]
-This option provides an authenticated sender address that is sent with any
-bounce messages generated by Exim that are sent over an authenticated SMTP
-connection. A typical setting might be:
-
- bounce_sender_authentication = mailer-daemon@my.domain.example
-
-which would cause bounce messages to be sent using the SMTP command:
-
- MAIL FROM:<> AUTH=mailer-daemon@my.domain.example
-
-The value of %bounce_sender_authentication% must always be a complete email
-address.
-
-oindex:[%callout_domain_negative_expire%]
-`..'=
-%callout_domain_negative_expire%, Use: 'main', Type: 'time', Default: '3h'
-===
-
-cindex:[caching,callout timeouts]
-cindex:[callout,caching timeouts]
-This option specifies the expiry time for negative callout cache data for a
-domain. See section <<SECTcallver>> for details of callout verification, and
-section <<SECTcallvercache>> for details of the caching.
-
-
-oindex:[%callout_domain_positive_expire%]
-`..'=
-%callout_domain_positive_expire%, Use: 'main', Type: 'time', Default: '7d'
-===
-
-This option specifies the expiry time for positive callout cache data for a
-domain. See section <<SECTcallver>> for details of callout verification, and
-section <<SECTcallvercache>> for details of the caching.
-
-
-oindex:[%callout_negative_expire%]
-`..'=
-%callout_negative_expire%, Use: 'main', Type: 'time', Default: '2h'
-===
-
-This option specifies the expiry time for negative callout cache data for an
-address. See section <<SECTcallver>> for details of callout verification, and
-section <<SECTcallvercache>> for details of the caching.
-
-
-oindex:[%callout_positive_expire%]
-`..'=
-%callout_positive_expire%, Use: 'main', Type: 'time', Default: '24h'
-===
-
-This option specifies the expiry time for positive callout cache data for an
-address. See section <<SECTcallver>> for details of callout verification, and
-section <<SECTcallvercache>> for details of the caching.
-
-
-oindex:[%callout_random_local_part%]
-`..'=
-%callout_random_local_part%, Use: 'main', Type: 'string'!!, Default: 'see below'
-===
-
-This option defines the ``random'' local part that can be used as part of callout
-verification. The default value is
-
- $primary_host_name-$tod_epoch-testing
-
-See section <<CALLaddparcall>> for details of how this value is used.
-
-
-oindex:[%check_log_inodes%]
-`..'=
-%check_log_inodes%, Use: 'main', Type: 'integer', Default: '0'
-===
-
-See %check_spool_space% below.
-
-
-oindex:[%check_log_space%]
-`..'=
-%check_log_space%, Use: 'main', Type: 'integer', Default: '0'
-===
-
-See %check_spool_space% below.
-
-oindex:[%check_rfc2047_length%]
-cindex:[RFC 2047,disabling length check]
-`..'=
-%check_rfc2047_length%, User: 'main', Type: 'boolean', Default: 'true'
-===
-
-RFC 2047 defines a way of encoding non-ASCII characters in headers using a
-system of ``encoded words''. The RFC specifies a maximum length for an encoded
-word; strings to be encoded that exceed this length are supposed to use
-multiple encoded words. By default, Exim does not recognize encoded words that
-exceed the maximum length. However, it seems that some software, in violation
-of the RFC, generates overlong encoded words. If %check_rfc2047_length% is set
-false, Exim recognizes encoded words of any length.
-
-
-oindex:[%check_spool_inodes%]
-`..'=
-%check_spool_inodes%, Use: 'main', Type: 'integer', Default: '0'
-===
-
-See %check_spool_space% below.
-
-
-oindex:[%check_spool_space%]
-`..'=
-%check_spool_space%, Use: 'main', Type: 'integer', Default: '0'
-===
-
-cindex:[checking disk space]
-cindex:[disk space, checking]
-cindex:[spool directory,checking space]
-The four %check_...% options allow for checking of disk resources before a
-message is accepted.
-
-cindex:[$log_inodes$]
-cindex:[$log_space$]
-cindex:[$spool_inodes$]
-cindex:[$spool_space$]
-When any of these options are set, they apply to all incoming messages. If you
-want to apply different checks to different kinds of message, you can do so by
-testing the the variables $log_inodes$, $log_space$, $spool_inodes$, and
-$spool_space$ in an ACL with appropriate additional conditions.
-
-
-%check_spool_space% and %check_spool_inodes% check the spool partition if
-either value is greater than zero, for example:
-
- check_spool_space = 10M
- check_spool_inodes = 100
-
-The spool partition is the one that contains the directory defined by
-SPOOL_DIRECTORY in _Local/Makefile_. It is used for holding messages in
-transit.
-
-%check_log_space% and %check_log_inodes% check the partition in which log
-files are written if either is greater than zero. These should be set only if
-%log_file_path% and %spool_directory% refer to different partitions.
-
-If there is less space or fewer inodes than requested, Exim refuses to accept
-incoming mail. In the case of SMTP input this is done by giving a 452 temporary
-error response to the MAIL command. If ESMTP is in use and there was a
-SIZE parameter on the MAIL command, its value is added to the
-%check_spool_space% value, and the check is performed even if
-%check_spool_space% is zero, unless %no_smtp_check_spool_space% is set.
-
-The values for %check_spool_space% and %check_log_space% are held as a
-number of kilobytes. If a non-multiple of 1024 is specified, it is rounded up.
-
-For non-SMTP input and for batched SMTP input, the test is done at start-up; on
-failure a message is written to stderr and Exim exits with a non-zero code, as
-it obviously cannot send an error message of any kind.
-
-oindex:[%daemon_smtp_ports%]
-`..'=
-%daemon_smtp_ports%, Use: 'main', Type: 'string', Default: `smtp`
-===
-
-cindex:[port,for daemon]
-cindex:[TCP/IP,setting listening ports]
-This option specifies one or more default SMTP ports on which the Exim daemon
-listens. See chapter <<CHAPinterfaces>> for details of how it is used. For
-backward compatibility, %daemon_smtp_port% (singular) is a synonym.
-
-oindex:[%daemon_startup_retries%]
-`..'=
-%daemon_startup_retries%, Use: 'main', Type: 'integer', Default: '9'
-===
-
-[revisionflag="changed"]
-cindex:[daemon startup,retrying]
-This option, along with %daemon_startup_sleep%, controls the retrying done by
-the daemon at startup when it cannot immediately bind a listening socket
-(typically because the socket is already in use): %daemon_startup_retries%
-defines the number of retries after the first failure, and
-%daemon_startup_sleep% defines the length of time to wait between retries.
-
-oindex:[%daemon_startup_sleep%]
-`..'=
-%daemon_startup_sleep%, Use: 'main', Type: 'time', Default: '30s'
-===
-
-[revisionflag="changed"]
-See %daemon_startup_retries%.
-
-oindex:[%delay_warning%]
-`..'=
-%delay_warning%, Use: 'main', Type: 'time list', Default: '24h'
-===
-
-cindex:[warning of delay]
-cindex:[delay warning, specifying]
-When a message is delayed, Exim sends a warning message to the sender at
-intervals specified by this option. The data is a colon-separated list of times
-after which to send warning messages.
-
-If the value of the option is an empty string or a zero time, no warnings are
-sent.
-
-Up to 10 times may be given. If a message has been on the queue for longer than
-the last time, the last interval between the times is used to compute
-subsequent warning times. For example, with
-
- delay_warning = 4h:8h:24h
-
-the first message is sent after 4 hours, the second after 8 hours, and
-the third one after 24 hours. After that, messages are sent every 16 hours,
-because that is the interval between the last two times on the list. If you set
-just one time, it specifies the repeat interval. For example, with:
-
- delay_warning = 6h
-
-messages are repeated every six hours. To stop warnings after a given time, set
-a very large time at the end of the list. For example:
-
- delay_warning = 2h:12h:99d
-
-
-
-oindex:[%delay_warning_condition%]
-`..'=
-%delay_warning_condition%, Use: 'main', Type: 'string'!!, Default: 'see below'
-===
-
-cindex:[$domain$]
-The string is expanded at the time a warning message might be sent. If all the
-deferred addresses have the same domain, it is set in $domain$ during the
-expansion. Otherwise $domain$ is empty. If the result of the expansion is a
-forced failure, an empty string, or a string matching any of ``0'', ``no'' or
-``false'' (the comparison being done caselessly) then the warning message is not
-sent. The default is
-
-....
-delay_warning_condition = \
- ${if match{$h_precedence:}{(?i)bulk|list|junk}{no}{yes}}
-....
-
-which suppresses the sending of warnings about messages that have ``bulk'',
-``list'' or ``junk'' in a 'Precedence:' header.
-
-oindex:[%deliver_drop_privilege%]
-`..'=
-%deliver_drop_privilege%, Use: 'main', Type: 'boolean', Default: 'false'
-===
-
-cindex:[unprivileged delivery]
-cindex:[delivery,unprivileged]
-If this option is set true, Exim drops its root privilege at the start of a
-delivery process, and runs as the Exim user throughout. This severely restricts
-the kinds of local delivery that are possible, but is viable in certain types
-of configuration. There is a discussion about the use of root privilege in
-chapter <<CHAPsecurity>>.
-
-oindex:[%deliver_queue_load_max%]
-`..'=
-%deliver_queue_load_max%, Use: 'main', Type: 'fixed-point', Default: 'unset'
-===
-
-cindex:[load average]
-cindex:[queue runner,abandoning]
-When this option is set, a queue run is abandoned if the system load average
-becomes greater than the value of the option. The option has no effect on
-ancient operating systems on which Exim cannot determine the load average.
-See also %queue_only_load% and %smtp_load_reserve%.
-
-
-oindex:[%delivery_date_remove%]
-`..'=
-%delivery_date_remove%, Use: 'main', Type: 'boolean', Default: 'true'
-===
-
-cindex:['Delivery-date:' header line]
-Exim's transports have an option for adding a 'Delivery-date:' header to a
-message when it is delivered -- in exactly the same way as 'Return-path:' is
-handled. 'Delivery-date:' records the actual time of delivery. Such headers
-should not be present in incoming messages, and this option causes them to be
-removed at the time the message is received, to avoid any problems that might
-occur when a delivered message is subsequently sent on to some other recipient.
-
-oindex:[%dns_again_means_nonexist%]
-`..'=
-%dns_again_means_nonexist%, Use: 'main', Type: 'domain list'!!, Default: 'unset'
-===
-
-cindex:[DNS,``try again'' response; overriding]
-DNS lookups give a ``try again'' response for the DNS errors ``non-authoritative
-host not found'' and ``SERVERFAIL''. This can cause Exim to keep trying to
-deliver a message, or to give repeated temporary errors to incoming mail.
-Sometimes the effect is caused by a badly set up name server and may persist
-for a long time. If a domain which exhibits this problem matches anything in
-%dns_again_means_nonexist%, it is treated as if it did not exist. This
-option should be used with care.
-You can make it apply to reverse lookups by a setting such as this:
-
- dns_again_means_nonexist = *.in-addr.arpa
-
-This option applies to all DNS lookups that Exim does. The ^dnslookup^ router
-has some options of its own for controlling what happens when lookups for MX or
-SRV records give temporary errors. These more specific options are applied
-after the global option.
-
-oindex:[%dns_check_names_pattern%]
-`..'=
-%dns_check_names_pattern%, Use: 'main', Type: 'string', Default: 'see below'
-===
-
-cindex:[DNS,pre-check of name syntax]
-When this option is set to a non-empty string, it causes Exim to check domain
-names for illegal characters before handing them to the DNS resolver, because
-some resolvers give temporary errors for malformed names. If a domain name
-contains any illegal characters, a ``not found'' result is forced, and the
-resolver is not called. The check is done by matching the domain name against a
-regular expression, which is the value of this option. The default pattern is
-
-....
-dns_check_names_pattern = \
- (?i)^(?>(?(1)\.|())[^\W_](?>[a-z0-9-]*[^\W_])?)+$
-....
-
-which permits only letters, digits, and hyphens in components, but they may not
-start or end with a hyphen.
-If you set %allow_utf8_domains%, you must modify this pattern, or set the
-option to an empty string.
-
-oindex:[%dns_csa_search_limit%]
-`..'=
-%dns_csa_search_limit%, Use: 'main', Type: 'integer', Default: '5'
-===
-
-[revisionflag="changed"]
-This option controls the depth of parental searching for CSA SRV records in the
-DNS, as described in more detail in section <<SECTverifyCSA>>.
-
-
-oindex:[%dns_csa_use_reverse%]
-`..'=
-%dns_csa_use_reverse%, Use: 'main', Type: 'boolean', Default: 'true'
-===
-
-[revisionflag="changed"]
-This option controls whether or not an IP address, given as a CSA domain, is
-reversed and looked up in the reverse DNS, as described in more detail in
-section <<SECTverifyCSA>>.
-
-
-oindex:[%dns_ipv4_lookup%]
-`..'=
-%dns_ipv4_lookup%, Use: 'main', Type: 'domain list'!!, Default: 'unset'
-===
-
-cindex:[IPv6,DNS lookup for AAAA records]
-cindex:[DNS,IPv6 lookup for AAAA records]
-When Exim is compiled with IPv6 support, it looks for IPv6 address records
-(AAAA and, if configured, A6) as well as IPv4 address records when trying to
-find IP addresses for hosts, unless the host's domain matches this list.
-
-This is a fudge to help with name servers that give big delays or otherwise do
-not work for the new IPv6 record types. If Exim is handed an IPv6 address
-record as a result of an MX lookup, it always recognizes it, and may as a
-result make an outgoing IPv6 connection. All this option does is to make Exim
-look only for IPv4-style A records when it needs to find an IP address for a
-host name. In due course, when the world's name servers have all been upgraded,
-there should be no need for this option.
-
-
-oindex:[%dns_retrans%]
-`..'=
-%dns_retrans%, Use: 'main', Type: 'time', Default: '0s'
-===
-
-cindex:[DNS,resolver options]
-The options %dns_retrans% and %dns_retry% can be used to set the
-retransmission and retry parameters for DNS lookups. Values of zero (the
-defaults) leave the system default settings unchanged. The first value is the
-time between retries, and the second is the number of retries. It isn't
-totally clear exactly how these settings affect the total time a DNS lookup may
-take. I haven't found any documentation about timeouts on DNS lookups; these
-parameter values are available in the external resolver interface structure,
-but nowhere does it seem to describe how they are used or what you might want
-to set in them.
-
-
-oindex:[%dns_retry%]
-`..'=
-%dns_retry%, Use: 'main', Type: 'integer', Default: '0'
-===
-
-See %dns_retrans% above.
-
-
-oindex:[%drop_cr%]
-`..'=
-%drop_cr%, Use: 'main', Type: 'boolean', Default: 'false'
-===
-
-This is an obsolete option that is now a no-op. It used to affect the way Exim
-handled CR and LF characters in incoming messages. What happens now is
-described in section <<SECTlineendings>>.
-
-
-oindex:[%envelope_to_remove%]
-`..'=
-%envelope_to_remove%, Use: 'main', Type: 'boolean', Default: 'true'
-===
-
-cindex:['Envelope-to:' header line]
-Exim's transports have an option for adding an 'Envelope-to:' header to a
-message when it is delivered -- in exactly the same way as 'Return-path:' is
-handled. 'Envelope-to:' records the original recipient address from the
-messages's envelope that caused the delivery to happen. Such headers should not
-be present in incoming messages, and this option causes them to be removed at
-the time the message is received, to avoid any problems that might occur when a
-delivered message is subsequently sent on to some other recipient.
-
-
-oindex:[%errors_copy%]
-`..'=
-%errors_copy%, Use: 'main', Type: 'string list'!!, Default: 'unset'
-===
-
-cindex:[bounce message,copy to other address]
-cindex:[copy of bounce message]
-Setting this option causes Exim to send bcc copies of bounce messages that it
-generates to other addresses. *Note*: this does not apply to bounce messages
-coming from elsewhere. The value of the option is a colon-separated list of
-items. Each item consists of a pattern, terminated by white space, followed by
-a comma-separated list of email addresses. If a pattern contains spaces, it
-must be enclosed in double quotes.
-
-Each pattern is processed in the same way as a single item in an address list
-(see section <<SECTaddresslist>>). When a pattern matches the recipient of the
-bounce message, the message is copied to the addresses on the list. The items
-are scanned in order, and once a matching one is found, no further items are
-examined. For example:
-
-....
-errors_copy = spqr@mydomain postmaster@mydomain.example :\
- rqps@mydomain hostmaster@mydomain.example,\
- postmaster@mydomain.example
-....
-
-cindex:[$domain$]
-cindex:[$local_part$]
-The address list is expanded before use. The expansion variables
-$local_part$ and $domain$ are set from the original recipient of the error
-message, and if there was any wildcard matching in the pattern, the expansion
-
-cindex:[numerical variables ($1$ $2$ etc),in %errors_copy%]
-variables $0$, $1$, etc. are set in the normal way.
-
-
-oindex:[%errors_reply_to%]
-`..'=
-%errors_reply_to%, Use: 'main', Type: 'string', Default: 'unset'
-===
-
-cindex:[bounce message,'Reply-to:' in]
-Exim's bounce and delivery warning messages contain the header line
-
- From: Mail Delivery System <Mailer-Daemon@<qualify-domain>>
-
-where <'qualify-domain'> is the value of the %qualify_domain% option.
-Experience shows that people reply to bounce messages. If the
-%errors_reply_to% option is set, a 'Reply-To:' header is added to bounce and
-warning messages. For example:
-
- errors_reply_to = postmaster@my.domain.example
-
-The value of the option is not expanded. It must specify a valid RFC 2822
-address.
-
-
-oindex:[%exim_group%]
-`..'=
-%exim_group%, Use: 'main', Type: 'string', Default: 'compile-time configured'
-===
-
-cindex:[gid (group id),Exim's own]
-cindex:[Exim group]
-This option changes the gid under which Exim runs when it gives up root
-privilege. The default value is compiled into the binary. The value of this
-option is used only when %exim_user% is also set. Unless it consists entirely
-of digits, the string is looked up using 'getgrnam()', and failure causes a
-configuration error. See chapter <<CHAPsecurity>> for a discussion of security
-issues.
-
-
-oindex:[%exim_path%]
-`..'=
-%exim_path%, Use: 'main', Type: 'string', Default: 'see below'
-===
-
-cindex:[Exim binary, path name]
-This option specifies the path name of the Exim binary, which is used when Exim
-needs to re-exec itself. The default is set up to point to the file 'exim' in
-the directory configured at compile time by the BIN_DIRECTORY setting. It
-is necessary to change %exim_path% if, exceptionally, Exim is run from some
-other place.
-*Warning*: Do not use a macro to define the value of this option, because
-you will break those Exim utilities that scan the configuration file to find
-where the binary is. (They then use the %-bP% option to extract option
-settings such as the value of %spool_directory%.)
-
-
-oindex:[%exim_user%]
-`..'=
-%exim_user%, Use: 'main', Type: 'string', Default: 'compile-time configured'
-===
-
-cindex:[uid (user id),Exim's own]
-cindex:[Exim user]
-This option changes the uid under which Exim runs when it gives up root
-privilege. The default value is compiled into the binary. Ownership of the run
-time configuration file and the use of the %-C% and %-D% command line options
-is checked against the values in the binary, not what is set here.
-
-Unless it consists entirely of digits, the string is looked up using
-'getpwnam()', and failure causes a configuration error. If %exim_group% is
-not also supplied, the gid is taken from the result of 'getpwnam()' if it is
-used. See chapter <<CHAPsecurity>> for a discussion of security issues.
-
-
-oindex:[%extra_local_interfaces%]
-`..'=
-%extra_local_interfaces%, Use: 'main', Type: 'string list', Default: 'unset'
-===
-
-This option defines network interfaces that are to be considered local when
-routing, but which are not used for listening by the daemon. See section
-<<SECTreclocipadd>> for details.
-
-
-oindex:[%extract_addresses_remove_arguments%]
-`..'=
-%extract_addresses_remove_ ~arguments%, Use: 'main', Type: 'boolean', Default: 'true'
-===
-
-cindex:[%-t% option]
-cindex:[command line,addresses with %-t%]
-cindex:[Sendmail compatibility,%-t% option]
-According to some Sendmail documentation (Sun, IRIX, HP-UX), if any addresses
-are present on the command line when the %-t% option is used to build an
-envelope from a message's 'To:', 'Cc:' and 'Bcc:' headers, the command line
-addresses are removed from the recipients list. This is also how Smail behaves.
-However, other Sendmail documentation (the O'Reilly book) states that command
-line addresses are added to those obtained from the header lines. When
-%extract_addresses_remove_arguments% is true (the default), Exim subtracts
-argument headers. If it is set false, Exim adds rather than removes argument
-addresses.
-
-
-oindex:[%finduser_retries%]
-`..'=
-%finduser_retries%, Use: 'main', Type: 'integer', Default: '0'
-===
-
-cindex:[NIS, looking up users; retrying]
-On systems running NIS or other schemes in which user and group information is
-distributed from a remote system, there can be times when 'getpwnam()' and
-related functions fail, even when given valid data, because things time out.
-Unfortunately these failures cannot be distinguished from genuine ``not found''
-errors. If %finduser_retries% is set greater than zero, Exim will try that
-many extra times to find a user or a group, waiting for one second between
-retries.
-
-cindex:[_/etc/passwd_, multiple reading of]
-You should not set this option greater than zero if your user information is in
-a traditional _/etc/passwd_ file, because it will cause Exim needlessly to
-search the file multiple times for non-existent users, and also cause delay.
-
-
-
-oindex:[%freeze_tell%]
-`..'=
-%freeze_tell%, Use: 'main', "Type: 'string list, comma separated'", Default: 'unset'
-===
-
-cindex:[freezing messages,sending a message when freezing]
-On encountering certain errors, or when configured to do so in a system filter,
-or in an ACL,
-Exim freezes a message. This means that no further delivery attempts take place
-until an administrator (or the %auto_thaw% feature) thaws the message. If
-%freeze_tell% is set, Exim generates a warning message whenever it freezes
-something, unless the message it is freezing is a
-locally-generated
-bounce message. (Without this exception there is the possibility of looping.)
-The warning message is sent to the addresses supplied as the comma-separated
-value of this option. If several of the message's addresses cause freezing,
-only a single message is sent.
-If the freezing was automatic, the reason(s) for freezing can be found in the
-message log. If you configure freezing in a filter or ACL, you must arrange for
-any logging that you require.
-
-
-oindex:[%gecos_name%]
-`..'=
-%gecos_name%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[HP-UX]
-cindex:[``gecos'' field, parsing]
-Some operating systems, notably HP-UX, use the ``gecos'' field in the system
-password file to hold other information in addition to users' real names. Exim
-looks up this field for use when it is creating 'Sender:' or 'From:' headers.
-If either %gecos_pattern% or %gecos_name% are unset, the contents of the
-field are used unchanged, except that, if an ampersand is encountered, it is
-replaced by the user's login name with the first character forced to
-upper case, since this is a convention that is observed on many systems.
-
-When these options are set, %gecos_pattern% is treated as a regular expression
-that is to be applied to the field (again with & replaced by the login name),
-and if it matches, %gecos_name% is expanded and used as the user's name.
-
-cindex:[numerical variables ($1$ $2$ etc),in %gecos_name%]
-Numeric variables such as $1$, $2$, etc. can be used in the expansion to
-pick up sub-fields that were matched by the pattern. In HP-UX, where the user's
-name terminates at the first comma, the following can be used:
-
- gecos_pattern = ([^,]*)
- gecos_name = $1
-
-
-
-oindex:[%gecos_pattern%]
-`..'=
-%gecos_pattern%, Use: 'main', Type: 'string', Default: 'unset'
-===
-
-See %gecos_name% above.
-
-
-oindex:[%headers_charset%]
-`..'=
-%headers_charset%, Use: 'main', Type: 'string', Default: 'see below'
-===
-
-This option sets a default character set for translating from encoded MIME
-``words'' in header lines, when referenced by an $h_xxx$ expansion item. The
-default is the value of HEADERS_CHARSET in _Local/Makefile_. The
-ultimate default is ISO-8859-1. For more details see the description of header
-insertions in section <<SECTexpansionitems>>.
-
-
-
-oindex:[%header_maxsize%]
-`..'=
-%header_maxsize%, Use: 'main', Type: 'integer', Default: 'see below'
-===
-
-cindex:[header section,maximum size of]
-cindex:[limit,size of message header section]
-This option controls the overall maximum size of a message's header
-section. The default is the value of HEADER_MAXSIZE in
-_Local/Makefile_; the default for that is 1M. Messages with larger header
-sections are rejected.
-
-
-oindex:[%header_line_maxsize%]
-`..'=
-%header_line_maxsize%, Use: 'main', Type: 'integer', Default: '0'
-===
-
-cindex:[header lines,maximum size of]
-cindex:[limit,size of one header line]
-This option limits the length of any individual header line in a message, after
-all the continuations have been joined together. Messages with individual
-header lines that are longer than the limit are rejected. The default value of
-zero means ``no limit''.
-
-
-
-
-oindex:[%helo_accept_junk_hosts%]
-`..'=
-%helo_accept_junk_hosts%, Use: 'main', Type: 'host list'!!, Default: 'unset'
-===
-
-cindex:[HELO,accepting junk data]
-cindex:[EHLO,accepting junk data]
-Exim checks the syntax of HELO and EHLO commands for incoming SMTP
-mail, and gives an error response for invalid data. Unfortunately, there are
-some SMTP clients that send syntactic junk. They can be accommodated by setting
-this option. Note that this is a syntax check only. See %helo_verify_hosts%
-if you want to do semantic checking.
-See also %helo_allow_chars% for a way of extending the permitted character
-set.
-
-
-oindex:[%helo_allow_chars%]
-`..'=
-%helo_allow_chars%, Use: 'main', Type: 'string', Default: 'unset'
-===
-
-cindex:[HELO,underscores in]
-cindex:[EHLO,underscores in]
-cindex:[underscore in EHLO/HELO]
-This option can be set to a string of rogue characters that are permitted in
-all EHLO and HELO names in addition to the standard letters, digits,
-hyphens, and dots. If you really must allow underscores, you can set
-
- helo_allow_chars = _
-
-Note that the value is one string, not a list.
-
-
-oindex:[%helo_lookup_domains%]
-`..'=
-%helo_lookup_domains%, Use: 'main', Type: 'domain list'!!, Default: `@:@[]`
-===
-
-cindex:[HELO,forcing reverse lookup]
-cindex:[EHLO,forcing reverse lookup]
-If the domain given by a client in a HELO or EHLO command matches this
-list, a reverse lookup is done in order to establish the host's true name. The
-default forces a lookup if the client host gives the server's name or any of
-its IP addresses (in brackets), something that broken clients have been seen to
-do.
-
-
-oindex:[%helo_try_verify_hosts%]
-`..'=
-%helo_try_verify_hosts%, Use: 'main', Type: 'host list'!!, Default: 'unset'
-===
-
-[revisionflag="changed"]
-cindex:[HELO verifying, optional]
-cindex:[EHLO verifying, optional]
-By default, Exim just checks the syntax of HELO and EHLO commands (see
-%helo_accept_junk_hosts% and %helo_allow_chars%). However, some sites like to
-do more extensive checking of the data supplied by these commands. The ACL
-condition `verify = helo` is provided to make this possible. Formerly, it was
-necessary also to set this option (%helo_try_verify_hosts%) to force the check
-to occur. From release 4.53 onwards, this is no longer necessary. If the check
-has not been done before `verify = helo` is encountered, it is done at that
-time. Consequently, this option is obsolete. Its specification is retained here
-for backwards compatibility.
-
-[revisionflag="changed"]
-When an EHLO or HELO command is received, if the calling host matches
-%helo_try_verify_hosts%, Exim checks that the host name given in the HELO or
-EHLO command either:
-
-- is an IP literal matching the calling address of the host, or
-
-- cindex:[DNS,reverse lookup]
-cindex:[reverse DNS lookup]
-matches the host name that Exim obtains by doing a reverse lookup of the
-calling host address, or
-
-- when looked up using 'gethostbyname()' (or 'getipnodebyname()' when
-available) yields the calling host address.
-
-However, the EHLO or HELO command is not rejected if any of the checks
-fail. Processing continues, but the result of the check is remembered, and can
-be detected later in an ACL by the `verify = helo` condition.
-
-
-oindex:[%helo_verify_hosts%]
-`..'=
-%helo_verify_hosts%, Use: 'main', Type: 'host list'!!, Default: 'unset'
-===
-
-[revisionflag="changed"]
-cindex:[HELO verifying, mandatory]
-cindex:[EHLO verifying, mandatory]
-Like %helo_try_verify_hosts%, this option is obsolete, and retained only for
-backwards compatibility. For hosts that match this option, Exim checks the host
-name given in the HELO or EHLO in the same way as for %helo_try_verify_hosts%.
-If the check fails, the HELO or EHLO command is rejected with a 550 error, and
-entries are written to the main and reject logs. If a MAIL command is received
-before EHLO or HELO, it is rejected with a 503 error.
-
-
-oindex:[%hold_domains%]
-`..'=
-%hold_domains%, Use: 'main', Type: 'domain list'!!, Default: 'unset'
-===
-
-cindex:[domain,delaying delivery]
-cindex:[delivery,delaying certain domains]
-This option allows mail for particular domains to be held on the queue
-manually. The option is overridden if a message delivery is forced with the
-%-M%, %-qf%, %-Rf% or %-Sf% options, and also while testing or verifying
-addresses using %-bt% or %-bv%. Otherwise, if a domain matches an item in
-%hold_domains%, no routing or delivery for that address is done, and it is
-deferred every time the message is looked at.
-
-This option is intended as a temporary operational measure for delaying the
-delivery of mail while some problem is being sorted out, or some new
-configuration tested. If you just want to delay the processing of some
-domains until a queue run occurs, you should use %queue_domains% or
-%queue_smtp_domains%, not %hold_domains%.
-
-A setting of %hold_domains% does not override Exim's code for removing
-messages from the queue if they have been there longer than the longest retry
-time in any retry rule. If you want to hold messages for longer than the normal
-retry times, insert a dummy retry rule with a long retry time.
-
-
-oindex:[%host_lookup%]
-`..'=
-%host_lookup%, Use: 'main', Type: 'host list'!!, Default: 'unset'
-===
-
-cindex:[host name lookup, forcing]
-Exim does not look up the name of a calling host from its IP address unless it
-is required to compare against some host list, or the host matches
-%helo_try_verify_hosts% or %helo_verify_hosts%, or the host matches this
-option (which normally contains IP addresses rather than host names). The
-default configuration file contains
-
- host_lookup = *
-
-which causes a lookup to happen for all hosts. If the expense of these lookups
-is felt to be too great, the setting can be changed or removed.
-
-After a successful reverse lookup, Exim does a forward lookup on the name it
-has obtained, to verify that it yields the IP address that it started with. If
-this check fails, Exim behaves as if the name lookup failed.
-
-cindex:[$host_lookup_failed$]
-cindex:[$sender_host_name$]
-After any kind of failure, the host name (in $sender_host_name$) remains
-unset, and $host_lookup_failed$ is set to the string ``1''. See also
-%dns_again_means_nonexist%, %helo_lookup_domains%, and `verify =
-reverse_host_lookup` in ACLs.
-
-
-oindex:[%host_lookup_order%]
-`..'=
-%host_lookup_order%, Use: 'main', Type: 'string list', Default: `bydns:byaddr`
-===
-
-This option specifies the order of different lookup methods when Exim is trying
-to find a host name from an IP address. The default is to do a DNS lookup
-first, and then to try a local lookup (using 'gethostbyaddr()' or equivalent)
-if that fails. You can change the order of these lookups, or omit one entirely,
-if you want.
-
-*Warning*: the ``byaddr'' method does not always yield aliases when there are
-multiple PTR records in the DNS and the IP address is not listed in
-_/etc/hosts_. Different operating systems give different results in this
-case. That is why the default tries a DNS lookup first.
-
-
-
-oindex:[%host_reject_connection%]
-`..'=
-%host_reject_connection%, Use: 'main', Type: 'host list'!!, Default: 'unset'
-===
-
-cindex:[host,rejecting connections from]
-If this option is set, incoming SMTP calls from the hosts listed are rejected
-as soon as the connection is made.
-This option is obsolete, and retained only for backward compatibility, because
-nowadays the ACL specified by %acl_smtp_connect% can also reject incoming
-connections immediately.
-
-The ability to give an immediate rejection (either by this option or using an
-ACL) is provided for use in unusual cases. Many hosts will just try again,
-sometimes without much delay. Normally, it is better to use an ACL to reject
-incoming messages at a later stage, such as after RCPT commands. See
-chapter <<CHAPACL>>.
-
-
-oindex:[%hosts_connection_nolog%]
-`..'=
-%hosts_connection_nolog%, Use: 'main', Type: 'host list'!!, Default: 'unset'
-===
-
-cindex:[host,not logging connections from]
-This option defines a list of hosts for which connection logging does not
-happen, even though the %smtp_connection% log selector is set. For example,
-you might want not to log SMTP connections from local processes, or from
-127.0.0.1, or from your local LAN. This option is consulted in the main loop of
-the daemon; you should therefore strive to restrict its value to a short inline
-list of IP addresses and networks. To disable logging SMTP connections from
-local processes, you must create a host list with an empty item. For example:
-
- hosts_connection_nolog = :
-
-If the %smtp_connection% log selector is not set, this option has no effect.
-
-
-
-oindex:[%hosts_treat_as_local%]
-`..'=
-%hosts_treat_as_local%, Use: 'main', Type: 'domain list'!!, Default: 'unset'
-===
-
-cindex:[local host,domains treated as]
-cindex:[host,treated as local]
-If this option is set, any host names that match the domain list are treated as
-if they were the local host when Exim is scanning host lists obtained from MX
-records
-or other sources. Note that the value of this option is a domain list, not a
-host list, because it is always used to check host names, not IP addresses.
-
-This option also applies when Exim is matching the special items
-`@mx_any`, `@mx_primary`, and `@mx_secondary` in a domain list (see
-section <<SECTdomainlist>>), and when checking the %hosts% option in the ^smtp^
-transport for the local host (see the %allow_localhost% option in that
-transport).
-See also %local_interfaces%, %extra_local_interfaces%, and chapter
-<<CHAPinterfaces>>, which contains a discussion about local network interfaces
-and recognising the local host.
-
-
-oindex:[%ignore_bounce_errors_after%]
-`..'=
-%ignore_bounce_errors_after%, Use: 'main', Type: 'time', Default: '10w'
-===
-
-cindex:[bounce message,discarding]
-cindex:[discarding bounce message]
-This option affects the processing of bounce messages that cannot be delivered,
-that is, those that suffer a permanent delivery failure. (Bounce messages that
-suffer temporary delivery failures are of course retried in the usual way.)
-
-After a permanent delivery failure, bounce messages are frozen,
-because there is no sender to whom they can be returned. When a frozen bounce
-message has been on the queue for more than the given time, it is unfrozen at
-the next queue run, and a further delivery is attempted. If delivery fails
-again, the bounce message is discarded. This makes it possible to keep failed
-bounce messages around for a shorter time than the normal maximum retry time
-for frozen messages. For example,
-
- ignore_bounce_errors_after = 12h
-
-retries failed bounce message deliveries after 12 hours, discarding any further
-failures. If the value of this option is set to a zero time period, bounce
-failures are discarded immediately. Setting a very long time (as in the default
-value) has the effect of disabling this option. For ways of automatically
-dealing with other kinds of frozen message, see %auto_thaw% and
-%timeout_frozen_after%.
-
-
-oindex:[%ignore_fromline_hosts%]
-`..'=
-%ignore_fromline_hosts%, Use: 'main', Type: 'host list'!!, Default: 'unset'
-===
-
-cindex:[``From'' line]
-cindex:[UUCP,``From'' line]
-Some broken SMTP clients insist on sending a UUCP-like ``From'' line before the
-headers of a message. By default this is treated as the start of the message's
-body, which means that any following headers are not recognized as such. Exim
-can be made to ignore it by setting %ignore_fromline_hosts% to match those
-hosts that insist on sending it. If the sender is actually a local process
-rather than a remote host, and is using %-bs% to inject the messages,
-%ignore_fromline_local% must be set to achieve this effect.
-
-
-oindex:[%ignore_fromline_local%]
-`..'=
-%ignore_fromline_local%, Use: 'main', Type: 'boolean', Default: 'false'
-===
-
-See %ignore_fromline_hosts% above.
-
-
-oindex:[%keep_malformed%]
-`..'=
-%keep_malformed%, Use: 'main', Type: 'time', Default: '4d'
-===
-
-This option specifies the length of time to keep messages whose spool files
-have been corrupted in some way. This should, of course, never happen. At the
-next attempt to deliver such a message, it gets removed. The incident is
-logged.
-
-
-oindex:[%ldap_default_servers%]
-`..'=
-%ldap_default_servers%, Use: 'main', Type: 'string list', Default: 'unset'
-===
-
-cindex:[LDAP,default servers]
-This option provides a list of LDAP servers which are tried in turn when an
-LDAP query does not contain a server. See section <<SECTforldaque>> for details
-of LDAP queries. This option is available only when Exim has been built with
-LDAP support.
-
-
-oindex:[%ldap_version%]
-`..'=
-%ldap_version%, Use: 'main', Type: 'integer', Default: 'unset'
-===
-
-cindex:[LDAP protocol version, forcing]
-This option can be used to force Exim to set a specific protocol version for
-LDAP. If it option is unset, it is shown by the %-bP% command line option as
--1. When this is the case, the default is 3 if LDAP_VERSION3 is defined in
-the LDAP headers; otherwise it is 2. This option is available only when Exim
-has been built with LDAP support.
-
-
-
-oindex:[%local_from_check%]
-`..'=
-%local_from_check%, Use: 'main', Type: 'boolean', Default: 'true'
-===
-
-cindex:['Sender:' header line,disabling addition of]
-cindex:['From:' header line,disabling checking of]
-When a message is submitted locally (that is, not over a TCP/IP connection) by
-an untrusted user, Exim removes any existing 'Sender:' header line, and checks
-that the 'From:' header line matches the login of the calling user and the
-domain specified by %qualify_domain%.
-
-*Note*: An unqualified address (no domain) in the 'From:' header in a
-locally submitted message is automatically qualified by Exim, unless the
-%-bnq% command line option is used.
-
-You can use %local_from_prefix% and %local_from_suffix% to permit affixes
-on the local part. If the 'From:' header line does not match, Exim adds a
-'Sender:' header with an address constructed from the calling user's login and
-the default qualify domain.
-
-If %local_from_check% is set false, the 'From:' header check is disabled,
-and no 'Sender:' header is ever added. If, in addition, you want to retain
-'Sender:' header lines supplied by untrusted users, you must also set
-%local_sender_retain% to be true.
-
-cindex:[envelope sender]
-These options affect only the header lines in the message. The envelope sender
-is still forced to be the login id at the qualify domain unless
-%untrusted_set_sender% permits the user to supply an envelope sender.
-
-For messages received over TCP/IP, an ACL can specify ``submission mode'' to
-request similar header line checking. See section <<SECTthesenhea>>, which has
-more details about 'Sender:' processing.
-
-
-
-
-oindex:[%local_from_prefix%]
-`..'=
-%local_from_prefix%, Use: 'main', Type: 'string', Default: 'unset'
-===
-
-When Exim checks the 'From:' header line of locally submitted messages for
-matching the login id (see %local_from_check% above), it can be configured to
-ignore certain prefixes and suffixes in the local part of the address. This is
-done by setting %local_from_prefix% and/or %local_from_suffix% to
-appropriate lists, in the same form as the %local_part_prefix% and
-%local_part_suffix% router options (see chapter <<CHAProutergeneric>>). For
-example, if
-
- local_from_prefix = *-
-
-is set, a 'From:' line containing
-
- From: anything-user@your.domain.example
-
-will not cause a 'Sender:' header to be added if 'user@your.domain.example'
-matches the actual sender address that is constructed from the login name and
-qualify domain.
-
-
-oindex:[%local_from_suffix%]
-`..'=
-%local_from_suffix%, Use: 'main', Type: 'string', Default: 'unset'
-===
-
-See %local_from_prefix% above.
-
-
-oindex:[%local_interfaces%]
-`..'=
-%local_interfaces%, Use: 'main', Type: 'string list', Default: 'see below'
-===
-
-This option controls which network interfaces are used by the daemon for
-listening; they are also used to identify the local host when routing. Chapter
-<<CHAPinterfaces>> contains a full description of this option and the related
-options
-
-%daemon_smtp_ports%, %extra_local_interfaces%, %hosts_treat_as_local%,
-and %tls_on_connect_ports%.
-
-The default value for %local_interfaces% is
-
- local_interfaces = 0.0.0.0
-
-when Exim is built without IPv6 support; otherwise it is
-
- local_interfaces = <; ::0 ; 0.0.0.0
-
-
-
-oindex:[%local_scan_timeout%]
-`..'=
-%local_scan_timeout%, Use: 'main', Type: 'time', Default: '5m'
-===
-
-cindex:[timeout,for 'local_scan()' function]
-cindex:['local_scan()' function,timeout]
-This timeout applies to the 'local_scan()' function (see chapter
-<<CHAPlocalscan>>). Zero means ``no timeout''. If the timeout is exceeded, the
-incoming message is rejected with a temporary error if it is an SMTP message.
-For a non-SMTP message, the message is dropped and Exim ends with a non-zero
-code. The incident is logged on the main and reject logs.
-
-
-
-oindex:[%local_sender_retain%]
-`..'=
-%local_sender_retain%, Use: 'main', Type: 'boolean', Default: 'false'
-===
-
-cindex:['Sender:' header line,retaining from local submission]
-When a message is submitted locally (that is, not over a TCP/IP connection) by
-an untrusted user, Exim removes any existing 'Sender:' header line. If you
-do not want this to happen, you must set %local_sender_retain%, and you must
-also set %local_from_check% to be false (Exim will complain if you do not).
-See also the ACL modifier `control = suppress_local_fixups`. Section
-<<SECTthesenhea>> has more details about 'Sender:' processing.
-
-
-
-
-oindex:[%localhost_number%]
-`..'=
-%localhost_number%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[host,locally unique number for]
-cindex:[message ids, with multiple hosts]
-cindex:[$localhost_number$]
-Exim's message ids are normally unique only within the local host. If
-uniqueness among a set of hosts is required, each host must set a different
-value for the %localhost_number% option. The string is expanded immediately
-after reading the configuration file (so that a number can be computed from the
-host name, for example) and the result of the expansion must be a number in the
-range 0--16 (or 0--10 on operating systems with case-insensitive file systems).
-This is available in subsequent string expansions via the variable
-$localhost_number$. When %localhost_number is set%, the final two
-characters of the message id, instead of just being a fractional part of the
-time, are computed from the time and the local host number as described in
-section <<SECTmessiden>>.
-
-
-
-oindex:[%log_file_path%]
-`..'=
-%log_file_path%, Use: 'main', Type: 'string list'!!, Default: 'set at compile time'
-===
-
-cindex:[log,file path for]
-This option sets the path which is used to determine the names of Exim's log
-files, or indicates that logging is to be to syslog, or both. It is expanded
-when Exim is entered, so it can, for example, contain a reference to the host
-name. If no specific path is set for the log files at compile or run time, they
-are written in a sub-directory called _log_ in Exim's spool directory.
-Chapter <<CHAPlog>> contains further details about Exim's logging, and section
-<<SECTwhelogwri>> describes how the contents of %log_file_path% are used. If
-this string is fixed at your installation (contains no expansion variables) it
-is recommended that you do not set this option in the configuration file, but
-instead supply the path using LOG_FILE_PATH in _Local/Makefile_ so that
-it is available to Exim for logging errors detected early on -- in particular,
-failure to read the configuration file.
-
-
-oindex:[%log_selector%]
-`..'=
-%log_selector%, Use: 'main', Type: 'string', Default: 'unset'
-===
-
-cindex:[log,selectors]
-This option can be used to reduce or increase the number of things that Exim
-writes to its log files. Its argument is made up of names preceded by plus or
-minus characters. For example:
-
- log_selector = +arguments -retry_defer
-
-A list of possible names and what they control is given in the chapter on
-logging, in section <<SECTlogselector>>.
-
-
-oindex:[%log_timezone%]
-`..'=
-%log_timezone%, Use: 'main', Type: 'boolean', Default: 'false'
-===
-
-cindex:[log,timezone for entries]
-cindex:[$tod_log$]
-cindex:[$tod_zone$]
-By default, the timestamps on log lines are in local time without the
-timezone. This means that if your timezone changes twice a year, the timestamps
-in log lines are ambiguous for an hour when the clocks go back. One way of
-avoiding this problem is to set the timezone to UTC. An alternative is to set
-%log_timezone% true. This turns on the addition of the timezone offset to
-timestamps in log lines. Turning on this option can add quite a lot to the size
-of log files because each line is extended by 6 characters. Note that the
-$tod_log$ variable contains the log timestamp without the zone, but there is
-another variable called $tod_zone$ that contains just the timezone offset.
-
-
-oindex:[%lookup_open_max%]
-`..'=
-%lookup_open_max%, Use: 'main', Type: 'integer', Default: '25'
-===
-
-cindex:[too many open files]
-cindex:[open files, too many]
-cindex:[file,too many open]
-cindex:[lookup,maximum open files]
-cindex:[limit,open files for lookups]
-This option limits the number of simultaneously open files for single-key
-lookups that use regular files (that is, ^lsearch^, ^dbm^, and ^cdb^). Exim
-normally keeps these files open during routing, because often the same file is
-required several times. If the limit is reached, Exim closes the least recently
-used file. Note that if you are using the 'ndbm' library, it actually opens
-two files for each logical DBM database, though it still counts as one for the
-purposes of %lookup_open_max%. If you are getting ``too many open files''
-errors with NDBM, you need to reduce the value of %lookup_open_max%.
-
-
-oindex:[%max_username_length%]
-`..'=
-%max_username_length%, Use: 'main', Type: 'integer', Default: '0'
-===
-
-cindex:[length of login name]
-cindex:[user name,maximum length]
-cindex:[limit,user name length]
-Some operating systems are broken in that they truncate long arguments to
-'getpwnam()' to eight characters, instead of returning ``no such user''. If
-this option is set greater than zero, any attempt to call 'getpwnam()' with
-an argument that is longer behaves as if 'getpwnam()' failed.
-
-
-
-oindex:[%message_body_visible%]
-`..'=
-%message_body_visible%, Use: 'main', Type: 'integer', Default: '500'
-===
-
-cindex:[body of message,visible size]
-cindex:[message body, visible size]
-cindex:[$message_body$]
-cindex:[$message_body_end$]
-This option specifies how much of a message's body is to be included in the
-$message_body$ and $message_body_end$ expansion variables.
-
-
-oindex:[%message_id_header_domain%]
-`..'=
-%message_id_header_domain%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:['Message-ID:' header line]
-If this option is set, the string is expanded and used as the right hand side
-(domain) of the 'Message-ID:' header that Exim creates if a
-locally-originated incoming message does not have one. ``Locally-originated''
-means ``not received over TCP/IP.''
-Otherwise, the primary host name is used.
-Only letters, digits, dot and hyphen are accepted; any other characters are
-replaced by hyphens. If the expansion is forced to fail, or if the result is an
-empty string, the option is ignored.
-
-
-oindex:[%message_id_header_text%]
-`..'=
-%message_id_header_text%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-If this variable is set, the string is expanded and used to augment the text of
-the 'Message-id:' header that Exim creates if a locally-originated incoming
-message does not have one. The text of this header is required by RFC 2822 to
-take the form of an address. By default, Exim uses its internal message id as
-the local part, and the primary host name as the domain. If this option is set,
-it is expanded, and provided the expansion is not forced to fail, and does not
-yield an empty string, the result is inserted into the header immediately
-before the @, separated from the internal message id by a dot. Any characters
-that are illegal in an address are automatically converted into hyphens. This
-means that variables such as $tod_log$ can be used, because the spaces and
-colons will become hyphens.
-
-
-oindex:[%message_logs%]
-`..'=
-%message_logs%, Use: 'main', Type: 'boolean', Default: 'true'
-===
-
-cindex:[message log, disabling]
-cindex:[log,message log; disabling]
-If this option is turned off, per-message log files are not created in the
-_msglog_ spool sub-directory. This reduces the amount of disk I/O required by
-Exim, by reducing the number of files involved in handling a message from a
-minimum of four (header spool file, body spool file, delivery journal, and
-per-message log) to three. The other major I/O activity is Exim's main log,
-which is not affected by this option.
-
-
-oindex:[%message_size_limit%]
-`..'=
-%message_size_limit%, Use: 'main', Type: 'string'!!, Default: '50M'
-===
-
-cindex:[message,size limit]
-cindex:[limit,message size]
-cindex:[size of message, limit]
-This option limits the maximum size of message that Exim will process. The
-value is expanded for each incoming
-connection so, for example, it can be made to depend on the IP address of the
-remote host for messages arriving via TCP/IP. *Note*: This limit cannot be
-made to depend on a message's sender or any other properties of an individual
-message, because it has to be advertised in the server's response to EHLO.
-String expansion failure causes a temporary error. A value of zero means no
-limit, but its use is not recommended. See also %bounce_return_size_limit%.
-
-Incoming SMTP messages are failed with a 552 error if the limit is
-exceeded; locally-generated messages either get a stderr message or a delivery
-failure message to the sender, depending on the %-oe% setting. Rejection of an
-oversized message is logged in both the main and the reject logs. See also the
-generic transport option %message_size_limit%, which limits the size of
-message that an individual transport can process.
-
-
-oindex:[%move_frozen_messages%]
-`..'=
-%move_frozen_messages%, Use: 'main', Type: 'boolean', Default: 'false'
-===
-
-cindex:[frozen messages,moving]
-This option, which is available only if Exim has been built with the setting
-
- SUPPORT_MOVE_FROZEN_MESSAGES=yes
-
-in _Local/Makefile_, causes frozen messages and their message logs to be
-moved from the _input_ and _msglog_ directories on the spool to _Finput_
-and _Fmsglog_, respectively. There is currently no support in Exim or the
-standard utilities for handling such moved messages, and they do not show up in
-lists generated by %-bp% or by the Exim monitor.
-
-
-oindex:[%mua_wrapper%]
-`..'=
-%mua_wrapper%, Use: 'main', Type: 'boolean', Default: 'false'
-===
-
-Setting this option true causes Exim to run in a very restrictive mode in which
-it passes messages synchronously to a smart host. Chapter <<CHAPnonqueueing>>
-contains a full description of this facility.
-
-
-
-oindex:[%mysql_servers%]
-`..'=
-%mysql_servers%, Use: 'main', Type: 'string list', Default: 'unset'
-===
-
-cindex:[MySQL,server list]
-This option provides a list of MySQL servers and associated connection data, to
-be used in conjunction with ^mysql^ lookups (see section <<SECTsql>>). The
-option is available only if Exim has been built with MySQL support.
-
-
-oindex:[%never_users%]
-`..'=
-%never_users%, Use: 'main', Type: 'string list'!!, Default: 'unset'
-===
-
-[revisionflag="changed"]
-This option is expanded just once, at the start of Exim's processing. Local
-message deliveries are normally run in processes that are setuid to the
-recipient, and remote deliveries are normally run under Exim's own uid and gid.
-It is usually desirable to prevent any deliveries from running as root, as a
-safety precaution.
-
-When Exim is built, an option called FIXED_NEVER_USERS can be set to a
-list of users that must not be used for local deliveries. This list is fixed in
-the binary and cannot be overridden by the configuration file. By default, it
-contains just the single user name ``root''. The %never_users% runtime option
-can be used to add more users to the fixed list.
-
-If a message is to be delivered as one of the users on the fixed list or the
-%never_users% list, an error occurs, and delivery is deferred. A common
-example is
-
- never_users = root:daemon:bin
-
-Including root is redundant if it is also on the fixed list, but it does no
-harm. This option overrides the %pipe_as_creator% option of the ^pipe^
-transport driver.
-
-
-oindex:[%oracle_servers%]
-`..'=
-%oracle_servers%, Use: 'main', Type: 'string list', Default: 'unset'
-===
-
-cindex:[Oracle,server list]
-This option provides a list of Oracle servers and associated connection data,
-to be used in conjunction with ^oracle^ lookups (see section <<SECTsql>>). The
-option is available only if Exim has been built with Oracle support.
-
-
-oindex:[%percent_hack_domains%]
-`..'=
-%percent_hack_domains%, Use: 'main', Type: 'domain list'!!, Default: 'unset'
-===
-
-cindex:[``percent hack'']
-cindex:[source routing,in email address]
-cindex:[address,source-routed]
-The ``percent hack'' is the convention whereby a local part containing a percent
-sign is re-interpreted as a new email address, with the percent replaced by @.
-This is sometimes called ``source routing'', though that term is also applied to
-RFC 2822 addresses that begin with an @ character. If this option is set, Exim
-implements the percent facility for those domains listed, but no others. This
-happens before an incoming SMTP address is tested against an ACL.
-
-*Warning*: The ``percent hack'' has often been abused by people who are
-trying to get round relaying restrictions. For this reason, it is best avoided
-if at all possible. Unfortunately, a number of less security-conscious MTAs
-implement it unconditionally. If you are running Exim on a gateway host, and
-routing mail through to internal MTAs without processing the local parts, it is
-a good idea to reject recipient addresses with percent characters in their
-local parts. Exim's default configuration does this.
-
-
-oindex:[%perl_at_start%]
-`..'=
-%perl_at_start%, Use: 'main', Type: 'boolean', Default: 'false'
-===
-
-This option is available only when Exim is built with an embedded Perl
-interpreter. See chapter <<CHAPperl>> for details of its use.
-
-
-oindex:[%perl_startup%]
-`..'=
-%perl_startup%, Use: 'main', Type: 'string', Default: 'unset'
-===
-
-This option is available only when Exim is built with an embedded Perl
-interpreter. See chapter <<CHAPperl>> for details of its use.
-
-
-oindex:[%pgsql_servers%]
-`..'=
-%pgsql_servers%, Use: 'main', Type: 'string list', Default: 'unset'
-===
-
-cindex:[PostgreSQL lookup type,server list]
-This option provides a list of PostgreSQL servers and associated connection
-data, to be used in conjunction with ^pgsql^ lookups (see section <<SECTsql>>).
-The option is available only if Exim has been built with PostgreSQL support.
-
-
-oindex:[%pid_file_path%]
-`..'=
-%pid_file_path%, Use: 'main', Type: 'string'!!, Default: 'set at compile time'
-===
-
-cindex:[daemon,pid file path]
-cindex:[pid file, path for]
-This option sets the name of the file to which the Exim daemon writes its
-process id. The string is expanded, so it can contain, for example, references
-to the host name:
-
- pid_file_path = /var/log/$primary_hostname/exim.pid
-
-If no path is set, the pid is written to the file _exim-daemon.pid_ in Exim's
-spool directory.
-The value set by the option can be overridden by the %-oP% command line
-option. A pid file is not written if a ``non-standard'' daemon is run by means of
-the %-oX% option, unless a path is explicitly supplied by %-oP%.
-
-
-oindex:[%pipelining_advertise_hosts%]
-`..'=
-%pipelining_advertise_hosts%, Use: 'main', Type: 'host list'!!, Default: '\*'
-===
-
-cindex:[PIPELINING advertising, suppressing]
-This option can be used to suppress the advertisement of the SMTP
-PIPELINING extension to specific hosts. When PIPELINING is not
-advertised and %smtp_enforce_sync% is true, an Exim server enforces strict
-synchronization for each SMTP command and response.
-When PIPELINING is advertised, Exim assumes that clients will use it; ``out
-of order'' commands that are ``expected'' do not count as protocol errors (see
-%smtp_max_synprot_errors%).
-
-
-oindex:[%preserve_message_logs%]
-`..'=
-%preserve_message_logs%, Use: 'main', Type: 'boolean', Default: 'false'
-===
-
-cindex:[message logs, preserving]
-If this option is set, message log files are not deleted when messages are
-completed. Instead, they are moved to a sub-directory of the spool directory
-called _msglog.OLD_, where they remain available for statistical or debugging
-purposes. This is a dangerous option to set on systems with any appreciable
-volume of mail. Use with care!
-
-
-oindex:[%primary_hostname%]
-`..'=
-%primary_hostname%, Use: 'main', Type: 'string', Default: 'see below'
-===
-
-cindex:[name,of local host]
-cindex:[host,name of local]
-cindex:[local host,name of]
-cindex:[$primary_hostname$]
-This specifies the name of the current host. It is used in the default EHLO or
-HELO command for outgoing SMTP messages (changeable via the %helo_data% option
-in the ^smtp^ transport), and as the default for %qualify_domain%. The value is
-also used by default in some SMTP response messages from an Exim server. This
-can be changed dynamically by setting %smtp_active_hostname%.
-
-If %primary_hostname% is not set, Exim calls 'uname()' to find the host name.
-If this fails, Exim panics and dies. If the name returned by 'uname()' contains
-only one component, Exim passes it to 'gethostbyname()' (or 'getipnodebyname()'
-when available) in order to obtain the fully qualified version. The variable
-$primary_hostname$ contains the host name, whether set explicitly by this
-option, or defaulted.
-
-
-oindex:[%print_topbitchars%]
-`..'=
-%print_topbitchars%, Use: 'main', Type: 'boolean', Default: 'false'
-===
-
-cindex:[printing characters]
-cindex:[8-bit characters]
-By default, Exim considers only those characters whose codes lie in the range
-32--126 to be printing characters. In a number of circumstances (for example,
-when writing log entries) non-printing characters are converted into escape
-sequences, primarily to avoid messing up the layout. If %print_topbitchars% is
-set, code values of 128 and above are also considered to be printing
-characters.
-
-
-oindex:[%process_log_path%]
-`..'=
-%process_log_path%, Use: 'main', Type: 'string', Default: 'unset'
-===
-
-cindex:[process log path]
-cindex:[log,process log]
-cindex:['exiwhat']
-This option sets the name of the file to which an Exim process writes its
-``process log'' when sent a USR1 signal. This is used by the 'exiwhat' utility
-script. If this option is unset, the file called _exim-process.info_ in
-Exim's spool directory is used. The ability to specify the name explicitly can
-be useful in environments where two different Exims are running, using
-different spool directories.
-
-
-oindex:[%prod_requires_admin%]
-`..'=
-%prod_requires_admin%, Use: 'main', Type: 'boolean', Default: 'true'
-===
-
-cindex:[%-M% option]
-cindex:[%-R% option]
-cindex:[%-q% option]
-The %-M%, %-R%, and %-q% command-line options require the caller to be an
-admin user unless %prod_requires_admin% is set false. See also
-%queue_list_requires_admin%.
-
-
-oindex:[%qualify_domain%]
-`..'=
-%qualify_domain%, Use: 'main', Type: 'string', Default: 'see below'
-===
-
-cindex:[domain,for qualifying addresses]
-cindex:[address,qualification]
-This option specifies the domain name that is added to any envelope sender
-addresses that do not have a domain qualification. It also applies to
-recipient addresses if %qualify_recipient% is not set.
-
-Unqualified addresses are accepted by default only for locally-generated
-messages.
-
-Qualification is also applied to addresses in header lines such as 'From:' and
-'To:' for locally-generated messages, unless the %-bnq% command line option
-is used.
-
-
-Messages from external sources must always contain fully qualified addresses,
-unless the sending host matches %sender_unqualified_hosts% or
-%recipient_unqualified_hosts% (as appropriate), in which case incoming
-addresses are qualified with %qualify_domain% or %qualify_recipient% as
-necessary. Internally, Exim always works with fully qualified envelope
-addresses. If %qualify_domain% is not set, it defaults to the
-%primary_hostname% value.
-
-
-oindex:[%qualify_recipient%]
-`..'=
-%qualify_recipient%, Use: 'main', Type: 'string', Default: 'see below'
-===
-
-This option allows you to specify a different domain for qualifying recipient
-addresses to the one that is used for senders. See %qualify_domain% above.
-
-
-
-oindex:[%queue_domains%]
-`..'=
-%queue_domains%, Use: 'main', Type: 'domain list'!!, Default: 'unset'
-===
-
-cindex:[domain,specifying non-immediate delivery]
-cindex:[queueing incoming messages]
-cindex:[message,queueing certain domains]
-This option lists domains for which immediate delivery is not required.
-A delivery process is started whenever a message is received, but only those
-domains that do not match are processed. All other deliveries wait until the
-next queue run. See also %hold_domains% and %queue_smtp_domains%.
-
-
-oindex:[%queue_list_requires_admin%]
-`..'=
-%queue_list_requires_admin%, Use: 'main', Type: 'boolean', Default: 'true'
-===
-
-cindex:[%-bp% option]
-The %-bp% command-line option, which lists the messages that are on the queue,
-requires the caller to be an admin user unless %queue_list_requires_admin%
-is set false. See also %prod_requires_admin%.
-
-
-oindex:[%queue_only%]
-`..'=
-%queue_only%, Use: 'main', Type: 'boolean', Default: 'false'
-===
-
-cindex:[queueing incoming messages]
-cindex:[message,queueing unconditionally]
-If %queue_only% is set, a delivery process is not automatically started
-whenever a message is received. Instead, the message waits on the queue for the
-next queue run. Even if %queue_only% is false, incoming messages may not get
-delivered immediately when certain conditions (such as heavy load) occur.
-
-The %-odq% command line has the same effect as %queue_only%. The %-odb% and
-%-odi% command line options override %queue_only% unless
-%queue_only_override% is set false. See also %queue_only_file%,
-%queue_only_load%, and %smtp_accept_queue%.
-
-
-oindex:[%queue_only_file%]
-`..'=
-%queue_only_file%, Use: 'main', Type: 'string', Default: 'unset'
-===
-
-cindex:[queueing incoming messages]
-cindex:[message,queueing by file existence]
-This option can be set to a colon-separated list of absolute path names, each
-one optionally preceded by ``smtp''. When Exim is receiving a message,
-it tests for the existence of each listed path using a call to 'stat()'. For
-each path that exists, the corresponding queuing option is set.
-For paths with no prefix, %queue_only% is set; for paths prefixed by ``smtp'',
-%queue_smtp_domains% is set to match all domains. So, for example,
-
- queue_only_file = smtp/some/file
-
-causes Exim to behave as if %queue_smtp_domains% were set to ``\*'' whenever
-_/some/file_ exists.
-
-
-oindex:[%queue_only_load%]
-`..'=
-%queue_only_load%, Use: 'main', Type: 'fixed-point', Default: 'unset'
-===
-
-cindex:[load average]
-cindex:[queueing incoming messages]
-cindex:[message,queueing by load]
-If the system load average is higher than this value, incoming messages from
-all sources are queued, and no automatic deliveries are started. If this
-happens during local or remote SMTP input, all subsequent messages on the same
-connection are queued. Deliveries will subsequently be performed by queue
-runner processes. This option has no effect on ancient operating systems on
-which Exim cannot determine the load average. See also
-%deliver_queue_load_max% and %smtp_load_reserve%.
-
-
-oindex:[%queue_only_override%]
-`..'=
-%queue_only_override%, Use: 'main', Type: 'boolean', Default: 'true'
-===
-
-cindex:[queueing incoming messages]
-When this option is true, the %-od'x'% command line options override the
-setting of %queue_only% or %queue_only_file% in the configuration file. If
-%queue_only_override% is set false, the %-od'x'% options cannot be used to
-override; they are accepted, but ignored.
-
-
-oindex:[%queue_run_in_order%]
-`..'=
-%queue_run_in_order%, Use: 'main', Type: 'boolean', Default: 'false'
-===
-
-cindex:[queue runner,processing messages in order]
-If this option is set, queue runs happen in order of message arrival instead of
-in an arbitrary order. For this to happen, a complete list of the entire queue
-must be set up before the deliveries start. When the queue is all held in a
-single directory (the default),
-
-a single list is created for both the ordered and the non-ordered cases.
-However, if %split_spool_directory% is set, a single list is not created when
-%queue_run_in_order% is false. In this case, the sub-directories are
-processed one at a time (in a random order), and this avoids setting up one
-huge list for the whole queue. Thus, setting %queue_run_in_order% with
-%split_spool_directory% may degrade performance when the queue is large,
-because of the extra work in setting up the single, large list. In most
-situations, %queue_run_in_order% should not be set.
-
-
-
-oindex:[%queue_run_max%]
-`..'=
-%queue_run_max%, Use: 'main', Type: 'integer', Default: '5'
-===
-
-cindex:[queue runner,maximum number of]
-This controls the maximum number of queue runner processes that an Exim daemon
-can run simultaneously. This does not mean that it starts them all at once,
-but rather that if the maximum number are still running when the time comes to
-start another one, it refrains from starting another one. This can happen with
-very large queues and/or very sluggish deliveries. This option does not,
-however, interlock with other processes, so additional queue runners can be
-started by other means, or by killing and restarting the daemon.
-
-[revisionflag="changed"]
-Setting this option to zero does not suppress queue runs; rather, it disables
-the limit, allowing any number of simultaneous queue runner processes to be
-run. If you do not want queue runs to occur, omit the %-q%'xx' setting on the
-daemon's command line.
-
-
-oindex:[%queue_smtp_domains%]
-`..'=
-%queue_smtp_domains%, Use: 'main', Type: 'domain list'!!, Default: 'unset'
-===
-
-cindex:[queueing incoming messages]
-cindex:[message,queueing remote deliveries]
-When this option is set, a delivery process is started whenever a message is
-received, routing is performed, and local deliveries take place.
-However, if any SMTP deliveries are required for domains that match
-%queue_smtp_domains%, they are not immediately delivered, but instead the
-message waits on the queue for the next queue run. Since routing of the message
-has taken place, Exim knows to which remote hosts it must be delivered, and so
-when the queue run happens, multiple messages for the same host are delivered
-over a single SMTP connection. The %-odqs% command line option causes all SMTP
-deliveries to be queued in this way, and is equivalent to setting
-%queue_smtp_domains% to ``\*''. See also %hold_domains% and %queue_domains%.
-
-
-oindex:[%receive_timeout%]
-`..'=
-%receive_timeout%, Use: 'main', Type: 'time', Default: '0s'
-===
-
-cindex:[timeout,for non-SMTP input]
-This option sets the timeout for accepting a non-SMTP message, that is, the
-maximum time that Exim waits when reading a message on the standard input. If
-the value is zero, it will wait for ever. This setting is overridden by the
-%-or% command line option. The timeout for incoming SMTP messages is
-controlled by %smtp_receive_timeout%.
-
-oindex:[%received_header_text%]
-`..'=
-%received_header_text%, Use: 'main', Type: 'string'!!, Default: 'see below'
-===
-
-cindex:[customizing, 'Received:' header]
-cindex:['Received:' header line,customizing]
-This string defines the contents of the 'Received:' message header that is
-added to each message, except for the timestamp, which is automatically added
-on at the end (preceded by a semicolon). The string is expanded each time it is
-used. If the expansion yields an empty string, no 'Received:' header line is
-added to the message. Otherwise, the string should start with the text
-``Received:'' and conform to the RFC 2822 specification for 'Received:' header
-lines. The default setting is:
-
-[revisionflag="changed"]
-....
-received_header_text = Received: \
- ${if def:sender_rcvhost {from $sender_rcvhost\n\t}\
- {${if def:sender_ident {from ${quote_local_part: $sender_ident} }}\
- ${if def:sender_helo_name {(helo=$sender_helo_name)\n\t}}}}\
- by $primary_hostname \
- ${if def:received_protocol {with $received_protocol}} \
- ${if def:tls_cipher {($tls_cipher)\n\t}}\
- (Exim $version_number)\n\t\
- ${if def:sender_address {(envelope-from <$sender_address>)\n\t}}\
- id $message_exim_id\
- ${if def:received_for {\n\tfor $received_for}}
-....
-
-The reference to the TLS cipher is omitted when Exim is built without TLS
-support. The use of conditional expansions ensures that this works for both
-locally generated messages and messages received from remote hosts, giving
-header lines such as the following:
-
- Received: from scrooge.carol.example ([192.168.12.25] ident=root)
- by marley.carol.example with esmtp (Exim 4.00)
- (envelope-from <bob@carol.example>)
- id 16IOWa-00019l-00
- for chas@dickens.example; Tue, 25 Dec 2001 14:43:44 +0000
- Received: by scrooge.carol.example with local (Exim 4.00)
- id 16IOWW-000083-00; Tue, 25 Dec 2001 14:43:41 +0000
-
-Until the body of the message has been received, the timestamp is the time when
-the message started to be received. Once the body has arrived, and all policy
-checks have taken place, the timestamp is updated to the time at which the
-message was accepted.
-
-
-oindex:[%received_headers_max%]
-`..'=
-%received_headers_max%, Use: 'main', Type: 'integer', Default: '30'
-===
-
-cindex:[loop,prevention]
-cindex:[mail loop prevention]
-cindex:['Received:' header line,counting]
-When a message is to be delivered, the number of 'Received:' headers is
-counted, and if it is greater than this parameter, a mail loop is assumed to
-have occurred, the delivery is abandoned, and an error message is generated.
-This applies to both local and remote deliveries.
-
-
-oindex:[%recipient_unqualified_hosts%]
-`..'=
-%recipient_unqualified_hosts%, Use: 'main', Type: 'host list'!!, Default: 'unset'
-===
-
-cindex:[unqualified addresses]
-cindex:[host,unqualified addresses from]
-This option lists those hosts from which Exim is prepared to accept unqualified
-recipient addresses in message envelopes. The addresses are made fully
-qualified by the addition of the %qualify_recipient% value. This option also
-affects message header lines. Exim does not reject unqualified recipient
-addresses in headers, but it qualifies them only if the message came from a
-host that matches %recipient_unqualified_hosts%,
-or if the message was submitted locally (not using TCP/IP), and the %-bnq%
-option was not set.
-
-
-oindex:[%recipients_max%]
-`..'=
-%recipients_max%, Use: 'main', Type: 'integer', Default: '0'
-===
-
-cindex:[limit,number of recipients]
-cindex:[recipient,maximum number]
-If this option is set greater than zero, it specifies the maximum number of
-original recipients for any message. Additional recipients that are generated
-by aliasing or forwarding do not count. SMTP messages get a 452 response for
-all recipients over the limit; earlier recipients are delivered as normal.
-Non-SMTP messages with too many recipients are failed, and no deliveries are
-done.
-
-cindex:[RCPT,maximum number of incoming]
-Note that the RFCs specify that an SMTP server should accept at least 100
-RCPT commands in a single message.
-
-
-oindex:[%recipients_max_reject%]
-`..'=
-%recipients_max_reject%, Use: 'main', Type: 'boolean', Default: 'false'
-===
-
-If this option is set true, Exim rejects SMTP messages containing too many
-recipients by giving 552 errors to the surplus RCPT commands, and a 554
-error to the eventual DATA command. Otherwise (the default) it gives a 452
-error to the surplus RCPT commands and accepts the message on behalf of the
-initial set of recipients. The remote server should then re-send the message
-for the remaining recipients at a later time.
-
-
-oindex:[%remote_max_parallel%]
-`..'=
-%remote_max_parallel%, Use: 'main', Type: 'integer', Default: '2'
-===
-
-cindex:[delivery,parallelism for remote]
-This option controls parallel delivery of one message to a number of remote
-hosts. If the value is less than 2, parallel delivery is disabled, and Exim
-does all the remote deliveries for a message one by one. Otherwise, if a single
-message has to be delivered to more than one remote host, or if several copies
-have to be sent to the same remote host, up to %remote_max_parallel%
-deliveries are done simultaneously. If more than %remote_max_parallel%
-deliveries are required, the maximum number of processes are started, and as
-each one finishes, another is begun. The order of starting processes is the
-same as if sequential delivery were being done, and can be controlled by the
-%remote_sort_domains% option. If parallel delivery takes place while running
-with debugging turned on, the debugging output from each delivery process is
-tagged with its process id.
-
-This option controls only the maximum number of parallel deliveries for one
-message in one Exim delivery process. Because Exim has no central queue
-manager, there is no way of controlling the total number of simultaneous
-deliveries if the configuration allows a delivery attempt as soon as a message
-is received.
-
-cindex:[number of deliveries]
-cindex:[delivery,maximum number of]
-If you want to control the total number of deliveries on the system, you
-need to set the %queue_only% option. This ensures that all incoming messages
-are added to the queue without starting a delivery process. Then set up an Exim
-daemon to start queue runner processes at appropriate intervals (probably
-fairly often, for example, every minute), and limit the total number of queue
-runners by setting the %queue_run_max% parameter. Because each queue runner
-delivers only one message at a time, the maximum number of deliveries that can
-then take place at once is %queue_run_max% multiplied by
-%remote_max_parallel%.
-
-If it is purely remote deliveries you want to control, use
-%queue_smtp_domains% instead of %queue_only%. This has the added benefit of
-doing the SMTP routing before queuing, so that several messages for the same
-host will eventually get delivered down the same connection.
-
-
-oindex:[%remote_sort_domains%]
-`..'=
-%remote_sort_domains%, Use: 'main', Type: 'domain list'!!, Default: 'unset'
-===
-
-cindex:[sorting remote deliveries]
-cindex:[delivery,sorting remote]
-When there are a number of remote deliveries for a message, they are sorted by
-domain into the order given by this list. For example,
-
- remote_sort_domains = *.cam.ac.uk:*.uk
-
-would attempt to deliver to all addresses in the 'cam.ac.uk' domain first, then
-to those in the %uk% domain, then to any others.
-
-
-oindex:[%retry_data_expire%]
-`..'=
-%retry_data_expire%, Use: 'main', Type: 'time', Default: '7d'
-===
-
-cindex:[hints database,data expiry]
-This option sets a ``use before'' time on retry information in Exim's hints
-database. Any older retry data is ignored. This means that, for example, once a
-host has not been tried for 7 days, Exim behaves as if it has no knowledge of
-past failures.
-
-
-oindex:[%retry_interval_max%]
-`..'=
-%retry_interval_max%, Use: 'main', Type: 'time', Default: '24h'
-===
-
-cindex:[retry,limit on interval]
-cindex:[limit,on retry interval]
-Chapter <<CHAPretry>> describes Exim's mechanisms for controlling the intervals
-between delivery attempts for messages that cannot be delivered straight away.
-This option sets an overall limit to the length of time between retries.
-
-
-oindex:[%return_path_remove%]
-`..'=
-%return_path_remove%, Use: 'main', Type: 'boolean', Default: 'true'
-===
-
-cindex:['Return-path:' header line,removing]
-RFC 2821, section 4.4, states that an SMTP server must insert a 'Return-path:'
-header line into a message when it makes a ``final delivery''. The 'Return-path:'
-header preserves the sender address as received in the MAIL command. This
-description implies that this header should not be present in an incoming
-message. If %return_path_remove% is true, any existing 'Return-path:'
-headers are removed from messages at the time they are received. Exim's
-transports have options for adding 'Return-path:' headers at the time of
-delivery. They are normally used only for final local deliveries.
-
-
-oindex:[%return_size_limit%]
-`..'=
-%return_size_limit%, Use: 'main', Type: 'integer', Default: '100K'
-===
-
-This option is an obsolete synonym for %bounce_return_size_limit%.
-
-
-oindex:[%rfc1413_hosts%]
-`..'=
-%rfc1413_hosts%, Use: 'main', Type: 'host list'!!, Default: '\*'
-===
-
-cindex:[RFC 1413]
-cindex:[host,for RFC 1413 calls]
-RFC 1413 identification calls are made to any client host which matches an item
-in the list.
-
-
-oindex:[%rfc1413_query_timeout%]
-`..'=
-%rfc1413_query_timeout%, Use: 'main', Type: 'time', Default: '30s'
-===
-
-cindex:[RFC 1413,query timeout]
-cindex:[timeout,for RFC 1413 call]
-This sets the timeout on RFC 1413 identification calls. If it is set to zero,
-no RFC 1413 calls are ever made.
-
-
-oindex:[%sender_unqualified_hosts%]
-`..'=
-%sender_unqualified_hosts%, Use: 'main', Type: 'host list'!!, Default: 'unset'
-===
-
-cindex:[unqualified addresses]
-cindex:[host,unqualified addresses from]
-This option lists those hosts from which Exim is prepared to accept unqualified
-sender addresses. The addresses are made fully qualified by the addition of
-%qualify_domain%. This option also affects message header lines. Exim does not
-reject unqualified addresses in headers that contain sender addresses, but it
-qualifies them only if the message came from a host that matches
-%sender_unqualified_hosts%,
-or if the message was submitted locally (not using TCP/IP), and the %-bnq%
-option was not set.
-
-
-oindex:[%smtp_accept_keepalive%]
-`..'=
-%smtp_accept_keepalive%, Use: 'main', Type: 'boolean', Default: 'true'
-===
-
-cindex:[keepalive,on incoming connection]
-This option controls the setting of the SO_KEEPALIVE option on incoming
-TCP/IP socket connections. When set, it causes the kernel to probe idle
-connections periodically, by sending packets with ``old'' sequence numbers. The
-other end of the connection should send an acknowledgement if the connection is
-still okay or a reset if the connection has been aborted. The reason for doing
-this is that it has the beneficial effect of freeing up certain types of
-connection that can get stuck when the remote host is disconnected without
-tidying up the TCP/IP call properly. The keepalive mechanism takes several
-hours to detect unreachable hosts.
-
-
-
-oindex:[%smtp_accept_max%]
-`..'=
-%smtp_accept_max%, Use: 'main', Type: 'integer', Default: '20'
-===
-
-cindex:[limit,incoming SMTP connections]
-cindex:[SMTP,incoming connection count]
-cindex:[inetd]
-This option specifies the maximum number of simultaneous incoming SMTP calls
-that Exim will accept. It applies only to the listening daemon; there is no
-control (in Exim) when incoming SMTP is being handled by 'inetd'. If the value
-is set to zero, no limit is applied. However, it is required to be non-zero if
-either %smtp_accept_max_per_host% or %smtp_accept_queue% is set. See also
-%smtp_accept_reserve%.
-
-
-
-oindex:[%smtp_accept_max_nonmail%]
-`..'=
-%smtp_accept_max_nonmail%, Use: 'main', Type: 'integer', Default: '10'
-===
-
-cindex:[limit,non-mail SMTP commands]
-cindex:[SMTP,limiting non-mail commands]
-Exim counts the number of ``non-mail'' commands in an SMTP session, and drops the
-connection if there are too many. This option defines ``too many''. The check
-catches some denial-of-service attacks, repeated failing AUTHs, or a mad
-client looping sending EHLO, for example. The check is applied only if the
-client host matches %smtp_accept_max_nonmail_hosts%.
-
-When a new message is expected, one occurrence of RSET is not counted. This
-allows a client to send one RSET between messages (this is not necessary,
-but some clients do it). Exim also allows one uncounted occurence of HELO
-or EHLO, and one occurrence of STARTTLS between messages. After
-starting up a TLS session, another EHLO is expected, and so it too is not
-counted. The first occurrence of AUTH in a connection, or immediately
-following STARTTLS is not counted. Otherwise, all commands other than
-MAIL, RCPT, DATA, and QUIT are counted.
-
-
-oindex:[%smtp_accept_max_nonmail_hosts%]
-`..'=
-%smtp_accept_max_nonmail_hosts%, Use: 'main', Type: 'host list'!!, Default: '\*'
-===
-
-You can control which hosts are subject to the %smtp_accept_max_nonmail%
-check by setting this option. The default value makes it apply to all hosts. By
-changing the value, you can exclude any badly-behaved hosts that you have to
-live with.
-
-
-
-oindex:[%smtp_accept_max_per_connection%]
-`..'=
-%smtp_accept_max_per_connection%, Use: 'main', Type: 'integer', Default: '1000'
-===
-
-cindex:[SMTP incoming message count, limiting]
-cindex:[limit,messages per SMTP connection]
-The value of this option limits the number of MAIL commands that Exim is
-prepared to accept over a single SMTP connection, whether or not each command
-results in the transfer of a message. After the limit is reached, a 421
-response is given to subsequent MAIL commands. This limit is a safety
-precaution against a client that goes mad (incidents of this type have been
-seen).
-
-
-oindex:[%smtp_accept_max_per_host%]
-`..'=
-%smtp_accept_max_per_host%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[limit,SMTP connections from one host]
-cindex:[host,limiting SMTP connections from]
-This option restricts the number of simultaneous IP connections from a single
-host (strictly, from a single IP address) to the Exim daemon. The option is
-expanded, to enable different limits to be applied to different hosts by
-reference to $sender_host_address$. Once the limit is reached, additional
-connection attempts from the same host are rejected with error code 421. The
-default value of zero imposes no limit. If this option is set, it is required
-that %smtp_accept_max% be non-zero.
-
-*Warning*: When setting this option you should not use any expansion
-constructions that take an appreciable amount of time. The expansion and test
-happen in the main daemon loop, in order to reject additional connections
-without forking additional processes (otherwise a denial-of-service attack
-could cause a vast number or processes to be created). While the daemon is
-doing this processing, it cannot accept any other incoming connections.
-
-
-
-oindex:[%smtp_accept_queue%]
-`..'=
-%smtp_accept_queue%, Use: 'main', Type: 'integer', Default: '0'
-===
-
-cindex:[SMTP,incoming connection count]
-cindex:[queueing incoming messages]
-cindex:[message,queueing by SMTP connection count]
-If the number of simultaneous incoming SMTP calls handled via the listening
-daemon exceeds this value, messages received by SMTP are just placed on the
-queue; no delivery processes are started automatically. A value of zero implies
-no limit, and clearly any non-zero value is useful only if it is less than the
-%smtp_accept_max% value (unless that is zero). See also %queue_only%,
-%queue_only_load%, %queue_smtp_domains%, and the various %-od% command
-line options.
-
-
-oindex:[%smtp_accept_queue_per_connection%]
-`..'=
-%smtp_accept_queue_per_connection%, Use: 'main', Type: 'integer', Default: '10'
-===
-
-cindex:[queueing incoming messages]
-cindex:[message,queueing by message count]
-This option limits the number of delivery processes that Exim starts
-automatically when receiving messages via SMTP, whether via the daemon or by
-the use of %-bs% or %-bS%. If the value of the option is greater than zero,
-and the number of messages received in a single SMTP session exceeds this
-number, subsequent messages are placed on the queue, but no delivery processes
-are started. This helps to limit the number of Exim processes when a server
-restarts after downtime and there is a lot of mail waiting for it on other
-systems. On large systems, the default should probably be increased, and on
-dial-in client systems it should probably be set to zero (that is, disabled).
-
-
-oindex:[%smtp_accept_reserve%]
-`..'=
-%smtp_accept_reserve%, Use: 'main', Type: 'integer', Default: '0'
-===
-
-cindex:[SMTP,incoming call count]
-cindex:[host,reserved]
-When %smtp_accept_max% is set greater than zero, this option specifies a
-number of SMTP connections that are reserved for connections from the hosts
-that are specified in %smtp_reserve_hosts%. The value set in
-%smtp_accept_max% includes this reserve pool. The specified hosts are not
-restricted to this number of connections; the option specifies a minimum number
-of connection slots for them, not a maximum. It is a guarantee that that group
-of hosts can always get at least %smtp_accept_reserve% connections.
-
-For example, if %smtp_accept_max% is set to 50 and %smtp_accept_reserve% is
-set to 5, once there are 45 active connections (from any hosts), new
-connections are accepted only from hosts listed in %smtp_reserve_hosts%.
-See also %smtp_accept_max_per_host%.
-
-
-oindex:[%smtp_active_hostname%]
-`..'=
-%smtp_active_hostname%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[host,name in SMTP responses]
-cindex:[SMTP,host name in responses]
-cindex:[$primary_hostname$]
-This option is provided for multi-homed servers that want to masquerade as
-several different hosts. At the start of an SMTP connection, its value is
-expanded and used instead of the value of $primary_hostname$ in SMTP
-responses. For example, it is used as domain name in the response to an
-incoming HELO or EHLO command.
-
-cindex:[$smtp_active_hostname$]
-It is also used in HELO commands for callout verification. The active hostname
-is placed in the $smtp_active_hostname$ variable, which is saved with any
-messages that are received. It is therefore available for use in routers and
-transports when the message is later delivered.
-
-If this option is unset, or if its expansion is forced to fail, or if the
-expansion results in an empty string, the value of $primary_hostname$ is
-used. Other expansion failures cause a message to be written to the main and
-panic logs, and the SMTP command receives a temporary error. Typically, the
-value of %smtp_active_hostname% depends on the incoming interface address.
-For example:
-
-....
-smtp_active_hostname = ${if eq{$interface_address}{10.0.0.1}\
- {cox.mydomain}{box.mydomain}}
-....
-
-
-oindex:[%smtp_banner%]
-`..'=
-%smtp_banner%, Use: 'main', Type: 'string'!!, Default: 'see below'
-===
-
-cindex:[SMTP,welcome banner]
-cindex:[banner for SMTP]
-cindex:[welcome banner for SMTP]
-cindex:[customizing,SMTP banner]
-This string, which is expanded every time it is used, is output as the initial
-positive response to an SMTP connection. The default setting is:
-
-....
-smtp_banner = $smtp_active_hostname ESMTP Exim \
- $version_number $tod_full
-....
-
-Failure to expand the string causes a panic error. If you want to create a
-multiline response to the initial SMTP connection, use ``\n'' in the string at
-appropriate points, but not at the end. Note that the 220 code is not included
-in this string. Exim adds it automatically (several times in the case of a
-multiline response).
-
-
-oindex:[%smtp_check_spool_space%]
-`..'=
-%smtp_check_spool_space%, Use: 'main', Type: 'boolean', Default: 'true'
-===
-
-cindex:[checking disk space]
-cindex:[disk space, checking]
-cindex:[spool directory,checking space]
-When this option is set, if an incoming SMTP session encounters the SIZE
-option on a MAIL command, it checks that there is enough space in the
-spool directory's partition to accept a message of that size, while still
-leaving free the amount specified by %check_spool_space% (even if that value
-is zero). If there isn't enough space, a temporary error code is returned.
-
-
-oindex:[%smtp_connect_backlog%]
-`..'=
-%smtp_connect_backlog%, Use: 'main', Type: 'integer', Default: '20'
-===
-
-cindex:[connection backlog]
-cindex:[SMTP,connection backlog]
-cindex:[backlog of connections]
-This option specifies a maximum number of waiting SMTP connections. Exim passes
-this value to the TCP/IP system when it sets up its listener. Once this number
-of connections are waiting for the daemon's attention, subsequent connection
-attempts are refused at the TCP/IP level. At least, that is what the manuals
-say; in some circumstances such connection attempts have been observed to time
-out instead. For large systems it is probably a good idea to increase the
-value (to 50, say). It also gives some protection against denial-of-service
-attacks by SYN flooding.
-
-
-oindex:[%smtp_enforce_sync%]
-`..'=
-%smtp_enforce_sync%, Use: 'main', Type: 'boolean', Default: 'true'
-===
-
-cindex:[SMTP,synchronization checking]
-cindex:[synchronization checking in SMTP]
-The SMTP protocol specification requires the client to wait for a response from
-the server at certain points in the dialogue. Without PIPELINING these
-synchronization points are after every command; with PIPELINING they are
-fewer, but they still exist.
-
-Some spamming sites send out a complete set of SMTP commands without waiting
-for any response. Exim protects against this by rejecting a message if the
-client has sent further input when it should not have. The error response ``554
-SMTP synchronization error'' is sent, and the connection is dropped. Testing for
-this error cannot be perfect because of transmission delays (unexpected input
-may be on its way but not yet received when Exim checks). However, it does
-detect many instances.
-
-The check can be globally disabled by setting %smtp_enforce_sync% false.
-If you want to disable the check selectively (for example, only for certain
-hosts), you can do so by an appropriate use of a %control% modifier in an ACL
-(see section <<SECTcontrols>>). See also %pipelining_advertise_hosts%.
-
-
-
-oindex:[%smtp_etrn_command%]
-`..'=
-%smtp_etrn_command%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[ETRN,command to be run]
-cindex:[$domain$]
-If this option is set, the given command is run whenever an SMTP ETRN
-command is received from a host that is permitted to issue such commands (see
-chapter <<CHAPACL>>). The string is split up into separate arguments which are
-independently expanded. The expansion variable $domain$ is set to the
-argument of the ETRN command, and no syntax checking is done on it. For
-example:
-
- smtp_etrn_command = /etc/etrn_command $domain $sender_host_address
-
-A new process is created to run the command, but Exim does not wait for it to
-complete. Consequently, its status cannot be checked. If the command cannot be
-run, a line is written to the panic log, but the ETRN caller still receives
-a 250 success response. Exim is normally running under its own uid when
-receiving SMTP, so it is not possible for it to change the uid before running
-the command.
-
-
-oindex:[%smtp_etrn_serialize%]
-`..'=
-%smtp_etrn_serialize%, Use: 'main', Type: 'boolean', Default: 'true'
-===
-
-cindex:[ETRN,serializing]
-When this option is set, it prevents the simultaneous execution of more than
-one identical command as a result of ETRN in an SMTP connection. See
-section <<SECTETRN>> for details.
-
-
-oindex:[%smtp_load_reserve%]
-`..'=
-%smtp_load_reserve%, Use: 'main', Type: 'fixed-point', Default: 'unset'
-===
-
-cindex:[load average]
-If the system load average ever gets higher than this, incoming SMTP calls are
-accepted only from those hosts that match an entry in %smtp_reserve_hosts%.
-If %smtp_reserve_hosts% is not set, no incoming SMTP calls are accepted when
-the load is over the limit. The option has no effect on ancient operating
-systems on which Exim cannot determine the load average. See also
-%deliver_queue_load_max% and %queue_only_load%.
-
-
-
-oindex:[%smtp_max_synprot_errors%]
-`..'=
-%smtp_max_synprot_errors%, Use: 'main', Type: 'integer', Default: '3'
-===
-
-cindex:[SMTP,limiting syntax and protocol errors]
-cindex:[limit,SMTP syntax and protocol errors]
-Exim rejects SMTP commands that contain syntax or protocol errors. In
-particular, a syntactically invalid email address, as in this command:
-
- RCPT TO:<abc xyz@a.b.c>
-
-causes immediate rejection of the command, before any other tests are done.
-(The ACL cannot be run if there is no valid address to set up for it.) An
-example of a protocol error is receiving RCPT before MAIL. If there are
-too many syntax or protocol errors in one SMTP session, the connection is
-dropped. The limit is set by this option.
-
-cindex:[PIPELINING,expected errors]
-When the PIPELINING extension to SMTP is in use, some protocol errors are
-``expected'', for instance, a RCPT command after a rejected MAIL command.
-Exim assumes that PIPELINING will be used if it advertises it (see
-%pipelining_advertise_hosts%), and in this situation, ``expected'' errors do
-not count towards the limit.
-
-
-
-oindex:[%smtp_max_unknown_commands%]
-`..'=
-%smtp_max_unknown_commands%, Use: 'main', Type: 'integer', Default: '3'
-===
-
-cindex:[SMTP,limiting unknown commands]
-cindex:[limit,unknown SMTP commands]
-If there are too many unrecognized commands in an incoming SMTP session, an
-Exim server drops the connection. This is a defence against some kinds of abuse
-that subvert web
-clients
-into making connections to SMTP ports; in these circumstances, a number of
-non-SMTP command lines are sent first.
-
-
-
-oindex:[%smtp_ratelimit_hosts%]
-`..'=
-%smtp_ratelimit_hosts%, Use: 'main', Type: 'host list'!!, Default: 'unset'
-===
-
-cindex:[SMTP,rate limiting]
-cindex:[limit,rate of message arrival]
-cindex:[RCPT,rate limiting]
-Some sites find it helpful to be able to limit the rate at which certain hosts
-can send them messages, and the rate at which an individual message can specify
-recipients. When a host matches %smtp_ratelimit_hosts%, the values of
-%smtp_ratelimit_mail% and %smtp_ratelimit_rcpt% are used to control the
-rate of acceptance of MAIL and RCPT commands in a single SMTP session,
-respectively. Each option, if set, must contain a set of four comma-separated
-values:
-
-- A threshold, before which there is no rate limiting.
-
-- An initial time delay. Unlike other times in Exim, numbers with decimal
-fractional parts are allowed here.
-
-- A factor by which to increase the delay each time.
-
-- A maximum value for the delay. This should normally be less than 5 minutes,
-because after that time, the client is liable to timeout the SMTP command.
-
-For example, these settings have been used successfully at the site which
-first suggested this feature, for controlling mail from their customers:
-
- smtp_ratelimit_mail = 2,0.5s,1.05,4m
- smtp_ratelimit_rcpt = 4,0.25s,1.015,4m
-
-The first setting specifies delays that are applied to MAIL commands after
-two have been received over a single connection. The initial delay is 0.5
-seconds, increasing by a factor of 1.05 each time. The second setting applies
-delays to RCPT commands when more than four occur in a single message.
-
-It is also possible to configure delays explicitly in ACLs. See section
-<<SECTACLmodi>> for details.
-
-
-
-oindex:[%smtp_ratelimit_mail%]
-`..'=
-%smtp_ratelimit_mail%, Use: 'main', Type: 'string', Default: 'unset'
-===
-
-See %smtp_ratelimit_hosts% above.
-
-
-oindex:[%smtp_ratelimit_rcpt%]
-`..'=
-%smtp_ratelimit_rcpt%, Use: 'main', Type: 'string', Default: 'unset'
-===
-
-See %smtp_ratelimit_hosts% above.
-
-
-oindex:[%smtp_receive_timeout%]
-`..'=
-%smtp_receive_timeout%, Use: 'main', Type: 'time', Default: '5m'
-===
-
-cindex:[timeout,for SMTP input]
-cindex:[SMTP timeout, input]
-This sets a timeout value for SMTP reception. It applies to all forms of SMTP
-input, including batch SMTP. If a line of input (either an SMTP command or a
-data line) is not received within this time, the SMTP connection is dropped and
-the message is abandoned.
-A line is written to the log containing one of the following messages:
-
- SMTP command timeout on connection from...
- SMTP data timeout on connection from...
-
-The former means that Exim was expecting to read an SMTP command; the latter
-means that it was in the DATA phase, reading the contents of a message.
-
-
-cindex:[%-os% option]
-The value set by this option can be overridden by the
-%-os% command-line option. A setting of zero time disables the timeout, but
-this should never be used for SMTP over TCP/IP. (It can be useful in some cases
-of local input using %-bs% or %-bS%.) For non-SMTP input, the reception
-timeout is controlled by %receive_timeout% and %-or%.
-
-
-oindex:[%smtp_reserve_hosts%]
-`..'=
-%smtp_reserve_hosts%, Use: 'main', Type: 'host list'!!, Default: 'unset'
-===
-
-This option defines hosts for which SMTP connections are reserved; see
-%smtp_accept_reserve% and %smtp_load_reserve% above.
-
-
-oindex:[%smtp_return_error_details%]
-`..'=
-%smtp_return_error_details%, Use: 'main', Type: 'boolean', Default: 'false'
-===
-
-cindex:[SMTP,details policy failures]
-cindex:[policy control rejection, returning details]
-In the default state, Exim uses bland messages such as
-``Administrative prohibition'' when it rejects SMTP commands for policy
-reasons. Many sysadmins like this because it gives away little information
-to spammers. However, some other syadmins who are applying strict checking
-policies want to give out much fuller information about failures. Setting
-%smtp_return_error_details% true causes Exim to be more forthcoming. For
-example, instead of ``Administrative prohibition'', it might give:
-
- 550-Rejected after DATA: '>' missing at end of address:
- 550 failing address in "From" header is: <user@dom.ain
-
-
-
-oindex:[%spamd_address%]
-`..'=
-%spamd_address%, Use: 'main', Type: 'string', Default: `127.0.0.1 783`
-===
-
-This option is available when Exim is compiled with the content-scanning
-extension. It specifies how Exim connects to SpamAssassin's %spamd% daemon. See
-section <<SECTscanspamass>> for more details.
-
-
-
-oindex:[%split_spool_directory%]
-`..'=
-%split_spool_directory%, Use: 'main', Type: 'boolean', Default: 'false'
-===
-
-cindex:[multiple spool directories]
-cindex:[spool directory,split]
-cindex:[directories, multiple]
-If this option is set, it causes Exim to split its input directory into 62
-subdirectories, each with a single alphanumeric character as its name. The
-sixth character of the message id is used to allocate messages to
-subdirectories; this is the least significant base-62 digit of the time of
-arrival of the message.
-
-Splitting up the spool in this way may provide better performance on systems
-where there are long mail queues, by reducing the number of files in any one
-directory. The msglog directory is also split up in a similar way to the input
-directory; however, if %preserve_message_logs% is set, all old msglog files
-are still placed in the single directory _msglog.OLD_.
-
-It is not necessary to take any special action for existing messages when
-changing %split_spool_directory%. Exim notices messages that are in the
-``wrong'' place, and continues to process them. If the option is turned off after
-a period of being on, the subdirectories will eventually empty and be
-automatically deleted.
-
-When %split_spool_directory% is set, the behaviour of queue runner processes
-changes. Instead of creating a list of all messages in the queue, and then
-trying to deliver each one in turn, it constructs a list of those in one
-sub-directory and tries to deliver them, before moving on to the next
-sub-directory. The sub-directories are processed in a random order. This
-spreads out the scanning of the input directories, and uses less memory. It is
-particularly beneficial when there are lots of messages on the queue. However,
-if %queue_run_in_order% is set, none of this new processing happens. The
-entire queue has to be scanned and sorted before any deliveries can start.
-
-
-oindex:[%spool_directory%]
-`..'=
-%spool_directory%, Use: 'main', Type: 'string'!!, Default: 'set at compile time'
-===
-
-cindex:[spool directory,path to]
-This defines the directory in which Exim keeps its spool, that is, the messages
-it is waiting to deliver. The default value is taken from the compile-time
-configuration setting, if there is one. If not, this option must be set. The
-string is expanded, so it can contain, for example, a reference to
-$primary_hostname$.
-
-If the spool directory name is fixed on your installation, it is recommended
-that you set it at build time rather than from this option, particularly if the
-log files are being written to the spool directory (see %log_file_path%).
-Otherwise log files cannot be used for errors that are detected early on, such
-as failures in the configuration file.
-
-By using this option to override the compiled-in path, it is possible to run
-tests of Exim without using the standard spool.
-
-oindex:[%sqlite_lock_timeout%]
-`..'=
-%sqlite_lock_timeout%, Use: 'main', Type: 'time', Default: '5s'
-===
-
-[revisionflag="changed"]
-cindex:[sqlite,lock timeout]
-This option controls the timeout that the ^sqlite^ lookup uses when trying to
-access an SQLite database. See section <<SECTsqlite>> for more details.
-
-
-oindex:[%strip_excess_angle_brackets%]
-`..'=
-%strip_excess_angle_brackets%, Use: 'main', Type: 'boolean', Default: 'false'
-===
-
-cindex:[angle brackets, excess]
-If this option is set, redundant pairs of angle brackets round ``route-addr''
-items in addresses are stripped. For example, `\<\<xxx@a.b.c.d\>\>` is treated
-as `<xxx@a.b.c.d>`. If this is in the envelope and the message is passed on
-to another MTA, the excess angle brackets are not passed on. If this option is
-not set, multiple pairs of angle brackets cause a syntax error.
-
-
-oindex:[%strip_trailing_dot%]
-`..'=
-%strip_trailing_dot%, Use: 'main', Type: 'boolean', Default: 'false'
-===
-
-cindex:[trailing dot on domain]
-cindex:[dot,trailing on domain]
-If this option is set, a trailing dot at the end of a domain in an address is
-ignored. If this is in the envelope and the message is passed on to another
-MTA, the dot is not passed on. If this option is not set, a dot at the end of a
-domain causes a syntax error.
-However, addresses in header lines are checked only when an ACL requests header
-syntax checking.
-
-
-oindex:[%syslog_duplication%]
-`..'=
-%syslog_duplication%, Use: 'main', Type: 'boolean', Default: 'true'
-===
-
-cindex:[syslog,duplicate log lines; suppressing]
-When Exim is logging to syslog, it writes the log lines for its three
-separate logs at different syslog priorities so that they can in principle
-be separated on the logging hosts. Some installations do not require this
-separation, and in those cases, the duplication of certain log lines is a
-nuisance. If %syslog_duplication% is set false, only one copy of any
-particular log line is written to syslog. For lines that normally go to
-both the main log and the reject log, the reject log version (possibly
-containing message header lines) is written, at LOG_NOTICE priority.
-Lines that normally go to both the main and the panic log are written at
-the LOG_ALERT priority.
-
-
-oindex:[%syslog_facility%]
-`..'=
-%syslog_facility%, Use: 'main', Type: 'string', Default: 'unset'
-===
-
-cindex:[syslog,facility; setting]
-This option sets the syslog ``facility'' name, used when Exim is logging to
-syslog. The value must be one of the strings ``mail'', ``user'', ``news'', ``uucp'',
-``daemon'', or ``local'x'##'' where 'x' is a digit between 0 and 7. If this
-option is unset, ``mail'' is used. See chapter <<CHAPlog>> for details of Exim's
-logging.
-
-
-
-oindex:[%syslog_processname%]
-`..'=
-%syslog_processname%, Use: 'main', Type: 'string', Default: `exim`
-===
-
-cindex:[syslog,process name; setting]
-This option sets the syslog ``ident'' name, used when Exim is logging to syslog.
-The value must be no longer than 32 characters. See chapter <<CHAPlog>> for
-details of Exim's logging.
-
-
-
-oindex:[%syslog_timestamp%]
-`..'=
-%syslog_timestamp%, Use: 'main', Type: 'boolean', Default: 'true'
-===
-
-cindex:[syslog,timestamps]
-If %syslog_timestamp% is set false, the timestamps on Exim's log lines are
-omitted when these lines are sent to syslog. See chapter <<CHAPlog>> for
-details of Exim's logging.
-
-
-oindex:[%system_filter%]
-`..'=
-%system_filter%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[filter,system filter]
-cindex:[system filter,specifying]
-cindex:[Sieve filter,not available for system filter]
-This option specifies an Exim filter file that is applied to all messages at
-the start of each delivery attempt, before any routing is done. System filters
-must be Exim filters; they cannot be Sieve filters. If the system filter
-generates any deliveries to files or pipes, or any new mail messages, the
-appropriate %system_filter_..._transport% option(s) must be set, to define
-which transports are to be used. Details of this facility are given in chapter
-<<CHAPsystemfilter>>.
-
-
-oindex:[%system_filter_directory_transport%]
-`..'=
-%system_filter_directory_transport%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[$address_file$]
-This sets the name of the transport driver that is to be used when the
-%save% command in a system message filter specifies a path ending in ``/'',
-implying delivery of each message into a separate file in some directory.
-During the delivery, the variable $address_file$ contains the path name.
-
-
-oindex:[%system_filter_file_transport%]
-`..'=
-%system_filter_file_transport%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[file,transport for system filter]
-This sets the name of the transport driver that is to be used when the %save%
-command in a system message filter specifies a path not ending in ``/''. During
-the delivery, the variable $address_file$ contains the path name.
-
-oindex:[%system_filter_group%]
-`..'=
-%system_filter_group%, Use: 'main', Type: 'string', Default: 'unset'
-===
-
-cindex:[gid (group id),system filter]
-This option is used only when %system_filter_user% is also set. It sets the
-gid under which the system filter is run, overriding any gid that is associated
-with the user. The value may be numerical or symbolic.
-
-oindex:[%system_filter_pipe_transport%]
-`..'=
-%system_filter_pipe_transport%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[^pipe^ transport,for system filter]
-cindex:[$address_pipe$]
-This specifies the transport driver that is to be used when a %pipe% command is
-used in a system filter. During the delivery, the variable $address_pipe$
-contains the pipe command.
-
-
-oindex:[%system_filter_reply_transport%]
-`..'=
-%system_filter_reply_transport%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[^autoreply^ transport,for system filter]
-This specifies the transport driver that is to be used when a %mail% command is
-used in a system filter.
-
-oindex:[%system_filter_user%]
-`..'=
-%system_filter_user%, Use: 'main', Type: 'string', Default: 'unset'
-===
-
-cindex:[uid (user id),system filter]
-If this option is not set, the system filter is run in the main Exim delivery
-process, as root. When the option is set, the system filter runs in a separate
-process, as the given user. Unless the string consists entirely of digits, it
-is looked up in the password data. Failure to find the named user causes a
-configuration error. The gid is either taken from the password data, or
-specified by %system_filter_group%. When the uid is specified numerically,
-%system_filter_group% is required to be set.
-
-If the system filter generates any pipe, file, or reply deliveries, the uid
-under which the filter is run is used when transporting them, unless a
-transport option overrides. Normally you should set %system_filter_user% if
-your system filter generates these kinds of delivery.
-
-
-oindex:[%tcp_nodelay%]
-`..'=
-%tcp_nodelay%, Use: 'main', Type: 'boolean', Default: 'true'
-===
-
-cindex:[daemon,TCP_NODELAY on sockets]
-cindex:[Nagle algorithm]
-cindex:[TCP_NODELAY on listening sockets]
-If this option is set false, it stops the Exim daemon setting the
-TCP_NODELAY option on its listening sockets. Setting TCP_NODELAY
-turns off the ``Nagle algorithm'', which is a way of improving network
-performance in interactive (character-by-character) situations. Turning it off
-should improve Exim's performance a bit, so that is what happens by default.
-However, it appears that some broken clients cannot cope, and time out. Hence
-this option. It affects only those sockets that are set up for listening by the
-daemon. Sockets created by the smtp transport for delivering mail always set
-TCP_NODELAY.
-
-
-oindex:[%timeout_frozen_after%]
-`..'=
-%timeout_frozen_after%, Use: 'main', Type: 'time', Default: '0s'
-===
-
-cindex:[frozen messages,timing out]
-cindex:[timeout,frozen messages]
-If %timeout_frozen_after% is set to a time greater than zero, a frozen
-message of any kind that has been on the queue for longer than the given
-time is automatically cancelled at the next queue run. If it is a bounce
-message, it is just discarded; otherwise, a bounce is sent to the sender, in a
-similar manner to cancellation by the %-Mg% command line option. If you want
-to timeout frozen bounce messages earlier than other kinds of frozen message,
-see %ignore_bounce_errors_after%.
-
-
-oindex:[%timezone%]
-`..'=
-%timezone%, Use: 'main', Type: 'string', Default: 'unset'
-===
-
-cindex:[timezone, setting]
-The value of %timezone% is used to set the environment variable TZ while
-running Exim (if it is different on entry). This ensures that all timestamps
-created by Exim are in the required timezone. If you want all your timestamps
-to be in UTC (aka GMT) you should set
-
- timezone = UTC
-
-The default value is taken from TIMEZONE_DEFAULT in _Local/Makefile_,
-or, if that is not set, from the value of the TZ environment variable when Exim
-is built. If %timezone% is set to the empty string, either at build or run
-time, any existing TZ variable is removed from the environment when Exim
-runs. This is appropriate behaviour for obtaining wall-clock time on some, but
-unfortunately not all, operating systems.
-
-
-oindex:[%tls_advertise_hosts%]
-`..'=
-%tls_advertise_hosts%, Use: 'main', Type: 'host list'!!, Default: 'unset'
-===
-
-cindex:[TLS,advertising]
-cindex:[encryption,on SMTP connection]
-cindex:[SMTP,encrypted connection]
-When Exim is built with support for TLS encrypted connections, the availability
-of the STARTTLS command to set up an encrypted session is advertised in
-response to EHLO only to those client hosts that match this option. See
-chapter <<CHAPTLS>> for details of Exim's support for TLS.
-
-
-oindex:[%tls_certificate%]
-`..'=
-%tls_certificate%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[TLS,server certificate; location of]
-cindex:[certificate for server, location of]
-The value of this option is expanded, and must then be the absolute path to a
-file which contains the server's certificates. The server's private key is also
-assumed to be in this file if %tls_privatekey% is unset. See chapter <<CHAPTLS>>
-for further details.
-
-*Note*: The certificates defined by this option are used only when Exim is
-receiving incoming messages as a server. If you want to supply certificates for
-use when sending messages as a client, you must set the %tls_certificate%
-option in the relevant ^smtp^ transport.
-
-
-oindex:[%tls_crl%]
-`..'=
-%tls_crl%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[TLS,server certificate revocation list]
-cindex:[certificate,revocation list for server]
-This option specifies a certificate revocation list. The expanded value must
-be the name of a file that contains a CRL in PEM format.
-
-
-oindex:[%tls_dhparam%]
-`..'=
-%tls_dhparam%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[TLS,D-H parameters for server]
-The value of this option is expanded, and must then be the absolute path to
-a file which contains the server's DH parameter values.
-This is used only for OpenSSL. When Exim is linked with GnuTLS, this option is
-ignored. See section <<SECTopenvsgnu>> for further details.
-
-
-oindex:[%tls_on_connect_ports%]
-`..'=
-%tls_on_connect_ports%, Use: 'main', Type: 'string list', Default: 'unset'
-===
-
-This option specifies a list of incoming SSMTP (aka SMTPS) ports that should
-operate the obsolete SSMTP (SMTPS) protocol, where a TLS session is immediately
-set up without waiting for the client to issue a STARTTLS command. For
-further details, see section <<SECTsupobssmt>>.
-
-
-
-oindex:[%tls_privatekey%]
-`..'=
-%tls_privatekey%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[TLS,server private key; location of]
-The value of this option is expanded, and must then be the absolute path to a
-file which contains the server's private key. If this option is unset, the
-private key is assumed to be in the same file as the server's certificates. See
-chapter <<CHAPTLS>> for further details.
-
-
-oindex:[%tls_remember_esmtp%]
-`..'=
-%tls_remember_esmtp%, Use: 'main', Type: 'boolean', Default: 'false'
-===
-
-cindex:[TLS,esmtp state; remembering]
-cindex:[TLS,broken clients]
-If this option is set true, Exim violates the RFCs by remembering that it is in
-``esmtp'' state after successfully negotiating a TLS session. This provides
-support for broken clients that fail to send a new EHLO after starting a
-TLS session.
-
-
-oindex:[%tls_require_ciphers%]
-`..'=
-%tls_require_ciphers%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[TLS,requiring specific ciphers]
-cindex:[cipher,requiring specific]
-This option controls which ciphers can be used for incoming TLS connections.
-The ^smtp^ transport has an option of the same name for controlling outgoing
-connections. This option is expanded for each connection, so can be varied for
-different clients if required. The value of this option must be a list of
-permitted cipher suites. The OpenSSL and GnuTLS libraries handle cipher control
-in somewhat different ways.
-
-If GnuTLS is being used, the client controls the preference order of the
-available ciphers.
-
-Details are given in sections <<SECTreqciphssl>> and <<SECTreqciphgnu>>.
-
-
-oindex:[%tls_try_verify_hosts%]
-`..'=
-%tls_try_verify_hosts%, Use: 'main', Type: 'host list'!!, Default: 'unset'
-===
-
-cindex:[TLS,client certificate verification]
-cindex:[certificate,verification of client]
-See %tls_verify_hosts% below.
-
-
-oindex:[%tls_verify_certificates%]
-`..'=
-%tls_verify_certificates%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[TLS,client certificate verification]
-cindex:[certificate,verification of client]
-The value of this option is expanded, and must then be the absolute path to
-a file containing permitted certificates for clients that
-match %tls_verify_hosts% or %tls_try_verify_hosts%. Alternatively, if you
-are using OpenSSL, you can set %tls_verify_certificates% to the name of a
-directory containing certificate files. This does not work with GnuTLS; the
-option must be set to the name of a single file if you are using GnuTLS.
-
-
-oindex:[%tls_verify_hosts%]
-`..'=
-%tls_verify_hosts%, Use: 'main', Type: 'host list'!!, Default: 'unset'
-===
-
-cindex:[TLS,client certificate verification]
-cindex:[certificate,verification of client]
-This option, along with %tls_try_verify_hosts%, controls the checking of
-certificates from clients.
-The expected certificates are defined by %tls_verify_certificates%, which
-must be set. A configuration error occurs if either %tls_verify_hosts% or
-%tls_try_verify_hosts% is set and %tls_verify_certificates% is not set.
-
-Any client that matches %tls_verify_hosts% is constrained by
-%tls_verify_certificates%. The client must present one of the listed
-certificates. If it does not, the connection is aborted.
-
-A weaker form of checking is provided by %tls_try_verify_hosts%. If a client
-matches this option (but not %tls_verify_hosts%), Exim requests a
-certificate and checks it against %tls_verify_certificates%, but does not
-abort the connection if there is no certificate or if it does not match. This
-state can be detected in an ACL, which makes it possible to implement policies
-such as ``accept for relay only if a verified certificate has been received, but
-accept for local delivery if encrypted, even without a verified certificate''.
-
-Client hosts that match neither of these lists are not asked to present
-certificates.
-
-
-oindex:[%trusted_groups%]
-`..'=
-%trusted_groups%, Use: 'main', Type: 'string list'!!, Default: 'unset'
-===
-
-[revisionflag="changed"]
-cindex:[trusted group]
-cindex:[group,trusted]
-This option is expanded just once, at the start of Exim's processing. If this
-option is set, any process that is running in one of the listed groups, or
-which has one of them as a supplementary group, is trusted. The groups can be
-specified numerically or by name. See section <<SECTtrustedadmin>> for details
-of what trusted callers are permitted to do. If neither %trusted_groups% nor
-%trusted_users% is set, only root and the Exim user are trusted.
-
-
-oindex:[%trusted_users%]
-`..'=
-%trusted_users%, Use: 'main', Type: 'string list'!!, Default: 'unset'
-===
-
-[revisionflag="changed"]
-cindex:[trusted user]
-cindex:[user,trusted]
-This option is expanded just once, at the start of Exim's processing. If this
-option is set, any process that is running as one of the listed users is
-trusted. The users can be specified numerically or by name. See section
-<<SECTtrustedadmin>> for details of what trusted callers are permitted to do.
-If neither %trusted_groups% nor %trusted_users% is set, only root and the Exim
-user are trusted.
-
-oindex:[%unknown_login%]
-`..'=
-%unknown_login%, Use: 'main', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[uid (user id),unknown caller]
-cindex:[$caller_uid$]
-This is a specialized feature for use in unusual configurations. By default, if
-the uid of the caller of Exim cannot be looked up using 'getpwuid()', Exim
-gives up. The %unknown_login% option can be used to set a login name to be
-used in this circumstance. It is expanded, so values like %user\$caller_uid%
-can be set. When %unknown_login% is used, the value of %unknown_username% is
-used for the user's real name (gecos field), unless this has been set by the
-%-F% option.
-
-
-oindex:[%unknown_username%]
-`..'=
-%unknown_username%, Use: 'main', Type: 'string', Default: 'unset'
-===
-
-See %unknown_login%.
-
-
-oindex:[%untrusted_set_sender%]
-`..'=
-%untrusted_set_sender%, Use: 'main', Type: 'address list'!!, Default: 'unset'
-===
-
-cindex:[trusted user]
-cindex:[sender,setting by untrusted user]
-cindex:[untrusted user, setting sender]
-cindex:[user,untrusted setting sender]
-cindex:[envelope sender]
-When an untrusted user submits a message to Exim using the standard input, Exim
-normally creates an envelope sender address from the user's login and the
-default qualification domain. Data from the %-f% option (for setting envelope
-senders on non-SMTP messages) or the SMTP MAIL command (if %-bs% or %-bS%
-is used) is ignored.
-
-However, untrusted users are permitted to set an empty envelope sender address,
-to declare that a message should never generate any bounces. For example:
-
- exim -f '<>' user@domain.example
-
-cindex:[$sender_ident$]
-The %untrusted_set_sender% option allows you to permit untrusted users to set
-other envelope sender addresses in a controlled way. When it is set, untrusted
-users are allowed to set envelope sender addresses that match any of the
-patterns in the list. Like all address lists, the string is expanded. The
-identity of the user is in $sender_ident$, so you can, for example, restrict
-users to setting senders that start with their login ids
-followed by a hyphen
-by a setting like this:
-
- untrusted_set_sender = ^$sender_ident-
-
-If you want to allow untrusted users to set envelope sender addresses without
-restriction, you can use
-
- untrusted_set_sender = *
-
-The %untrusted_set_sender% option applies to all forms of local input, but
-only to the setting of the envelope sender. It does not permit untrusted users
-to use the other options which trusted user can use to override message
-parameters. Furthermore, it does not stop Exim from removing an existing
-'Sender:' header in the message, or from adding a 'Sender:' header if
-necessary. See %local_sender_retain% and %local_from_check% for ways of
-overriding these actions. The handling of the 'Sender:' header is also
-described in section <<SECTthesenhea>>.
-
-The log line for a message's arrival shows the envelope sender following ``<=''.
-For local messages, the user's login always follows, after ``U=''. In %-bp%
-displays, and in the Exim monitor, if an untrusted user sets an envelope sender
-address, the user's login is shown in parentheses after the sender address.
-
-
-oindex:[%uucp_from_pattern%]
-`..'=
-%uucp_from_pattern%, Use: 'main', Type: 'string', Default: 'see below'
-===
-
-cindex:[``From'' line]
-cindex:[UUCP,``From'' line]
-Some applications that pass messages to an MTA via a command line interface use
-an initial line starting with ``From'' to pass the envelope sender. In
-particular, this is used by UUCP software. Exim recognizes such a line by means
-of a regular expression that is set in %uucp_from_pattern%. When the pattern
-matches, the sender address is constructed by expanding the contents of
-%uucp_from_sender%, provided that the caller of Exim is a trusted user. The
-default pattern recognizes lines in the following two forms:
-
- From ph10 Fri Jan 5 12:35 GMT 1996
- From ph10 Fri, 7 Jan 97 14:00:00 GMT
-
-The pattern can be seen by running
-
- exim -bP uucp_from_pattern
-
-It checks only up to the hours and minutes, and allows for a 2-digit or 4-digit
-year in the second case. The first word after ``From'' is matched in the regular
-expression by a parenthesized subpattern. The default value for
-%uucp_from_sender% is ``$1'', which therefore just uses this first word
-(``ph10'' in the example above) as the message's sender. See also
-%ignore_fromline_hosts%.
-
-
-oindex:[%uucp_from_sender%]
-`..'=
-%uucp_from_sender%, Use: 'main', Type: 'string'!!, Default: `\$1`
-===
-
-See %uucp_from_pattern% above.
-
-
-oindex:[%warn_message_file%]
-`..'=
-%warn_message_file%, Use: 'main', Type: 'string', Default: 'unset'
-===
-
-cindex:[warning of delay,customizing the message]
-cindex:[customizing,warning message]
-This option defines a template file containing paragraphs of text to be used
-for constructing the warning message which is sent by Exim when a message has
-been on the queue for a specified amount of time, as specified by
-%delay_warning%. Details of the file's contents are given in chapter
-<<CHAPemsgcust>>. See also %bounce_message_file%.
-
-
-oindex:[%write_rejectlog%]
-`..'=
-%write_rejectlog%, Use: 'main', Type: 'boolean', Default: 'true'
-===
-
-cindex:[reject log,disabling]
-If this option is set false, Exim no longer writes anything to the reject log.
-See chapter <<CHAPlog>> for details of what Exim writes to its logs.
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAProutergeneric]]
-Generic options for routers
----------------------------
-cindex:[options,generic; for routers]
-cindex:[generic options,router]
-This chapter describes the generic options that apply to all routers.
-Those that are preconditions are marked with !? in the ``use'' field.
-
-For a general description of how a router operates, see sections
-<<SECTrunindrou>> and <<SECTrouprecon>>. The latter specifies the order in
-which the preconditions are tested. The order of expansion of the options that
-provide data for a transport is: %errors_to%, %headers_add%, %headers_remove%,
-%transport%.
-
-
-
-oindex:[%address_data%]
-`..'=
-%address_data%, Use: 'routers', Type: 'string'!!, Default: 'unset'
-===
-
-[revisionflag="changed"]
-cindex:[router,data attached to address]
-The string is expanded just before the router is run, that is, after all the
-precondition tests have succeeded. If the expansion is forced to fail, the
-router declines, the value of %address_data% remains unchanged, and the %more%
-option controls what happens next. Other expansion failures cause delivery of
-the address to be deferred.
-
-cindex:[$address_data$]
-When the expansion succeeds, the value is retained with the address, and can be
-accessed using the variable $address_data$ in the current router, subsequent
-routers, and the eventual transport.
-
-*Warning*: if the current or any subsequent router is a ^redirect^ router
-that runs a user's filter file, the contents of $address_data$ are accessible
-in the filter. This is not normally a problem, because such data is usually
-either not confidential or it ``belongs'' to the current user, but if you do
-put confidential data into $address_data$ you need to remember this point.
-
-Even if the router declines or passes, the value of $address_data$ remains
-with the address, though it can be changed by another %address_data% setting
-on a subsequent router. If a router generates child addresses, the value of
-$address_data$ propagates to them. This also applies to the special kind of
-``child'' that is generated by a router with the %unseen% option.
-
-The idea of %address_data% is that you can use it to look up a lot of data for
-the address once, and then pick out parts of the data later. For example, you
-could use a single LDAP lookup to return a string of the form
-
- uid=1234 gid=5678 mailbox=/mail/xyz forward=/home/xyz/.forward
-
-In the transport you could pick out the mailbox by a setting such as
-
- file = ${extract{mailbox}{$address_data}}
-
-This makes the configuration file less messy, and also reduces the number of
-lookups (though Exim does cache lookups).
-
-The %address_data% facility is also useful as a means of passing information
-from one router to another, and from a router to a transport. In addition, if
-
-cindex:[$sender_address_data$]
-cindex:[$address_data$]
-When $address_data$ is set by a router when verifying a recipient address from
-an ACL, it remains available for use in the rest of the ACL statement. After
-verifying a sender, the value is transferred to $sender_address_data$.
-
-
-
-
-oindex:[%address_test%]
-`..'=
-%address_test%, Use: 'routers'!?, Type: 'boolean', Default: 'true'
-===
-
-cindex:[%-bt% option]
-cindex:[router,skipping when address testing]
-If this option is set false, the router is skipped when routing is being tested
-by means of the %-bt% command line option. This can be a convenience when your
-first router sends messages to an external scanner, because it saves you
-having to set the ``already scanned'' indicator when testing real address
-routing.
-
-
-
-oindex:[%cannot_route_message%]
-`..'=
-%cannot_route_message%, Use: 'routers', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[router,customizing ``cannot route'' message]
-cindex:[customizing,``cannot route'' message]
-This option specifies a text message that is used when an address cannot be
-routed because Exim has run out of routers. The default message is ``Unrouteable
-address''. This option is useful only on routers that have %more% set false, or
-on the very last router in a configuration, because the value that is used is
-taken from the last router that inspects an address. For example, using the
-default configuration, you could put:
-
- cannot_route_message = Remote domain not found in DNS
-
-on the first (^dnslookup^) router, and
-
- cannot_route_message = Unknown local user
-
-on the final router that checks for local users. If string expansion fails, the
-default message is used.
-Unless the expansion failure was explicitly forced, a message about the failure
-is written to the main and panic logs, in addition to the normal message about
-the routing failure.
-
-
-oindex:[%caseful_local_part%]
-`..'=
-%caseful_local_part%, Use: 'routers', Type: 'boolean', Default: 'false'
-===
-
-cindex:[case of local parts]
-cindex:[router,case of local parts]
-By default, routers handle the local parts of addresses in a case-insensitive
-manner, though the actual case is preserved for transmission with the message.
-If you want the case of letters to be significant in a router, you must set
-this option true. For individual router options that contain address or local
-part lists (for example, %local_parts%), case-sensitive matching can be turned
-on by ``+caseful'' as a list item. See section <<SECTcasletadd>> for more details.
-
-cindex:[$local_part$]
-cindex:[$original_local_part$]
-cindex:[$parent_local_part$]
-The value of the $local_part$ variable is forced to lower case while a
-router is running unless %caseful_local_part% is set. When a router assigns
-an address to a transport, the value of $local_part$ when the transport runs
-is the same as it was in the router. Similarly, when a router generates child
-addresses by aliasing or forwarding, the values of $original_local_part$
-and $parent_local_part$ are those that were used by the redirecting router.
-
-This option applies to the processing of an address by a router. When a
-recipient address is being processed in an ACL, there is a separate %control%
-modifier that can be used to specify case-sensitive processing within the ACL
-(see section <<SECTcontrols>>).
-
-
-
-oindex:[%check_local_user%]
-`..'=
-%check_local_user%, Use: 'routers'!?, Type: 'boolean', Default: 'false'
-===
-
-cindex:[local user, checking in router]
-cindex:[router,checking for local user]
-cindex:[_/etc/passwd_]
-cindex:[$home$]
-When this option is true, Exim checks that the local part of the recipient
-address (with affixes removed if relevant) is the name of an account on the
-local system. The check is done by calling the 'getpwnam()' function rather
-than trying to read _/etc/passwd_ directly. This means that other methods of
-holding password data (such as NIS) are supported. If the local part is a local
-user, $home$ is set from the password data, and can be tested in other
-preconditions that are evaluated after this one (the order of evaluation is
-given in section <<SECTrouprecon>>). However, the value of $home$ can be
-overridden by %router_home_directory%. If the local part is not a local user,
-the router is skipped.
-
-If you want to check that the local part is either the name of a local user
-or matches something else, you cannot combine %check_local_user% with a
-setting of %local_parts%, because that specifies the logical 'and' of the
-two conditions. However, you can use a ^passwd^ lookup in a %local_parts%
-setting to achieve this. For example:
-
- local_parts = passwd;$local_part : lsearch;/etc/other/users
-
-Note, however, that the side effects of %check_local_user% (such as setting
-up a home directory) do not occur when a ^passwd^ lookup is used in a
-%local_parts% (or any other) precondition.
-
-
-
-oindex:[%condition%]
-`..'=
-%condition%, Use: 'routers'!?, Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[router,customized precondition]
-This option specifies a general precondition test that has to succeed for the
-router to be called. The %condition% option is the last precondition to be
-evaluated (see section <<SECTrouprecon>>). The string is expanded, and if the
-result is a forced failure, or an empty string, or one of the strings ``0'' or
-``no'' or ``false'' (checked without regard to the case of the letters), the router
-is skipped, and the address is offered to the next one.
-
-If the result is any other value, the router is run (as this is the last
-precondition to be evaluated, all the other preconditions must be true).
-
-The %condition% option provides a means of applying custom conditions to the
-running of routers. Note that in the case of a simple conditional expansion,
-the default expansion values are exactly what is wanted. For example:
-
- condition = ${if >{$message_age}{600}}
-
-Because of the default behaviour of the string expansion, this is equivalent to
-
- condition = ${if >{$message_age}{600}{true}{}}
-
-
-If the expansion fails (other than forced failure) delivery is deferred. Some
-of the other precondition options are common special cases that could in fact
-be specified using %condition%.
-
-
-
-oindex:[%debug_print%]
-`..'=
-%debug_print%, Use: 'routers', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[testing,variables in drivers]
-If this option is set and debugging is enabled (see the %-d% command line
-option), the string is expanded and included in the debugging output.
-If expansion of the string fails, the error message is written to the debugging
-output, and Exim carries on processing.
-This option is provided to help with checking out the values of variables and
-so on when debugging router configurations. For example, if a %condition%
-option appears not to be working, %debug_print% can be used to output the
-variables it references. The output happens after checks for %domains%,
-%local_parts%, and %check_local_user% but before any other preconditions are
-tested. A newline is added to the text if it does not end with one.
-
-
-
-oindex:[%disable_logging%]
-`..'=
-%disable_logging%, Use: 'routers', Type: 'boolean', Default: 'false'
-===
-
-If this option is set true, nothing is logged for any routing errors
-or for any deliveries caused by this router. You should not set this option
-unless you really, really know what you are doing. See also the generic
-transport option of the same name.
-
-
-oindex:[%domains%]
-`..'=
-%domains%, Use: 'routers'!?, Type: 'domain list'!!, Default: 'unset'
-===
-
-cindex:[router,restricting to specific domains]
-cindex:[$domain_data$]
-If this option is set, the router is skipped unless the current domain matches
-the list. If the match is achieved by means of a file lookup, the data that the
-lookup returned for the domain is placed in $domain_data$ for use in string
-expansions of the driver's private options. See section <<SECTrouprecon>> for a
-list of the order in which preconditions are evaluated.
-
-
-
-oindex:[%driver%]
-`..'=
-%driver%, Use: 'routers', Type: 'string', Default: 'unset'
-===
-
-This option must always be set. It specifies which of the available routers is
-to be used.
-
-
-
-oindex:[%errors_to%]
-`..'=
-%errors_to%, Use: 'routers', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[envelope sender]
-cindex:[router,changing address for errors]
-If a router successfully handles an address, it may queue the address for
-delivery or it may generate child addresses. In both cases, if there is a
-delivery problem during later processing, the resulting bounce message is sent
-to the address that results from expanding this string, provided that the
-address verifies successfully. %errors_to% is expanded before %headers_add%,
-%headers_remove%, and %transport%.
-
-If the option is unset, or the expansion is forced to fail, or the result of
-the expansion fails to verify, the errors address associated with the incoming
-address is used. At top level, this is the envelope sender. A non-forced
-expansion failure causes delivery to be deferred.
-
-If an address for which %errors_to% has been set ends up being delivered over
-SMTP, the envelope sender for that delivery is the %errors_to% value, so that
-any bounces that are generated by other MTAs on the delivery route are also
-sent there. The most common use of %errors_to% is probably to direct mailing
-list bounces to the manager of the list, as described in section
-<<SECTmailinglists>>.
-
-The %errors_to% setting associated with an address can be overridden if it
-subsequently passes through other routers that have their own %errors_to%
-settings,
-or if it is delivered by a transport with a %return_path% setting.
-
-You can set %errors_to% to the empty string by either of these settings:
-
- errors_to =
- errors_to = ""
-
-An expansion item that yields an empty string has the same effect. If you do
-this, a locally detected delivery error for addresses processed by this router
-no longer gives rise to a bounce message; the error is discarded. If the
-address is delivered to a remote host, the return path is set to `<>`, unless
-overridden by the %return_path% option on the transport.
-
-cindex:[$address_data$]
-If for some reason you want to discard local errors, but use a non-empty
-MAIL command for remote delivery, you can preserve the original return
-path in $address_data$ in the router, and reinstate it in the transport by
-setting %return_path%.
-
-
-
-oindex:[%expn%]
-`..'=
-%expn%, Use: 'routers'!?, Type: 'boolean', Default: 'true'
-===
-
-cindex:[address,testing]
-cindex:[testing,addresses]
-cindex:[EXPN,router skipping]
-cindex:[router,skipping for EXPN]
-If this option is turned off, the router is skipped when testing an address
-as a result of processing an SMTP EXPN command. You might, for example,
-want to turn it off on a router for users' _.forward_ files, while leaving it
-on for the system alias file.
-See section <<SECTrouprecon>> for a list of the order in which preconditions
-are evaluated.
-
-The use of the SMTP EXPN command is controlled by an ACL (see chapter
-<<CHAPACL>>). When Exim is running an EXPN command, it is similar to testing
-an address with %-bt%. Compare VRFY, whose counterpart is %-bv%.
-
-
-
-oindex:[%fail_verify%]
-`..'=
-%fail_verify%, Use: 'routers', Type: 'boolean', Default: 'false'
-===
-
-cindex:[router,forcing verification failure]
-Setting this option has the effect of setting both %fail_verify_sender% and
-%fail_verify_recipient% to the same value.
-
-
-
-oindex:[%fail_verify_recipient%]
-`..'=
-%fail_verify_recipient%, Use: 'routers', Type: 'boolean', Default: 'false'
-===
-
-If this option is true and an address is accepted by this router when
-verifying a recipient, verification fails.
-
-
-
-oindex:[%fail_verify_sender%]
-`..'=
-%fail_verify_sender%, Use: 'routers', Type: 'boolean', Default: 'false'
-===
-
-If this option is true and an address is accepted by this router when
-verifying a sender, verification fails.
-
-
-
-oindex:[%fallback_hosts%]
-`..'=
-%fallback_hosts%, Use: 'routers', Type: 'string list', Default: 'unset'
-===
-
-[revisionflag="changed"]
-cindex:[router,fallback hosts]
-cindex:[fallback,hosts specified on router]
-String expansion is not applied to this option. The argument must be a
-colon-separated list of host names or IP addresses. The list separator can be
-changed (see section <<SECTlistconstruct>>), and a port can be specified with
-each name or address. In fact, the format of each item is exactly the same as
-defined for the list of hosts in a ^manualroute^ router (see section
-<<SECTformatonehostitem>>).
-
-If a router queues an address for a remote transport, this host list is
-associated with the address, and used instead of the transport's fallback host
-list. If %hosts_randomize% is set on the transport, the order of the list is
-randomized for each use. See the %fallback_hosts% option of the ^smtp^
-transport for further details.
-
-
-oindex:[%group%]
-`..'=
-%group%, Use: 'routers', Type: 'string'!!, Default: 'see below'
-===
-
-cindex:[gid (group id),local delivery]
-cindex:[local transports,uid and gid]
-cindex:[transport,local]
-cindex:[router,setting group]
-When a router queues an address for a transport, and the transport does not
-specify a group, the group given here is used when running the delivery
-process.
-The group may be specified numerically or by name. If expansion fails, the
-error is logged and delivery is deferred.
-The default is unset, unless %check_local_user% is set, when the default
-is taken from the password information. See also %initgroups% and %user% and
-the discussion in chapter <<CHAPenvironment>>.
-
-
-
-oindex:[%headers_add%]
-`..'=
-%headers_add%, Use: 'routers', Type: 'string'!!, Default: 'unset'
-===
-
-[revisionflag="changed"]
-cindex:[header lines,adding]
-cindex:[router,adding header lines]
-This option specifies a string of text that is expanded at routing time, and
-associated with any addresses that are accepted by the router. However, this
-option has no effect when an address is just being verified. The way in which
-the text is used to add header lines at transport time is described in section
-<<SECTheadersaddrem>>. New header lines are not actually added until the
-message is in the process of being transported. This means that references to
-header lines in string expansions in the transport's configuration do not
-``see'' the added header lines.
-
-The %headers_add% option is expanded after %errors_to%, but before
-%headers_remove% and %transport%. If the expanded string is empty, or if the
-expansion is forced to fail, the option has no effect. Other expansion failures
-are treated as configuration errors.
-
-*Warning 1*: The %headers_add% option cannot be used for a ^redirect^
-router that has the %one_time% option set.
-
-[revisionflag="changed"]
-*Warning 2*: If the %unseen% option is set on the router, all header additions
-are deleted when the address is passed on to subsequent routers.
-
-
-
-
-oindex:[%headers_remove%]
-`..'=
-%headers_remove%, Use: 'routers', Type: 'string'!!, Default: 'unset'
-===
-
-[revisionflag="changed"]
-cindex:[header lines,removing]
-cindex:[router,removing header lines]
-This option specifies a string of text that is expanded at routing time, and
-associated with any addresses that are accepted by the router. However, this
-option has no effect when an address is just being verified. The way in which
-the text is used to remove header lines at transport time is described in
-section <<SECTheadersaddrem>>. Header lines are not actually removed until the
-message is in the process of being transported. This means that references to
-header lines in string expansions in the transport's configuration still
-``see'' the original header lines.
-
-The %headers_remove% option is expanded after %errors_to% and %headers_add%,
-but before %transport%. If the expansion is forced to fail, the option has no
-effect. Other expansion failures are treated as configuration errors.
-
-*Warning 1*: The %headers_remove% option cannot be used for a ^redirect^
-router that has the %one_time% option set.
-
-[revisionflag="changed"]
-*Warning 2*: If the %unseen% option is set on the router, all header removal
-requests are deleted when the address is passed on to subsequent routers.
-
-
-
-oindex:[%ignore_target_hosts%]
-`..'=
-%ignore_target_hosts%, Use: 'routers', Type: 'host list'!!, Default: 'unset'
-===
-
-cindex:[IP address,discarding]
-cindex:[router,discarding IP addresses]
-Although this option is a host list, it should normally contain IP address
-entries rather than names. If any host that is looked up by the router has an
-IP address that matches an item in this list, Exim behaves as if that IP
-address did not exist. This option allows you to cope with rogue DNS entries
-like
-
- remote.domain.example. A 127.0.0.1
-
-by setting
-
- ignore_target_hosts = 127.0.0.1
-
-on the relevant router. If all the hosts found by a ^dnslookup^ router are
-discarded in this way, the router declines. In a conventional configuration, an
-attempt to mail to such a domain would normally provoke the ``unrouteable
-domain'' error, and an attempt to verify an address in the domain would fail.
-
-Similarly, if %ignore_target_hosts% is set on an ^ipliteral^ router, the
-router declines if presented with one of the listed addresses.
-
-This option may also be useful for ignoring link-local and site-local IPv6
-addresses. Because, like all host lists, the value of %ignore_target_hosts%
-is expanded before use as a list, it is possible to make it dependent on the
-domain that is being routed.
-
-cindex:[$host_address$]
-During its expansion, $host_address$ is set to the IP address that is being
-checked.
-
-oindex:[%initgroups%]
-`..'=
-%initgroups%, Use: 'routers', Type: 'boolean', Default: 'false'
-===
-
-cindex:[additional groups]
-cindex:[groups, additional]
-cindex:[local transports,uid and gid]
-cindex:[transport,local]
-If the router queues an address for a transport, and this option is true, and
-the uid supplied by the router is not overridden by the transport, the
-'initgroups()' function is called when running the transport to ensure that
-any additional groups associated with the uid are set up. See also %group% and
-%user% and the discussion in chapter <<CHAPenvironment>>.
-
-
-
-oindex:[%local_part_prefix%]
-`..'=
-%local_part_prefix%, Use: 'routers'!?, Type: 'string list', Default: 'unset'
-===
-
-cindex:[router,prefix for local part]
-cindex:[prefix,for local part; used in router]
-If this option is set, the router is skipped unless the local part starts with
-one of the given strings, or %local_part_prefix_optional% is true. See section
-<<SECTrouprecon>> for a list of the order in which preconditions are evaluated.
-
-The list is scanned from left to right, and the first prefix that matches is
-used. A limited form of wildcard is available; if the prefix begins with an
-asterisk, it matches the longest possible sequence of arbitrary characters at
-the start of the local part. An asterisk should therefore always be followed by
-some character that does not occur in normal local parts.
-cindex:[multiple mailboxes]
-cindex:[mailbox,multiple]
-Wildcarding can be used to set up multiple user mailboxes, as described in
-section <<SECTmulbox>>.
-
-[revisionflag="changed"]
-cindex:[$local_part$]
-cindex:[$local_part_prefix$]
-During the testing of the %local_parts% option, and while the router is
-running, the prefix is removed from the local part, and is available in the
-expansion variable $local_part_prefix$. When a message is being delivered, if
-the router accepts the address, this remains true during subsequent delivery by
-a transport. In particular, the local part that is transmitted in the RCPT
-command for LMTP, SMTP, and BSMTP deliveries has the prefix removed by default.
-This behaviour can be overridden by setting %rcpt_include_affixes% true on the
-relevant transport.
-
-[revisionflag="changed"]
-When an address is being verified, %local_part_prefix% affects only the
-behaviour of the router. If the callout feature of verification is in use, this
-means that the full address, including the prefix, will be used during the
-callout.
-
-The prefix facility is commonly used to handle local parts of the form
-%owner-something%. Another common use is to support local parts of the form
-%real-username% to bypass a user's _.forward_ file -- helpful when trying to
-tell a user their forwarding is broken -- by placing a router like this one
-immediately before the router that handles _.forward_ files:
-
- real_localuser:
- driver = accept
- local_part_prefix = real-
- check_local_user
- transport = local_delivery
-
-If both %local_part_prefix% and %local_part_suffix% are set for a router,
-both conditions must be met if not optional. Care must be taken if wildcards
-are used in both a prefix and a suffix on the same router. Different
-separator characters must be used to avoid ambiguity.
-
-
-oindex:[%local_part_prefix_optional%]
-`..'=
-%local_part_prefix_optional%, Use: 'routers', Type: 'boolean', Default: 'false'
-===
-
-See %local_part_prefix% above.
-
-
-
-oindex:[%local_part_suffix%]
-`..'=
-%local_part_suffix%, Use: 'routers'!?, Type: 'string list', Default: 'unset'
-===
-
-cindex:[router,suffix for local part]
-cindex:[suffix for local part, used in router]
-This option operates in the same way as %local_part_prefix%, except that the
-local part must end (rather than start) with the given string, the
-%local_part_suffix_optional% option determines whether the suffix is
-mandatory, and the wildcard \* character, if present, must be the last
-character of the suffix. This option facility is commonly used to handle local
-parts of the form %something-request% and multiple user mailboxes of the form
-%username-foo%.
-
-
-oindex:[%local_part_suffix_optional%]
-`..'=
-%local_part_suffix_optional%, Use: 'routers', Type: 'boolean', Default: 'false'
-===
-
-See %local_part_suffix% above.
-
-
-
-oindex:[%local_parts%]
-`..'=
-%local_parts%, Use: 'routers'!?, Type: 'local part list'!!, Default: 'unset'
-===
-
-cindex:[router,restricting to specific local parts]
-cindex:[local part,checking in router]
-The router is run only if the local part of the address matches the list.
-See section <<SECTrouprecon>> for a list of the order in which preconditions
-are evaluated, and
-section <<SECTlocparlis>> for a discussion of local part lists. Because the
-string is expanded, it is possible to make it depend on the domain, for
-example:
-
- local_parts = dbm;/usr/local/specials/$domain
-
-cindex:[$local_part_data$]
-If the match is achieved by a lookup, the data that the lookup returned
-for the local part is placed in the variable $local_part_data$ for use in
-expansions of the router's private options. You might use this option, for
-example, if you have a large number of local virtual domains, and you want to
-send all postmaster mail to the same place without having to set up an alias in
-each virtual domain:
-
- postmaster:
- driver = redirect
- local_parts = postmaster
- data = postmaster@real.domain.example
-
-
-
-
-oindex:[%log_as_local%]
-`..'=
-%log_as_local%, Use: 'routers', Type: 'boolean', Default: 'see below'
-===
-
-cindex:[log,delivery line]
-cindex:[delivery,log line format]
-Exim has two logging styles for delivery, the idea being to make local
-deliveries stand out more visibly from remote ones. In the ``local'' style, the
-recipient address is given just as the local part, without a domain. The use of
-this style is controlled by this option. It defaults to true for the ^accept^
-router, and false for all the others.
-
-
-
-oindex:[%more%]
-`..'=
-%more%, Use: 'routers', Type: 'boolean'!!, Default: 'true'
-===
-
-The result of string expansion for this option must be a valid boolean value,
-that is, one of the strings ``yes'', ``no'', ``true'', or ``false''. Any other
-result causes an error, and delivery is deferred. If the expansion is forced to
-fail, the default value for the option (true) is used. Other failures cause
-delivery to be deferred.
-
-If this option is set false, and the router declines to handle the address, no
-further routers are tried, routing fails, and the address is bounced.
-cindex:[%self% option] However, if the router explicitly passes an address to
-the following router by means of the setting
-
- self = pass
-
-or otherwise, the setting of %more% is ignored. Also, the setting of %more%
-does not affect the behaviour if one of the precondition tests fails. In that
-case, the address is always passed to the next router.
-
-[revisionflag="changed"]
-Note that %address_data% is not considered to be a precondition. If its
-expansion is forced to fail, the router declines, and the value of %more%
-controls what happens next.
-
-
-
-oindex:[%pass_on_timeout%]
-`..'=
-%pass_on_timeout%, Use: 'routers', Type: 'boolean', Default: 'false'
-===
-
-cindex:[timeout,of router]
-cindex:[router,timeout]
-If a router times out during a host lookup, it normally causes deferral of the
-address. If %pass_on_timeout% is set, the address is passed on to the next
-router, overriding %no_more%. This may be helpful for systems that are
-intermittently connected to the Internet, or those that want to pass to a smart
-host any messages that cannot immediately be delivered.
-
-There are occasional other temporary errors that can occur while doing DNS
-lookups. They are treated in the same way as a timeout, and this option
-applies to all of them.
-
-
-
-oindex:[%pass_router%]
-`..'=
-%pass_router%, Use: 'routers', Type: 'string', Default: 'unset'
-===
-
-cindex:[router,go to after ``pass'']
-When a router returns ``pass'', the address is normally handed on to the next
-router in sequence. This can be changed by setting %pass_router% to the name
-of another router. However (unlike %redirect_router%) the named router must be
-below the current router, to avoid loops. Note that this option applies only to
-the special case of ``pass''. It does not apply when a router returns ``decline''.
-
-
-
-oindex:[%redirect_router%]
-`..'=
-%redirect_router%, Use: 'routers', Type: 'string', Default: 'unset'
-===
-
-cindex:[router,start at after redirection]
-Sometimes an administrator knows that it is pointless to reprocess addresses
-generated from alias or forward files with the same router again. For
-example, if an alias file translates real names into login ids there is no
-point searching the alias file a second time, especially if it is a large file.
-
-The %redirect_router% option can be set to the name of any router instance. It
-causes the routing of any generated addresses to start at the named router
-instead of at the first router. This option has no effect if the router in
-which it is set does not generate new addresses.
-
-
-
-oindex:[%require_files%]
-`..'=
-%require_files%, Use: 'routers'!?, Type: 'string list'!!, Default: 'unset'
-===
-
-cindex:[file,requiring for router]
-cindex:[router,requiring file existence]
-This option provides a general mechanism for predicating the running of a
-router on the existence or non-existence of certain files or directories.
-Before running a router, as one of its precondition tests, Exim works its way
-through the %require_files% list, expanding each item separately.
-
-Because the list is split before expansion, any colons in expansion items must
-be doubled, or the facility for using a different list separator must be used.
-If any expansion is forced to fail, the item is ignored. Other expansion
-failures cause routing of the address to be deferred.
-
-If any expanded string is empty, it is ignored. Otherwise, except as described
-below, each string must be a fully qualified file path, optionally preceded by
-``!''. The paths are passed to the 'stat()' function to test for the existence
-of the files or directories. The router is skipped if any paths not preceded by
-``!'' do not exist, or if any paths preceded by ``!'' do exist.
-
-cindex:[NFS]
-If 'stat()' cannot determine whether a file exists or not, delivery of
-the message is deferred. This can happen when NFS-mounted filesystems are
-unavailable.
-
-This option is checked after the %domains%, %local_parts%, and %senders%
-options, so you cannot use it to check for the existence of a file in which to
-look up a domain, local part, or sender. (See section <<SECTrouprecon>> for a
-full list of the order in which preconditions are evaluated.) However, as
-these options are all expanded, you can use the %exists% expansion condition to
-make such tests. The %require_files% option is intended for checking files
-that the router may be going to use internally, or which are needed by a
-transport (for example _.procmailrc_).
-
-During delivery, the 'stat()' function is run as root, but there is a
-facility for some checking of the accessibility of a file by another user.
-This is not a proper permissions check, but just a ``rough'' check that
-operates as follows:
-
-If an item in a %require_files% list does not contain any forward slash
-characters, it is taken to be the user (and optional group, separated by a
-comma) to be checked for subsequent files in the list. If no group is specified
-but the user is specified symbolically, the gid associated with the uid is
-used. For example:
-
- require_files = mail:/some/file
- require_files = $local_part:$home/.procmailrc
-
-If a user or group name in a %require_files% list does not exist, the
-%require_files% condition fails.
-
-Exim performs the check by scanning along the components of the file path, and
-checking the access for the given uid and gid. It checks for ``x'' access on
-directories, and ``r'' access on the final file. Note that this means that file
-access control lists, if the operating system has them, are ignored.
-
-*Warning 1*: When the router is being run to verify addresses for an
-incoming SMTP message, Exim is not running as root, but under its own uid. This
-may affect the result of a %require_files% check. In particular, 'stat()'
-may yield the error EACCES (``Permission denied''). This means that the Exim
-user is not permitted to read one of the directories on the file's path.
-
-*Warning 2*: Even when Exim is running as root while delivering a message,
-'stat()' can yield EACCES for a file in an NFS directory that is mounted
-without root access.
-
-In this case, if a check for access by a particular user is requested, Exim
-creates a subprocess that runs as that user, and tries the check again in that
-process.
-
-The default action for handling an unresolved EACCES is to consider it to
-be caused by a configuration error,
-
-and routing is deferred because the existence or non-existence of the file
-cannot be determined. However, in some circumstances it may be desirable to
-treat this condition as if the file did not exist. If the file name (or the
-exclamation mark that precedes the file name for non-existence) is preceded by
-a plus sign, the EACCES error is treated as if the file did not exist. For
-example:
-
- require_files = +/some/file
-
-If the router is not an essential part of verification (for example, it
-handles users' _.forward_ files), another solution is to set the %verify%
-option false so that the router is skipped when verifying.
-
-
-
-oindex:[%retry_use_local_part%]
-`..'=
-%retry_use_local_part%, Use: 'routers', Type: 'boolean', Default: 'see below'
-===
-
-cindex:[hints database,retry keys]
-cindex:[local part,in retry keys]
-When a delivery suffers a temporary routing failure, a retry record is created
-in Exim's hints database. For addresses whose routing depends only on the
-domain, the key for the retry record should not involve the local part, but for
-other addresses, both the domain and the local part should be included.
-Usually, remote routing is of the former kind, and local routing is of the
-latter kind.
-
-This option controls whether the local part is used to form the key for retry
-hints for addresses that suffer temporary errors while being handled by this
-router. The default value is true for any router that has %check_local_user%
-set, and false otherwise. Note that this option does not apply to hints keys
-for transport delays; they are controlled by a generic transport option of the
-same name.
-
-The setting of %retry_use_local_part% applies only to the router on which it
-appears. If the router generates child addresses, they are routed
-independently; this setting does not become attached to them.
-
-
-
-oindex:[%router_home_directory%]
-`..'=
-%router_home_directory%, Use: 'routers', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[router,home directory for]
-cindex:[home directory,for router]
-cindex:[$home$]
-This option sets a home directory for use while the router is running. (Compare
-%transport_home_directory%, which sets a home directory for later
-transporting.) In particular, if used on a ^redirect^ router, this option
-sets a value for $home$ while a filter is running. The value is expanded;
-forced expansion failure causes the option to be ignored -- other failures
-cause the router to defer.
-
-Expansion of %router_home_directory% happens immediately after the
-%check_local_user% test (if configured), before any further expansions take
-place.
-(See section <<SECTrouprecon>> for a list of the order in which preconditions
-are evaluated.)
-While the router is running, %router_home_directory% overrides the value of
-$home$ that came from %check_local_user%.
-
-When a router accepts an address and routes it to a transport (including the
-cases when a redirect router generates a pipe, file, or autoreply delivery),
-the home directory setting for the transport is taken from the first of these
-values that is set:
-
-- The %home_directory% option on the transport;
-
-- The %transport_home_directory% option on the router;
-
-- The password data if %check_local_user% is set on the router;
-
-- The %router_home_directory% option on the router.
-
-In other words, %router_home_directory% overrides the password data for the
-router, but not for the transport.
-
-
-
-oindex:[%self%]
-`..'=
-%self%, Use: 'routers', Type: 'string', Default: 'freeze'
-===
-
-cindex:[MX record,pointing to local host]
-cindex:[local host,MX pointing to]
-This option applies to those routers that use a recipient address to find a
-list of remote hosts. Currently, these are the ^dnslookup^, ^ipliteral^,
-and ^manualroute^ routers.
-Certain configurations of the ^queryprogram^ router can also specify a list
-of remote hosts.
-Usually such routers are configured to send the message to a remote host via an
-^smtp^ transport. The %self% option specifies what happens when the first
-host on the list turns out to be the local host.
-The way in which Exim checks for the local host is described in section
-<<SECTreclocipadd>>.
-
-Normally this situation indicates either an error in Exim's configuration (for
-example, the router should be configured not to process this domain), or an
-error in the DNS (for example, the MX should not point to this host). For this
-reason, the default action is to log the incident, defer the address, and
-freeze the message. The following alternatives are provided for use in special
-cases:
-
-%defer%::
-Delivery of the message is tried again later, but the message is not frozen.
-
-%reroute%: <'domain'>::
-The domain is changed to the given domain, and the address is passed back to
-be reprocessed by the routers. No rewriting of headers takes place. This
-behaviour is essentially a redirection.
-
-%reroute: rewrite:% <'domain'>::
-The domain is changed to the given domain, and the address is passed back to be
-reprocessed by the routers. Any headers that contain the original domain are
-rewritten.
-
-%pass%::
-The router passes the address to the next router, or to the router named in the
-%pass_router% option if it is set.
-cindex:[%more% option]
-This overrides %no_more%.
-+
-cindex:[$self_hostname$]
-During subsequent routing and delivery, the variable $self_hostname$ contains
-the name of the local host that the router encountered. This can be used to
-distinguish between different cases for hosts with multiple names. The
-combination
-
- self = pass
- no_more
-+
-ensures that only those addresses that routed to the local host are passed on.
-Without %no_more%, addresses that were declined for other reasons would also
-be passed to the next router.
-
-%fail%::
-Delivery fails and an error report is generated.
-
-%send%::
-cindex:[local host,sending to]
-The anomaly is ignored and the address is queued for the transport. This
-setting should be used with extreme caution. For an ^smtp^ transport, it makes
-sense only in cases where the program that is listening on the SMTP port is not
-this version of Exim. That is, it must be some other MTA, or Exim with a
-different configuration file that handles the domain in another way.
-
-
-
-oindex:[%senders%]
-`..'=
-%senders%, Use: 'routers'!?, Type: 'address list'!!, Default: 'unset'
-===
-
-cindex:[router,checking senders]
-If this option is set, the router is skipped unless the message's sender
-address matches something on the list.
-See section <<SECTrouprecon>> for a list of the order in which preconditions
-are evaluated.
-
-There are issues concerning verification when the running of routers is
-dependent on the sender. When Exim is verifying the address in an %errors_to%
-setting, it sets the sender to the null string. When using the %-bt% option to
-check a configuration file, it is necessary also to use the %-f% option to set
-an appropriate sender. For incoming mail, the sender is unset when verifying
-the sender, but is available when verifying any recipients. If the SMTP
-VRFY command is enabled, it must be used after MAIL if the sender
-address matters.
-
-
-oindex:[%translate_ip_address%]
-`..'=
-%translate_ip_address%, Use: 'routers', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[IP address,translating]
-cindex:[packet radio]
-cindex:[router,IP address translation]
-There exist some rare networking situations (for example, packet radio) where
-it is helpful to be able to translate IP addresses generated by normal routing
-mechanisms into other IP addresses, thus performing a kind of manual IP
-routing. This should be done only if the normal IP routing of the TCP/IP stack
-is inadequate or broken. Because this is an extremely uncommon requirement, the
-code to support this option is not included in the Exim binary unless
-SUPPORT_TRANSLATE_IP_ADDRESS=yes is set in _Local/Makefile_.
-
-cindex:[$host_address$]
-The %translate_ip_address% string is expanded for every IP address generated
-by the router, with the generated address set in $host_address$. If the
-expansion is forced to fail, no action is taken.
-For any other expansion error, delivery of the message is deferred.
-If the result of the expansion is an IP address, that replaces the original
-address; otherwise the result is assumed to be a host name -- this is looked up
-using 'gethostbyname()' (or 'getipnodebyname()' when available) to produce
-one or more replacement IP addresses. For example, to subvert all IP addresses
-in some specific networks, this could be added to a router:
-
-....
-translate_ip_address = \
- ${lookup{${mask:$host_address/26}}lsearch{/some/file}{$value}fail}}
-....
-
-The file would contain lines like
-
- 10.2.3.128/26 some.host
- 10.8.4.34/26 10.44.8.15
-
-You should not make use of this facility unless you really understand what you
-are doing.
-
-
-
-oindex:[%transport%]
-`..'=
-%transport%, Use: 'routers', Type: 'string'!!, Default: 'unset'
-===
-
-This option specifies the transport to be used when a router accepts an address
-and sets it up for delivery. A transport is never needed if a router is used
-only for verification. The value of the option is expanded at routing time,
-after the expansion of %errors_to%, %headers_add%, and %headers_remove%, and
-result must be the name of one of the configured transports. If it is not,
-delivery is deferred.
-
-The %transport% option is not used by the ^redirect^ router, but it does have
-some private options that set up transports for pipe and file deliveries (see
-chapter <<CHAPredirect>>).
-
-
-
-oindex:[%transport_current_directory%]
-`..'=
-%transport_current_directory%, Use: 'routers', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[current directory for local transport]
-This option associates a current directory with any address that is routed
-to a local transport. This can happen either because a transport is
-explicitly configured for the router, or because it generates a delivery to a
-file or a pipe. During the delivery process (that is, at transport time), this
-option string is expanded and is set as the current directory, unless
-overridden by a setting on the transport.
-If the expansion fails for any reason, including forced failure, an error is
-logged, and delivery is deferred.
-See chapter <<CHAPenvironment>> for details of the local delivery environment.
-
-
-
-
-oindex:[%transport_home_directory%]
-`..'=
-%transport_home_directory%, Use: 'routers', Type: 'string'!!, Default: 'see below'
-===
-
-cindex:[home directory,for local transport]
-This option associates a home directory with any address that is routed to a
-local transport. This can happen either because a transport is explicitly
-configured for the router, or because it generates a delivery to a file or a
-pipe. During the delivery process (that is, at transport time), the option
-string is expanded and is set as the home directory, unless overridden by a
-setting of %home_directory% on the transport.
-If the expansion fails for any reason, including forced failure, an error is
-logged, and delivery is deferred.
-
-If the transport does not specify a home directory, and
-%transport_home_directory% is not set for the router, the home directory for
-the tranport is taken from the password data if %check_local_user% is set for
-the router. Otherwise it is taken from %router_home_directory% if that option
-is set; if not, no home directory is set for the transport.
-
-See chapter <<CHAPenvironment>> for further details of the local delivery
-environment.
-
-
-
-
-oindex:[%unseen%]
-`..'=
-%unseen%, Use: 'routers', Type: 'boolean'!!, Default: 'false'
-===
-
-cindex:[router,carrying on after success]
-The result of string expansion for this option must be a valid boolean value,
-that is, one of the strings ``yes'', ``no'', ``true'', or ``false''. Any other
-result causes an error, and delivery is deferred. If the expansion is forced to
-fail, the default value for the option (false) is used. Other failures cause
-delivery to be deferred.
-
-When this option is set true, routing does not cease if the router accepts the
-address. Instead, a copy of the incoming address is passed to the next router,
-overriding a false setting of %more%. There is little point in setting %more%
-false if %unseen% is always true, but it may be useful in cases when the value
-of %unseen% contains expansion items (and therefore, presumably, is sometimes
-true and sometimes false).
-
-[revisionflag="changed"]
-cindex:[copy of message (%unseen% option)]
-The %unseen% option can be used to cause copies of messages to be delivered to
-some other destination, while also carrying out a normal delivery. In effect,
-the current address is made into a ``parent'' that has two children -- one that
-is delivered as specified by this router, and a clone that goes on to be routed
-further. For this reason, %unseen% may not be combined with the %one_time%
-option in a ^redirect^ router.
-
-*Warning*: Header lines added to the address (or specified for removal) by this
-router or by previous routers affect the ``unseen'' copy of the message only.
-The clone that continues to be processed by further routers starts with no
-added headers and none specified for removal. However, any data that was set by
-the %address_data% option in the current or previous routers is passed on.
-Setting the %unseen% option has a similar effect to the %unseen% command
-qualifier in filter files.
-
-
-
-oindex:[%user%]
-`..'=
-%user%, Use: 'routers', Type: 'string'!!, Default: 'see below'
-===
-
-cindex:[uid (user id),local delivery]
-cindex:[local transports,uid and gid]
-cindex:[transport,local]
-cindex:[router,user for filter processing]
-cindex:[filter,user for processing]
-When a router queues an address for a transport, and the transport does not
-specify a user, the user given here is used when running the delivery process.
-The user may be specified numerically or by name. If expansion fails, the
-error is logged and delivery is deferred.
-This user is also used by the ^redirect^ router when running a filter file.
-The default is unset, except when %check_local_user% is set. In this case,
-the default is taken from the password information. If the user is specified as
-a name, and %group% is not set, the group associated with the user is used. See
-also %initgroups% and %group% and the discussion in chapter <<CHAPenvironment>>.
-
-
-
-oindex:[%verify%]
-`..'=
-%verify%, Use: 'routers'!?, Type: 'boolean', Default: 'true'
-===
-
-Setting this option has the effect of setting %verify_sender% and
-%verify_recipient% to the same value.
-
-
-oindex:[%verify_only%]
-`..'=
-%verify_only%, Use: 'routers'!?, Type: 'boolean', Default: 'false'
-===
-
-cindex:[EXPN,with %verify_only%]
-cindex:[%-bv% option]
-cindex:[router,used only when verifying]
-If this option is set, the router is used only when verifying an address or
-testing with the %-bv% option, not when actually doing a delivery, testing
-with the %-bt% option, or running the SMTP EXPN command. It can be further
-restricted to verifying only senders or recipients by means of %verify_sender%
-and %verify_recipient%.
-
-*Warning*: When the router is being run to verify addresses for an incoming
-SMTP message, Exim is not running as root, but under its own uid. If the router
-accesses any files, you need to make sure that they are accessible to the Exim
-user or group.
-
-
-oindex:[%verify_recipient%]
-`..'=
-%verify_recipient%, Use: 'routers'!?, Type: 'boolean', Default: 'true'
-===
-
-If this option is false, the router is skipped when verifying recipient
-addresses
-or testing recipient verification using %-bv%.
-See section <<SECTrouprecon>> for a list of the order in which preconditions
-are evaluated.
-
-
-oindex:[%verify_sender%]
-`..'=
-%verify_sender%, Use: 'routers'!?, Type: 'boolean', Default: 'true'
-===
-
-If this option is false, the router is skipped when verifying sender addresses
-or testing sender verification using %-bvs%.
-See section <<SECTrouprecon>> for a list of the order in which preconditions
-are evaluated.
-
-
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-The accept router
------------------
-cindex:[^accept^ router]
-cindex:[routers,^accept^]
-The ^accept^ router has no private options of its own. Unless it is being used
-purely for verification (see %verify_only%) a transport is required to be
-defined by the generic %transport% option. If the preconditions that are
-specified by generic options are met, the router accepts the address and queues
-it for the given transport. The most common use of this router is for setting
-up deliveries to local mailboxes. For example:
-
- localusers:
- driver = accept
- domains = mydomain.example
- check_local_user
- transport = local_delivery
-
-The %domains% condition in this example checks the domain of the address, and
-%check_local_user% checks that the local part is the login of a local user.
-When both preconditions are met, the ^accept^ router runs, and queues the
-address for the ^local_delivery^ transport.
-
-
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPdnslookup]]
-The dnslookup router
---------------------
-cindex:[^dnslookup^ router]
-cindex:[routers,^dnslookup^]
-The ^dnslookup^ router looks up the hosts that handle mail for the
-recipient's domain in the DNS. A transport must always be set for this router,
-unless %verify_only% is set.
-
-If SRV support is configured (see %check_srv% below), Exim first searches for
-SRV records. If none are found, or if SRV support is not configured,
-MX records are looked up. If no MX records exist, address records are sought.
-However, %mx_domains% can be set to disable the direct use of address records.
-
-MX records of equal priority are sorted by Exim into a random order. Exim then
-looks for address records for the host names obtained from MX or SRV records.
-When a host has more than one IP address, they are sorted into a random order,
-except that IPv6 addresses are always sorted before IPv4 addresses. If all the
-IP addresses found are discarded by a setting of the %ignore_target_hosts%
-generic option, the router declines.
-
-Unless they have the highest priority (lowest MX value), MX records that point
-to the local host, or to any host name that matches %hosts_treat_as_local%,
-are discarded, together with any other MX records of equal or lower priority.
-
-cindex:[MX record,pointing to local host]
-cindex:[local host,MX pointing to]
-cindex:[%self% option,in ^dnslookup^ router]
-If the host pointed to by the highest priority MX record, or looked up as an
-address record, is the local host, or matches %hosts_treat_as_local%, what
-happens is controlled by the generic %self% option.
-
-
-[[SECTprowitdnsloo]]
-Problems with DNS lookups
-~~~~~~~~~~~~~~~~~~~~~~~~~
-There have been problems with DNS servers when SRV records are looked up.
-Some mis-behaving servers return a DNS error or timeout when a non-existent
-SRV record is sought. Similar problems have in the past been reported for
-MX records. The global %dns_again_means_nonexist% option can help with this
-problem, but it is heavy-handed because it is a global option.
-
-For this reason, there are two options, %srv_fail_domains% and
-%mx_fail_domains%, that control what happens when a DNS lookup in a
-^dnslookup^ router results in a DNS failure or a ``try again'' response. If an
-attempt to look up an SRV or MX record causes one of these results, and the
-domain matches the relevant list, Exim behaves as if the DNS had responded ``no
-such record''. In the case of an SRV lookup, this means that the router proceeds
-to look for MX records; in the case of an MX lookup, it proceeds to look for A
-or AAAA records, unless the domain matches %mx_domains%, in which case routing
-fails.
-
-
-
-
-Private options for dnslookup
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[options,^dnslookup^ router]
-The private options for the ^dnslookup^ router are as follows:
-
-oindex:[%check_secondary_mx%]
-`..'=
-%check_secondary_mx%, Use: 'dnslookup', Type: 'boolean', Default: 'false'
-===
-
-cindex:[MX record,checking for secondary]
-If this option is set, the router declines unless the local host is found in
-(and removed from) the list of hosts obtained by MX lookup. This can be used to
-process domains for which the local host is a secondary mail exchanger
-differently to other domains. The way in which Exim decides whether a host is
-the local host is described in section <<SECTreclocipadd>>.
-
-
-oindex:[%check_srv%]
-`..'=
-%check_srv%, Use: 'dnslookup', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[SRV record,enabling use of]
-The ^dnslookup^ router supports the use of SRV records (see RFC 2782) in
-addition to MX and address records. The support is disabled by default. To
-enable SRV support, set the %check_srv% option to the name of the service
-required. For example,
-
- check_srv = smtp
-
-looks for SRV records that refer to the normal smtp service. The option is
-expanded, so the service name can vary from message to message or address
-to address. This might be helpful if SRV records are being used for a
-submission service. If the expansion is forced to fail, the %check_srv%
-option is ignored, and the router proceeds to look for MX records in the
-normal way.
-
-When the expansion succeeds, the router searches first for SRV records for
-the given service (it assumes TCP protocol). A single SRV record with a
-host name that consists of just a single dot indicates ``no such service for
-this domain''; if this is encountered, the router declines. If other kinds of
-SRV record are found, they are used to construct a host list for delivery
-according to the rules of RFC 2782. MX records are not sought in this case.
-
-When no SRV records are found, MX records (and address records) are sought in
-the traditional way. In other words, SRV records take precedence over MX
-records, just as MX records take precedence over address records. Note that
-this behaviour is not sanctioned by RFC 2782, though a previous draft RFC
-defined it. It is apparently believed that MX records are sufficient for email
-and that SRV records should not be used for this purpose. However, SRV records
-have an additional ``weight'' feature which some people might find useful when
-trying to split an SMTP load between hosts of different power.
-
-See section <<SECTprowitdnsloo>> above for a discussion of Exim's behaviour when
-there is a DNS lookup error.
-
-
-
-oindex:[%mx_domains%]
-`..'=
-%mx_domains%, Use: 'dnslookup', Type: 'domain list'!!, Default: 'unset'
-===
-
-cindex:[MX record,required to exist]
-cindex:[SRV record,required to exist]
-A domain that matches %mx_domains% is required to have either an MX or an SRV
-record in order to be recognised. (The name of this option could be improved.)
-For example, if all the mail hosts in 'fict.example' are known to have MX
-records, except for those in 'discworld.fict.example', you could use this
-setting:
-
- mx_domains = ! *.discworld.fict.example : *.fict.example
-
-This specifies that messages addressed to a domain that matches the list but
-has no MX record should be bounced immediately instead of being routed using
-the address record.
-
-
-oindex:[%mx_fail_domains%]
-`..'=
-%mx_fail_domains%, Use: 'dnslookup', Type: 'domain list'!!, Default: 'unset'
-===
-
-If the DNS lookup for MX records for one of the domains in this list causes a
-DNS lookup error, Exim behaves as if no MX records were found. See section
-<<SECTprowitdnsloo>> for more discussion.
-
-
-
-
-oindex:[%qualify_single%]
-`..'=
-%qualify_single%, Use: 'dnslookup', Type: 'boolean', Default: 'true'
-===
-
-cindex:[DNS,resolver options]
-cindex:[DNS,qualifying single-component names]
-When this option is true, the resolver option RES_DEFNAMES is set for DNS
-lookups. Typically, but not standardly, this causes the resolver to qualify
-single-component names with the default domain. For example, on a machine
-called 'dictionary.ref.example', the domain 'thesaurus' would be changed to
-'thesaurus.ref.example' inside the resolver. For details of what your resolver
-actually does, consult your man pages for 'resolver' and 'resolv.conf'.
-
-
-
-oindex:[%rewrite_headers%]
-`..'=
-%rewrite_headers%, Use: 'dnslookup', Type: 'boolean', Default: 'true'
-===
-
-cindex:[rewriting,header lines]
-cindex:[header lines,rewriting]
-If the domain name in the address that is being processed is not fully
-qualified, it may be expanded to its full form by a DNS lookup. For example, if
-an address is specified as 'dormouse@teaparty', the domain might be
-expanded to 'teaparty.wonderland.fict.example'. Domain expansion can also
-occur as a result of setting the %widen_domains% option. If %rewrite_headers%
-is true, all occurrences of the abbreviated domain name in any 'Bcc:', 'Cc:',
-'From:', 'Reply-to:', 'Sender:', and 'To:' header lines of the message are
-rewritten with the full domain name.
-
-This option should be turned off only when it is known that no message is
-ever going to be sent outside an environment where the abbreviation makes
-sense.
-
-When an MX record is looked up in the DNS and matches a wildcard record, name
-servers normally return a record containing the name that has been looked up,
-making it impossible to detect whether a wildcard was present or not. However,
-some name servers have recently been seen to return the wildcard entry. If the
-name returned by a DNS lookup begins with an asterisk, it is not used for
-header rewriting.
-
-
-oindex:[%same_domain_copy_routing%]
-`..'=
-%same_domain_copy_routing%, Use: 'dnslookup', Type: 'boolean', Default: 'false'
-===
-
-cindex:[address,copying routing]
-Addresses with the same domain are normally routed by the ^dnslookup^ router
-to the same list of hosts. However, this cannot be presumed, because the router
-options and preconditions may refer to the local part of the address. By
-default, therefore, Exim routes each address in a message independently. DNS
-servers run caches, so repeated DNS lookups are not normally expensive, and in
-any case, personal messages rarely have more than a few recipients.
-
-If you are running mailing lists with large numbers of subscribers at the same
-domain, and you are using a ^dnslookup^ router which is independent of the
-local part, you can set %same_domain_copy_routing% to bypass repeated DNS
-lookups for identical domains in one message. In this case, when ^dnslookup^
-routes an address to a remote transport, any other unrouted addresses in the
-message that have the same domain are automatically given the same routing
-without processing them independently,
-provided the following conditions are met:
-
-- No router that processed the address specified %headers_add% or
-%headers_remove%.
-
-- The router did not change the address in any way, for example, by ``widening''
-the domain.
-
-
-
-
-oindex:[%search_parents%]
-`..'=
-%search_parents%, Use: 'dnslookup', Type: 'boolean', Default: 'false'
-===
-
-cindex:[DNS,resolver options]
-When this option is true, the resolver option RES_DNSRCH is set for DNS
-lookups. This is different from the %qualify_single% option in that it applies
-to domains containing dots. Typically, but not standardly, it causes the
-resolver to search for the name in the current domain and in parent domains.
-For example, on a machine in the 'fict.example' domain, if looking up
-'teaparty.wonderland' failed, the resolver would try
-'teaparty.wonderland.fict.example'. For details of what your resolver
-actually does, consult your man pages for 'resolver' and 'resolv.conf'.
-
-Setting this option true can cause problems in domains that have a wildcard MX
-record, because any domain that does not have its own MX record matches the
-local wildcard.
-
-
-
-oindex:[%srv_fail_domains%]
-`..'=
-%srv_fail_domains%, Use: 'dnslookup', Type: 'domain list'!!, Default: 'unset'
-===
-
-If the DNS lookup for SRV records for one of the domains in this list causes a
-DNS lookup error, Exim behaves as if no SRV records were found. See section
-<<SECTprowitdnsloo>> for more discussion.
-
-
-
-
-oindex:[%widen_domains%]
-`..'=
-%widen_domains%, Use: 'dnslookup', Type: 'string list', Default: 'unset'
-===
-
-cindex:[domain,partial; widening]
-If a DNS lookup fails and this option is set, each of its strings in turn is
-added onto the end of the domain, and the lookup is tried again. For example,
-if
-
- widen_domains = fict.example:ref.example
-
-is set and a lookup of 'klingon.dictionary' fails,
-'klingon.dictionary.fict.example' is looked up, and if this fails,
-'klingon.dictionary.ref.example' is tried. Note that the %qualify_single%
-and %search_parents% options can cause some widening to be undertaken inside
-the DNS resolver.
-
-[revisionflag="changed"]
-%widen_domains% is not applied to sender addresses when verifying, unless
-%rewrite_headers% is false (not the default).
-
-
-
-Effect of qualify_single and search_parents
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-When a domain from an envelope recipient is changed by the resolver as a result
-of the %qualify_single% or %search_parents% options, Exim rewrites the
-corresponding address in the message's header lines unless %rewrite_headers%
-is set false. Exim then re-routes the address, using the full domain.
-
-These two options affect only the DNS lookup that takes place inside the router
-for the domain of the address that is being routed. They do not affect lookups
-such as that implied by
-
- domains = @mx_any
-
-that may happen while processing a router precondition before the router is
-entered. No widening ever takes place for these lookups.
-
-
-
-
-
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-The ipliteral router
---------------------
-cindex:[^ipliteral^ router]
-cindex:[domain literal,routing]
-cindex:[routers,^ipliteral^]
-This router has no private options. Unless it is being used purely for
-verification (see %verify_only%) a transport is required to be defined by the
-generic %transport% option. The router accepts the address if its domain part
-takes the form of an RFC 2822 domain literal, that is, an IP address enclosed
-in square brackets. For example, this router handles the address
-
- root@[192.168.1.1]
-
-by setting up delivery to the host with that IP address.
-
-cindex:[%self% option,in ^ipliteral^ router]
-If the IP address matches something in %ignore_target_hosts%, the router
-declines. If an IP literal turns out to refer to the local host, the generic
-%self% option determines what happens.
-
-The RFCs require support for domain literals; however, their use is
-controversial in today's Internet. If you want to use this router, you must
-also set the main configuration option %allow_domain_literals%. Otherwise,
-Exim will not recognize the domain literal syntax in addresses.
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-The iplookup router
--------------------
-cindex:[^iplookup^ router]
-cindex:[routers,^iplookup^]
-The ^iplookup^ router was written to fulfil a specific requirement in
-Cambridge University (which in fact no longer exists). For this reason, it is
-not included in the binary of Exim by default. If you want to include it, you
-must set
-
- ROUTER_IPLOOKUP=yes
-
-in your _Local/Makefile_ configuration file.
-
-The ^iplookup^ router routes an address by sending it over a TCP or UDP
-connection to one or more specific hosts. The host can then return the same or
-a different address -- in effect rewriting the recipient address in the
-message's envelope. The new address is then passed on to subsequent routers. If
-this process fails, the address can be passed on to other routers, or delivery
-can be deferred.
-
-Background, for those that are interested: We have an Oracle database of all
-Cambridge users, and one of the items of data it maintains for each user is
-where to send mail addressed to 'user@cam.ac.uk'. The MX records for
-'cam.ac.uk' point to a central machine that has a large alias list that is
-abstracted from the database. Mail from outside is switched by this system, and
-originally internal mail was also done this way. However, this resulted in a
-fair number of messages travelling from some of our larger systems to the
-switch and back again. The Oracle machine now runs a UDP service that can be
-called by the ^iplookup^ router in Exim to find out where 'user@cam.ac.uk'
-addresses really have to go; this saves passing through the central switch, and
-in many cases saves doing any remote delivery at all.
-
-Since ^iplookup^ is just a rewriting router, a transport must not be
-specified for it.
-cindex:[options,^iplookup^ router]
-
-
-oindex:[%hosts%]
-`..'=
-%hosts%, Use: 'iplookup', Type: 'string', Default: 'unset'
-===
-
-This option must be supplied. Its value is a colon-separated list of host
-names. The hosts are looked up using 'gethostbyname()'
-(or 'getipnodebyname()' when available)
-and are tried in order until one responds to the query. If none respond, what
-happens is controlled by %optional%.
-
-
-oindex:[%optional%]
-`..'=
-%optional%, Use: 'iplookup', Type: 'boolean', Default: 'false'
-===
-
-If %optional% is true, if no response is obtained from any host, the address is
-passed to the next router, overriding %no_more%. If %optional% is false,
-delivery to the address is deferred.
-
-
-oindex:[%port%]
-`..'=
-%port%, Use: 'iplookup', Type: 'integer', Default: '0'
-===
-
-cindex:[port,^iplookup^ router]
-This option must be supplied. It specifies the port number for the TCP or UDP
-call.
-
-
-oindex:[%protocol%]
-`..'=
-%protocol%, Use: 'iplookup', Type: 'string', Default: 'udp'
-===
-
-This option can be set to ``udp'' or ``tcp'' to specify which of the two protocols
-is to be used.
-
-
-oindex:[%query%]
-`..'=
-%query%, Use: 'iplookup', Type: 'string'!!, Default: `\$local_part@\$domain \$local_part@\$domain`
-===
-
-This defines the content of the query that is sent to the remote hosts. The
-repetition serves as a way of checking that a response is to the correct query
-in the default case (see %response_pattern% below).
-
-
-oindex:[%reroute%]
-`..'=
-%reroute%, Use: 'iplookup', Type: 'string'!!, Default: 'unset'
-===
-
-If this option is not set, the rerouted address is precisely the byte string
-returned by the remote host, up to the first white space, if any. If set, the
-string is expanded to form the rerouted address. It can include parts matched
-in the response by %response_pattern% by means of numeric variables such as
-$1$, $2$, etc. The variable $0$ refers to the entire input string,
-whether or not a pattern is in use. In all cases, the rerouted address must end
-up in the form 'local_part@domain'.
-
-
-oindex:[%response_pattern%]
-`..'=
-%response_pattern%, Use: 'iplookup', Type: 'string', Default: 'unset'
-===
-
-This option can be set to a regular expression that is applied to the string
-returned from the remote host. If the pattern does not match the response, the
-router declines. If %response_pattern% is not set, no checking of the response
-is done, unless the query was defaulted, in which case there is a check that
-the text returned after the first white space is the original address. This
-checks that the answer that has been received is in response to the correct
-question. For example, if the response is just a new domain, the following
-could be used:
-
- response_pattern = ^([^@]+)$
- reroute = $local_part@$1
-
-
-
-oindex:[%timeout%]
-`..'=
-%timeout%, Use: 'iplookup', Type: 'time', Default: '5s'
-===
-
-This specifies the amount of time to wait for a response from the remote
-machine. The same timeout is used for the 'connect()' function for a TCP
-call. It does not apply to UDP.
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-The manualroute router
-----------------------
-cindex:[^manualroute^ router]
-cindex:[routers,^manualroute^]
-cindex:[domain,manually routing]
-The ^manualroute^ router is so-called because it provides a way of manually
-routing an address according to its domain. It is mainly used when you want to
-route addresses to remote hosts according to your own rules, bypassing the
-normal DNS routing that looks up MX records. However, ^manualroute^ can also
-route to local transports, a facility that may be useful if you want to save
-messages for dial-in hosts in local files.
-
-The ^manualroute^ router compares a list of domain patterns with the domain it
-is trying to route. If there is no match, the router declines. Each pattern has
-associated with it a list of hosts and some other optional data, which may
-include a transport. The combination of a pattern and its data is called a
-``routing rule''. For patterns that do not have an associated transport, the
-generic %transport% option must specify a transport, unless the router is being
-used purely for verification (see %verify_only%).
-
-cindex:[$host$]
-In the case of verification, matching the domain pattern is sufficient for the
-router to accept the address. When actually routing an address for delivery,
-an address that matches a domain pattern is queued for the associated
-transport. If the transport is not a local one, a host list must be associated
-with the pattern; IP addresses are looked up for the hosts, and these are
-passed to the transport along with the mail address. For local transports, a
-host list is optional. If it is present, it is passed in $host$ as a single
-text string.
-
-The list of routing rules can be provided as an inline string in %route_list%,
-or the data can be obtained by looking up the domain in a file or database by
-setting %route_data%. Only one of these settings may appear in any one
-instance of ^manualroute^. The format of routing rules is described below,
-following the list of private options.
-
-
-[[SECTprioptman]]
-Private options for manualroute
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-cindex:[options,^manualroute^ router]
-The private options for the ^manualroute^ router are as follows:
-
-
-oindex:[%host_find_failed%]
-`..'=
-%host_find_failed%, Use: 'manualroute', Type: 'string', Default: 'freeze'
-===
-
-This option controls what happens when ^manualroute^ tries to find an IP
-address for a host, and the host does not exist. The option can be set to one
-of
-
- decline
- defer
- fail
- freeze
- pass
-
-The default assumes that this state is a serious configuration error. The
-difference between ``pass'' and ``decline'' is that the former forces the address
-to be passed to the next router (or the router defined by %pass_router%),
-cindex:[%more% option]
-overriding %no_more%, whereas the latter passes the address to the next router
-only if %more% is true.
-
-This option applies only to a definite ``does not exist'' state; if a host lookup
-gets a temporary error, delivery is deferred unless the generic
-%pass_on_timeout% option is set.
-
-
-oindex:[%hosts_randomize%]
-`..'=
-%hosts_randomize%, Use: 'manualroute', Type: 'boolean', Default: 'false'
-===
-
-cindex:[randomized host list]
-cindex:[host,list of; randomized]
-If this option is set, the order of the items in a host list in a routing rule
-is randomized each time the list is used, unless an option in the routing rule
-overrides (see below). Randomizing the order of a host list can be used to do
-crude load sharing. However, if more than one mail address is routed by the
-same router to the same host list, the host lists are considered to be the same
-(even though they may be randomized into different orders) for the purpose of
-deciding whether to batch the deliveries into a single SMTP transaction.
-
-When %hosts_randomize% is true, a host list may be split
-into groups whose order is separately randomized. This makes it possible to
-set up MX-like behaviour. The boundaries between groups are indicated by an
-item that is just `+` in the host list. For example:
-
- route_list = * host1:host2:host3:+:host4:host5
-
-The order of the first three hosts and the order of the last two hosts is
-randomized for each use, but the first three always end up before the last two.
-If %hosts_randomize% is not set, a `+` item in the list is ignored. If a
-randomized host list is passed to an ^smtp^ transport that also has
-%hosts_randomize set%, the list is not re-randomized.
-
-
-oindex:[%route_data%]
-`..'=
-%route_data%, Use: 'manualroute', Type: 'string'!!, Default: 'unset'
-===
-
-If this option is set, it must expand to yield the data part of a routing rule.
-Typically, the expansion string includes a lookup based on the domain. For
-example:
-
- route_data = ${lookup{$domain}dbm{/etc/routes}}
-
-If the expansion is forced to fail, or the result is an empty string, the
-router declines. Other kinds of expansion failure cause delivery to be
-deferred.
-
-
-oindex:[%route_list%]
-`..'=
-%route_list%, Use: 'manualroute', "Type: 'string list, semicolon-separated'", Default: 'unset'
-===
-
-This string is a list of routing rules, in the form defined below. Note that,
-unlike most string lists, the items are separated by semicolons. This is so
-that they may contain colon-separated host lists.
-
-
-oindex:[%same_domain_copy_routing%]
-`..'=
-%same_domain_copy_routing%, Use: 'manualroute', Type: 'boolean', Default: 'false'
-===
-
-cindex:[address,copying routing]
-Addresses with the same domain are normally routed by the ^manualroute^ router
-to the same list of hosts. However, this cannot be presumed, because the router
-options and preconditions may refer to the local part of the address. By
-default, therefore, Exim routes each address in a message independently. DNS
-servers run caches, so repeated DNS lookups are not normally expensive, and in
-any case, personal messages rarely have more than a few recipients.
-
-If you are running mailing lists with large numbers of subscribers at the same
-domain, and you are using a ^manualroute^ router which is independent of the
-local part, you can set %same_domain_copy_routing% to bypass repeated DNS
-lookups for identical domains in one message. In this case, when ^manualroute^
-routes an address to a remote transport, any other unrouted addresses in the
-message that have the same domain are automatically given the same routing
-without processing them independently. However, this is only done if
-%headers_add% and %headers_remove% are unset.
-
-
-
-
-Routing rules in route_list
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The value of %route_list% is a string consisting of a sequence of routing
-rules, separated by semicolons. If a semicolon is needed in a rule, it can be
-entered as two semicolons. Alternatively, the list separator can be changed as
-described (for colon-separated lists) in section <<SECTlistconstruct>>.
-Empty rules are ignored. The format of each rule is
-
- <domain pattern> <list of hosts> <options>
-
-The following example contains two rules, each with a simple domain pattern and
-no options:
-
-....
-route_list = \
- dict.ref.example mail-1.ref.example:mail-2.ref.example ; \
- thes.ref.example mail-3.ref.example:mail-4.ref.example
-....
-
-The three parts of a rule are separated by white space. The pattern and the
-list of hosts can be enclosed in quotes if necessary, and if they are, the
-usual quoting rules apply. Each rule in a %route_list% must start with a
-single domain pattern, which is the only mandatory item in the rule. The
-pattern is in the same format as one item in a domain list (see section
-<<SECTdomainlist>>),
-except that it may not be the name of an interpolated file.
-That is, it may be wildcarded, or a regular expression, or a file or database
-lookup (with semicolons doubled, because of the use of semicolon as a separator
-in a %route_list%).
-
-The rules in %route_list% are searched in order until one of the patterns
-matches the domain that is being routed. The list of hosts and then options are
-then used as described below. If there is no match, the router declines. When
-%route_list% is set, %route_data% must not be set.
-
-
-
-Routing rules in route_data
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The use of %route_list% is convenient when there are only a small number of
-routing rules. For larger numbers, it is easier to use a file or database to
-hold the routing information, and use the %route_data% option instead.
-The value of %route_data% is a list of hosts, followed by (optional) options.
-Most commonly, %route_data% is set as a string that contains an
-expansion lookup. For example, suppose we place two routing rules in a file
-like this:
-
- dict.ref.example: mail-1.ref.example:mail-2.ref.example
- thes.ref.example: mail-3.ref.example:mail-4.ref.example
-
-This data can be accessed by setting
-
- route_data = ${lookup{$domain}lsearch{/the/file/name}}
-
-Failure of the lookup results in an empty string, causing the router to
-decline. However, you do not have to use a lookup in %route_data%. The only
-requirement is that the result of expanding the string is a list of hosts,
-possibly followed by options, separated by white space. The list of hosts must
-be enclosed in quotes if it contains white space.
-
-
-
-
-Format of the list of hosts
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
-[revisionflag="changed"]
-A list of hosts, whether obtained via %route_data% or %route_list%, is always
-separately expanded before use. If the expansion fails, the router declines.
-The result of the expansion must be a colon-separated list of names and/or
-IP addresses, optionally also including ports. The format of each item in the
-list is described in the next section. The list separator can be changed as
-described in section <<SECTlistconstruct>>.
-
-If the list of hosts was obtained from a %route_list% item, the following
-variables are set during its expansion:
-
-- cindex:[numerical variables ($1$ $2$ etc),in ^manualroute^ router]
-If the domain was matched against a regular expression, the numeric variables
-$1$, $2$, etc. may be set. For example:
-
-....
- route_list = ^domain(\d+) host-$1.text.example
-....
-
-- $0$ is always set to the entire domain.
-
-- $1$ is also set when partial matching is done in a file lookup.
-
-- cindex:[$value$]
-If the pattern that matched the domain was a lookup item, the data that was
-looked up is available in the expansion variable $value$. For example:
-
-....
- route_list = lsearch;;/some/file.routes $value
-....
-
-Note the doubling of the semicolon in the pattern that is necessary because
-semicolon is the default route list separator.
-
-
-
-[[SECTformatonehostitem]]
-Format of one host item
-~~~~~~~~~~~~~~~~~~~~~~~
-[revisionflag="changed"]
-Each item in the list of hosts is either a host name or an IP address,
-optionally with an attached port number. When no port is given, an IP address
-is not enclosed in brackets. When a port is specified, it overrides the port
-specification on the transport. The port is separated from the name or address
-by a colon. This leads to some complications:
-
-[revisionflag="changed"]
-- Because colon is the default separator for the list of hosts, either
-the colon that specifies a port must be doubled, or the list separator must
-be changed. The following two examples have the same effect:
-+
- route_list = * "host1.tld::1225 : host2.tld::1226"
- route_list = * "<+ host1.tld:1225 + host2.tld:1226"
-
-[revisionflag="changed"]
-- When IPv6 addresses are involved, it gets worse, because they contain
-colons of their own. To make this case easier, it is permitted to
-enclose an IP address (either v4 or v6) in square brackets if a port
-number follows. For example:
-+
- route_list = * "</ [10.1.1.1]:1225 / [::1]:1226"
-
-
-
-[[SECThostshowused]]
-How the list of hosts is used
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-When an address is routed to an ^smtp^ transport by ^manualroute^, each of
-the hosts is tried, in the order specified, when carrying out the SMTP
-delivery. However, the order can be changed by setting the %hosts_randomize%
-option, either on the router (see section <<SECTprioptman>> above), or on the
-transport.
-
-Hosts may be listed by name or by IP address. An unadorned name in the list of
-hosts is interpreted as a host name. A name that is followed by `/MX` is
-interpreted as an indirection to a sublist of hosts obtained by looking up MX
-records in the DNS. For example:
-
- route_list = * x.y.z:p.q.r/MX:e.f.g
-
-[revisionflag="changed"]
-If this feature is used with a port specifier, the port must come last. For
-example:
-
- route_list = * dom1.tld/mx::1225
-
-If the %hosts_randomize% option is set, the order of the items in the list is
-randomized before any lookups are done. Exim then scans the list; for any name
-that is not followed by `/MX` it looks up an IP address. If this turns out to
-be an interface on the local host and the item is not the first in the list,
-Exim discards it and any subsequent items. If it is the first item, what
-happens is controlled by the
-cindex:[%self% option,in ^manualroute^ router]
-%self% option of the router.
-
-A name on the list that is followed by `/MX` is replaced with the list of
-hosts obtained by looking up MX records for the name. This is always a DNS
-lookup; the %bydns% and %byname% options (see section <<SECThowoptused>> below)
-are not relevant here. The order of these hosts is determined by the preference
-values in the MX records, according to the usual rules. Because randomizing
-happens before the MX lookup, it does not affect the order that is defined by
-MX preferences.
-
-If the local host is present in the sublist obtained from MX records, but is
-not the most preferred host in that list, it and any equally or less
-preferred hosts are removed before the sublist is inserted into the main list.
-
-If the local host is the most preferred host in the MX list, what happens
-depends on where in the original list of hosts the `/MX` item appears. If it
-is not the first item (that is, there are previous hosts in the main list),
-Exim discards this name and any subsequent items in the main list.
-
-If the MX item is first in the list of hosts, and the local host is the
-most preferred host, what happens is controlled by the %self% option of the
-router.
-
-DNS failures when lookup up the MX records are treated in the same way as DNS
-failures when looking up IP addresses: %pass_on_timeout% and
-%host_find_failed% are used when relevant.
-
-The generic %ignore_target_hosts% option applies to all hosts in the list,
-whether obtained from an MX lookup or not.
-
-
-
-[[SECThowoptused]]
-How the options are used
-~~~~~~~~~~~~~~~~~~~~~~~~
-The options are a sequence of words; in practice no more than three are ever
-present. One of the words can be the name of a transport; this overrides the
-%transport% option on the router for this particular routing rule only. The
-other words (if present) control randomization of the list of hosts on a
-per-rule basis, and how the IP addresses of the hosts are to be found when
-routing to a remote transport. These options are as follows:
-
-- %randomize%: randomize the order of the hosts in this list, overriding the
-setting of %hosts_randomize% for this routing rule only.
-
-- %no_randomize%: do not randomize the order of the hosts in this list,
-overriding the setting of %hosts_randomize% for this routing rule only.
-
-- %byname%: use 'getipnodebyname()' ('gethostbyname()' on older systems) to
-find IP addresses. This function may ultimately cause a DNS lookup, but it may
-also look in _/etc/hosts_ or other sources of information.
-
-- %bydns%: look up address records for the hosts directly in the DNS; fail if
-no address records are found. If there is a temporary DNS error (such as a
-timeout), delivery is deferred.
-
-For example:
-
-....
-route_list = domain1 host1:host2:host3 randomize bydns;\
- domain2 host4:host5
-....
-
-If neither %byname% nor %bydns% is given, Exim behaves as follows: First, a DNS
-lookup is done. If this yields anything other than HOST_NOT_FOUND, that
-result is used. Otherwise, Exim goes on to try a call to 'getipnodebyname()'
-or 'gethostbyname()', and the result of the lookup is the result of that
-call.
-
-*Warning*: It has been discovered that on some systems, if a DNS lookup
-called via 'getipnodebyname()' times out, HOST_NOT_FOUND is returned
-instead of TRY_AGAIN. That is why the default action is to try a DNS
-lookup first. Only if that gives a definite ``no such host'' is the local
-function called.
-
-
-
-If no IP address for a host can be found, what happens is controlled by the
-%host_find_failed% option.
-
-cindex:[$host$]
-When an address is routed to a local transport, IP addresses are not looked up.
-The host list is passed to the transport in the $host$ variable.
-
-
-
-Manualroute examples
-~~~~~~~~~~~~~~~~~~~~
-In some of the examples that follow, the presence of the %remote_smtp%
-transport, as defined in the default configuration file, is assumed:
-
-- cindex:[smart host,example router]
-The ^manualroute^ router can be used to forward all external mail to a
-'smart host'. If you have set up, in the main part of the configuration, a
-named domain list that contains your local domains, for example,
-
- domainlist local_domains = my.domain.example
-+
-you can arrange for all other domains to be routed to a smart host by making
-your first router something like this:
-+
- smart_route:
- driver = manualroute
- domains = !+local_domains
- transport = remote_smtp
- route_list = * smarthost.ref.example
-+
-This causes all non-local addresses to be sent to the single host
-'smarthost.ref.example'. If a colon-separated list of smart hosts is given,
-they are tried in order
-(but you can use %hosts_randomize% to vary the order each time).
-Another way of configuring the same thing is this:
-+
- smart_route:
- driver = manualroute
- transport = remote_smtp
- route_list = !+local_domains smarthost.ref.example
-+
-There is no difference in behaviour between these two routers as they stand.
-However, they behave differently if %no_more% is added to them. In the first
-example, the router is skipped if the domain does not match the %domains%
-precondition; the following router is always tried. If the router runs, it
-always matches the domain and so can never decline. Therefore, %no_more% would
-have no effect. In the second case, the router is never skipped; it always
-runs. However, if it doesn't match the domain, it declines. In this case
-%no_more% would prevent subsequent routers from running.
-
-- cindex:[mail hub example]
-A 'mail hub' is a host which receives mail for a number of domains via MX
-records in the DNS and delivers it via its own private routing mechanism. Often
-the final destinations are behind a firewall, with the mail hub being the one
-machine that can connect to machines both inside and outside the firewall. The
-^manualroute^ router is usually used on a mail hub to route incoming messages
-to the correct hosts. For a small number of domains, the routing can be inline,
-using the %route_list% option, but for a larger number a file or database
-lookup is easier to manage.
-+
-If the domain names are in fact the names of the machines to which the mail is
-to be sent by the mail hub, the configuration can be quite simple. For
-example,
-
- hub_route:
- driver = manualroute
- transport = remote_smtp
- route_list = *.rhodes.tvs.example $domain
-+
-This configuration routes domains that match `*.rhodes.tvs.example` to hosts
-whose names are the same as the mail domains. A similar approach can be taken
-if the host name can be obtained from the domain name by a string manipulation
-that the expansion facilities can handle. Otherwise, a lookup based on the
-domain can be used to find the host:
-
- through_firewall:
- driver = manualroute
- transport = remote_smtp
- route_data = ${lookup {$domain} cdb {/internal/host/routes}}
-+
-The result of the lookup must be the name or IP address of the host (or
-hosts) to which the address is to be routed. If the lookup fails, the route
-data is empty, causing the router to decline. The address then passes to the
-next router.
-
-- cindex:[batched SMTP output example]
-cindex:[SMTP,batched outgoing; example]
-You can use ^manualroute^ to deliver messages to pipes or files in batched
-SMTP format for onward transportation by some other means. This is one way of
-storing mail for a dial-up host when it is not connected. The route list entry
-can be as simple as a single domain name in a configuration like this:
-
- save_in_file:
- driver = manualroute
- transport = batchsmtp_appendfile
- route_list = saved.domain.example
-+
-though often a pattern is used to pick up more than one domain. If there are
-several domains or groups of domains with different transport requirements,
-different transports can be listed in the routing information:
-+
-....
-save_in_file:
- driver = manualroute
- route_list = \
- *.saved.domain1.example $domain batch_appendfile; \
- *.saved.domain2.example \
- ${lookup{$domain}dbm{/domain2/hosts}{$value}fail} \
- batch_pipe
-....
-+
-cindex:[$domain$]
-cindex:[$host$]
-The first of these just passes the domain in the $host$ variable, which
-doesn't achieve much (since it is also in $domain$), but the second does a
-file lookup to find a value to pass, causing the router to decline to handle
-the address if the lookup fails.
-
-- cindex:[UUCP,example of router for]
-Routing mail directly to UUCP software is a specific case of the use of
-^manualroute^ in a gateway to another mail environment. This is an example of
-one way it can be done:
-+
-....
-# Transport
-uucp:
- driver = pipe
- user = nobody
- command = /usr/local/bin/uux -r - \
- ${substr_-5:$host}!rmail ${local_part}
- return_fail_output = true
-
-# Router
-uucphost:
- transport = uucp
- driver = manualroute
- route_data = \
- ${lookup{$domain}lsearch{/usr/local/exim/uucphosts}}
-....
-+
-The file _/usr/local/exim/uucphosts_ contains entries like
-
- darksite.ethereal.example: darksite.UUCP
-+
-It can be set up more simply without adding and removing ``.UUCP'' but this way
-makes clear the distinction between the domain name
-'darksite.ethereal.example' and the UUCP host name 'darksite'.
-
-
-
-
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPdriverlast]]
-The queryprogram router
------------------------
-cindex:[^queryprogram^ router]
-cindex:[routers,^queryprogram^]
-cindex:[routing,by external program]
-The ^queryprogram^ router routes an address by running an external command and
-acting on its output. This is an expensive way to route, and is intended mainly
-for use in lightly-loaded systems, or for performing experiments. However, if
-it is possible to use the precondition options (%domains%, %local_parts%,
-etc) to skip this router for most addresses, it could sensibly be used in
-special cases, even on a busy host. There are the following private options:
-cindex:[options,^queryprogram^ router]
-
-oindex:[%command%]
-`..'=
-%command%, Use: 'queryprogram', Type: 'string'!!, Default: 'unset'
-===
-
-This option must be set. It specifies the command that is to be run. The
-command is split up into a command name and arguments, and then each is
-expanded separately (exactly as for a ^pipe^ transport, described in chapter
-<<CHAPpipetransport>>).
-
-
-oindex:[%command_group%]
-`..'=
-%command_group%, Use: 'queryprogram', Type: 'string', Default: 'unset'
-===
-
-cindex:[gid (group id),in ^queryprogram^ router]
-This option specifies a gid to be set when running the command. It must be set
-if %command_user% specifies a numerical uid. If it begins with a digit, it is
-interpreted as the numerical value of the gid. Otherwise it is looked up using
-'getgrnam()'.
-
-
-oindex:[%command_user%]
-`..'=
-%command_user%, Use: 'queryprogram', Type: 'string', Default: 'unset'
-===
-
-cindex:[uid (user id),for ^queryprogram^]
-This option must be set. It specifies the uid which is set when running the
-command. If it begins with a digit it is interpreted as the numerical value of
-the uid. Otherwise, it is looked up using 'getpwnam()' to obtain a value for
-the uid and, if %command_group% is not set, a value for the gid also.
-
-
-oindex:[%current_directory%]
-`..'=
-%current_directory%, Use: 'queryprogram', Type: 'string', Default: '/'
-===
-
-This option specifies an absolute path which is made the current directory
-before running the command.
-
-
-oindex:[%timeout%]
-`..'=
-%timeout%, Use: 'queryprogram', Type: 'time', Default: '1h'
-===
-
-If the command does not complete within the timeout period, its process group
-is killed and the message is frozen. A value of zero time specifies no
-timeout.
-
-
-The standard output of the command is connected to a pipe, which is read when
-the command terminates. It should consist of a single line of output,
-containing up to five fields, separated by white space. The maximum length of
-the line is 1023 characters. Longer lines are silently truncated. The first
-field is one of the following words (case-insensitive):
-
-- 'Accept': routing succeeded; the remaining fields specify what to do (see
-below).
-
-- 'Decline': the router declines; pass the address to the next router, unless
-%no_more% is set.
-
-- 'Fail': routing failed; do not pass the address to any more routers. Any
-subsequent text on the line is an error message. If the router is run as part
-of address verification during an incoming SMTP message, the message is
-included in the SMTP response.
-
-- 'Defer': routing could not be completed at this time; try again later. Any
-subsequent text on the line is an error message which is logged. It is not
-included in any SMTP response.
-
-- 'Freeze': the same as 'defer', except that the message is frozen.
-
-- 'Pass': pass the address to the next router (or the router specified by
-%pass_router%), overriding %no_more%.
-
-- 'Redirect': the message is redirected. The remainder of the line is a list of
-new addresses, which are routed independently, starting with the first router,
-or the router specified by %redirect_router%, if set.
-
-When the first word is 'accept', the remainder of the line consists of a
-number of keyed data values, as follows (split into two lines here, to fit on
-the page):
-
- ACCEPT TRANSPORT=<transport> HOSTS=<list of hosts>
- LOOKUP=byname|bydns DATA=<text>
-
-The data items can be given in any order, and all are optional. If no transport
-is included, the transport specified by the generic %transport% option is used.
-The list of hosts and the lookup type are needed only if the transport is an
-^smtp^ transport that does not itself supply a list of hosts.
-
-The format of the list of hosts is the same as for the ^manualroute^ router.
-As well as host names and IP addresses with optional port numbers, as described
-in section <<SECTformatonehostitem>>, it may contain names followed by `/MX` to
-specify sublists of hosts that are obtained by looking up MX records (see
-section <<SECThostshowused>>).
-
-If the lookup type is not specified, Exim behaves as follows when trying to
-find an IP address for each host: First, a DNS lookup is done. If this yields
-anything other than HOST_NOT_FOUND, that result is used. Otherwise, Exim
-goes on to try a call to 'getipnodebyname()' or 'gethostbyname()', and the
-result of the lookup is the result of that call.
-
-cindex:[$address_data$]
-If the DATA field is set, its value is placed in the $address_data$
-variable. For example, this return line
-
- accept hosts=x1.y.example:x2.y.example data="rule1"
-
-routes the address to the default transport, passing a list of two hosts. When
-the transport runs, the string ``rule1'' is in $address_data$.
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPredirect]]
-The redirect router
--------------------
-cindex:[^redirect^ router]
-cindex:[routers,^redirect^]
-cindex:[alias file,in a ^redirect^ router]
-cindex:[address redirection,^redirect^ router]
-The ^redirect^ router handles several kinds of address redirection. Its most
-common uses are for resolving local part aliases from a central alias file
-(usually called _/etc/aliases_) and for handling users' personal _.forward_
-files, but it has many other potential uses. The incoming address can be
-redirected in several different ways:
-
-- It can be replaced by one or more new addresses which are themselves routed
-independently.
-
-- It can be routed to be delivered to a given file or directory.
-
-- It can be routed to be delivered to a specified pipe command.
-
-- It can cause an automatic reply to be generated.
-
-- It can be forced to fail, with a custom error message.
-
-- It can be temporarily deferred.
-
-- It can be discarded.
-
-The generic %transport% option must not be set for ^redirect^ routers.
-However, there are some private options which define transports for delivery to
-files and pipes, and for generating autoreplies. See the %file_transport%,
-%pipe_transport% and %reply_transport% descriptions below.
-
-
-
-Redirection data
-~~~~~~~~~~~~~~~~
-The router operates by interpreting a text string which it obtains either by
-expanding the contents of the %data% option, or by reading the entire contents
-of a file whose name is given in the %file% option. These two options are
-mutually exclusive. The first is commonly used for handling system aliases, in
-a configuration like this:
-
- system_aliases:
- driver = redirect
- data = ${lookup{$local_part}lsearch{/etc/aliases}}
-
-If the lookup fails, the expanded string in this example is empty. When the
-expansion of %data% results in an empty string, the router declines. A forced
-expansion failure also causes the router to decline; other expansion failures
-cause delivery to be deferred.
-
-A configuration using %file% is commonly used for handling users' _.forward_
-files, like this:
-
- userforward:
- driver = redirect
- check_local_user
- file = $home/.forward
- no_verify
-
-If the file does not exist, or causes no action to be taken (for example, it is
-empty or consists only of comments), the router declines. *Warning*: This
-is not the case when the file contains syntactically valid items that happen to
-yield empty addresses, for example, items containing only RFC 2822 address
-comments.
-
-
-
-Forward files and address verification
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[address redirection,while verifying]
-It is usual to set %no_verify% on ^redirect^ routers which handle users'
-_.forward_ files, as in the example above. There are two reasons for this:
-
-- When Exim is receiving an incoming SMTP message from a remote host, it is
-running under the Exim uid, not as root.
-No additional groups are set up, even if the Exim uid is a member of other
-groups (that is, the 'initgroups()' function is not run).
-Exim is unable to change uid to read the file as the user, and it may not be
-able to read it as the Exim user. So in practice the router may not be able to
-operate.
-
-- However, even when the router can operate, the existence of a _.forward_ file
-is unimportant when verifying an address. What should be checked is whether the
-local part is a valid user name or not. Cutting out the redirection processing
-saves some resources.
-
-
-
-
-
-
-Interpreting redirection data
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[Sieve filter,specifying in redirection data]
-cindex:[filter,specifying in redirection data]
-The contents of the data string, whether obtained from %data% or %file%, can be
-interpreted in two different ways:
-
-- If the %allow_filter% option is set true, and the data begins with the text
-``#Exim filter'' or ``#Sieve filter'', it is interpreted as a list of
-'filtering' instructions in the form of an Exim or Sieve filter file,
-respectively. Details of the syntax and semantics of filter files are described
-in a separate document entitled 'Exim's interfaces to mail filtering'; this
-document is intended for use by end users.
-
-- Otherwise, the data must be a comma-separated list of redirection items, as
-described in the next section.
-
-When a message is redirected to a file (a ``mail folder''), the file name given
-in a non-filter redirection list must always be an absolute path. A filter may
-generate a relative path -- how this is handled depends on the transport's
-configuration. See section <<SECTfildiropt>> for a discussion of this issue for
-the ^appendfile^ transport.
-
-
-
-[[SECTitenonfilred]]
-Items in a non-filter redirection list
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[address redirection,non-filter list items]
-When the redirection data is not an Exim or Sieve filter, for example, if it
-comes from a conventional alias or forward file, it consists of a list of
-addresses, file names, pipe commands, or certain special items (see section
-<<SECTspecitredli>> below). The special items can be individually enabled or
-disabled by means of options whose names begin with %allow_% or %forbid_%,
-depending on their default values. The items in the list are separated by
-commas or newlines.
-If a comma is required in an item, the entire item must be enclosed in double
-quotes.
-
-Lines starting with a # character are comments, and are ignored, and # may
-also appear following a comma, in which case everything between the # and the
-next newline character is ignored.
-
-If an item is entirely enclosed in double quotes, these are removed. Otherwise
-double quotes are retained because some forms of mail address require their use
-(but never to enclose the entire address). In the following description,
-``item'' refers to what remains after any surrounding double quotes have been
-removed.
-
-cindex:[$local_part$]
-*Warning*: If you use an Exim expansion to construct a redirection address,
-and the expansion contains a reference to $local_part$, you should make use
-of the %quote_local_part% expansion operator, in case the local part contains
-special characters. For example, to redirect all mail for the domain
-'obsolete.example', retaining the existing local part, you could use this
-setting:
-
- data = ${quote_local_part:$local_part}@newdomain.example
-
-
-
-
-[[SECTredlocmai]]
-Redirecting to a local mailbox
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[routing,loops in]
-cindex:[loop while routing, avoidance of]
-cindex:[address redirection,to local mailbox]
-A redirection item may safely be the same as the address currently under
-consideration. This does not cause a routing loop, because a router is
-automatically skipped if any ancestor of the address that is being processed
-is the same as the current address and was processed by the current router.
-Such an address is therefore passed to the following routers, so it is handled
-as if there were no redirection. When making this loop-avoidance test, the
-complete local part, including any prefix or suffix, is used.
-
-cindex:[address redirection,local part without domain]
-Specifying the same local part without a domain is a common usage in personal
-filter files when the user wants to have messages delivered to the local
-mailbox and also forwarded elsewhere. For example, the user whose login is
-'cleo' might have a _.forward_ file containing this:
-
- cleo, cleopatra@egypt.example
-
-cindex:[backslash in alias file]
-cindex:[alias file,backslash in]
-For compatibility with other MTAs, such unqualified local parts may be
-preceeded by ``\'', but this is not a requirement for loop prevention. However,
-it does make a difference if more than one domain is being handled
-synonymously.
-
-If an item begins with ``\'' and the rest of the item parses as a valid RFC 2822
-address that does not include a domain, the item is qualified using the domain
-of the incoming address. In the absence of a leading ``\'', unqualified
-addresses are qualified using the value in %qualify_recipient%, but you can
-force the incoming domain to be used by setting %qualify_preserve_domain%.
-
-Care must be taken if there are alias names for local users.
-Consider an MTA handling a single local domain where the system alias file
-contains:
-
- Sam.Reman: spqr
-
-Now suppose that Sam (whose login id is 'spqr') wants to save copies of
-messages in the local mailbox, and also forward copies elsewhere. He creates
-this forward file:
-
- Sam.Reman, spqr@reme.elsewhere.example
-
-With these settings, an incoming message addressed to 'Sam.Reman' fails. The
-^redirect^ router for system aliases does not process 'Sam.Reman' the
-second time round, because it has previously routed it,
-and the following routers presumably cannot handle the alias. The forward file
-should really contain
-
- spqr, spqr@reme.elsewhere.example
-
-but because this is such a common error, the %check_ancestor% option (see
-below) exists to provide a way to get round it. This is normally set on a
-^redirect^ router that is handling users' _.forward_ files.
-
-
-
-[[SECTspecitredli]]
-Special items in redirection lists
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-In addition to addresses, the following types of item may appear in redirection
-lists (that is, in non-filter redirection data):
-
-- cindex:[pipe,in redirection list]
-cindex:[address redirection,to pipe]
-An item is treated as a pipe command if it begins with ``|'' and does not parse
-as a valid RFC 2822 address that includes a domain. A transport for running the
-command must be specified by the %pipe_transport% option.
-Normally, either the router or the transport specifies a user and a group under
-which to run the delivery. The default is to use the Exim user and group.
-+
-Single or double quotes can be used for enclosing the individual arguments of
-the pipe command; no interpretation of escapes is done for single quotes. If
-the command contains a comma character, it is necessary to put the whole item
-in double quotes, for example:
-
- "|/some/command ready,steady,go"
-+
-since items in redirection lists are terminated by commas. Do not, however,
-quote just the command. An item such as
-
- |"/some/command ready,steady,go"
-+
-is interpreted as a pipe with a rather strange command name, and no arguments.
-
-- cindex:[file,in redirection list]
-cindex:[address redirection,to file]
-An item is interpreted as a path name if it begins with ``/'' and does not parse
-as a valid RFC 2822 address that includes a domain. For example,
-
- /home/world/minbari
-+
-is treated as a file name, but
-
- /s=molari/o=babylon/@x400gate.way
-+
-is treated as an address. For a file name, a transport must be specified using
-the %file_transport% option. However, if the generated path name ends with a
-forward slash character, it is interpreted as a directory name rather than a
-file name, and %directory_transport% is used instead.
-+
-Normally, either the router or the transport specifies a user and a group under
-which to run the delivery. The default is to use the Exim user and group.
-+
-cindex:[_/dev/null_]
-However, if a redirection item is the path _/dev/null_, delivery to it is
-bypassed at a high level, and the log entry shows ``\*\*bypassed\*\*''
-instead of a transport name. In this case the user and group are not used.
-
-- cindex:[included address list]
-cindex:[address redirection,included external list]
-If an item is of the form
-
- :include:<path name>
-+
-a list of further items is taken from the given file and included at that
-point. *Note*: such a file can not be a filter file; it is just an out-of-line
-addition to the list. The items in the included list are separated by commas or
-newlines and are not subject to expansion. If this is the first item in an
-alias list in an ^lsearch^ file, a colon must be used to terminate the alias
-name. This example is incorrect:
-
- list1 :include:/opt/lists/list1
-+
-It must be given as
-
- list1: :include:/opt/lists/list1
-+
-- cindex:[address redirection,to black hole]
-Sometimes you want to throw away mail to a particular local part. Making the
-%data% option expand to an empty string does not work, because that causes the
-router to decline. Instead, the alias item
-cindex:[black hole]
-cindex:[abandoning mail]
-
- :blackhole:
-+
-can be used. It does what its name implies. No delivery is done, and no error
-message is generated. This has the same effect as specifing _/dev/null_, but
-can be independently disabled.
-+
-*Warning*: If `:blackhole:` appears anywhere in a redirection list, no
-delivery is done for the original local part, even if other redirection items
-are present. If you are generating a multi-item list (for example, by reading a
-database) and need the ability to provide a no-op item, you must use
-_/dev/null_.
-
-- cindex:[delivery,forcing failure]
-cindex:[delivery,forcing deferral]
-cindex:[failing delivery,forcing]
-cindex:[deferred delivery, forcing]
-cindex:[customizing,failure message]
-An attempt to deliver a particular address can be deferred or forced to fail by
-redirection items of the form
-
- :defer:
- :fail:
-+
-respectively. When a redirection list contains such an item, it applies to the
-entire redirection; any other items in the list are ignored (':blackhole:' is
-different). Any text following ':fail:' or ':defer:' is placed in the error
-text associated with the failure. For example, an alias file might contain:
-
- X.Employee: :fail: Gone away, no forwarding address
-+
-In the case of an address that is being verified from an ACL or as the subject
-of a
-cindex:[VRFY error text, display of]
-VRFY command, the text is included in the SMTP error response by
-default.
-cindex:[EXPN error text, display of]
-The text is not included in the response to an EXPN command.
-+
-cindex:[$acl_verify_message$]
-In an ACL, an explicitly provided message overrides the default, but the
-default message is available in the variable $acl_verify_message$ and can
-therefore be included in a custom message if this is desired. Exim sends a 451
-SMTP code for a ':defer:', and 550 for ':fail:'. In non-SMTP cases the text
-is included in the error message that Exim generates.
-+
-Normally the error text is the rest of the redirection list -- a comma does not
-terminate it -- but a newline does act as a terminator. Newlines are not
-normally present in alias expansions. In ^lsearch^ lookups they are removed as
-part of the continuation process, but they may exist in other kinds of lookup
-and in ':include:' files.
-+
-During routing for message delivery (as opposed to verification), a redirection
-containing ':fail:' causes an immediate failure of the incoming address,
-whereas ':defer:' causes the message to remain on the queue so that a
-subsequent delivery attempt can happen at a later time. If an address is
-deferred for too long, it will ultimately fail, because the normal retry
-rules still apply.
-
-- cindex:[alias file,exception to default]
-Sometimes it is useful to use a single-key search type with a default (see
-chapter <<CHAPfdlookup>>) to look up aliases. However, there may be a need for
-exceptions to the default. These can be handled by aliasing them to
-
- :unknown:
-+
-This differs from ':fail:' in that it causes the ^redirect^ router to decline,
-whereas ':fail:' forces routing to fail. A lookup which results in an empty
-redirection list has the same effect.
-
-
-
-Duplicate addresses
-~~~~~~~~~~~~~~~~~~~
-cindex:[duplicate addresses]
-cindex:[address duplicate, discarding]
-cindex:[pipe,duplicated]
-Exim removes duplicate addresses from the list to which it is delivering, so as
-to deliver just one copy to each address. This does not apply to deliveries
-routed to pipes by different immediate parent addresses, but an indirect
-aliasing scheme of the type
-
- pipe: |/some/command $local_part
- localpart1: pipe
- localpart2: pipe
-
-does not work with a message that is addressed to both local parts, because
-when the second is aliased to the intermediate local part ``pipe'' it gets
-discarded as being the same as a previously handled address. However, a scheme
-such as
-
- localpart1: |/some/command $local_part
- localpart2: |/some/command $local_part
-
-does result in two different pipe deliveries, because the immediate parents of
-the pipes are distinct.
-
-
-
-Repeated redirection expansion
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[repeated redirection expansion]
-cindex:[address redirection,repeated for each delivery attempt]
-When a message cannot be delivered to all of its recipients immediately,
-leading to two or more delivery attempts, redirection expansion is carried out
-afresh each time for those addresses whose children were not all previously
-delivered. If redirection is being used as a mailing list, this can lead to new
-members of the list receiving copies of old messages. The %one_time% option
-can be used to avoid this.
-
-
-Errors in redirection lists
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[address redirection,errors]
-If %skip_syntax_errors% is set, a malformed address that causes a parsing
-error is skipped, and an entry is written to the main log. This may be useful
-for mailing lists that are automatically managed. Otherwise, if an error is
-detected while generating the list of new addresses, the original address is
-deferred. See also %syntax_errors_to%.
-
-
-
-Private options for the redirect router
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-cindex:[options,^redirect^ router]
-The private options for the ^redirect^ router are as follows:
-
-
-oindex:[%allow_defer%]
-`..'=
-%allow_defer%, Use: 'redirect', Type: 'boolean', Default: 'false'
-===
-
-Setting this option allows the use of ':defer:' in non-filter redirection
-data,
-or the %defer% command in an Exim filter file.
-
-
-oindex:[%allow_fail%]
-`..'=
-%allow_fail%, Use: 'redirect', Type: 'boolean', Default: 'false'
-===
-
-cindex:[failing delivery,from filter]
-If this option is true, the ':fail:' item can be used in a redirection list,
-and the %fail% command may be used in a filter file.
-
-
-oindex:[%allow_filter%]
-`..'=
-%allow_filter%, Use: 'redirect', Type: 'boolean', Default: 'false'
-===
-
-cindex:[filter,enabling use of]
-cindex:[Sieve filter,enabling use of]
-Setting this option allows Exim to interpret redirection data that starts with
-``#Exim filter'' or ``#Sieve filter'' as a set of filtering instructions. There
-are some features of Exim filter files that some administrators may wish to
-lock out; see the %forbid_filter_xxx% options below.
-
-It is also possible to lock out Exim filters or Sieve filters while allowing
-the other type; see %forbid_exim_filter% and %forbid_sieve_filter%.
-
-
-The filter is run using the uid and gid set by the generic %user% and %group%
-options. These take their defaults from the password data if
-%check_local_user% is set, so in the normal case of users' personal filter
-files, the filter is run as the relevant user. When %allow_filter% is set
-true, Exim insists that either %check_local_user% or %user% is set.
-
-
-
-oindex:[%allow_freeze%]
-`..'=
-%allow_freeze%, Use: 'redirect', Type: 'boolean', Default: 'false'
-===
-
-cindex:[freezing messages,allowing in filter]
-Setting this option allows the use of the %freeze% command in an Exim filter.
-This command is more normally encountered in system filters, and is disabled by
-default for redirection filters because it isn't something you usually want to
-let ordinary users do.
-
-
-
-oindex:[%check_ancestor%]
-`..'=
-%check_ancestor%, Use: 'redirect', Type: 'boolean', Default: 'false'
-===
-
-This option is concerned with handling generated addresses that are the same
-as some address in the list of redirection ancestors of the current address.
-Although it is turned off by default in the code, it is set in the default
-configuration file for handling users' _.forward_ files. It is recommended
-for this use of the ^redirect^ router.
-
-When %check_ancestor% is set, if a generated address (including the domain) is
-the same as any ancestor of the current address, it is replaced by a copy of
-the current address. This helps in the case where local part A is aliased to B,
-and B has a _.forward_ file pointing back to A. For example, within a single
-domain, the local part ``Joe.Bloggs'' is aliased to ``jb'' and _~jb/.forward_
-contains:
-
- \Joe.Bloggs, <other item(s)>
-
-Without the %check_ancestor% setting, either local part (``jb'' or ``joe.bloggs'')
-gets processed once by each router and so ends up as it was originally. If ``jb''
-is the real mailbox name, mail to ``jb'' gets delivered (having been turned into
-``joe.bloggs'' by the _.forward_ file and back to ``jb'' by the alias), but mail
-to ``joe.bloggs'' fails. Setting %check_ancestor% on the ^redirect^ router that
-handles the _.forward_ file prevents it from turning ``jb'' back into
-``joe.bloggs'' when that was the original address. See also the %repeat_use%
-option below.
-
-
-oindex:[%check_group%]
-`..'=
-%check_group%, Use: 'redirect', Type: 'boolean', Default: 'see below'
-===
-
-When the %file% option is used, the group owner of the file is checked only
-when this option is set. The permitted groups are those listed in the
-%owngroups% option, together with the user's default group if
-%check_local_user% is set. If the file has the wrong group, routing is
-deferred. The default setting for this option is true if %check_local_user%
-is set and the %modemask% option permits the group write bit, or if the
-%owngroups% option is set. Otherwise it is false, and no group check occurs.
-
-
-
-oindex:[%check_owner%]
-`..'=
-%check_owner%, Use: 'redirect', Type: 'boolean', Default: 'see below'
-===
-
-When the %file% option is used, the owner of the file is checked only when this
-option is set. If %check_local_user% is set, the local user is permitted;
-otherwise the owner must be one of those listed in the %owners% option. The
-default value for this option is true if %check_local_user% or %owners% is
-set. Otherwise the default is false, and no owner check occurs.
-
-
-oindex:[%data%]
-`..'=
-%data%, Use: 'redirect', Type: 'string'!!, Default: 'unset'
-===
-
-This option is mutually exclusive with %file%. One or other of them must be
-set, but not both. The contents of %data% are expanded, and then used as the
-list of forwarding items, or as a set of filtering instructions. If the
-expansion is forced to fail, or the result is an empty string or a string that
-has no effect (consists entirely of comments), the router declines.
-
-When filtering instructions are used, the string must begin with ``#Exim
-filter'', and all comments in the string, including this initial one, must be
-terminated with newline characters. For example:
-
-....
-data = #Exim filter\n\
- if $h_to: contains Exim then save $home/mail/exim endif
-....
-
-If you are reading the data from a database where newlines cannot be included,
-you can use the $\{sg\}$ expansion item to turn the escape string of your
-choice into a newline.
-
-
-oindex:[%directory_transport%]
-`..'=
-%directory_transport%, Use: 'redirect', Type: 'string'!!, Default: 'unset'
-===
-
-A ^redirect^ router sets up a direct delivery to a directory when a path name
-ending with a slash is specified as a new ``address''. The transport used is
-specified by this option, which, after expansion, must be the name of a
-configured transport. This should normally be an ^appendfile^ transport.
-
-
-oindex:[%file%]
-`..'=
-%file%, Use: 'redirect', Type: 'string'!!, Default: 'unset'
-===
-
-This option specifies the name of a file that contains the redirection data. It
-is mutually exclusive with the %data% option. The string is expanded before
-use; if the expansion is forced to fail, the router declines. Other expansion
-failures cause delivery to be deferred. The result of a successful expansion
-must be an absolute path. The entire file is read and used as the redirection
-data. If the data is an empty string or a string that has no effect (consists
-entirely of comments), the router declines.
-
-cindex:[NFS,checking for file existence]
-If the attempt to open the file fails with a ``does not exist'' error, Exim
-runs a check on the containing directory,
-unless %ignore_enotdir% is true (see below).
-If the directory does not appear to exist, delivery is deferred. This can
-happen when users' _.forward_ files are in NFS-mounted directories, and there
-is a mount problem. If the containing directory does exist, but the file does
-not, the router declines.
-
-
-oindex:[%file_transport%]
-`..'=
-%file_transport%, Use: 'redirect', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[$address_file$]
-A ^redirect^ router sets up a direct delivery to a file when a path name not
-ending in a slash is specified as a new ``address''. The transport used is
-specified by this option, which, after expansion, must be the name of a
-configured transport. This should normally be an ^appendfile^ transport. When
-it is running, the file name is in $address_file$.
-
-
-oindex:[%forbid_blackhole%]
-`..'=
-%forbid_blackhole%, Use: 'redirect', Type: 'boolean', Default: 'false'
-===
-
-If this option is true, the ':blackhole:' item may not appear in a redirection
-list.
-
-
-oindex:[%forbid_exim_filter%]
-`..'=
-%forbid_exim_filter%, Use: 'redirect', Type: 'boolean', Default: 'false'
-===
-
-If this option is set true, only Sieve filters are permitted when
-%allow_filter% is true.
-
-
-
-
-oindex:[%forbid_file%]
-`..'=
-%forbid_file%, Use: 'redirect', Type: 'boolean', Default: 'false'
-===
-
-cindex:[delivery,to file; forbidding]
-cindex:[Sieve filter,forbidding delivery to a file]
-cindex:[Sieve filter,``keep'' facility; disabling]
-If this option is true, this router may not generate a new address that
-specifies delivery to a local file or directory, either from a filter or from a
-conventional forward file. This option is forced to be true if %one_time% is
-set. It applies to Sieve filters as well as to Exim filters, but if true, it
-locks out the Sieve's ``keep'' facility.
-
-
-oindex:[%forbid_filter_dlfunc%]
-`..'=
-%forbid_filter_dlfunc%, Use: 'redirect', Type: 'boolean', Default: 'false'
-===
-
-[revisionflag="changed"]
-cindex:[filter,locking out certain features]
-If this option is true, string expansions in Exim filters are not allowed to
-make use of the %dlfunc% expansion facility to run dynamically loaded
-functions.
-
-
-oindex:[%forbid_filter_existstest%]
-`..'=
-%forbid_filter_existstest%, Use: 'redirect', Type: 'boolean', Default: 'false'
-===
-
-[revisionflag="changed"]
-cindex:[expansion,statting a file]
-If this option is true, string expansions in Exim filters are not allowed to
-make use of the %exists% condition or the %stat% expansion item.
-
-
-oindex:[%forbid_filter_logwrite%]
-`..'=
-%forbid_filter_logwrite%, Use: 'redirect', Type: 'boolean', Default: 'false'
-===
-
-If this option is true, use of the logging facility in Exim filters is not
-permitted. Logging is in any case available only if the filter is being run
-under some unprivileged uid (which is normally the case for ordinary users'
-_.forward_ files).
-
-
-oindex:[%forbid_filter_lookup%]
-`..'=
-%forbid_filter_lookup%, Use: 'redirect', Type: 'boolean', Default: 'false'
-===
-
-If this option is true, string expansions in Exim filter files are not allowed
-to make use of %lookup% items.
-
-
-oindex:[%forbid_filter_perl%]
-`..'=
-%forbid_filter_perl%, Use: 'redirect', Type: 'boolean', Default: 'false'
-===
-
-This option has an effect only if Exim is built with embedded Perl support. If
-it is true, string expansions in Exim filter files are not allowed to make use
-of the embedded Perl support.
-
-
-oindex:[%forbid_filter_readfile%]
-`..'=
-%forbid_filter_readfile%, Use: 'redirect', Type: 'boolean', Default: 'false'
-===
-
-If this option is true, string expansions in Exim filter files are not allowed
-to make use of %readfile% items.
-
-
-oindex:[%forbid_filter_readsocket%]
-`..'=
-%forbid_filter_readsocket%, Use: 'redirect', Type: 'boolean', Default: 'false'
-===
-
-If this option is true, string expansions in Exim filter files are not allowed
-to make use of %readsocket% items.
-
-
-oindex:[%forbid_filter_reply%]
-`..'=
-%forbid_filter_reply%, Use: 'redirect', Type: 'boolean', Default: 'false'
-===
-
-If this option is true, this router may not generate an automatic reply
-message. Automatic replies can be generated only from Exim
-
-or Sieve filter files, not from traditional forward files.
-
-This option is forced to be true if %one_time% is set.
-
-
-oindex:[%forbid_filter_run%]
-`..'=
-%forbid_filter_run%, Use: 'redirect', Type: 'boolean', Default: 'false'
-===
-
-If this option is true, string expansions in Exim filter files are not allowed
-to make use of %run% items.
-
-
-oindex:[%forbid_include%]
-`..'=
-%forbid_include%, Use: 'redirect', Type: 'boolean', Default: 'false'
-===
-
-If this option is true, items of the form
-
- :include:<path name>
-
-are not permitted in non-filter redirection lists.
-
-
-oindex:[%forbid_pipe%]
-`..'=
-%forbid_pipe%, Use: 'redirect', Type: 'boolean', Default: 'false'
-===
-
-cindex:[delivery,to pipe; forbidding]
-If this option is true, this router may not generate a new address which
-specifies delivery to a pipe, either from an Exim filter or from a conventional
-forward file. This option is forced to be true if %one_time% is set.
-
-
-oindex:[%forbid_sieve_filter%]
-`..'=
-%forbid_sieve_filter%, Use: 'redirect', Type: 'boolean', Default: 'false'
-===
-
-If this option is set true, only Exim filters are permitted when
-%allow_filter% is true.
-
-
-
-
-oindex:[%hide_child_in_errmsg%]
-`..'=
-%hide_child_in_errmsg%, Use: 'redirect', Type: 'boolean', Default: 'false'
-===
-
-cindex:[bounce message,redirection details; suppressing]
-If this option is true, it prevents Exim from quoting a child address if it
-generates a bounce or delay message for it. Instead it says ``an address
-generated from <''the top level address'>'. Of course, this applies only to
-bounces generated locally. If a message is forwarded to another host, 'its'
-bounce may well quote the generated address.
-
-
-oindex:[%ignore_eacces%]
-`..'=
-%ignore_eacces%, Use: 'redirect', Type: 'boolean', Default: 'false'
-===
-
-cindex:[EACCES]
-If this option is set and an attempt to open a redirection file yields the
-EACCES error (permission denied), the ^redirect^ router behaves as if the
-file did not exist.
-
-
-oindex:[%ignore_enotdir%]
-`..'=
-%ignore_enotdir%, Use: 'redirect', Type: 'boolean', Default: 'false'
-===
-
-cindex:[ENOTDIR]
-If this option is set and an attempt to open a redirection file yields the
-ENOTDIR error (something on the path is not a directory), the ^redirect^
-router behaves as if the file did not exist.
-
-Setting %ignore_enotdir% has another effect as well: When a ^redirect^
-router that has the %file% option set discovers that the file does not exist
-(the ENOENT error), it tries to 'stat()' the parent directory, as a check
-against unmounted NFS directories. If the parent can not be statted, delivery
-is deferred. However, it seems wrong to do this check when %ignore_enotdir% is
-set, because that option tells Exim to ignore ``something on the path is not a
-directory'' (the ENOTDIR error). This is a confusing area, because it seems
-that some operating systems give ENOENT where others give ENOTDIR.
-
-
-
-oindex:[%include_directory%]
-`..'=
-%include_directory%, Use: 'redirect', Type: 'string', Default: 'unset'
-===
-
-If this option is set, the path names of any ':include:' items in a redirection
-list must start with this directory.
-
-
-oindex:[%modemask%]
-`..'=
-%modemask%, Use: 'redirect', Type: 'octal integer', Default: '022'
-===
-
-This specifies mode bits which must not be set for a file specified by the
-%file% option. If any of the forbidden bits are set, delivery is deferred.
-
-
-oindex:[%one_time%]
-`..'=
-%one_time%, Use: 'redirect', Type: 'boolean', Default: 'false'
-===
-
-cindex:[one-time aliasing/forwarding expansion]
-cindex:[alias file,one-time expansion]
-cindex:[forward file,one-time expansion]
-cindex:[mailing lists,one-time expansion]
-cindex:[address redirection,one-time expansion]
-Sometimes the fact that Exim re-evaluates aliases and reprocesses redirection
-files each time it tries to deliver a message causes a problem when one or more
-of the generated addresses fails be delivered at the first attempt. The problem
-is not one of duplicate delivery -- Exim is clever enough to handle that -- but
-of what happens when the redirection list changes during the time that the
-message is on Exim's queue. This is particularly true in the case of mailing
-lists, where new subscribers might receive copies of messages that were posted
-before they subscribed.
-
-If %one_time% is set and any addresses generated by the router fail to deliver
-at the first attempt, the failing addresses are added to the message as ``top
-level'' addresses, and the parent address that generated them is marked
-``delivered''. Thus, redirection does not happen again at the next delivery
-attempt.
-
-*Warning 1*: Any header line addition or removal that is specified by this
-router would be lost if delivery did not succeed at the first attempt. For this
-reason, the %headers_add% and %headers_remove% generic options are not
-permitted when %one_time% is set.
-
-*Warning 2*: To ensure that the router generates only addresses (as opposed
-to pipe or file deliveries or auto-replies) %forbid_file%, %forbid_pipe%,
-and %forbid_filter_reply% are forced to be true when %one_time% is set.
-
-[revisionflag="changed"]
-*Warning 3*: The %unseen% generic router option may not be set with %one_time%.
-
-The original top-level address is remembered with each of the generated
-addresses, and is output in any log messages. However, any intermediate parent
-addresses are not recorded. This makes a difference to the log only if
-%all_parents% log selector is set. It is expected that %one_time% will
-typically be used for mailing lists, where there is normally just one level of
-expansion.
-
-
-oindex:[%owners%]
-`..'=
-%owners%, Use: 'redirect', Type: 'string list', Default: 'unset'
-===
-
-cindex:[ownership,alias file]
-cindex:[ownership,forward file]
-cindex:[alias file,ownership]
-cindex:[forward file,ownership]
-This specifies a list of permitted owners for the file specified by %file%.
-This list is in addition to the local user when %check_local_user% is set.
-See %check_owner% above.
-
-
-oindex:[%owngroups%]
-`..'=
-%owngroups%, Use: 'redirect', Type: 'string list', Default: 'unset'
-===
-
-This specifies a list of permitted groups for the file specified by %file%. The
-list is in addition to the local user's primary group when %check_local_user%
-is set. See %check_group% above.
-
-
-oindex:[%pipe_transport%]
-`..'=
-%pipe_transport%, Use: 'redirect', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[$address_pipe$]
-A ^redirect^ router sets up a direct delivery to a pipe when a string starting
-with a vertical bar character is specified as a new ``address''. The transport
-used is specified by this option, which, after expansion, must be the name of a
-configured transport. This should normally be a ^pipe^ transport. When the
-transport is run, the pipe command is in $address_pipe$.
-
-
-oindex:[%qualify_domain%]
-`..'=
-%qualify_domain%, Use: 'redirect', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[$qualify_recipient$]
-If this option is set and an unqualified address (one without a domain) is
-generated, it is qualified with the domain specified by expanding this string,
-instead of the global setting in %qualify_recipient%. If the expansion fails,
-the router declines. If you want to revert to the default, you can have the
-expansion generate $qualify_recipient$.
-
-
-oindex:[%qualify_preserve_domain%]
-`..'=
-%qualify_preserve_domain%, Use: 'redirect', Type: 'boolean', Default: 'false'
-===
-
-cindex:[domain,in redirection; preserving]
-cindex:[preserving domain in redirection]
-cindex:[address redirection,domain; preserving]
-If this is set and an unqualified address (one without a domain) is generated,
-it is qualified with the domain of the
-parent address (the immediately preceding ancestor) instead of the local
-%qualify_domain% or global %qualify_recipient% value.
-
-
-oindex:[%repeat_use%]
-`..'=
-%repeat_use%, Use: 'redirect', Type: 'boolean', Default: 'true'
-===
-
-If this option is set false, the router is skipped for a child address that has
-any ancestor that was routed by this router. This test happens before any of
-the other preconditions are tested. Exim's default anti-looping rules skip
-only when the ancestor is the same as the current address. See also
-%check_ancestor% above and the generic %redirect_router% option.
-
-
-oindex:[%reply_transport%]
-`..'=
-%reply_transport%, Use: 'redirect', Type: 'string'!!, Default: 'unset'
-===
-
-A ^redirect^ router sets up an automatic reply when a %mail% or %vacation%
-command is used in a filter file. The transport used is specified by this
-option, which, after expansion, must be the name of a configured transport.
-This should normally be an ^autoreply^ transport. Other transports are
-unlikely to do anything sensible or useful.
-
-
-oindex:[%rewrite%]
-`..'=
-%rewrite%, Use: 'redirect', Type: 'boolean', Default: 'true'
-===
-
-cindex:[address redirection,disabling rewriting]
-If this option is set false, addresses generated by the router are not
-subject to address rewriting. Otherwise, they are treated like new addresses
-and are rewritten according to the global rewriting rules.
-
-
-oindex:[%sieve_subaddress%]
-`..'=
-%sieve_subaddress%, Use: 'redirect', Type: 'string'!!, Default: 'unset'
-===
-
-[revisionflag="changed"]
-The value of this option is passed to a Sieve filter to specify the
-:subaddress part of an address.
-
-
-oindex:[%sieve_useraddress%]
-`..'=
-%sieve_useraddress%, Use: 'redirect', Type: 'string'!!, Default: 'unset'
-===
-
-[revisionflag="changed"]
-The value of this option is passed to a Sieve filter to specify the :user part
-of an address. However, if it is unset, the entire original local part
-(including any prefix or suffix) is used for :user.
-
-
-
-oindex:[%sieve_vacation_directory%]
-`..'=
-%sieve_vacation_directory%, Use: 'redirect', Type: 'string'!!, Default: 'unset'
-===
-
-[revisionflag="changed"]
-cindex:[Sieve filter,vacation directory]
-To enable the ``vacation'' extension for Sieve filters, you must set
-%sieve_vacation_directory% to the directory where vacation databases are held
-(do not put anything else in that directory), and ensure that the
-%reply_transport% option refers to an ^autoreply^ transport. Each user needs
-their own directory; Exim will create it if necessary.
-
-
-
-
-oindex:[%skip_syntax_errors%]
-`..'=
-%skip_syntax_errors%, Use: 'redirect', Type: 'boolean', Default: 'false'
-===
-
-cindex:[forward file,broken]
-cindex:[address redirection,broken files]
-cindex:[alias file,broken]
-cindex:[broken alias or forward files]
-cindex:[ignoring faulty addresses]
-cindex:[skipping faulty addresses]
-cindex:[error,skipping bad syntax]
-If %skip_syntax_errors% is set, syntactically malformed addresses in
-non-filter redirection data are skipped, and each failing address is logged. If
-%syntax_errors_to% is set, a message is sent to the address it defines,
-giving details of the failures. If %syntax_errors_text% is set, its contents
-are expanded and placed at the head of the error message generated by
-%syntax_errors_to%. Usually it is appropriate to set %syntax_errors_to% to
-be the same address as the generic %errors_to% option. The
-%skip_syntax_errors% option is often used when handling mailing lists.
-
-If all the addresses in a redirection list are skipped because of syntax
-errors, the router declines to handle the original address, and it is passed to
-the following routers.
-
-If %skip_syntax_errors% is set when an Exim filter is interpreted, any syntax
-error in the filter causes filtering to be abandoned without any action being
-taken. The incident is logged, and the router declines to handle the address,
-so it is passed to the following routers.
-
-cindex:[Sieve filter,syntax errors in]
-Syntax errors in a Sieve filter file cause the ``keep'' action to occur. This
-action is specified by RFC 3028. The values of %skip_syntax_errors%,
-%syntax_errors_to%, and %syntax_errors_text% are not used.
-
-%skip_syntax_errors% can be used to specify that errors in users' forward
-lists or filter files should not prevent delivery. The %syntax_errors_to%
-option, used with an address that does not get redirected, can be used to
-notify users of these errors, by means of a router like this:
-
-....
-userforward:
- driver = redirect
- allow_filter
- check_local_user
- file = $home/.forward
- file_transport = address_file
- pipe_transport = address_pipe
- reply_transport = address_reply
- no_verify
- skip_syntax_errors
- syntax_errors_to = real-$local_part\$domain
- syntax_errors_text = \
- This is an automatically generated message. An error has\n\
- been found in your .forward file. Details of the error are\n\
- reported below. While this error persists, you will receive\n\
- a copy of this message for every message that is addressed\n\
- to you. If your .forward file is a filter file, or if it is\n\
- a non-filter file containing no valid forwarding addresses,\n\
- a copy of each incoming message will be put in your normal\n\
- mailbox. If a non-filter file contains at least one valid\n\
- forwarding address, forwarding to the valid addresses will\n\
- happen, and those will be the only deliveries that occur.
-....
-
-You also need a router to ensure that local addresses that are prefixed by
-`real-` are recognized, but not forwarded or filtered. For example, you could
-put this immediately before the ^userforward^ router:
-
- real_localuser:
- driver = accept
- check_local_user
- local_part_prefix = real-
- transport = local_delivery
-
-
-
-oindex:[%syntax_errors_text%]
-`..'=
-%syntax_errors_text%, Use: 'redirect', Type: 'string'!!, Default: 'unset'
-===
-
-See %skip_syntax_errors% above.
-
-
-oindex:[%syntax_errors_to%]
-`..'=
-%syntax_errors_to%, Use: 'redirect', Type: 'string', Default: 'unset'
-===
-
-See %skip_syntax_errors% above.
-
-
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPenvironment]]
-[titleabbrev="Environment for local transports"]
-Environment for running local transports
-----------------------------------------
-cindex:[local transports,environment for]
-cindex:[environment for local transports]
-cindex:[transport,local; environment for]
-Local transports handle deliveries to files and pipes. (The ^autoreply^
-transport can be thought of as similar to a pipe.) Exim always runs transports
-in subprocesses, under specified uids and gids. Typical deliveries to local
-mailboxes run under the uid and gid of the local user.
-
-Exim also sets a specific current directory while running the transport; for
-some transports a home directory setting is also relevant. The ^pipe^
-transport is the only one that sets up environment variables; see section
-<<SECTpipeenv>> for details.
-
-The values used for the uid, gid, and the directories may come from several
-different places. In many cases, the router that handles the address associates
-settings with that address as a result of its %check_local_user%, %group%, or
-%user% options. However, values may also be given in the transport's own
-configuration, and these override anything that comes from the router.
-
-
-
-Concurrent deliveries
-~~~~~~~~~~~~~~~~~~~~~
-cindex:[concurrent deliveries]
-cindex:[simultaneous deliveries]
-If two different messages for the same local recpient arrive more or less
-simultaneously, the two delivery processes are likely to run concurrently. When
-the ^appendfile^ transport is used to write to a file, Exim applies locking
-rules to stop concurrent processes from writing to the same file at the same
-time.
-
-However, when you use a ^pipe^ transport, it is up to you to arrange any
-locking that is needed. Here is a silly example:
-
- my_transport:
- driver = pipe
- command = /bin/sh -c 'cat >>/some/file'
-
-This is supposed to write the message at the end of the file. However, if two
-messages arrive at the same time, the file will be scrambled. You can use the
-%exim_lock% utility program (see section <<SECTmailboxmaint>>) to lock a file
-using the same algorithm that Exim itself uses.
-
-
-
-
-[[SECTenvuidgid]]
-Uids and gids
-~~~~~~~~~~~~~
-cindex:[local transports,uid and gid]
-cindex:[transport,local; uid and gid]
-All transports have the options %group% and %user%. If %group% is set, it
-overrides any group that the router set in the address, even if %user% is not
-set for the transport. This makes it possible, for example, to run local mail
-delivery under the uid of the recipient (set by the router), but in a special
-group (set by the transport). For example:
-
- # Routers ...
- # User/group are set by check_local_user in this router
- local_users:
- driver = accept
- check_local_user
- transport = group_delivery
-
- # Transports ...
- # This transport overrides the group
- group_delivery:
- driver = appendfile
- file = /var/spool/mail/$local_part
- group = mail
-
-If %user% is set for a transport, its value overrides what is set in the
-address. If %user% is non-numeric and %group% is not set, the gid associated
-with the user is used. If %user% is numeric, %group% must be set.
-
-cindex:[%initgroups% option]
-When the uid is taken from the transport's configuration, the 'initgroups()'
-function is called for the groups associated with that uid if the %initgroups%
-option is set for the transport. When the uid is not specified by the
-transport, but is associated with the address by a router, the option for
-calling 'initgroups()' is taken from the router configuration.
-
-cindex:[^pipe^ transport,uid for]
-The ^pipe^ transport contains the special option %pipe_as_creator%. If this
-is set and %user% is not set, the uid of the process that called Exim to
-receive the message is used, and if %group% is not set, the corresponding
-original gid is also used.
-
-
-
-Current and home directories
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[current directory for local transport]
-cindex:[home directory,for local transport]
-cindex:[transport,local; home directory for]
-cindex:[transport,local; current directory for]
-Routers may set current and home directories for local transports by means of
-the %transport_current_directory% and %transport_home_directory% options.
-However, if the transport's %current_directory% or %home_directory% options
-are set, they override the router's values. In detail, the home directory
-for a local transport is taken from the first of these values that is set:
-
-- The %home_directory% option on the transport;
-
-- The %transport_home_directory% option on the router;
-
-- The password data if %check_local_user% is set on the router;
-
-- The %router_home_directory% option on the router.
-
-The current directory is taken from the first of these values that is set:
-
-- The %current_directory% option on the transport;
-
-- The %transport_current_directory% option on the router.
-
-
-If neither the router nor the transport sets a current directory, Exim uses the
-value of the home directory, if it is set. Otherwise it sets the current
-directory to _/_ before running a local transport.
-
-
-
-Expansion variables derived from the address
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[$domain$]
-cindex:[$local_part$]
-cindex:[$original_domain$]
-Normally a local delivery is handling a single address, and in that case the
-variables such as $domain$ and $local_part$ are set during local deliveries.
-However, in some circumstances more than one address may be handled at once
-(for example, while writing batch SMTP for onward transmission by some other
-means). In this case, the variables associated with the local part are never
-set, $domain$ is set only if all the addresses have the same domain, and
-$original_domain$ is never set.
-
-
-
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPtransportgeneric]]
-Generic options for transports
-------------------------------
-
-cindex:[generic options,transport]
-cindex:[options,generic; for transports]
-cindex:[transport,generic options for]
-The following generic options apply to all transports:
-
-
-oindex:[%body_only%]
-`..'=
-%body_only%, Use: 'transports', Type: 'boolean', Default: 'false'
-===
-
-cindex:[transport,body only]
-cindex:[message,transporting body only]
-cindex:[body of message,transporting]
-If this option is set, the message's headers are not transported. It is
-mutually exclusive with %headers_only%. If it is used with the ^appendfile^ or
-^pipe^ transports, the settings of %message_prefix% and %message_suffix%
-should be checked, because this option does not automatically suppress them.
-
-
-oindex:[%current_directory%]
-`..'=
-%current_directory%, Use: 'transports', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[transport,current directory for]
-This specifies the current directory that is to be set while running the
-transport, overriding any value that may have been set by the router.
-If the expansion fails for any reason, including forced failure, an error is
-logged, and delivery is deferred.
-
-
-oindex:[%disable_logging%]
-`..'=
-%disable_logging%, Use: 'transports', Type: 'boolean', Default: 'false'
-===
-
-If this option is set true, nothing is logged for any
-deliveries by the transport or for any
-transport errors. You should not set this option unless you really, really know
-what you are doing.
-
-
-oindex:[%debug_print%]
-`..'=
-%debug_print%, Use: 'transports', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[testing,variables in drivers]
-If this option is set and debugging is enabled (see the %-d% command line
-option), the string is expanded and included in the debugging output when the
-transport is run.
-If expansion of the string fails, the error message is written to the debugging
-output, and Exim carries on processing.
-This facility is provided to help with checking out the values of variables and
-so on when debugging driver configurations. For example, if a %headers_add%
-option is not working properly, %debug_print% could be used to output the
-variables it references. A newline is added to the text if it does not end with
-one.
-
-
-oindex:[%delivery_date_add%]
-`..'=
-%delivery_date_add%, Use: 'transports', Type: 'boolean', Default: 'false'
-===
-
-cindex:['Delivery-date:' header line]
-If this option is true, a 'Delivery-date:' header is added to the message. This
-gives the actual time the delivery was made. As this is not a standard header,
-Exim has a configuration option (%delivery_date_remove%) which requests its
-removal from incoming messages, so that delivered messages can safely be resent
-to other recipients.
-
-
-oindex:[%driver%]
-`..'=
-%driver%, Use: 'transports', Type: 'string', Default: 'unset'
-===
-
-This specifies which of the available transport drivers is to be used.
-There is no default, and this option must be set for every transport.
-
-
-oindex:[%envelope_to_add%]
-`..'=
-%envelope_to_add%, Use: 'transports', Type: 'boolean', Default: 'false'
-===
-
-cindex:['Envelope-to:' header line]
-If this option is true, an 'Envelope-to:' header is added to the message. This
-gives the original address(es) in the incoming envelope that caused this
-delivery to happen. More than one address may be present if the transport is
-configured to handle several addresses at once, or if more than one original
-address was redirected to the same final address. As this is not a standard
-header, Exim has a configuration option (%envelope_to_remove%) which requests
-its removal from incoming messages, so that delivered messages can safely be
-resent to other recipients.
-
-
-oindex:[%group%]
-`..'=
-%group%, Use: 'transports', Type: 'string'!!, Default: 'Exim group'
-===
-
-cindex:[transport,group; specifying]
-This option specifies a gid for running the transport process, overriding any
-value that the router supplies, and also overriding any value associated with
-%user% (see below).
-
-
-oindex:[%headers_add%]
-`..'=
-%headers_add%, Use: 'transports', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[header lines,adding in transport]
-cindex:[transport,header lines; adding]
-This option specifies a string of text that is expanded and added to the header
-portion of a message as it is transported, as described in section
-<<SECTheadersaddrem>>. Additional header lines can also be specified by routers.
-If the result of the expansion is an empty string, or if the expansion is
-forced to fail, no action is taken. Other expansion failures are treated as
-errors and cause the delivery to be deferred.
-
-
-
-oindex:[%headers_only%]
-`..'=
-%headers_only%, Use: 'transports', Type: 'boolean', Default: 'false'
-===
-
-cindex:[transport,header lines only]
-cindex:[message,transporting headers only]
-cindex:[header lines,transporting]
-If this option is set, the message's body is not transported. It is mutually
-exclusive with %body_only%. If it is used with the ^appendfile^ or ^pipe^
-transports, the settings of %message_prefix% and %message_suffix% should be
-checked, since this option does not automatically suppress them.
-
-
-oindex:[%headers_remove%]
-`..'=
-%headers_remove%, Use: 'transports', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[header lines,removing]
-cindex:[transport,header lines; removing]
-This option specifies a string that is expanded into a list of header names;
-these headers are omitted from the message as it is transported, as described
-in section <<SECTheadersaddrem>>. Header removal can also be specified by
-routers. If the result of the expansion is an empty string, or if the expansion
-is forced to fail, no action is taken. Other expansion failures are treated as
-errors and cause the delivery to be deferred.
-
-
-
-oindex:[%headers_rewrite%]
-`..'=
-%headers_rewrite%, Use: 'transports', Type: 'string', Default: 'unset'
-===
-
-cindex:[transport,header lines; rewriting]
-cindex:[rewriting,at transport time]
-This option allows addresses in header lines to be rewritten at transport time,
-that is, as the message is being copied to its destination. The contents of the
-option are a colon-separated list of rewriting rules. Each rule is in exactly
-the same form as one of the general rewriting rules that are applied when a
-message is received. These are described in chapter <<CHAPrewrite>>. For example,
-
-....
-headers_rewrite = a@b c@d f : \
- x@y w@z
-....
-
-changes %a@b% into %c@d% in 'From:' header lines, and %x@y% into %w@z% in
-all address-bearing header lines. The rules are applied to the header lines
-just before they are written out at transport time, so they affect only those
-copies of the message that pass through the transport. However, only the
-message's original header lines, and any that were added by a system filter,
-are rewritten. If a router or transport adds header lines, they are
-not affected by this option. These rewriting rules are 'not' applied to the
-envelope. You can change the return path using %return_path%, but you cannot
-change envelope recipients at this time.
-
-
-oindex:[%home_directory%]
-`..'=
-%home_directory%, Use: 'transports', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[transport,home directory for]
-cindex:[$home$]
-This option specifies a home directory setting for the transport, overriding
-any value that may be set by the router. The home directory is placed in
-$home$ while expanding the transport's private options. It is also used as
-the current directory if no current directory is set by the
-%current_directory% option on the transport or the
-%transport_current_directory% option on the router.
-If the expansion fails for any reason, including forced failure, an error is
-logged, and delivery is deferred.
-
-
-oindex:[%initgroups%]
-`..'=
-%initgroups%, Use: 'transports', Type: 'boolean', Default: 'false'
-===
-
-cindex:[additional groups]
-cindex:[groups, additional]
-cindex:[transport,group; additional]
-If this option is true and the uid for the delivery process is provided by the
-transport, the 'initgroups()' function is called when running the transport
-to ensure that any additional groups associated with the uid are set up.
-
-
-oindex:[%message_size_limit%]
-`..'=
-%message_size_limit%, Use: 'transports', Type: 'string'!!, Default: '0'
-===
-
-cindex:[limit,message size per transport]
-cindex:[size of message, limit]
-cindex:[transport,message size; limiting]
-This option controls the size of messages passed through the transport. It is
-expanded before use; the result of the expansion must be a sequence of digits,
-optionally followed by K or M.
-If the expansion fails for any reason, including forced failure, or if the
-result is not of the required form, delivery is deferred.
-If the value is greater than zero and the size of a message exceeds this
-limit, the address is failed. If there is any chance that the resulting bounce
-message could be routed to the same transport, you should ensure that
-%return_size_limit% is less than the transport's %message_size_limit%, as
-otherwise the bounce message will fail to get delivered.
-
-
-
-oindex:[%rcpt_include_affixes%]
-`..'=
-%rcpt_include_affixes%, Use: 'transports', Type: 'boolean', Default: 'false'
-===
-
-cindex:[prefix,for local part; including in envelope]
-cindex:[suffix,for local part; including in envelope]
-cindex:[local part,prefix]
-cindex:[local part,suffix]
-When this option is false (the default), and an address that has had any
-affixes (prefixes or suffixes) removed from the local part is delivered by any
-form of SMTP or LMTP, the affixes are not included. For example, if a router
-that contains
-
- local_part_prefix = *-
-
-routes the address 'abc-xyz@some.domain' to an SMTP transport, the envelope
-is delivered with
-
- RCPT TO:<xyz@some.domain>
-
-[revisionflag="changed"]
-This is also the case when an ACL-time callout is being used to verify a
-recipient address.
-
-If %rcpt_include_affixes% is set true, the whole local part is included in
-the RCPT command. This option applies to BSMTP deliveries by the
-^appendfile^ and ^pipe^ transports as well as to the ^lmtp^ and ^smtp^
-transports.
-
-
-oindex:[%retry_use_local_part%]
-`..'=
-%retry_use_local_part%, Use: 'transports', Type: 'boolean', Default: 'see below'
-===
-
-cindex:[hints database,retry keys]
-When a delivery suffers a temporary failure, a retry record is created
-in Exim's hints database. For remote deliveries, the key for the retry record
-is based on the name and/or IP address of the failing remote host. For local
-deliveries, the key is normally the entire address, including both the local
-part and the domain. This is suitable for most common cases of local delivery
-temporary failure -- for example, exceeding a mailbox quota should delay only
-deliveries to that mailbox, not to the whole domain.
-
-However, in some special cases you may want to treat a temporary local delivery
-as a failure associated with the domain, and not with a particular local part.
-(For example, if you are storing all mail for some domain in files.) You can do
-this by setting %retry_use_local_part% false.
-
-For all the local transports, its default value is true. For remote transports,
-the default value is false for tidiness, but changing the value has no effect
-on a remote transport in the current implementation.
-
-
-oindex:[%return_path%]
-`..'=
-%return_path%, Use: 'transports', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[envelope sender]
-cindex:[transport,return path; changing]
-cindex:[return path,changing in transport]
-If this option is set, the string is expanded at transport time and replaces
-the existing return path (envelope sender) value in the copy of the message
-that is being delivered. An empty return path is permitted. This feature is
-designed for remote deliveries, where the value of this option is used in the
-SMTP MAIL command. If you set %return_path% for a local transport, the
-only effect is to change the address that is placed in the 'Return-path:'
-header line, if one is added to the message (see the next option).
-
-cindex:[$return_path$]
-The expansion can refer to the existing value via $return_path$. This is
-either the message's envelope sender, or an address set by the
-%errors_to% option on a router. If the expansion is forced to fail, no
-replacement occurs; if it fails for another reason, delivery is deferred. This
-option can be used to support VERP (Variable Envelope Return Paths) -- see
-chapter <<CHAPSMTP>>.
-
-*Note*: If a delivery error is detected locally,
-including the case when a remote server rejects a message at SMTP time,
-the bounce message is not sent to the value of this option, but to the
-previously set errors address (which defaults to the incoming sender address).
-
-
-
-oindex:[%return_path_add%]
-`..'=
-%return_path_add%, Use: 'transports', Type: 'boolean', Default: 'false'
-===
-
-cindex:['Return-path:' header line]
-If this option is true, a 'Return-path:' header is added to the message.
-Although the return path is normally available in the prefix line of BSD
-mailboxes, this is commonly not displayed by MUAs, and so the user does not
-have easy access to it.
-
-RFC 2821 states that the 'Return-path:' header is added to a message ``when the
-delivery SMTP server makes the final delivery''. This implies that this header
-should not be present in incoming messages. Exim has a configuration option,
-%return_path_remove%, which requests removal of this header from incoming
-messages, so that delivered messages can safely be resent to other recipients.
-
-
-oindex:[%shadow_condition%]
-`..'=
-%shadow_condition%, Use: 'transports', Type: 'string'!!, Default: 'unset'
-===
-
-See %shadow_transport% below.
-
-
-oindex:[%shadow_transport%]
-`..'=
-%shadow_transport%, Use: 'transports', Type: 'string', Default: 'unset'
-===
-
-cindex:[shadow transport]
-cindex:[transport,shadow]
-A local transport may set the %shadow_transport% option to the name of another
-local transport. Shadow remote transports are not supported.
-
-Whenever a delivery to the main transport succeeds, and either
-%shadow_condition% is unset, or its expansion does not result in the empty
-string or one of the strings ``0'' or ``no'' or ``false'', the message is also passed
-to the shadow transport, with the same delivery address or addresses.
-If expansion fails, no action is taken except that non-forced expansion
-failures cause a log line to be written.
-
-The result of the shadow transport is discarded and does not affect the
-subsequent processing of the message. Only a single level of shadowing is
-provided; the %shadow_transport% option is ignored on any transport when it is
-running as a shadow. Options concerned with output from pipes are also ignored.
-
-The log line for the successful delivery has an item added on the end, of the
-form
-
- ST=<shadow transport name>
-
-If the shadow transport did not succeed, the error message is put in
-parentheses afterwards.
-
-Shadow transports can be used for a number of different purposes, including
-keeping more detailed log information than Exim normally provides, and
-implementing automatic acknowledgement policies based on message headers that
-some sites insist on.
-
-
-oindex:[%transport_filter%]
-`..'=
-%transport_filter%, Use: 'transports', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[transport,filter]
-cindex:[filter,transport filter]
-This option sets up a filtering (in the Unix shell sense) process for messages
-at transport time. It should not be confused with mail filtering as set up by
-individual users or via a system filter.
-
-When the message is about to be written out, the command specified by
-%transport_filter% is started up in a separate process, and the entire message,
-including the header lines, is passed to it on its standard input (this in fact
-is done from a third process, to avoid deadlock). The command must be specified
-as an absolute path.
-
-The lines of the message that are written to the transport filter are
-terminated by newline (``\n''). The message is passed to the filter before any
-SMTP-specific processing, such as turning ``\n'' into ``\r\n'' and escaping
-lines beginning with a dot, and also before any processing implied by the
-settings of %check_string% and %escape_string% in the ^appendfile^ or ^pipe^
-transports.
-
-The standard error for the filter process is set to the same destination as its
-standard output; this is read and written to the message's ultimate
-destination. The filter can perform any transformations it likes, but of course
-should take care not to break RFC 2822 syntax. A demonstration Perl script is
-provided in _util/transport-filter.pl_; this makes a few arbitrary
-modifications just to show the possibilities. Exim does not check the result,
-except to test for a final newline when SMTP is in use. All messages
-transmitted over SMTP must end with a newline, so Exim supplies one if it is
-missing.
-
-[revisionflag="changed"]
-cindex:[content scanning,per user]
-A transport filter can be used to provide content-scanning on a per-user basis
-at delivery time if the only required effect of the scan is to modify the
-message. For example, a content scan could insert a new header line containing
-a spam score. This could be interpreted by a filter in the user's MUA. It is
-not possible to discard a message at this stage.
-
-cindex:[SMTP,SIZE]
-A problem might arise if the filter increases the size of a message that is
-being sent down an SMTP connection. If the receiving SMTP server has indicated
-support for the SIZE parameter, Exim will have sent the size of the message
-at the start of the SMTP session. If what is actually sent is substantially
-more, the server might reject the message. This can be worked round by setting
-the %size_addition% option on the ^smtp^ transport, either to allow for
-additions to the message, or to disable the use of SIZE altogether.
-
-cindex:[$pipe_addresses$]
-The value of the %transport_filter% option is the command string for starting
-the filter, which is run directly from Exim, not under a shell. The string is
-parsed by Exim in the same way as a command string for the ^pipe^ transport:
-Exim breaks it up into arguments and then expands each argument separately. The
-special argument $pipe_addresses$ is replaced by a number of arguments, one
-for each address that applies to this delivery. (This isn't an ideal name for
-this feature here, but as it was already implemented for the ^pipe^
-transport, it seemed sensible not to change it.)
-
-cindex:[$host$]
-cindex:[$host_address$]
-The expansion variables $host$ and $host_address$ are available when the
-transport is a remote one. They contain the name and IP address of the host to
-which the message is being sent. For example:
-
-....
-transport_filter = /some/directory/transport-filter.pl \
- $host $host_address $sender_address $pipe_addresses
-....
-
-The filter process is run under the same uid and gid as the normal delivery.
-For remote deliveries this is the Exim uid/gid by default.
-
-The command should normally yield a zero return code. A non-zero code is taken
-to mean that the transport filter failed in some way. Delivery of the message
-is deferred. It is not possible to cause a message to be bounced from a
-transport filter.
-
-
-If a transport filter is set on an autoreply transport, the original message is
-passed through the filter as it is being copied into the newly generated
-message, which happens if the %return_message% option is set.
-
-
-oindex:[%transport_filter_timeout%]
-`..'=
-%transport_filter_timeout%, Use: 'transports', Type: 'time', Default: '5m'
-===
-
-[revisionflag="changed"]
-cindex:[transport filter, timeout]
-When Exim is reading the output of a transport filter, it a applies a timeout
-that can be set by this option. Exceeding the timeout is normally treated as a
-temporary delivery failure. However, if a transport filter is used with a
-^pipe^ transport, a timeout in the transport filter is treated in the same way
-as a timeout in the pipe command itself. By default, a timeout is a hard error,
-but if the ^pipe^ transport's %timeout_defer% option is set true, it becomes a
-temporary error.
-
-
-
-oindex:[%user%]
-`..'=
-%user%, Use: 'transports', Type: 'string'!!, Default: 'Exim user'
-===
-
-cindex:[uid (user id),local delivery]
-cindex:[transport user, specifying]
-This option specifies the user under whose uid the delivery process is to be
-run, overriding any uid that may have been set by the router. If the user is
-given as a name, the uid is looked up from the password data, and the
-associated group is taken as the value of the gid to be used if the %group%
-option is not set.
-
-For deliveries that use local transports, a user and group are normally
-specified explicitly or implicitly (for example, as a result of
-%check_local_user%) by the router or transport.
-
-cindex:[hints database,access by remote transport]
-For remote transports, you should leave this option unset unless you really are
-sure you know what you are doing. When a remote transport is running, it needs
-to be able to access Exim's hints databases, because each host may have its own
-retry data.
-
-
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPbatching]]
-[titleabbrev="Address batching"]
-Address batching in local transports
-------------------------------------
-cindex:[transport,local; address batching in]
-The only remote transport (^smtp^) is normally configured to handle more than
-one address at a time, so that when several addresses are routed to the same
-remote host, just one copy of the message is sent. Local transports, however,
-normally handle one address at a time. That is, a separate instance of the
-transport is run for each address that is routed to the transport. A separate
-copy of the message is delivered each time.
-
-cindex:[batched local delivery]
-cindex:[%batch_max%]
-cindex:[%batch_id%]
-In special cases, it may be desirable to handle several addresses at once in a
-local transport, for example:
-
-- In an ^appendfile^ transport, when storing messages in files for later
-delivery by some other means, a single copy of the message with multiple
-recipients saves space.
-
-- In an ^lmtp^ transport, when delivering over ``local SMTP'' to some process,
-a single copy saves time, and is the normal way LMTP is expected to work.
-
-- In a ^pipe^ transport, when passing the message
-to a scanner program or
-to some other delivery mechanism such as UUCP, multiple recipients may be
-acceptable.
-
-The three local transports (^appendfile^, ^lmtp^, and ^pipe^) all have
-the same options for controlling multiple (``batched'') deliveries, namely
-%batch_max% and %batch_id%. To save repeating the information for each
-transport, these options are described here.
-
-The %batch_max% option specifies the maximum number of addresses that can be
-delivered together in a single run of the transport. Its default value is one.
-When more than one address is routed to a transport that has a %batch_max%
-value greater than one, the addresses are delivered in a batch (that is, in a
-single run of the transport), subject to certain conditions:
-
-- cindex:[$local_part$]
-If any of the transport's options contain a reference to $local_part$, no
-batching is possible.
-
-- cindex:[$domain$]
-If any of the transport's options contain a reference to $domain$, only
-addresses with the same domain are batched.
-
-- cindex:[customizing,batching condition]
-If %batch_id% is set, it is expanded for each address, and only those
-addresses with the same expanded value are batched. This allows you to specify
-customized batching conditions.
-Failure of the expansion for any reason, including forced failure, disables
-batching, but it does not stop the delivery from taking place.
-
-- Batched addresses must also have the same errors address (where to send
-delivery errors), the same header additions and removals, the same user and
-group for the transport, and if a host list is present, the first host must
-be the same.
-
-cindex:['Envelope-to:' header line]
-If the generic %envelope_to_add% option is set for the transport, the
-'Envelope-to:' header that is added to the message contains all the addresses
-that are batched together.
-
-The ^appendfile^ and ^pipe^ transports have an option called %use_bsmtp%,
-which causes them to deliver the message in ``batched SMTP'' format, with the
-envelope represented as SMTP commands. The %check_string% and %escape_string%
-options are forced to the values
-
- check_string = "."
- escape_string = ".."
-
-when batched SMTP is in use. A full description of the batch SMTP mechanism is
-given in section <<SECTbatchSMTP>>. The ^lmtp^ transport does not have a
-%use_bsmtp% option, because it always delivers using the SMTP protocol.
-
-cindex:[^pipe^ transport,with multiple addresses]
-cindex:[$pipe_addresses$]
-If you are not using BSMTP, but are using a ^pipe^ transport, you can include
-$pipe_addresses$ as part of the command. This is not a true variable; it is
-a bit of magic that causes each of the recipient addresses to be inserted into
-the command as a separate argument. This provides a way of accessing all the
-addresses that are being delivered in the batch.
-
-If you are using a batching ^appendfile^ transport without %use_bsmtp%, the
-only way to preserve the recipient addresses is to set the %envelope_to_add%
-option. This causes an 'Envelope-to:' header line to be added to the message,
-containing all the recipients.
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPappendfile]]
-The appendfile transport
-------------------------
-cindex:[^appendfile^ transport]
-cindex:[transports,^appendfile^]
-cindex:[directory creation]
-cindex:[creating directories]
-The ^appendfile^ transport delivers a message by appending it to an existing
-file, or by creating an entirely new file in a specified directory. Single
-files to which messages are appended can be in the traditional Unix mailbox
-format, or optionally in the MBX format supported by the Pine MUA and
-University of Washington IMAP daemon, 'inter alia'. When each message is
-being delivered as a separate file, ``maildir'' format can optionally be used to
-give added protection against failures that happen part-way through the
-delivery. A third form of separate-file delivery known as ``mailstore'' is also
-supported. For all file formats, Exim attempts to create as many levels of
-directory as necessary, provided that %create_directory% is set.
-
-The code for the optional formats is not included in the Exim binary by
-default. It is necessary to set SUPPORT_MBX, SUPPORT_MAILDIR and/or
-SUPPORT_MAILSTORE in _Local/Makefile_ to have the appropriate code
-included.
-
-cindex:[quota,system]
-Exim recognises system quota errors, and generates an appropriate message. Exim
-also supports its own quota control within the transport, for use when the
-system facility is unavailable or cannot be used for some reason.
-
-If there is an error while appending to a file (for example, quota exceeded or
-partition filled), Exim attempts to reset the file's length and last
-modification time back to what they were before. If there is an error while
-creating an entirely new file, the new file is removed.
-
-Before appending to a file, a number of security checks are made, and the
-file is locked. A detailed description is given below, after the list of
-private options.
-
-^appendfile^ is most commonly used for local deliveries to users' mailboxes.
-However, it can also be used as a pseudo-remote transport for putting messages
-into files for remote delivery by some means other than Exim. ``Batch SMTP''
-format is often used in this case (see the %use_bsmtp% option).
-
-
-
-[[SECTfildiropt]]
-The file and directory options
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The %file% option specifies a single file, to which the message is appended;
-the %directory% option specifies a directory, in which a new file containing
-the message is created. Only one of these two options can be set, and for
-normal deliveries to mailboxes, one of them 'must' be set.
-
-cindex:[$address_file$]
-cindex:[$local_part$]
-However, ^appendfile^ is also used for delivering messages to files or
-directories whose names (or parts of names) are obtained from alias,
-forwarding, or filtering operations (for example, a %save% command in a user's
-Exim filter). When such a transport is running, $local_part$ contains the
-local part that was aliased or forwarded, and $address_file$ contains the
-name (or partial name) of the file or directory generated by the redirection
-operation. There are two cases:
-
-- If neither %file% nor %directory% is set, the redirection operation
-must specify an absolute path (one that begins with `/`). This is the most
-common case when users with local accounts use filtering to sort mail into
-different folders. See for example, the ^address_file^ transport in the
-default configuration. If the path ends with a slash, it is assumed to be the
-name of a directory. A delivery to a directory can also be forced by setting
-%maildir_format% or %mailstore_format%.
-
-- If %file% or %directory% is set for a delivery from a redirection, it is used
-to determine the file or directory name for the delivery. Normally, the
-contents of $address_file$ are used in some way in the string expansion.
-
-
-cindex:[Sieve filter,configuring ^appendfile^]
-cindex:[Sieve filter,relative mailbox path handling]
-As an example of the second case, consider an environment where users do not
-have home directories. They may be permitted to use Exim filter commands of the
-form:
-
- save folder23
-
-or Sieve filter commands of the form:
-
- require "fileinto";
- fileinto "folder23";
-
-In this situation, the expansion of %file% or %directory% in the transport must
-transform the relative path into an appropriate absolute file name. In the case
-of Sieve filters, the name 'inbox' must be handled. It is the name that is
-used as a result of a ``keep'' action in the filter. This example shows one way
-of handling this requirement:
-
-....
-file = ${if eq{$address_file}{inbox} \
- {/var/mail/$local_part} \
- {${if eq{${substr_0_1:$address_file}}{/} \
- {$address_file} \
- {$home/mail/$address_file} \
- }} \
- }
-....
-
-With this setting of %file%, 'inbox' refers to the standard mailbox location,
-absolute paths are used without change, and other folders are in the _mail_
-directory within the home directory.
-
-*Note 1*: While processing an Exim filter, a relative path such as
-_folder23_ is turned into an absolute path if a home directory is known to
-the router. In particular, this is the case if %check_local_user% is set. If
-you want to prevent this happening at routing time, you can set
-%router_home_directory% empty. This forces the router to pass the relative
-path to the transport.
-
-*Note 2*: An absolute path in $address_file$ is not treated specially;
-the %file% or %directory% option is still used if it is set.
-
-
-
-
-Private options for appendfile
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[options,^appendfile^ transport]
-
-
-
-oindex:[%allow_fifo%]
-`..'=
-%allow_fifo%, Use: 'appendfile', Type: 'boolean', Default: 'false'
-===
-
-cindex:[fifo (named pipe)]
-cindex:[named pipe (fifo)]
-cindex:[pipe,named (fifo)]
-Setting this option permits delivery to named pipes (FIFOs) as well as to
-regular files. If no process is reading the named pipe at delivery time, the
-delivery is deferred.
-
-
-oindex:[%allow_symlink%]
-`..'=
-%allow_symlink%, Use: 'appendfile', Type: 'boolean', Default: 'false'
-===
-
-cindex:[symbolic link,to mailbox]
-cindex:[mailbox,symbolic link]
-By default, ^appendfile^ will not deliver if the path name for the file is
-that of a symbolic link. Setting this option relaxes that constraint, but there
-are security issues involved in the use of symbolic links. Be sure you know
-what you are doing if you set this. Details of exactly what this option affects
-are included in the discussion which follows this list of options.
-
-
-oindex:[%batch_id%]
-`..'=
-%batch_id%, Use: 'appendfile', Type: 'string'!!, Default: 'unset'
-===
-
-See the description of local delivery batching in chapter <<CHAPbatching>>.
-However, batching is automatically disabled for ^appendfile^ deliveries that
-happen as a result of forwarding or aliasing or other redirection directly to a
-file.
-
-
-oindex:[%batch_max%]
-`..'=
-%batch_max%, Use: 'appendfile', Type: 'integer', Default: '1'
-===
-
-See the description of local delivery batching in chapter <<CHAPbatching>>.
-
-
-oindex:[%check_group%]
-`..'=
-%check_group%, Use: 'appendfile', Type: 'boolean', Default: 'false'
-===
-
-When this option is set, the group owner of the file defined by the %file%
-option is checked to see that it is the same as the group under which the
-delivery process is running. The default setting is false because the default
-file mode is 0600, which means that the group is irrelevant.
-
-
-oindex:[%check_owner%]
-`..'=
-%check_owner%, Use: 'appendfile', Type: 'boolean', Default: 'true'
-===
-
-When this option is set, the owner of the file defined by the %file% option is
-checked to ensure that it is the same as the user under which the delivery
-process is running.
-
-
-oindex:[%check_string%]
-`..'=
-%check_string%, Use: 'appendfile', Type: 'string', Default: 'see below'
-===
-
-cindex:[``From'' line]
-As ^appendfile^ writes the message, the start of each line is tested for
-matching %check_string%, and if it does, the initial matching characters are
-replaced by the contents of %escape_string%. The value of %check_string% is a
-literal string, not a regular expression, and the case of any letters it
-contains is significant.
-
-If %use_bsmtp% is set the values of %check_string% and %escape_string% are
-forced to ``.'' and ``..'' respectively, and any settings in the configuration are
-ignored. Otherwise, they default to ``From '' and ``>From '' when the %file% option
-is set, and unset when
-any of the %directory%, %maildir%, or %mailstore% options are set.
-
-The default settings, along with %message_prefix% and %message_suffix%, are
-suitable for traditional ``BSD'' mailboxes, where a line beginning with ``From
-'' indicates the start of a new message. All four options need changing if
-another format is used. For example, to deliver to mailboxes in MMDF format:
-cindex:[MMDF format mailbox]
-cindex:[mailbox,MMDF format]
-
- check_string = "\1\1\1\1\n"
- escape_string = "\1\1\1\1 \n"
- message_prefix = "\1\1\1\1\n"
- message_suffix = "\1\1\1\1\n"
-
-oindex:[%create_directory%]
-`..'=
-%create_directory%, Use: 'appendfile', Type: 'boolean', Default: 'true'
-===
-
-cindex:[directory creation]
-When this option is true, Exim attempts to create any missing superior
-directories for the file that it is about to write. A created directory's mode
-is given by the %directory_mode% option.
-
-The group ownership of a newly created directory is highly dependent on the
-operating system (and possibly the file system) that is being used. For
-example, in Solaris, if the parent directory has the setgid bit set, its group
-is propagated to the child; if not, the currently set group is used. However,
-in FreeBSD, the parent's group is always used.
-
-
-
-oindex:[%create_file%]
-`..'=
-%create_file%, Use: 'appendfile', Type: 'string', Default: 'anywhere'
-===
-
-This option constrains the location of files and directories that are created
-by this transport. It applies to files defined by the %file% option and
-directories defined by the %directory% option. In the case of maildir delivery,
-it applies to the top level directory, not the maildir directories beneath.
-
-The option must be set to one of the words ``anywhere'', ``inhome'', or
-``belowhome''. In the second and third cases, a home directory must have been set
-for the transport. This option is not useful when an explicit file name is
-given for normal mailbox deliveries. It is intended for the case when file
-names are generated from users' _.forward_ files. These are usually handled
-by an ^appendfile^ transport called %address_file%. See also
-%file_must_exist%.
-
-
-oindex:[%directory%]
-`..'=
-%directory%, Use: 'appendfile', Type: 'string'!!, Default: 'unset'
-===
-
-This option is mutually exclusive with the %file% option, but one of %file% or
-%directory% must be set, unless the delivery is the direct result of a
-redirection (see section <<SECTfildiropt>>).
-
-When %directory% is set, the string is expanded, and the message is delivered
-into a new file or files in or below the given directory, instead of being
-appended to a single mailbox file. A number of different formats are provided
-(see %maildir_format% and %mailstore_format%), and see section <<SECTopdir>>
-for further details of this form of delivery.
-
-
-oindex:[%directory_file%]
-`..'=
-%directory_file%, Use: 'appendfile', Type: 'string'!!, Default: `q\$\{base62{co}\$tod_epoch\}-\$inode`
-===
-
-cindex:[base62]
-cindex:[$inode$]
-When %directory% is set, but neither %maildir_format% nor %mailstore_format%
-is set, ^appendfile^ delivers each message into a file whose name is obtained
-by expanding this string. The default value generates a unique name from the
-current time, in base 62 form, and the inode of the file. The variable
-$inode$ is available only when expanding this option.
-
-
-oindex:[%directory_mode%]
-`..'=
-%directory_mode%, Use: 'appendfile', Type: 'octal integer', Default: '0700'
-===
-
-If ^appendfile^ creates any directories as a result of the %create_directory%
-option, their mode is specified by this option.
-
-
-oindex:[%escape_string%]
-`..'=
-%escape_string%, Use: 'appendfile', Type: 'string', Default: 'see description'
-===
-
-See %check_string% above.
-
-
-oindex:[%file%]
-`..'=
-%file%, Use: 'appendfile', Type: 'string'!!, Default: 'unset'
-===
-
-This option is mutually exclusive with the %directory% option, but one of
-%file% or %directory% must be set, unless the delivery is the direct result of
-a redirection (see section <<SECTfildiropt>>). The %file% option specifies a
-single file, to which the message is appended. One or more of
-%use_fcntl_lock%, %use_flock_lock%, or %use_lockfile% must be set with
-%file%.
-
-cindex:[NFS,lock file]
-cindex:[locking files]
-cindex:[lock files]
-If you are using more than one host to deliver over NFS into the same
-mailboxes, you should always use lock files.
-
-The string value is expanded for each delivery, and must yield an absolute
-path. The most common settings of this option are variations on one of these
-examples:
-
- file = /var/spool/mail/$local_part
- file = /home/$local_part/inbox
- file = $home/inbox
-
-cindex:[``sticky'' bit]
-In the first example, all deliveries are done into the same directory. If Exim
-is configured to use lock files (see %use_lockfile% below) it must be able to
-create a file in the directory, so the ``sticky'' bit must be turned on for
-deliveries to be possible, or alternatively the %group% option can be used to
-run the delivery under a group id which has write access to the directory.
-
-
-
-oindex:[%file_format%]
-`..'=
-%file_format%, Use: 'appendfile', Type: 'string', Default: 'unset'
-===
-
-cindex:[file,mailbox; checking existing format]
-This option requests the transport to check the format of an existing file
-before adding to it. The check consists of matching a specific string at the
-start of the file. The value of the option consists of an even number of
-colon-separated strings. The first of each pair is the test string, and the
-second is the name of a transport. If the transport associated with a matched
-string is not the current transport, control is passed over to the other
-transport. For example, suppose the standard ^local_delivery^ transport has
-this added to it:
-
-....
-file_format = "From : local_delivery :\
- \1\1\1\1\n : local_mmdf_delivery"
-....
-
-Mailboxes that begin with ``From'' are still handled by this transport, but if a
-mailbox begins with four binary ones followed by a newline, control is passed
-to a transport called %local_mmdf_delivery%, which presumably is configured
-to do the delivery in MMDF format. If a mailbox does not exist or is empty, it
-is assumed to match the current transport. If the start of a mailbox doesn't
-match any string, or if the transport named for a given string is not defined,
-delivery is deferred.
-
-
-oindex:[%file_must_exist%]
-`..'=
-%file_must_exist%, Use: 'appendfile', Type: 'boolean', Default: 'false'
-===
-
-If this option is true, the file specified by the %file% option must exist, and
-an error occurs if it does not. Otherwise, it is created if it does not exist.
-
-
-oindex:[%lock_fcntl_timeout%]
-`..'=
-%lock_fcntl_timeout%, Use: 'appendfile', Type: 'time', Default: '0s'
-===
-
-cindex:[timeout,mailbox locking]
-cindex:[mailbox locking,blocking and non-blocking]
-cindex:[locking files]
-By default, the ^appendfile^ transport uses non-blocking calls to 'fcntl()'
-when locking an open mailbox file. If the call fails, the delivery process
-sleeps for %lock_interval% and tries again, up to %lock_retries% times.
-Non-blocking calls are used so that the file is not kept open during the wait
-for the lock; the reason for this is to make it as safe as possible for
-deliveries over NFS in the case when processes might be accessing an NFS
-mailbox without using a lock file. This should not be done, but
-misunderstandings and hence misconfigurations are not unknown.
-
-On a busy system, however, the performance of a non-blocking lock approach is
-not as good as using a blocking lock with a timeout. In this case, the waiting
-is done inside the system call, and Exim's delivery process acquires the lock
-and can proceed as soon as the previous lock holder releases it.
-
-If %lock_fcntl_timeout% is set to a non-zero time, blocking locks, with that
-timeout, are used. There may still be some retrying: the maximum number of
-retries is
-
- (lock_retries * lock_interval) / lock_fcntl_timeout
-
-rounded up to the next whole number. In other words, the total time during
-which ^appendfile^ is trying to get a lock is roughly the same, unless
-%lock_fcntl_timeout% is set very large.
-
-You should consider setting this option if you are getting a lot of delayed
-local deliveries because of errors of the form
-
- failed to lock mailbox /some/file (fcntl)
-
-
-
-oindex:[%lock_flock_timeout%]
-`..'=
-%lock_flock_timeout%, Use: 'appendfile', Type: 'time', Default: '0s'
-===
-
-This timeout applies to file locking when using 'flock()' (see %use_flock%);
-the timeout operates in a similar manner to %lock_fcntl_timeout%.
-
-
-oindex:[%lock_interval%]
-`..'=
-%lock_interval%, Use: 'appendfile', Type: 'time', Default: '3s'
-===
-
-This specifies the time to wait between attempts to lock the file. See below
-for details of locking.
-
-
-oindex:[%lock_retries%]
-`..'=
-%lock_retries%, Use: 'appendfile', Type: 'integer', Default: '10'
-===
-
-This specifies the maximum number of attempts to lock the file. A value of zero
-is treated as 1. See below for details of locking.
-
-
-oindex:[%lockfile_mode%]
-`..'=
-%lockfile_mode%, Use: 'appendfile', Type: 'octal integer', Default: '0600'
-===
-
-This specifies the mode of the created lock file, when a lock file is being
-used (see %use_lockfile%).
-
-
-oindex:[%lockfile_timeout%]
-`..'=
-%lockfile_timeout%, Use: 'appendfile', Type: 'time', Default: '30m'
-===
-
-cindex:[timeout,mailbox locking]
-When a lock file is being used (see %use_lockfile%), if a lock file already
-exists and is older than this value, it is assumed to have been left behind by
-accident, and Exim attempts to remove it.
-
-
-oindex:[%mailbox_filecount%]
-`..'=
-%mailbox_filecount%, Use: 'appendfile', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[mailbox,specifying size of]
-cindex:[size,of mailbox]
-If this option is set, it is expanded, and the result is taken as the current
-number of files in the mailbox. It must be a decimal number, optionally
-followed by K or M. This provides a way of obtaining this information from an
-external source that maintains the data.
-
-
-oindex:[%mailbox_size%]
-`..'=
-%mailbox_size%, Use: 'appendfile', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[mailbox,specifying size of]
-cindex:[size,of mailbox]
-If this option is set, it is expanded, and the result is taken as the current
-size the mailbox. It must be a decimal number, optionally followed by K or M.
-This provides a way of obtaining this information from an external source that
-maintains the data. This is likely to be helpful for maildir deliveries where
-it is computationally expensive to compute the size of a mailbox.
-
-
-
-oindex:[%maildir_format%]
-`..'=
-%maildir_format%, Use: 'appendfile', Type: 'boolean', Default: 'false'
-===
-
-cindex:[maildir format,specifying]
-If this option is set with the %directory% option, the delivery is into a new
-file, in the ``maildir'' format that is used by other mail software. When the
-transport is activated directly from a ^redirect^ router (for example, the
-^address_file^ transport in the default configuration), setting
-%maildir_format% causes the path received from the router to be treated as a
-directory, whether or not it ends with `/`. This option is available only if
-SUPPORT_MAILDIR is present in _Local/Makefile_. See section
-<<SECTmaildirdelivery>> below for further details.
-
-
-oindex:[%maildir_quota_directory_regex%]
-`..'=
-%maildir_quota_directory_regex%, Use: 'appendfile', Type: 'string', Default: 'See below'
-===
-
-cindex:[maildir format,quota; directories included in]
-cindex:[quota,maildir; directories included in]
-This option is relevant only when %maildir_use_size_file% is set. It defines
-a regular expression for specifying directories that should be included in the
-quota calculation. The default value is
-
- maildir_quota_directory_regex = ^(?:cur|new|\..*)$
-
-which includes the _cur_ and _new_ directories, and any maildir++ folders
-(directories whose names begin with a dot). If you want to exclude the
-_Trash_
-folder from the count (as some sites do), you need to change this setting to
-
- maildir_quota_directory_regex = ^(?:cur|new|\.(?!Trash).*)$
-
-This uses a negative lookahead in the regular expression to exclude the
-directory whose name is _.Trash_.
-
-
-oindex:[%maildir_retries%]
-`..'=
-%maildir_retries%, Use: 'appendfile', Type: 'integer', Default: '10'
-===
-
-This option specifies the number of times to retry when writing a file in
-``maildir'' format. See section <<SECTmaildirdelivery>> below.
-
-
-oindex:[%maildir_tag%]
-`..'=
-%maildir_tag%, Use: 'appendfile', Type: 'string'!!, Default: 'unset'
-===
-
-This option applies only to deliveries in maildir format, and is described in
-section <<SECTmaildirdelivery>> below.
-
-
-oindex:[%maildir_use_size_file%]
-`..'=
-%maildir_use_size_file%, Use: 'appendfile', Type: 'boolean', Default: 'false'
-===
-
-cindex:[maildir format,_maildirsize_ file]
-Setting this option true enables support for _maildirsize_ files. Exim
-creates a _maildirsize_ file in a maildir if one does not exist, taking the
-quota from the %quota% option of the transport. If %quota% is unset, the value
-is zero. See section <<SECTmaildirdelivery>> below for further details.
-
-
-oindex:[%mailstore_format%]
-`..'=
-%mailstore_format%, Use: 'appendfile', Type: 'boolean', Default: 'false'
-===
-
-cindex:[mailstore format,specifying]
-If this option is set with the %directory% option, the delivery is into two new
-files in ``mailstore'' format. The option is available only if
-SUPPORT_MAILSTORE is present in _Local/Makefile_. See section
-<<SECTopdir>> below for further details.
-
-
-oindex:[%mailstore_prefix%]
-`..'=
-%mailstore_prefix%, Use: 'appendfile', Type: 'string'!!, Default: 'unset'
-===
-
-This option applies only to deliveries in mailstore format, and is described in
-section <<SECTopdir>> below.
-
-
-oindex:[%mailstore_suffix%]
-`..'=
-%mailstore_suffix%, Use: 'appendfile', Type: 'string'!!, Default: 'unset'
-===
-
-This option applies only to deliveries in mailstore format, and is described in
-section <<SECTopdir>> below.
-
-
-oindex:[%mbx_format%]
-`..'=
-%mbx_format%, Use: 'appendfile', Type: 'boolean', Default: 'false'
-===
-
-cindex:[locking files]
-cindex:[file,locking]
-cindex:[file,MBX format]
-cindex:[MBX format, specifying]
-This option is available only if Exim has been compiled with SUPPORT_MBX
-set in _Local/Makefile_. If %mbx_format% is set with the %file% option,
-the message is appended to the mailbox file in MBX format instead of
-traditional Unix format. This format is supported by Pine4 and its associated
-IMAP and POP daemons, by means of the 'c-client' library that they all use.
-
-*Note*: The %message_prefix% and %message_suffix% options are not
-automatically changed by the use of %mbx_format%. They should normally be set
-empty when using MBX format, so this option almost always appears in this
-combination:
-
- mbx_format = true
- message_prefix =
- message_suffix =
-
-
-If none of the locking options are mentioned in the configuration,
-%use_mbx_lock% is assumed and the other locking options default to false. It
-is possible to specify the other kinds of locking with %mbx_format%, but
-%use_fcntl_lock% and %use_mbx_lock% are mutually exclusive. MBX locking
-interworks with 'c-client', providing for shared access to the mailbox. It
-should not be used if any program that does not use this form of locking is
-going to access the mailbox, nor should it be used if the mailbox file is NFS
-mounted, because it works only when the mailbox is accessed from a single host.
-
-If you set %use_fcntl_lock% with an MBX-format mailbox, you cannot use
-the standard version of 'c-client', because as long as it has a mailbox open
-(this means for the whole of a Pine or IMAP session), Exim will not be able to
-append messages to it.
-
-
-oindex:[%message_prefix%]
-`..'=
-%message_prefix%, Use: 'appendfile', Type: 'string'!!, Default: 'see below'
-===
-
-cindex:[``From'' line]
-The string specified here is expanded and output at the start of every message.
-The default is unset unless %file% is specified and %use_bsmtp% is not set, in
-which case it is:
-
-....
-message_prefix = "From ${if def:return_path{$return_path}\
- {MAILER-DAEMON}} $tod_bsdinbox\n"
-....
-
-
-
-oindex:[%message_suffix%]
-`..'=
-%message_suffix%, Use: 'appendfile', Type: 'string'!!, Default: 'see below'
-===
-
-The string specified here is expanded and output at the end of every message.
-The default is unset unless %file% is specified and %use_bsmtp% is not set, in
-which case it is a single newline character. The suffix can be suppressed by
-setting
-
- message_suffix =
-
-
-
-oindex:[%mode%]
-`..'=
-%mode%, Use: 'appendfile', Type: 'octal integer', Default: '0600'
-===
-
-If the output file is created, it is given this mode. If it already exists and
-has wider permissions, they are reduced to this mode. If it has narrower
-permissions, an error occurs unless %mode_fail_narrower% is false. However,
-if the delivery is the result of a %save% command in a filter file specifing a
-particular mode, the mode of the output file is always forced to take that
-value, and this option is ignored.
-
-
-oindex:[%mode_fail_narrower%]
-`..'=
-%mode_fail_narrower%, Use: 'appendfile', Type: 'boolean', Default: 'true'
-===
-
-This option applies in the case when an existing mailbox file has a narrower
-mode than that specified by the %mode% option. If %mode_fail_narrower% is
-true, the delivery is deferred (``mailbox has the wrong mode''); otherwise Exim
-continues with the delivery attempt, using the existing mode of the file.
-
-
-oindex:[%notify_comsat%]
-`..'=
-%notify_comsat%, Use: 'appendfile', Type: 'boolean', Default: 'false'
-===
-
-If this option is true, the 'comsat' daemon is notified after every successful
-delivery to a user mailbox. This is the daemon that notifies logged on users
-about incoming mail.
-
-
-oindex:[%quota%]
-`..'=
-%quota%, Use: 'appendfile', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[quota,imposed by Exim]
-This option imposes a limit on the size of the file to which Exim is appending,
-or to the total space used in the directory tree when the %directory% option is
-set. In the latter case, computation of the space used is expensive, because
-all the files in the directory (and any sub-directories) have to be
-individually inspected and their sizes summed.
-(See %quota_size_regex% and %maildir_use_size_file% for ways to avoid this
-in environments where users have no shell access to their mailboxes).
-
-As there is no interlock against two simultaneous deliveries into a
-multi-file mailbox, it is possible for the quota to be overrun in this case.
-For single-file mailboxes, of course, an interlock is a necessity.
-
-A file's size is taken as its 'used' value. Because of blocking effects, this
-may be a lot less than the actual amount of disk space allocated to the file.
-If the sizes of a number of files are being added up, the rounding effect can
-become quite noticeable, especially on systems that have large block sizes.
-Nevertheless, it seems best to stick to the 'used' figure, because this is
-the obvious value which users understand most easily.
-
-[revisionflag="changed"]
-The value of the option is expanded, and must then be a numerical value
-(decimal point allowed), optionally followed by one of the letters K, M, or G,
-for kilobytes, megabytes, or gigabytes. If Exim is running on a system with
-large file support (Linux and FreeBSD have this), mailboxes larger than 2G can
-be handled.
-
-*Note*: A value of zero is interpreted as ``no quota''.
-
-The expansion happens while Exim is running as root, before it changes uid for
-the delivery. This means that files that are inaccessible to the end user can
-be used to hold quota values that are looked up in the expansion. When delivery
-fails because this quota is exceeded, the handling of the error is as for
-system quota failures.
-
-By default, Exim's quota checking mimics system quotas, and restricts the
-mailbox to the specified maximum size, though the value is not accurate to the
-last byte, owing to separator lines and additional headers that may get added
-during message delivery. When a mailbox is nearly full, large messages may get
-refused even though small ones are accepted, because the size of the current
-message is added to the quota when the check is made. This behaviour can be
-changed by setting %quota_is_inclusive% false. When this is done, the check
-for exceeding the quota does not include the current message. Thus, deliveries
-continue until the quota has been exceeded; thereafter, no further messages are
-delivered. See also %quota_warn_threshold%.
-
-
-oindex:[%quota_directory%]
-`..'=
-%quota_directory%, Use: 'appendfile', Type: 'string'!!, Default: 'unset'
-===
-
-This option defines the directory to check for quota purposes when delivering
-into individual files. The default is the delivery directory, or, if a file
-called _maildirfolder_ exists in a maildir directory, the parent of the
-delivery directory.
-
-
-oindex:[%quota_filecount%]
-`..'=
-%quota_filecount%, Use: 'appendfile', Type: 'string'!!, Default: '0'
-===
-
-This option applies when the %directory% option is set. It limits the total
-number of files in the directory (compare the inode limit in system quotas). It
-can only be used if %quota% is also set. The value is expanded; an expansion
-failure causes delivery to be deferred.
-
-
-oindex:[%quota_is_inclusive%]
-`..'=
-%quota_is_inclusive%, Use: 'appendfile', Type: 'boolean', Default: 'true'
-===
-
-See %quota% above.
-
-
-oindex:[%quota_size_regex%]
-`..'=
-%quota_size_regex%, Use: 'appendfile', Type: 'string', Default: 'unset'
-===
-
-This option applies when one of the delivery modes that writes a separate file
-for each message is being used. When Exim wants to find the size of one of
-these files in order to test the quota, it first checks %quota_size_regex%.
-If this is set to a regular expression that matches the file name, and it
-captures one string, that string is interpreted as a representation of the
-file's size. The value of %quota_size_regex% is not expanded.
-
-This feature is useful only when users have no shell access to their mailboxes
--- otherwise they could defeat the quota simply by renaming the files. This
-facility can be used with maildir deliveries, by setting %maildir_tag% to add
-the file length to the file name. For example:
-
- maildir_tag = ,S=$message_size
- quota_size_regex = ,S=(\d+)
-
-[revisionflag="changed"]
-An alternative to $message_size$ is $message_linecount$, which contains the
-number of lines in the message.
-
-The regular expression should not assume that the length is at the end of the
-file name (even though %maildir_tag% puts it there) because maildir MUAs
-sometimes add other information onto the ends of message file names.
-
-
-
-oindex:[%quota_warn_message%]
-`..'=
-%quota_warn_message%, Use: 'appendfile', Type: 'string'!!, Default: 'see below'
-===
-
-See below for the use of this option. If it is not set when
-%quota_warn_threshold% is set, it defaults to
-
-....
-quota_warn_message = "\
- To: $local_part@$domain\n\
- Subject: Your mailbox\n\n\
- This message is automatically created \
- by mail delivery software.\n\n\
- The size of your mailbox has exceeded \
- a warning threshold that is\n\
- set by the system administrator.\n"
-....
-
-
-
-oindex:[%quota_warn_threshold%]
-`..'=
-%quota_warn_threshold%, Use: 'appendfile', Type: 'string'!!, Default: '0'
-===
-
-cindex:[quota,warning threshold]
-cindex:[mailbox,size warning]
-cindex:[size,of mailbox]
-This option is expanded in the same way as %quota% (see above). If the
-resulting value is greater than zero, and delivery of the message causes the
-size of the file or total space in the directory tree to cross the given
-threshold, a warning message is sent. If %quota% is also set, the threshold may
-be specified as a percentage of it by following the value with a percent sign.
-For example:
-
- quota = 10M
- quota_warn_threshold = 75%
-
-If %quota% is not set, a setting of %quota_warn_threshold% that ends with a
-percent sign is ignored.
-
-[revisionflag="changed"]
-The warning message itself is specified by the %quota_warn_message% option,
-and it must start with a 'To:' header line containing the recipient(s) of the
-warning message. These do not necessarily have to include the recipient(s) of
-the original message. A 'Subject:' line should also normally be supplied. You
-can include any other header lines that you want.
-
-The %quota% option does not have to be set in order to use this option; they
-are independent of one another except when the threshold is specified as a
-percentage.
-
-
-oindex:[%use_bsmtp%]
-`..'=
-%use_bsmtp%, Use: 'appendfile', Type: 'boolean', Default: 'false'
-===
-
-cindex:[envelope sender]
-If this option is set true, ^appendfile^ writes messages in ``batch SMTP''
-format, with the envelope sender and recipient(s) included as SMTP commands. If
-you want to include a leading HELO command with such messages, you can do
-so by setting the %message_prefix% option. See section <<SECTbatchSMTP>> for
-details of batch SMTP.
-
-
-oindex:[%use_crlf%]
-`..'=
-%use_crlf%, Use: 'appendfile', Type: 'boolean', Default: 'false'
-===
-
-cindex:[carriage return]
-cindex:[linefeed]
-This option causes lines to be terminated with the two-character CRLF sequence
-(carriage return, linefeed) instead of just a linefeed character. In the case
-of batched SMTP, the byte sequence written to the file is then an exact image
-of what would be sent down a real SMTP connection.
-
-The contents of the %message_prefix% and %message_suffix% options are written
-verbatim, so must contain their own carriage return characters if these are
-needed. In cases where these options have non-empty defaults, the values end
-with a single linefeed, so they
-must
-be changed to end with `\r\n` if %use_crlf% is set.
-
-
-oindex:[%use_fcntl_lock%]
-`..'=
-%use_fcntl_lock%, Use: 'appendfile', Type: 'boolean', Default: 'see below'
-===
-
-This option controls the use of the 'fcntl()' function to lock a file for
-exclusive use when a message is being appended. It is set by default unless
-%use_flock_lock% is set. Otherwise, it should be turned off only if you know
-that all your MUAs use lock file locking. When both %use_fcntl_lock% and
-%use_flock_lock% are unset, %use_lockfile% must be set.
-
-
-oindex:[%use_flock_lock%]
-`..'=
-%use_flock_lock%, Use: 'appendfile', Type: 'boolean', Default: 'false'
-===
-
-This option is provided to support the use of 'flock()' for file locking, for
-the few situations where it is needed. Most modern operating systems support
-'fcntl()' and 'lockf()' locking, and these two functions interwork with
-each other. Exim uses 'fcntl()' locking by default.
-
-This option is required only if you are using an operating system where
-'flock()' is used by programs that access mailboxes (typically MUAs), and
-where 'flock()' does not correctly interwork with 'fcntl()'. You can use
-both 'fcntl()' and 'flock()' locking simultaneously if you want.
-
-cindex:[Solaris,'flock()' support]
-Not all operating systems provide 'flock()'. Some versions of Solaris do not
-have it (and some, I think, provide a not quite right version built on top of
-'lockf()'). If the OS does not have 'flock()', Exim will be built without
-the ability to use it, and any attempt to do so will cause a configuration
-error.
-
-*Warning*: 'flock()' locks do not work on NFS files (unless 'flock()'
-is just being mapped onto 'fcntl()' by the OS).
-
-
-oindex:[%use_lockfile%]
-`..'=
-%use_lockfile%, Use: 'appendfile', Type: 'boolean', Default: 'see below'
-===
-
-If this option is turned off, Exim does not attempt to create a lock file when
-appending to a mailbox file. In this situation, the only locking is by
-'fcntl()'. You should only turn %use_lockfile% off if you are absolutely
-sure that every MUA that is ever going to look at your users' mailboxes uses
-'fcntl()' rather than a lock file, and even then only when you are not
-delivering over NFS from more than one host.
-
-cindex:[NFS,lock file]
-In order to append to an NFS file safely from more than one host, it is
-necessary to take out a lock 'before' opening the file, and the lock file
-achieves this. Otherwise, even with 'fcntl()' locking, there is a risk of
-file corruption.
-
-The %use_lockfile% option is set by default unless %use_mbx_lock% is set. It
-is not possible to turn both %use_lockfile% and %use_fcntl_lock% off, except
-when %mbx_format% is set.
-
-
-oindex:[%use_mbx_lock%]
-`..'=
-%use_mbx_lock%, Use: 'appendfile', Type: 'boolean', Default: 'see below'
-===
-
-This option is available only if Exim has been compiled with SUPPORT_MBX
-set in _Local/Makefile_. Setting the option specifies that special MBX
-locking rules be used. It is set by default if %mbx_format% is set and none of
-the locking options are mentioned in the configuration. The locking rules are
-the same as are used by the 'c-client' library that underlies Pine and the
-IMAP4 and POP daemons that come with it (see the discussion below). The rules
-allow for shared access to the mailbox. However, this kind of locking does not
-work when the mailbox is NFS mounted.
-
-You can set %use_mbx_lock% with either (or both) of %use_fcntl_lock% and
-%use_flock_lock% to control what kind of locking is used in implementing the
-MBX locking rules. The default is to use 'fcntl()' if %use_mbx_lock% is set
-without %use_fcntl_lock% or %use_flock_lock%.
-
-
-
-
-[[SECTopappend]]
-Operational details for appending
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[appending to a file]
-cindex:[file,appending]
-Before appending to a file, the following preparations are made:
-
-- If the name of the file is _/dev/null_, no action is taken, and a success
-return is given.
-
-- cindex:[directory creation]
-If any directories on the file's path are missing, Exim creates them if the
-%create_directory% option is set. A created directory's mode is given by the
-%directory_mode% option.
-
-- If %file_format% is set, the format of an existing file is checked. If this
-indicates that a different transport should be used, control is passed to that
-transport.
-
-- cindex:[file,locking]
-cindex:[locking files]
-cindex:[NFS,lock file]
-If %use_lockfile% is set, a lock file is built in a way that will work
-reliably over NFS, as follows:
-+
---
-. Create a ``hitching post'' file whose name is that of the lock file with the
-current time, primary host name, and process id added, by opening for writing
-as a new file. If this fails with an access error, delivery is deferred.
-
-. Close the hitching post file, and hard link it to the lock file name.
-
-. If the call to 'link()' succeeds, creation of the lock file has succeeded.
-Unlink the hitching post name.
-
-. Otherwise, use 'stat()' to get information about the hitching post file, and
-then unlink hitching post name. If the number of links is exactly two, creation
-of the lock file succeeded but something (for example, an NFS server crash and
-restart) caused this fact not to be communicated to the 'link()' call.
-
-. If creation of the lock file failed, wait for %lock_interval% and try again,
-up to %lock_retries% times. However, since any program that writes to a
-mailbox should complete its task very quickly, it is reasonable to time out old
-lock files that are normally the result of user agent and system crashes. If an
-existing lock file is older than %lockfile_timeout% Exim attempts to unlink it
-before trying again.
---
-+
-- A call is made to 'lstat()' to discover whether the main file exists, and if
-so, what its characteristics are. If 'lstat()' fails for any reason other
-than non-existence, delivery is deferred.
-
-- cindex:[symbolic link,to mailbox]
-cindex:[mailbox,symbolic link]
-If the file does exist and is a symbolic link, delivery is deferred, unless the
-%allow_symlink% option is set, in which case the ownership of the link is
-checked, and then 'stat()' is called to find out about the real file, which
-is then subjected to the checks below. The check on the top-level link
-ownership prevents one user creating a link for another's mailbox in a sticky
-directory, though allowing symbolic links in this case is definitely not a good
-idea. If there is a chain of symbolic links, the intermediate ones are not
-checked.
-
-- If the file already exists but is not a regular file, or if the file's owner
-and group (if the group is being checked -- see %check_group% above) are
-different from the user and group under which the delivery is running,
-delivery is deferred.
-
-- If the file's permissions are more generous than specified, they are reduced.
-If they are insufficient, delivery is deferred, unless %mode_fail_narrower%
-is set false, in which case the delivery is tried using the existing
-permissions.
-
-- The file's inode number is saved, and the file is then opened for appending.
-If this fails because the file has vanished, ^appendfile^ behaves as if it
-hadn't existed (see below). For any other failures, delivery is deferred.
-
-- If the file is opened successfully, check that the inode number hasn't
-changed, that it is still a regular file, and that the owner and permissions
-have not changed. If anything is wrong, defer delivery and freeze the message.
-
-- If the file did not exist originally, defer delivery if the %file_must_exist%
-option is set. Otherwise, check that the file is being created in a permitted
-directory if the %create_file% option is set (deferring on failure), and then
-open for writing as a new file, with the O_EXCL and O_CREAT options,
-except when dealing with a symbolic link (the %allow_symlink% option must be
-set). In this case, which can happen if the link points to a non-existent file,
-the file is opened for writing using O_CREAT but not O_EXCL, because
-that prevents link following.
-
-- cindex:[loop,while file testing]
-If opening fails because the file exists, obey the tests given above for
-existing files. However, to avoid looping in a situation where the file is
-being continuously created and destroyed, the exists/not-exists loop is broken
-after 10 repetitions, and the message is then frozen.
-
-- If opening fails with any other error, defer delivery.
-
-- cindex:[file,locking]
-cindex:[locking files]
-Once the file is open, unless both %use_fcntl_lock% and %use_flock_lock%
-are false, it is locked using 'fcntl()' or 'flock()' or both. If
-%use_mbx_lock% is false, an exclusive lock is requested in each case.
-However, if %use_mbx_lock% is true,
-Exim takes out a shared lock on the open file,
-and an exclusive lock on the file whose name is
-
- /tmp/.<device-number>.<inode-number>
-+
-using the device and inode numbers of the open mailbox file, in accordance with
-the MBX locking rules.
-+
-If Exim fails to lock the file, there are two possible courses of action,
-depending on the value of the locking timeout. This is obtained from
-%lock_fcntl_timeout% or %lock_flock_timeout%, as appropriate.
-+
-If the timeout value is zero, the file is closed, Exim waits for
-%lock_interval%, and then goes back and re-opens the file as above and tries
-to lock it again. This happens up to %lock_retries% times, after which the
-delivery is deferred.
-+
-If the timeout has a value greater than zero, blocking calls to 'fcntl()' or
-'flock()' are used (with the given timeout), so there has already been some
-waiting involved by the time locking fails. Nevertheless, Exim does not give up
-immediately. It retries up to
-
- (lock_retries * lock_interval) / <timeout>
-+
-times (rounded up).
-
-
-At the end of delivery, Exim closes the file (which releases the 'fcntl()'
-and/or 'flock()' locks) and then deletes the lock file if one was created.
-
-
-[[SECTopdir]]
-Operational details for delivery to a new file
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[delivery,to single file]
-cindex:[``From'' line]
-When the %directory% option is set instead of %file%, each message is delivered
-into a newly-created file or set of files. When ^appendfile^ is activated
-directly from a ^redirect^ router, neither %file% nor %directory% is normally
-set, because the path for delivery is supplied by the router. (See for example,
-the ^address_file^ transport in the default configuration.) In this case,
-delivery is to a new file if either the path name ends in `/`, or the
-%maildir_format% or %mailstore_format% option is set.
-
-No locking is required while writing the message to a new file, so the various
-locking options of the transport are ignored. The ``From'' line that by default
-separates messages in a single file is not normally needed, nor is the escaping
-of message lines that start with ``From'', and there is no need to ensure a
-newline at the end of each message. Consequently, the default values for
-%check_string%, %message_prefix%, and %message_suffix% are all unset when
-any of %directory%, %maildir_format%, or %mailstore_format% is set.
-
-If Exim is required to check a %quota% setting, it adds up the sizes of all the
-files in the delivery directory by default. However, you can specify a
-different directory by setting %quota_directory%. Also, for maildir deliveries
-(see below) the _maildirfolder_ convention is honoured.
-
-
-cindex:[maildir format]
-cindex:[mailstore format]
-There are three different ways in which delivery to individual files can be
-done, controlled by the settings of the %maildir_format% and
-%mailstore_format% options. Note that code to support maildir or mailstore
-formats is not included in the binary unless SUPPORT_MAILDIR or
-SUPPORT_MAILSTORE, respectively, is set in _Local/Makefile_.
-
-cindex:[directory creation]
-In all three cases an attempt is made to create the directory and any necessary
-sub-directories if they do not exist, provided that the %create_directory%
-option is set (the default). The location of a created directory can be
-constrained by setting %create_file%. A created directory's mode is given by
-the %directory_mode% option. If creation fails, or if the %create_directory%
-option is not set when creation is required, delivery is deferred.
-
-
-
-[[SECTmaildirdelivery]]
-Maildir delivery
-~~~~~~~~~~~~~~~~
-cindex:[maildir format,description of]
-If the %maildir_format% option is true, Exim delivers each message by writing
-it to a file whose name is _tmp/<stime>.H<mtime>P<pid>.<host>_ in the
-given directory. If the delivery is successful, the file is renamed into the
-_new_ subdirectory.
-
-In the file name, <'stime'> is the current time of day in seconds, and
-<'mtime'> is the microsecond fraction of the time. After a maildir delivery,
-Exim checks that the time-of-day clock has moved on by at least one microsecond
-before terminating the delivery process. This guarantees uniqueness for the
-file name. However, as a precaution, Exim calls 'stat()' for the file before
-opening it. If any response other than ENOENT (does not exist) is given,
-Exim waits 2 seconds and tries again, up to %maildir_retries% times.
-
-cindex:[quota,in maildir delivery]
-cindex:[maildir++]
-If Exim is required to check a %quota% setting before a maildir delivery, and
-%quota_directory% is not set, it looks for a file called _maildirfolder_ in
-the maildir directory (alongside _new_, _cur_, _tmp_). If this exists,
-Exim assumes the directory is a maildir++ folder directory, which is one level
-down from the user's top level mailbox directory. This causes it to start at
-the parent directory instead of the current directory when calculating the
-amount of space used.
-
-One problem with delivering into a multi-file mailbox is that it is
-computationally expensive to compute the size of the mailbox for quota
-checking. Various approaches have been taken to reduce the amount of work
-needed. The next two sections describe two of them. A third alternative is to
-use some external process for maintaining the size data, and use the expansion
-of the %mailbox_size% option as a way of importing it into Exim.
-
-
-
-
-Using tags to record message sizes
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-If %maildir_tag% is set, the string is expanded for each delivery.
-When the maildir file is renamed into the _new_ sub-directory, the
-tag is added to its name. However, if adding the tag takes the length of the
-name to the point where the test 'stat()' call fails with ENAMETOOLONG,
-the tag is dropped and the maildir file is created with no tag.
-
-cindex:[$message_size$]
-Tags can be used to encode the size of files in their names; see
-%quota_size_regex% above for an example. The expansion of %maildir_tag% happens
-after the message has been written. The value of the $message_size$ variable is
-set to the number of bytes actually written. If the expansion is forced to
-fail, the tag is ignored, but a non-forced failure causes delivery to be
-deferred. The expanded tag may contain any printing characters except ``/''.
-Non-printing characters in the string are ignored; if the resulting string is
-empty, it is ignored. If it starts with an alphanumeric character, a leading
-colon is inserted.
-
-
-
-Using a maildirsize file
-~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[quota,in maildir delivery]
-cindex:[maildir format,_maildirsize_ file]
-If %maildir_use_size_file% is true, Exim implements the maildir++ rules for
-storing quota and message size information in a file called _maildirsize_
-within the maildir directory. If this file does not exist, Exim creates it,
-setting the quota from the %quota% option of the transport. If the maildir
-directory itself does not exist, it is created before any attempt to write a
-_maildirsize_ file.
-
-The _maildirsize_ file is used to hold information about the sizes of
-messages in the maildir, thus speeding up quota calculations. The quota value
-in the file is just a cache; if the quota is changed in the transport, the new
-value overrides the cached value when the next message is delivered. The cache
-is maintained for the benefit of other programs that access the maildir and
-need to know the quota.
-
-If the %quota% option in the transport is unset or zero, the _maildirsize_
-file is maintained (with a zero quota setting), but no quota is imposed.
-
-A regular expression is available for controlling which directories in the
-maildir participate in quota calculations. See the description of the
-%maildir_quota_directory_regex% option above for details.
-
-
-
-Mailstore delivery
-~~~~~~~~~~~~~~~~~~
-cindex:[mailstore format,description of]
-If the %mailstore_format% option is true, each message is written as two files
-in the given directory. A unique base name is constructed from the message id
-and the current delivery process, and the files that are written use this base
-name plus the suffixes _.env_ and _.msg_. The _.env_ file contains the
-message's envelope, and the _.msg_ file contains the message itself. The base
-name is placed in the variable $mailstore_basename$.
-
-During delivery, the envelope is first written to a file with the suffix
-_.tmp_. The _.msg_ file is then written, and when it is complete, the
-_.tmp_ file is renamed as the _.env_ file. Programs that access messages in
-mailstore format should wait for the presence of both a _.msg_ and a _.env_
-file before accessing either of them. An alternative approach is to wait for
-the absence of a _.tmp_ file.
-
-The envelope file starts with any text defined by the %mailstore_prefix%
-option, expanded and terminated by a newline if there isn't one. Then follows
-the sender address on one line, then all the recipient addresses, one per line.
-There can be more than one recipient only if the %batch_max% option is set
-greater than one. Finally, %mailstore_suffix% is expanded and the result
-appended to the file, followed by a newline if it does not end with one.
-
-[revisionflag="changed"]
-If expansion of %mailstore_prefix% or %mailstore_suffix% ends with a forced
-failure, it is ignored. Other expansion errors are treated as serious
-configuration errors, and delivery is deferred. The variable
-$mailstore_basename$ is available for use during these expansions.
-
-
-
-Non-special new file delivery
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-If neither %maildir_format% nor %mailstore_format% is set, a single new file
-is created directly in the named directory. For example, when delivering
-messages into files in batched SMTP format for later delivery to some host (see
-section <<SECTbatchSMTP>>), a setting such as
-
- directory = /var/bsmtp/$host
-
-might be used. A message is written to a file with a temporary name, which is
-then renamed when the delivery is complete. The final name is obtained by
-expanding the contents of the %directory_file% option.
-
-
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-The autoreply transport
------------------------
-cindex:[transports,^autoreply^]
-cindex:[^autoreply^ transport]
-The ^autoreply^ transport is not a true transport in that it does not cause
-the message to be transmitted. Instead, it generates a new mail message.
-
-If the router that passes the message to this transport does not have the
-%unseen% option set, the original message (for the current recipient) is not
-delivered anywhere. However, when the %unseen% option is set on the router that
-passes the message to this transport, routing of the address continues, so
-another router can set up a normal message delivery.
-
-
-The ^autoreply^ transport is usually run as the result of mail filtering, a
-``vacation'' message being the standard example. However, it can also be run
-directly from a router like any other transport. To reduce the possibility of
-message cascades, messages created by the ^autoreply^ transport always have
-empty envelope sender addresses, like bounce messages.
-
-The parameters of the message to be sent can be specified in the configuration
-by options described below. However, these are used only when the address
-passed to the transport does not contain its own reply information. When the
-transport is run as a consequence of a
-%mail%
-or %vacation% command in a filter file, the parameters of the message are
-supplied by the filter, and passed with the address. The transport's options
-that define the message are then ignored (so they are not usually set in this
-case). The message is specified entirely by the filter or by the transport; it
-is never built from a mixture of options. However, the %file_optional%,
-%mode%, and %return_message% options apply in all cases.
-
-^Autoreply^ is implemented as a local transport. When used as a result of a
-command in a user's filter file, ^autoreply^ normally runs under the uid and
-gid of the user, and with appropriate current and home directories (see chapter
-<<CHAPenvironment>>).
-
-There is a subtle difference between routing a message to a ^pipe^ transport
-that generates some text to be returned to the sender, and routing it to an
-^autoreply^ transport. This difference is noticeable only if more than one
-address from the same message is so handled. In the case of a pipe, the
-separate outputs from the different addresses are gathered up and returned to
-the sender in a single message, whereas if ^autoreply^ is used, a separate
-message is generated for each address that is passed to it.
-
-Non-printing characters are not permitted in the header lines generated for the
-message that ^autoreply^ creates, with the exception of newlines that are
-immediately followed by white space. If any non-printing characters are found,
-the transport defers.
-Whether characters with the top bit set count as printing characters or not is
-controlled by the %print_topbitchars% global option.
-
-If any of the generic options for manipulating headers (for example,
-%headers_add%) are set on an ^autoreply^ transport, they apply to the copy of
-the original message that is included in the generated message when
-%return_message% is set. They do not apply to the generated message itself.
-
-cindex:[$sender_address$]
-If the ^autoreply^ transport receives return code 2 from Exim when it submits
-the message, indicating that there were no recipients, it does not treat this
-as an error. This means that autoreplies sent to $sender_address$ when this
-is empty (because the incoming message is a bounce message) do not cause
-problems. They are just discarded.
-
-
-
-Private options for autoreply
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[options,^autoreply^ transport]
-
-oindex:[%bcc%]
-`..'=
-%bcc%, Use: 'autoreply', Type: 'string'!!, Default: 'unset'
-===
-
-This specifies the addresses that are to receive ``blind carbon copies'' of the
-message when the message is specified by the transport.
-
-
-oindex:[%cc%]
-`..'=
-%cc%, Use: 'autoreply', Type: 'string'!!, Default: 'unset'
-===
-
-This specifies recipients of the message and the contents of the 'Cc:' header
-when the message is specified by the transport.
-
-
-oindex:[%file%]
-`..'=
-%file%, Use: 'autoreply', Type: 'string'!!, Default: 'unset'
-===
-
-The contents of the file are sent as the body of the message when the message
-is specified by the transport. If both %file% and %text% are set, the text
-string comes first.
-
-
-oindex:[%file_expand%]
-`..'=
-%file_expand%, Use: 'autoreply', Type: 'boolean', Default: 'false'
-===
-
-If this is set, the contents of the file named by the %file% option are
-subjected to string expansion as they are added to the message.
-
-
-oindex:[%file_optional%]
-`..'=
-%file_optional%, Use: 'autoreply', Type: 'boolean', Default: 'false'
-===
-
-If this option is true, no error is generated if the file named by the %file%
-option or passed with the address does not exist or cannot be read.
-
-
-oindex:[%from%]
-`..'=
-%from%, Use: 'autoreply', Type: 'string'!!, Default: 'unset'
-===
-
-This specifies the contents of the 'From:' header when the message is specified
-by the transport.
-
-
-oindex:[%headers%]
-`..'=
-%headers%, Use: 'autoreply', Type: 'string'!!, Default: 'unset'
-===
-
-This specifies additional RFC 2822 headers that are to be added to the message when
-the message is specified by the transport. Several can be given by using ``\n''
-to separate them. There is no check on the format.
-
-
-oindex:[%log%]
-`..'=
-%log%, Use: 'autoreply', Type: 'string'!!, Default: 'unset'
-===
-
-This option names a file in which a record of every message sent is logged when
-the message is specified by the transport.
-
-
-oindex:[%mode%]
-`..'=
-%mode%, Use: 'autoreply', Type: 'octal integer', Default: '0600'
-===
-
-If either the log file or the ``once'' file has to be created, this mode is
-used.
-
-
-oindex:[%never_mail%]
-`..'=
-%never_mail%, Use: 'autoreply', Type: 'address list'!!, Default: 'unset'
-===
-
-If any run of the transport creates a message with a recipient that matches any
-item in the list, that recipient is quietly discarded. If all recipients are
-discarded, no message is created.
-
-
-
-oindex:[%once%]
-`..'=
-%once%, Use: 'autoreply', Type: 'string'!!, Default: 'unset'
-===
-
-This option names a file or DBM database in which a record of each 'To:'
-recipient is kept when the message is specified by the transport. *Note*: This
-does not apply to 'Cc:' or 'Bcc:' recipients.
-
-If %once% is unset, or is set to an empty string, the message is always sent.
-By default, if %once% is set to a non-empty file name, the message
-is not sent if a potential recipient is already listed in the database.
-However, if the %once_repeat% option specifies a time greater than zero, the
-message is sent if that much time has elapsed since a message was last sent to
-this recipient. A setting of zero time for %once_repeat% (the default) prevents
-a message from being sent a second time -- in this case, zero means infinity.
-
-If %once_file_size% is zero, a DBM database is used to remember recipients, and
-it is allowed to grow as large as necessary. If %once_file_size% is set greater
-than zero, it changes the way Exim implements the %once% option. Instead of
-using a DBM file to record every recipient it sends to, it uses a regular file,
-whose size will never get larger than the given value.
-
-In the file, Exim keeps a linear list of recipient addresses and the times at
-which they were sent messages. If the file is full when a new address needs to
-be added, the oldest address is dropped. If %once_repeat% is not set, this
-means that a given recipient may receive multiple messages, but at
-unpredictable intervals that depend on the rate of turnover of addresses in the
-file. If %once_repeat% is set, it specifies a maximum time between repeats.
-
-
-oindex:[%once_file_size%]
-`..'=
-%once_file_size%, Use: 'autoreply', Type: 'integer', Default: '0'
-===
-
-See %once% above.
-
-
-oindex:[%once_repeat%]
-`..'=
-%once_repeat%, Use: 'autoreply', Type: 'time'!!, Default: '0s'
-===
-
-See %once% above.
-After expansion, the value of this option must be a valid time value.
-
-
-oindex:[%reply_to%]
-`..'=
-%reply_to%, Use: 'autoreply', Type: 'string'!!, Default: 'unset'
-===
-
-This specifies the contents of the 'Reply-To:' header when the message is
-specified by the transport.
-
-
-oindex:[%return_message%]
-`..'=
-%return_message%, Use: 'autoreply', Type: 'boolean', Default: 'false'
-===
-
-If this is set, a copy of the original message is returned with the new
-message, subject to the maximum size set in the %return_size_limit% global
-configuration option.
-
-
-oindex:[%subject%]
-`..'=
-%subject%, Use: 'autoreply', Type: 'string'!!, Default: 'unset'
-===
-
-This specifies the contents of the 'Subject:' header when the message is
-specified by the transport.
-
-It is tempting to quote the original subject in automatic responses. For
-example:
-
- subject = Re: $h_subject:
-
-There is a danger in doing this, however. It may allow a third party to
-subscribe your users to an opt-in mailing list, provided that the list accepts
-bounce messages as subscription confirmations. Well-managed lists require a
-non-bounce message to confirm a subscription, so the danger is relatively
-small.
-
-
-
-oindex:[%text%]
-`..'=
-%text%, Use: 'autoreply', Type: 'string'!!, Default: 'unset'
-===
-
-This specifies a single string to be used as the body of the message when the
-message is specified by the transport. If both %text% and %file% are set, the
-text comes first.
-
-
-oindex:[%to%]
-`..'=
-%to%, Use: 'autoreply', Type: 'string'!!, Default: 'unset'
-===
-
-This specifies recipients of the message and the contents of the 'To:' header
-when the message is specified by the transport.
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPLMTP]]
-The lmtp transport
-------------------
-cindex:[transports,^lmtp^]
-cindex:[^lmtp^ transport]
-cindex:[LMTP,over a pipe]
-cindex:[LMTP,over a socket]
-The ^lmtp^ transport runs the LMTP protocol (RFC 2033) over a pipe to a
-specified command
-or by interacting with a Unix domain socket.
-This transport is something of a cross between the ^pipe^ and ^smtp^
-transports. Exim also has support for using LMTP over TCP/IP; this is
-implemented as an option for the ^smtp^ transport. Because LMTP is expected
-to be of minority interest, the default build-time configure in _src/EDITME_
-has it commented out. You need to ensure that
-
- TRANSPORT_LMTP=yes
-
-is present in your _Local/Makefile_ in order to have the ^lmtp^ transport
-included in the Exim binary.
-
-cindex:[options,^lmtp^ transport]
-The private options of the ^lmtp^ transport are as follows:
-
-oindex:[%batch_id%]
-`..'=
-%batch_id%, Use: 'lmtp', Type: 'string'!!, Default: 'unset'
-===
-
-See the description of local delivery batching in chapter <<CHAPbatching>>.
-
-
-oindex:[%batch_max%]
-`..'=
-%batch_max%, Use: 'lmtp', Type: 'integer', Default: '1'
-===
-
-This limits the number of addresses that can be handled in a single delivery.
-Most LMTP servers can handle several addresses at once, so it is normally a
-good idea to increase this value. See the description of local delivery
-batching in chapter <<CHAPbatching>>.
-
-
-oindex:[%command%]
-`..'=
-%command%, Use: 'lmtp', Type: 'string'!!, Default: 'unset'
-===
-
-This option must be set if %socket% is not set. The string is a command which
-is run in a separate process. It is split up into a command name and list of
-arguments, each of which is separately expanded (so expansion cannot change the
-number of arguments). The command is run directly, not via a shell. The message
-is passed to the new process using the standard input and output to operate the
-LMTP protocol.
-
-oindex:[%ignore_quota%]
-`..'=
-%ignore_quota%, Use: 'lmtp', Type: 'boolean', Default: 'false'
-===
-
-[revisionflag="changed"]
-cindex:[LMTP,ignoring quota errors]
-If this option is set true, the string `IGNOREQUOTA` is added to RCPT commands,
-provided that the LMTP server has advertised support for IGNOREQUOTA in its
-response to the LHLO command.
-
-
-oindex:[%socket%]
-`..'=
-%socket%, Use: 'lmtp', Type: 'string'!!, Default: 'unset'
-===
-
-This option must be set if %command% is not set. The result of expansion must
-be the name of a Unix domain socket. The transport connects to the socket and
-delivers the message to it using the LMTP protocol.
-
-
-oindex:[%timeout%]
-`..'=
-%timeout%, Use: 'lmtp', Type: 'time', Default: '5m'
-===
-
-The transport is aborted if the created process
-or Unix domain socket
-does not respond to LMTP commands or message input within this timeout.
-
-
-Here is an example of a typical LMTP transport:
-
- lmtp:
- driver = lmtp
- command = /some/local/lmtp/delivery/program
- batch_max = 20
- user = exim
-
-This delivers up to 20 addresses at a time, in a mixture of domains if
-necessary, running as the user 'exim'.
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPpipetransport]]
-The pipe transport
-------------------
-cindex:[transports,^pipe^]
-cindex:[^pipe^ transport]
-The ^pipe^ transport is used to deliver messages via a pipe to a command
-running in another process.
-
-One example is the
-use of ^pipe^ as a pseudo-remote transport for passing messages to some other
-delivery mechanism (such as UUCP). Another is the use by individual users to
-automatically process their incoming messages. The ^pipe^ transport can be
-used in one of the following ways:
-
-- cindex:[$local_part$]
-A router routes one address to a transport in the normal way, and the
-transport is configured as a ^pipe^ transport. In this case, $local_part$
-contains the local part of the address (as usual), and the command that is run
-is specified by the %command% option on the transport.
-
-- cindex:[$pipe_addresses$]
-If the %batch_max% option is set greater than 1 (the default), the transport
-can be called upon to handle more than one address in a single run. In this
-case, $local_part$ is not set (because it is not unique). However, the
-pseudo-variable $pipe_addresses$ (described in section <<SECThowcommandrun>>
-below) contains all the addresses that are being handled.
-
-- cindex:[$address_pipe$]
-A router redirects an address directly to a pipe command (for example, from an
-alias or forward file). In this case, $local_part$ contains the local part
-that was redirected, and $address_pipe$ contains the text of the pipe
-command itself. The %command% option on the transport is ignored.
-
-
-The ^pipe^ transport is a non-interactive delivery method. Exim can also
-deliver messages over pipes using the LMTP interactive protocol. This is
-implemented by the ^lmtp^ transport.
-
-In the case when ^pipe^ is run as a consequence of an entry in a local user's
-_.forward_ file, the command runs under the uid and gid of that user. In other
-cases, the uid and gid have to be specified explicitly, either on the transport
-or on the router that handles the address. Current and ``home'' directories are
-also controllable. See chapter <<CHAPenvironment>> for details of the local
-delivery environment.
-
-
-
-Concurrent delivery
-~~~~~~~~~~~~~~~~~~~
-If two messages arrive at almost the same time, and both are routed to a pipe
-delivery, the two pipe transports may be run concurrently. You must ensure that
-any pipe commands you set up are robust against this happening. If the commands
-write to a file, the %exim_lock% utility might be of use.
-
-
-
-
-Returned status and data
-~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[^pipe^ transport,returned data]
-If the command exits with a non-zero return code, the delivery is deemed to
-have failed, unless either the %ignore_status% option is set (in which case
-the return code is treated as zero), or the return code is one of those listed
-in the %temp_errors% option, which are interpreted as meaning ``try again
-later''. In this case, delivery is deferred. Details of a permanent failure are
-logged, but are not included in the bounce message, which merely contains
-``local delivery failed''.
-
-If the return code is greater than 128 and the command being run is a shell
-script, it normally means that the script was terminated by a signal whose
-value is the return code minus 128.
-
-If Exim is unable to run the command (that is, if 'execve()' fails), the
-return code is set to 127. This is the value that a shell returns if it is
-asked to run a non-existent command. The wording for the log line suggests that
-a non-existent command may be the problem.
-
-The %return_output% option can affect the result of a pipe delivery. If it is
-set and the command produces any output on its standard output or standard
-error streams, the command is considered to have failed, even if it gave a zero
-return code or if %ignore_status% is set. The output from the command is
-included as part of the bounce message. The %return_fail_output% option is
-similar, except that output is returned only when the command exits with a
-failure return code, that is, a value other than zero or a code that matches
-%temp_errors%.
-
-
-
-[[SECThowcommandrun]]
-How the command is run
-~~~~~~~~~~~~~~~~~~~~~~
-cindex:[^pipe^ transport,path for command]
-The command line is (by default) broken down into a command name and arguments
-by the ^pipe^ transport itself. The %allow_commands% and %restrict_to_path%
-options can be used to restrict the commands that may be run.
-
-cindex:[quoting,in pipe command]
-Unquoted arguments are delimited by white space. If an argument appears in
-double quotes, backslash is interpreted as an escape character in the usual
-way. If an argument appears in single quotes, no escaping is done.
-
-String expansion is applied to the command line except when it comes from a
-traditional _.forward_ file (commands from a filter file are expanded). The
-expansion is applied to each argument in turn rather than to the whole line.
-For this reason, any string expansion item that contains white space must be
-quoted so as to be contained within a single argument. A setting such as
-
- command = /some/path ${if eq{$local_part}{postmaster}{xxx}{yyy}}
-
-will not work, because the expansion item gets split between several
-arguments. You have to write
-
- command = /some/path "${if eq{$local_part}{postmaster}{xxx}{yyy}}"
-
-to ensure that it is all in one argument. The expansion is done in this way,
-argument by argument, so that the number of arguments cannot be changed as a
-result of expansion, and quotes or backslashes in inserted variables do not
-interact with external quoting.
-
-cindex:[transport,filter]
-cindex:[filter,transport filter]
-cindex:[$pipe_addresses$]
-Special handling takes place when an argument consists of precisely the text
-`\$pipe_addresses\}`. This is not a general expansion variable; the only
-place this string is recognized is when it appears as an argument for a pipe or
-transport filter command. It causes each address that is being handled to be
-inserted in the argument list at that point 'as a separate argument'. This
-avoids any problems with spaces or shell metacharacters, and is of use when a
-^pipe^ transport is handling groups of addresses in a batch.
-
-After splitting up into arguments and expansion, the resulting command is run
-in a subprocess directly from the transport, 'not' under a shell. The
-message that is being delivered is supplied on the standard input, and the
-standard output and standard error are both connected to a single pipe that is
-read by Exim. The %max_output% option controls how much output the command may
-produce, and the %return_output% and %return_fail_output% options control
-what is done with it.
-
-Not running the command under a shell (by default) lessens the security risks
-in cases when a command from a user's filter file is built out of data that was
-taken from an incoming message. If a shell is required, it can of course be
-explicitly specified as the command to be run. However, there are circumstances
-where existing commands (for example, in _.forward_ files) expect to be run
-under a shell and cannot easily be modified. To allow for these cases, there is
-an option called %use_shell%, which changes the way the ^pipe^ transport
-works. Instead of breaking up the command line as just described, it expands it
-as a single string and passes the result to _/bin/sh_. The
-%restrict_to_path% option and the $pipe_addresses$ facility cannot be used
-with %use_shell%, and the whole mechanism is inherently less secure.
-
-
-
-[[SECTpipeenv]]
-Environment variables
-~~~~~~~~~~~~~~~~~~~~~
-cindex:[^pipe^ transport,environment for command]
-cindex:[environment for pipe transport]
-The environment variables listed below are set up when the command is invoked.
-This list is a compromise for maximum compatibility with other MTAs. Note that
-the %environment% option can be used to add additional variables to this
-environment.
-
-&&&
-`DOMAIN ` the domain of the address
-`HOME ` the home directory, if set
-`HOST ` the host name when called from a router (see below)
-`LOCAL_PART ` see below
-`LOCAL_PART_PREFIX ` see below
-`LOCAL_PART_SUFFIX ` see below
-`LOGNAME ` see below
-`MESSAGE_ID ` Exim's local ID for the message
-`PATH ` as specified by the %path% option below
-`QUALIFY_DOMAIN ` the sender qualification domain
-`RECIPIENT ` the complete recipient address
-`SENDER ` the sender of the message (empty if a bounce)
-`SHELL ` `/bin/sh`
-`TZ ` the value of the %timezone% option, if set
-`USER ` see below
-&&&
-
-When a ^pipe^ transport is called directly from (for example) an ^accept^
-router, LOCAL_PART is set to the local part of the address. When it is
-called as a result of a forward or alias expansion, LOCAL_PART is set to
-the local part of the address that was expanded. In both cases, any affixes are
-removed from the local part, and made available in LOCAL_PART_PREFIX and
-LOCAL_PART_SUFFIX, respectively. LOGNAME and USER are set to the
-same value as LOCAL_PART for compatibility with other MTAs.
-
-cindex:[HOST]
-HOST is set only when a ^pipe^ transport is called from a router that
-associates hosts with an address, typically when using ^pipe^ as a
-pseudo-remote transport. HOST is set to the first host name specified by
-the router.
-
-cindex:[HOME]
-If the transport's generic %home_directory% option is set, its value is used
-for the HOME environment variable. Otherwise, a home directory may be set
-by the router's %transport_home_directory% option, which defaults to the
-user's home directory if %check_local_user% is set.
-
-
-Private options for pipe
-~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[options,^pipe^ transport]
-
-
-
-oindex:[%allow_commands%]
-`..'=
-%allow_commands%, Use: 'pipe', Type: 'string list'!!, Default: 'unset'
-===
-
-cindex:[^pipe^ transport,permitted commands]
-The string is expanded, and is then interpreted as a colon-separated list of
-permitted commands. If %restrict_to_path% is not set, the only commands
-permitted are those in the %allow_commands% list. They need not be absolute
-paths; the %path% option is still used for relative paths. If
-%restrict_to_path% is set with %allow_commands%, the command must either be
-in the %allow_commands% list, or a name without any slashes that is found on
-the path. In other words, if neither %allow_commands% nor %restrict_to_path%
-is set, there is no restriction on the command, but otherwise only commands
-that are permitted by one or the other are allowed. For example, if
-
- allow_commands = /usr/bin/vacation
-
-and %restrict_to_path% is not set, the only permitted command is
-_/usr/bin/vacation_. The %allow_commands% option may not be set if
-%use_shell% is set.
-
-
-oindex:[%batch_id%]
-`..'=
-%batch_id%, Use: 'pipe', Type: 'string'!!, Default: 'unset'
-===
-
-See the description of local delivery batching in chapter <<CHAPbatching>>.
-
-
-oindex:[%batch_max%]
-`..'=
-%batch_max%, Use: 'pipe', Type: 'integer', Default: '1'
-===
-
-This limits the number of addresses that can be handled in a single delivery.
-See the description of local delivery batching in chapter <<CHAPbatching>>.
-
-
-oindex:[%check_string%]
-`..'=
-%check_string%, Use: 'pipe', Type: 'string', Default: 'unset'
-===
-
-As ^pipe^ writes the message, the start of each line is tested for matching
-%check_string%, and if it does, the initial matching characters are replaced
-by the contents of %escape_string%, provided both are set. The value of
-%check_string% is a literal string, not a regular expression, and the case of
-any letters it contains is significant. When %use_bsmtp% is set, the contents
-of %check_string% and %escape_string% are forced to values that implement the
-SMTP escaping protocol. Any settings made in the configuration file are
-ignored.
-
-
-oindex:[%command%]
-`..'=
-%command%, Use: 'pipe', Type: 'string'!!, Default: 'unset'
-===
-
-This option need not be set when ^pipe^ is being used to deliver to pipes
-obtained directly from address redirections. In other cases, the option must be
-set, to provide a command to be run. It need not yield an absolute path (see
-the %path% option below). The command is split up into separate arguments by
-Exim, and each argument is separately expanded, as described in section
-<<SECThowcommandrun>> above.
-
-
-oindex:[%environment%]
-`..'=
-%environment%, Use: 'pipe', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[^pipe^ transport,environment for command]
-cindex:[environment for ^pipe^ transport]
-This option is used to add additional variables to the environment in which the
-command runs (see section <<SECTpipeenv>> for the default list). Its value is a
-string which is expanded, and then interpreted as a colon-separated list of
-environment settings of the form ``<''name'>=<'value'>'.
-
-
-oindex:[%escape_string%]
-`..'=
-%escape_string%, Use: 'pipe', Type: 'string', Default: 'unset'
-===
-
-See %check_string% above.
-
-
-oindex:[%freeze_exec_fail%]
-`..'=
-%freeze_exec_fail%, Use: 'pipe', Type: 'boolean', Default: 'false'
-===
-
-cindex:[exec failure]
-cindex:[failure of exec]
-cindex:[^pipe^ transport,failure of exec]
-Failure to exec the command in a pipe transport is by default treated like
-any other failure while running the command. However, if %freeze_exec_fail%
-is set, failure to exec is treated specially, and causes the message to be
-frozen, whatever the setting of %ignore_status%.
-
-
-oindex:[%ignore_status%]
-`..'=
-%ignore_status%, Use: 'pipe', Type: 'boolean', Default: 'false'
-===
-
-If this option is true, the status returned by the subprocess that is set up to
-run the command is ignored, and Exim behaves as if zero had been returned.
-Otherwise, a non-zero status or termination by signal causes an error return
-from the transport unless the status value is one of those listed in
-%temp_errors%; these cause the delivery to be deferred and tried again later.
-
-[revisionflag="changed"]
-*Note*: This option does not apply to timeouts, which do not return a status.
-See the %timeout_defer% option for how timeouts are handled.
-
-
-oindex:[%log_defer_output%]
-`..'=
-%log_defer_output%, Use: 'pipe', Type: 'boolean', Default: 'false'
-===
-
-cindex:[^pipe^ transport,logging output]
-If this option is set, and the status returned by the command is
-one of the codes listed in %temp_errors% (that is, delivery was deferred),
-and any output was produced, the first line of it is written to the main log.
-
-
-oindex:[%log_fail_output%]
-`..'=
-%log_fail_output%, Use: 'pipe', Type: 'boolean', Default: 'false'
-===
-
-If this option is set, and the command returns any output, and also ends with a
-return code that is neither zero nor one of the return codes listed in
-%temp_errors% (that is, the delivery failed), the first line of output is
-written to the main log.
-
-This option and %log_output% are mutually exclusive. Only one of them may be
-set.
-
-
-
-oindex:[%log_output%]
-`..'=
-%log_output%, Use: 'pipe', Type: 'boolean', Default: 'false'
-===
-
-If this option is set and the command returns any output, the first line of
-output is written to the main log, whatever the return code.
-
-This option and %log_fail_output% are mutually exclusive. Only one of them
-may be set.
-
-
-
-oindex:[%max_output%]
-`..'=
-%max_output%, Use: 'pipe', Type: 'integer', Default: '20K'
-===
-
-This specifies the maximum amount of output that the command may produce on its
-standard output and standard error file combined. If the limit is exceeded, the
-process running the command is killed. This is intended as a safety measure to
-catch runaway processes. The limit is applied independently of the settings of
-the options that control what is done with such output (for example,
-%return_output%). Because of buffering effects, the amount of output may
-exceed the limit by a small amount before Exim notices.
-
-
-oindex:[%message_prefix%]
-`..'=
-%message_prefix%, Use: 'pipe', Type: 'string'!!, Default: 'see below'
-===
-
-The string specified here is expanded and output at the start of every message.
-The default is unset if %use_bsmtp% is set. Otherwise it is
-
-....
-message_prefix = \
- From ${if def:return_path{$return_path}{MAILER-DAEMON}}\
- ${tod_bsdinbox}\n
-....
-
-cindex:[Cyrus]
-cindex:[%tmail%]
-cindex:[``From'' line]
-This is required by the commonly used _/usr/bin/vacation_ program.
-However, it must 'not' be present if delivery is to the Cyrus IMAP server,
-or to the %tmail% local delivery agent. The prefix can be suppressed by setting
-
- message_prefix =
-
-
-
-oindex:[%message_suffix%]
-`..'=
-%message_suffix%, Use: 'pipe', Type: 'string'!!, Default: 'see below'
-===
-
-The string specified here is expanded and output at the end of every message.
-The default is unset if %use_bsmtp% is set. Otherwise it is a single newline.
-The suffix can be suppressed by setting
-
- message_suffix =
-
-
-
-oindex:[%path%]
-`..'=
-%path%, Use: 'pipe', Type: 'string', Default: `/bin:/usr/bin`
-===
-
-This option specifies the string that is set up in the PATH environment
-variable of the subprocess. If the %command% option does not yield an absolute
-path name, the command is sought in the PATH directories, in the usual way.
-*Warning*: This does not apply to a command specified as a transport
-filter.
-
-
-oindex:[%pipe_as_creator%]
-`..'=
-%pipe_as_creator%, Use: 'pipe', Type: 'boolean', Default: 'false'
-===
-
-cindex:[uid (user id),local delivery]
-If the generic %user% option is not set and this option is true, the delivery
-process is run under the uid that was in force when Exim was originally called
-to accept the message. If the group id is not otherwise set (via the generic
-%group% option), the gid that was in force when Exim was originally called to
-accept the message is used.
-
-
-oindex:[%restrict_to_path%]
-`..'=
-%restrict_to_path%, Use: 'pipe', Type: 'boolean', Default: 'false'
-===
-
-When this option is set, any command name not listed in %allow_commands% must
-contain no slashes. The command is searched for only in the directories listed
-in the %path% option. This option is intended for use in the case when a pipe
-command has been generated from a user's _.forward_ file. This is usually
-handled by a ^pipe^ transport called %address_pipe%.
-
-
-oindex:[%return_fail_output%]
-`..'=
-%return_fail_output%, Use: 'pipe', Type: 'boolean', Default: 'false'
-===
-
-If this option is true, and the command produced any output and ended with a
-return code other than zero or one of the codes listed in %temp_errors% (that
-is, the delivery failed), the output is returned in the bounce message.
-However, if the message has a null sender (that is, it is itself a bounce
-message), output from the command is discarded.
-
-This option and %return_output% are mutually exclusive. Only one of them may
-be set.
-
-
-
-oindex:[%return_output%]
-`..'=
-%return_output%, Use: 'pipe', Type: 'boolean', Default: 'false'
-===
-
-If this option is true, and the command produced any output, the delivery is
-deemed to have failed whatever the return code from the command, and the output
-is returned in the bounce message. Otherwise, the output is just discarded.
-However, if the message has a null sender (that is, it is a bounce message),
-output from the command is always discarded, whatever the setting of this
-option.
-
-This option and %return_fail_output% are mutually exclusive. Only one of them
-may be set.
-
-
-
-oindex:[%temp_errors%]
-`..'=
-%temp_errors%, Use: 'pipe', Type: 'string list', Default: 'see below'
-===
-
-cindex:[^pipe^ transport,temporary failure]
-This option contains either a colon-separated list of numbers, or a single
-asterisk. If %ignore_status% is false
-and %return_output% is not set,
-and the command exits with a non-zero return code, the failure is treated as
-temporary and the delivery is deferred if the return code matches one of the
-numbers, or if the setting is a single asterisk. Otherwise, non-zero return
-codes are treated as permanent errors. The default setting contains the codes
-defined by EX_TEMPFAIL and EX_CANTCREAT in _sysexits.h_. If Exim is
-compiled on a system that does not define these macros, it assumes values of 75
-and 73, respectively.
-
-
-oindex:[%timeout%]
-`..'=
-%timeout%, Use: 'pipe', Type: 'time', Default: '1h'
-===
-
-If the command fails to complete within this time, it is killed. This normally
-causes the delivery to fail (but see %timeout_defer%). A zero time interval
-specifies no timeout. In order to ensure that any subprocesses created by the
-command are also killed, Exim makes the initial process a process group leader,
-and kills the whole process group on a timeout. However, this can be defeated
-if one of the processes starts a new process group.
-
-oindex:[%timeout_defer%]
-`..'=
-%timeout_defer%, Use: 'pipe', Type: 'boolean', Default: 'false'
-===
-
-[revisionflag="changed"]
-A timeout in a ^pipe^ transport, either in the command that the transport runs,
-or in a transport filter that is associated with it, is by default treated as a
-hard error, and the delivery fails. However, if %timeout_defer% is set true,
-both kinds of timeout become temporary errors, causing the delivery to be
-deferred.
-
-
-oindex:[%umask%]
-`..'=
-%umask%, Use: 'pipe', Type: 'octal integer', Default: '022'
-===
-
-This specifies the umask setting for the subprocess that runs the command.
-
-
-oindex:[%use_bsmtp%]
-`..'=
-%use_bsmtp%, Use: 'pipe', Type: 'boolean', Default: 'false'
-===
-
-cindex:[envelope sender]
-If this option is set true, the ^pipe^ transport writes messages in ``batch
-SMTP'' format, with the envelope sender and recipient(s) included as SMTP
-commands. If you want to include a leading HELO command with such messages,
-you can do so by setting the %message_prefix% option. See section
-<<SECTbatchSMTP>> for details of batch SMTP.
-
-
-oindex:[%use_crlf%]
-`..'=
-%use_crlf%, Use: 'pipe', Type: 'boolean', Default: 'false'
-===
-
-cindex:[carriage return]
-cindex:[linefeed]
-This option causes lines to be terminated with the two-character CRLF sequence
-(carriage return, linefeed) instead of just a linefeed character. In the case
-of batched SMTP, the byte sequence written to the pipe is then an exact image
-of what would be sent down a real SMTP connection.
-
-The contents of the %message_prefix% and %message_suffix% options are written
-verbatim, so must contain their own carriage return characters if these are
-needed. Since the default values for both %message_prefix% and
-%message_suffix% end with a single linefeed, their values
-must
-be changed to end with `\r\n` if %use_crlf% is set.
-
-
-oindex:[%use_shell%]
-`..'=
-%use_shell%, Use: 'pipe', Type: 'boolean', Default: 'false'
-===
-
-cindex:[$pipe_addresses$]
-If this option is set, it causes the command to be passed to _/bin/sh_
-instead of being run directly from the transport, as described in section
-<<SECThowcommandrun>>. This is less secure, but is needed in some situations
-where the command is expected to be run under a shell and cannot easily be
-modified. The %allow_commands% and %restrict_to_path% options, and the
-`\$pipe_addresses` facility are incompatible with %use_shell%. The
-command is expanded as a single string, and handed to _/bin/sh_ as data for
-its %-c% option.
-
-
-
-Using an external local delivery agent
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[local delivery,using an external agent]
-cindex:['procmail']
-cindex:[external local delivery]
-cindex:[delivery,'procmail']
-cindex:[delivery,by external agent]
-The ^pipe^ transport can be used to pass all messages that require local
-delivery to a separate local delivery agent such as %procmail%. When doing
-this, care must be taken to ensure that the pipe is run under an appropriate
-uid and gid. In some configurations one wants this to be a uid that is trusted
-by the delivery agent to supply the correct sender of the message. It may be
-necessary to recompile or reconfigure the delivery agent so that it trusts an
-appropriate user. The following is an example transport and router
-configuration for %procmail%:
-
- # transport
- procmail_pipe:
- driver = pipe
- command = /usr/local/bin/procmail -d $local_part
- return_path_add
- delivery_date_add
- envelope_to_add
- check_string = "From "
- escape_string = ">From "
- user = $local_part
- group = mail
-
- # router
- procmail:
- driver = accept
- check_local_user
- transport = procmail_pipe
-
-
-In this example, the pipe is run as the local user, but with the group set to
-'mail'. An alternative is to run the pipe as a specific user such as 'mail'
-or 'exim', but in this case you must arrange for %procmail% to trust that
-user to supply a correct sender address. If you do not specify either a %group%
-or a %user% option, the pipe command is run as the local user. The home
-directory is the user's home directory by default.
-
-Note that the command that the pipe transport runs does 'not' begin with
-
- IFS=" "
-
-as shown in the %procmail% documentation, because Exim does not by default use
-a shell to run pipe commands.
-
-cindex:[Cyrus]
-The next example shows a transport and a router for a system where local
-deliveries are handled by the Cyrus IMAP server.
-
-....
-# transport
-local_delivery_cyrus:
- driver = pipe
- command = /usr/cyrus/bin/deliver \
- -m ${substr_1:$local_part_suffix} -- $local_part
- user = cyrus
- group = mail
- return_output
- log_output
- message_prefix =
- message_suffix =
-
-# router
-local_user_cyrus:
- driver = accept
- check_local_user
- local_part_suffix = .*
- transport = local_delivery_cyrus
-....
-
-Note the unsetting of %message_prefix% and %message_suffix%, and the use of
-%return_output% to cause any text written by Cyrus to be returned to the
-sender.
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPsmtptrans]]
-The smtp transport
-------------------
-cindex:[transports,^smtp^]
-cindex:[^smtp^ transport]
-The ^smtp^ transport delivers messages over TCP/IP connections using the SMTP
-or LMTP protocol. The list of hosts to try can either be taken from the address
-that is being processed (having been set up by the router), or specified
-explicitly for the transport. Timeout and retry processing (see chapter
-<<CHAPretry>>) is applied to each IP address independently.
-
-
-Multiple messages on a single connection
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The sending of multiple messages over a single TCP/IP connection can arise in
-two ways:
-
-- If a message contains more than %max_rcpt% (see below) addresses that are
-routed to the same host, more than one copy of the message has to be sent to
-that host. In this situation, multiple copies may be sent in a single run of
-the ^smtp^ transport over a single TCP/IP connection. (What Exim actually does
-when it has too many addresses to send in one message also depends on the value
-of the global %remote_max_parallel% option. Details are given in section
-<<SECToutSMTPTCP>>.)
-
-- cindex:[hints database,remembering routing]
-When a message has been successfully delivered over a TCP/IP connection, Exim
-looks in its hints database to see if there are any other messages awaiting a
-connection to the same host. If there are, a new delivery process is started
-for one of them, and the current TCP/IP connection is passed on to it. The new
-process may in turn send multiple copies and possibly create yet another
-process.
-
-
-For each copy sent over the same TCP/IP connection, a sequence counter is
-incremented, and if it ever gets to the value of %connection_max_messages%,
-no further messages are sent over that connection.
-
-
-
-Use of the \$host variable
-~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[$host$]
-cindex:[$host_address$]
-At the start of a run of the ^smtp^ transport, the values of $host$ and
-$host_address$ are the name and IP address of the first host on the host list
-passed by the router. However, when the transport is about to connect to a
-specific host, and while it is connected to that host, $host$ and
-$host_address$ are set to the values for that host. These are the values
-that are in force when the %helo_data%, %hosts_try_auth%, %interface%,
-%serialize_hosts%, and the various TLS options are expanded.
-
-
-
-Private options for smtp
-~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[options,^smtp^ transport]
-The private options of the ^smtp^ transport are as follows:
-
-
-oindex:[%allow_localhost%]
-`..'=
-%allow_localhost%, Use: 'smtp', Type: 'boolean', Default: 'false'
-===
-
-cindex:[local host,sending to]
-cindex:[fallback,hosts specified on transport]
-When a host specified in %hosts% or %fallback_hosts% (see below) turns out to
-be the local host, or is listed in %hosts_treat_as_local%, delivery is
-deferred by default. However, if %allow_localhost% is set, Exim goes on to do
-the delivery anyway. This should be used only in special cases when the
-configuration ensures that no looping will result (for example, a differently
-configured Exim is listening on the port to which the message is sent).
-
-
-oindex:[%authenticated_sender%]
-`..'=
-%authenticated_sender%, Use: 'smtp', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[Cyrus]
-When Exim has authenticated as a client, this option sets a value for the
-AUTH= item on outgoing MAIL commands, overriding any existing
-authenticated sender value. If the string expansion is forced to fail, the
-option is ignored. Other expansion failures cause delivery to be deferred. If
-the result of expansion is an empty string, that is also ignored.
-
-If the SMTP session is not authenticated, the expansion of
-%authenticated_sender% still happens (and can cause the delivery to be
-deferred if it fails), but no AUTH= item is added to MAIL commands.
-
-This option allows you to use the ^smtp^ transport in LMTP mode to
-deliver mail to Cyrus IMAP and provide the proper local part as the
-``authenticated sender'', via a setting such as:
-
- authenticated_sender = $local_part
-
-This removes the need for IMAP subfolders to be assigned special ACLs to
-allow direct delivery to those subfolders.
-
-Because of expected uses such as that just described for Cyrus (when no
-domain is involved), there is no checking on the syntax of the provided
-value.
-
-
-oindex:[%command_timeout%]
-`..'=
-%command_timeout%, Use: 'smtp', Type: 'time', Default: '5m'
-===
-
-This sets a timeout for receiving a response to an SMTP command that has been
-sent out. It is also used when waiting for the initial banner line from the
-remote host. Its value must not be zero.
-
-
-oindex:[%connect_timeout%]
-`..'=
-%connect_timeout%, Use: 'smtp', Type: 'time', Default: '5m'
-===
-
-This sets a timeout for the 'connect()' function, which sets up a TCP/IP call
-to a remote host. A setting of zero allows the system timeout (typically
-several minutes) to act. To have any effect, the value of this option must be
-less than the system timeout. However, it has been observed that on some
-systems there is no system timeout, which is why the default value for this
-option is 5 minutes, a value recommended by RFC 1123.
-
-
-oindex:[%connection_max_messages%]
-`..'=
-%connection_max_messages%, Use: 'smtp', Type: 'integer', Default: '500'
-===
-
-cindex:[SMTP,passed connection]
-cindex:[SMTP,multiple deliveries]
-cindex:[multiple SMTP deliveries]
-This controls the maximum number of separate message deliveries that are sent
-over a single TCP/IP connection. If the value is zero, there is no limit.
-For testing purposes, this value can be overridden by the %-oB% command line
-option.
-
-
-oindex:[%data_timeout%]
-`..'=
-%data_timeout%, Use: 'smtp', Type: 'time', Default: '5m'
-===
-
-This sets a timeout for the transmission of each block in the data portion of
-the message. As a result, the overall timeout for a message depends on the size
-of the message. Its value must not be zero. See also %final_timeout%.
-
-
-oindex:[%delay_after_cutoff%]
-`..'=
-%delay_after_cutoff%, Use: 'smtp', Type: 'boolean', Default: 'true'
-===
-
-This option controls what happens when all remote IP addresses for a given
-domain have been inaccessible for so long that they have passed their retry
-cutoff times.
-
-In the default state, if the next retry time has not been reached for any of
-them, the address is bounced without trying any deliveries. In other words,
-Exim delays retrying an IP address after the final cutoff time until a new
-retry time is reached, and can therefore bounce an address without ever trying
-a delivery, when machines have been down for a long time. Some people are
-unhappy at this prospect, so...
-
-If %delay_after_cutoff% is set false, Exim behaves differently. If all IP
-addresses are past their final cutoff time, Exim tries to deliver to those
-IP addresses that have not been tried since the message arrived. If there are
-none, of if they all fail, the address is bounced. In other words, it does not
-delay when a new message arrives, but immediately tries those expired IP
-addresses that haven't been tried since the message arrived. If there is a
-continuous stream of messages for the dead hosts, unsetting
-%delay_after_cutoff% means that there will be many more attempts to deliver
-to them.
-
-
-oindex:[%dns_qualify_single%]
-`..'=
-%dns_qualify_single%, Use: 'smtp', Type: 'boolean', Default: 'true'
-===
-
-If the %hosts% or %fallback_hosts% option is being used,
-and the %gethostbyname% option is false,
-the RES_DEFNAMES resolver option is set. See the %qualify_single% option
-in chapter <<CHAPdnslookup>> for more details.
-
-
-oindex:[%dns_search_parents%]
-`..'=
-%dns_search_parents%, Use: 'smtp', Type: 'boolean', Default: 'false'
-===
-
-cindex:[%search_parents%]
-If the %hosts% or %fallback_hosts% option is being used, and the
-%gethostbyname% option is false, the RES_DNSRCH resolver option is set.
-See the %search_parents% option in chapter <<CHAPdnslookup>> for more details.
-
-
-
-oindex:[%fallback_hosts%]
-`..'=
-%fallback_hosts%, Use: 'smtp', Type: 'string list', Default: 'unset'
-===
-
-[revisionflag="changed"]
-cindex:[fallback,hosts specified on transport]
-String expansion is not applied to this option. The argument must be a
-colon-separated list of host names or IP addresses, optionally also including
-port numbers, though the separator can be changed, as described in section
-<<SECTlistconstruct>>. Each individual item in the list is the same as an item
-in a %route_list% setting for the ^manualroute^ router, as described in section
-<<SECTformatonehostitem>>.
-
-Fallback hosts can also be specified on routers, which associate them with the
-addresses they process. As for the %hosts% option without %hosts_override%,
-%fallback_hosts% specified on the transport is used only if the address does
-not have its own associated fallback host list. Unlike %hosts%, a setting of
-%fallback_hosts% on an address is not overridden by %hosts_override%. However,
-%hosts_randomize% does apply to fallback host lists.
-
-If Exim is unable to deliver to any of the hosts for a particular address, and
-the errors are not permanent rejections, the address is put on a separate
-transport queue with its host list replaced by the fallback hosts, unless the
-address was routed via MX records and the current host was in the original MX
-list. In that situation, the fallback host list is not used.
-
-Once normal deliveries are complete, the fallback queue is delivered by
-re-running the same transports with the new host lists. If several failing
-addresses have the same fallback hosts (and %max_rcpt% permits it), a single
-copy of the message is sent.
-
-The resolution of the host names on the fallback list is controlled by the
-%gethostbyname% option, as for the %hosts% option. Fallback hosts apply
-both to cases when the host list comes with the address and when it is taken
-from %hosts%. This option provides a ``use a smart host only if delivery fails''
-facility.
-
-
-oindex:[%final_timeout%]
-`..'=
-%final_timeout%, Use: 'smtp', Type: 'time', Default: '10m'
-===
-
-This is the timeout that applies while waiting for the response to the final
-line containing just ``.'' that terminates a message. Its value must not be zero.
-
-
-oindex:[%gethostbyname%]
-`..'=
-%gethostbyname%, Use: 'smtp', Type: 'boolean', Default: 'false'
-===
-
-If this option is true when the %hosts% and/or %fallback_hosts% options are
-being used, names are looked up using 'gethostbyname()'
-(or 'getipnodebyname()' when available)
-instead of using the DNS. Of course, that function may in fact use the DNS, but
-it may also consult other sources of information such as _/etc/hosts_.
-
-oindex:[%helo_data%]
-`..'=
-%helo_data%, Use: 'smtp', Type: 'string'!!, Default: `\$primary_hostname`
-===
-
-cindex:[HELO argument, setting]
-cindex:[EHLO argument, setting]
-The value of this option is expanded, and used as the argument for the EHLO
-or HELO command that starts the outgoing SMTP session.
-
-
-oindex:[%hosts%]
-`..'=
-%hosts%, Use: 'smtp', Type: 'string list'!!, Default: 'unset'
-===
-
-Hosts are associated with an address by a router such as ^dnslookup^, which
-finds the hosts by looking up the address domain in the DNS, or by
-^manualroute^, which has lists of hosts in its configuration. However,
-email addresses can be passed to the ^smtp^ transport by any router, and not
-all of them can provide an associated list of hosts.
-
-The %hosts% option specifies a list of hosts to be used if the address being
-processed does not have any hosts associated with it. The hosts specified by
-%hosts% are also used, whether or not the address has its own hosts, if
-%hosts_override% is set.
-
-[revisionflag="changed"]
-The string is first expanded, before being interpreted as a colon-separated
-list of host names or IP addresses, possibly including port numbers. The
-separator may be changed to something other than colon, as described in section
-<<SECTlistconstruct>>. Each individual item in the list is the same as an item
-in a %route_list% setting for the ^manualroute^ router, as described in section
-<<SECTformatonehostitem>>. However, note that the `/MX` facility of the
-^manualroute^ router is not available here.
-
-If the expansion fails, delivery is deferred. Unless the failure was caused by
-the inability to complete a lookup, the error is logged to the panic log as
-well as the main log. Host names are looked up either by searching directly for
-address records in the DNS or by calling 'gethostbyname()' (or
-'getipnodebyname()' when available), depending on the setting of the
-%gethostbyname% option. When Exim is compiled with IPv6 support, if a host that
-is looked up in the DNS has both IPv4 and IPv6 addresses, both types of address
-are used.
-
-During delivery, the hosts are tried in order, subject to their retry status,
-unless %hosts_randomize% is set.
-
-
-oindex:[%hosts_avoid_esmtp%]
-`..'=
-%hosts_avoid_esmtp%, Use: 'smtp', Type: 'host list'!!, Default: 'unset'
-===
-
-cindex:[ESMTP, avoiding use of]
-cindex:[HELO,forcing use of]
-cindex:[EHLO,avoiding use of]
-cindex:[PIPELINING,avoiding the use of]
-This option is for use with broken hosts that announce ESMTP facilities (for
-example, PIPELINING) and then fail to implement them properly. When a host
-matches %hosts_avoid_esmtp%, Exim sends HELO rather than EHLO at the
-start of the SMTP session. This means that it cannot use any of the ESMTP
-facilities such as AUTH, PIPELINING, SIZE, and STARTTLS.
-
-
-oindex:[%hosts_avoid_tls%]
-`..'=
-%hosts_avoid_tls%, Use: 'smtp', Type: 'host list'!!, Default: 'unset'
-===
-
-cindex:[TLS,avoiding for certain hosts]
-Exim will not try to start a TLS session when delivering to any host that
-matches this list. See chapter <<CHAPTLS>> for details of TLS.
-
-
-oindex:[%hosts_max_try%]
-`..'=
-%hosts_max_try%, Use: 'smtp', Type: 'integer', Default: '5'
-===
-
-cindex:[host,maximum number to try]
-cindex:[limit,number of hosts tried]
-cindex:[limit,number of MX tried]
-cindex:[MX record,maximum tried]
-This option limits the number of IP addresses that are tried for any one
-delivery in cases where there are temporary delivery errors. Section
-<<SECTvalhosmax>> describes in detail how the value of this option is used.
-
-
-oindex:[%hosts_max_try_hardlimit%]
-`..'=
-%hosts_max_try_hardlimit%, Use: 'smtp', Type: 'integer', Default: '50'
-===
-
-This is an additional check on the maximum number of IP addresses that Exim
-tries for any one delivery. Section <<SECTvalhosmax>> describes its use and why
-it exists.
-
-
-
-oindex:[%hosts_nopass_tls%]
-`..'=
-%hosts_nopass_tls%, Use: 'smtp', Type: 'host list'!!, Default: 'unset'
-===
-
-cindex:[TLS,passing connection]
-cindex:[multiple SMTP deliveries]
-cindex:[TLS,multiple message deliveries]
-For any host that matches this list, a connection on which a TLS session has
-been started will not be passed to a new delivery process for sending another
-message on the same connection. See section <<SECTmulmessam>> for an explanation
-of when this might be needed.
-
-
-oindex:[%hosts_override%]
-`..'=
-%hosts_override%, Use: 'smtp', Type: 'boolean', Default: 'false'
-===
-
-If this option is set and the %hosts% option is also set, any hosts that are
-attached to the address are ignored, and instead the hosts specified by the
-%hosts% option are always used. This option does not apply to
-%fallback_hosts%.
-
-
-oindex:[%hosts_randomize%]
-`..'=
-%hosts_randomize%, Use: 'smtp', Type: 'boolean', Default: 'false'
-===
-
-cindex:[randomized host list]
-cindex:[host,list of; randomized]
-cindex:[fallback,randomized hosts]
-If this option is set, and either the list of hosts is taken from the
-%hosts% or the %fallback_hosts% option, or the hosts supplied by the router
-were not obtained from MX records (this includes fallback hosts from the
-router), and were not randomizied by the router, the order of trying the hosts
-is randomized each time the transport runs. Randomizing the order of a host
-list can be used to do crude load sharing.
-
-When %hosts_randomize% is true, a host list may be split into groups whose
-order is separately randomized. This makes it possible to set up MX-like
-behaviour. The boundaries between groups are indicated by an item that is just
-`+` in the host list. For example:
-
- hosts = host1:host2:host3:+:host4:host5
-
-The order of the first three hosts and the order of the last two hosts is
-randomized for each use, but the first three always end up before the last two.
-If %hosts_randomize% is not set, a `+` item in the list is ignored.
-
-oindex:[%hosts_require_auth%]
-`..'=
-%hosts_require_auth%, Use: 'smtp', Type: 'host list'!!, Default: 'unset'
-===
-
-cindex:[authentication,required by client]
-This option provides a list of servers for which authentication must succeed
-before Exim will try to transfer a message. If authentication fails for
-servers which are not in this list, Exim tries to send unauthenticated. If
-authentication fails for one of these servers, delivery is deferred. This
-temporary error is detectable in the retry rules, so it can be turned into a
-hard failure if required. See also %hosts_try_auth%, and chapter
-<<CHAPSMTPAUTH>> for details of authentication.
-
-
-oindex:[%hosts_require_tls%]
-`..'=
-%hosts_require_tls%, Use: 'smtp', Type: 'host list'!!, Default: 'unset'
-===
-
-cindex:[TLS,requiring for certain servers]
-Exim will insist on using a TLS session when delivering to any host that
-matches this list. See chapter <<CHAPTLS>> for details of TLS.
-*Note*: This option affects outgoing mail only. To insist on TLS for
-incoming messages, use an appropriate ACL.
-
-oindex:[%hosts_try_auth%]
-`..'=
-%hosts_try_auth%, Use: 'smtp', Type: 'host list'!!, Default: 'unset'
-===
-
-cindex:[authentication,optional in client]
-This option provides a list of servers to which, provided they announce
-authentication support, Exim will attempt to authenticate as a client when it
-connects. If authentication fails, Exim will try to transfer the message
-unauthenticated. See also %hosts_require_auth%, and chapter <<CHAPSMTPAUTH>>
-for details of authentication.
-
-oindex:[%interface%]
-`..'=
-%interface%, Use: 'smtp', Type: 'string list'!!, Default: 'unset'
-===
-
-cindex:[bind IP address]
-cindex:[IP address,binding]
-cindex:[$host$]
-cindex:[$host_address$]
-This option specifies which interface to bind to when making an outgoing SMTP
-call. The variables $host$ and $host_address$ refer to the host to which a
-connection is about to be made during the expansion of the string. Forced
-expansion failure, or an empty string result causes the option to be ignored.
-Otherwise, after expansion,
-the string must be a list of IP addresses, colon-separated by default, but the
-separator can be changed in the usual way.
-For example:
-
- interface = <; 192.168.123.123 ; 3ffe:ffff:836f::fe86:a061
-
-The first interface of the correct type (IPv4 or IPv6) is used for the outgoing
-connection. If none of them are the correct type, the option is ignored. If
-%interface% is not set, or is ignored, the system's IP functions choose which
-interface to use if the host has more than one.
-
-
-oindex:[%keepalive%]
-`..'=
-%keepalive%, Use: 'smtp', Type: 'boolean', Default: 'true'
-===
-
-cindex:[keepalive,on outgoing connection]
-This option controls the setting of SO_KEEPALIVE on outgoing TCP/IP socket
-connections. When set, it causes the kernel to probe idle connections
-periodically, by sending packets with ``old'' sequence numbers. The other end of
-the connection should send a acknowledgement if the connection is still okay or
-a reset if the connection has been aborted. The reason for doing this is that
-it has the beneficial effect of freeing up certain types of connection that can
-get stuck when the remote host is disconnected without tidying up the TCP/IP
-call properly. The keepalive mechanism takes several hours to detect
-unreachable hosts.
-
-
-oindex:[%lmtp_ignore_quota%]
-`..'=
-%lmtp_ignore_quota%, Use: 'smtp', Type: 'boolean', Default: 'false'
-===
-
-[revisionflag="changed"]
-cindex:[LMTP,ignoring quota errors]
-If this option is set true when the %protocol% option is set to ``lmtp'', the
-string `IGNOREQUOTA` is added to RCPT commands, provided that the LMTP server
-has advertised support for IGNOREQUOTA in its response to the LHLO command.
-
-
-oindex:[%max_rcpt%]
-`..'=
-%max_rcpt%, Use: 'smtp', Type: 'integer', Default: '100'
-===
-
-cindex:[RCPT,maximum number of outgoing]
-This option limits the number of RCPT commands that are sent in a single
-SMTP message transaction. Each set of addresses is treated independently, and
-so can cause parallel connections to the same host if %remote_max_parallel%
-permits this.
-
-
-oindex:[%multi_domain%]
-`..'=
-%multi_domain%, Use: 'smtp', Type: 'boolean', Default: 'true'
-===
-
-cindex:[$domain$]
-When this option is set, the ^smtp^ transport can handle a number of addresses
-containing a mixture of different domains provided they all resolve to the same
-list of hosts. Turning the option off restricts the transport to handling only
-one domain at a time. This is useful if you want to use $domain$ in an
-expansion for the transport, because it is set only when there is a single
-domain involved in a remote delivery.
-
-
-oindex:[%port%]
-`..'=
-%port%, Use: 'smtp', Type: 'string'!!, Default: 'see below'
-===
-
-cindex:[port,sending TCP/IP]
-cindex:[TCP/IP,setting outgoing port]
-This option specifies the TCP/IP port on the server to which Exim connects. If
-it begins with a digit it is taken as a port number; otherwise it is looked up
-using 'getservbyname()'. The default value is normally ``smtp'', but if
-%protocol% is set to ``lmtp'', the default is ``lmtp''.
-If the expansion fails, or if a port number cannot be found, delivery is
-deferred.
-
-
-
-oindex:[%protocol%]
-`..'=
-%protocol%, Use: 'smtp', Type: 'string', Default: 'smtp'
-===
-
-cindex:[LMTP,over TCP/IP]
-If this option is set to ``lmtp'' instead of ``smtp'', the default value for the
-%port% option changes to ``lmtp'', and the transport operates the LMTP protocol
-(RFC 2033) instead of SMTP. This protocol is sometimes used for local
-deliveries into closed message stores. Exim also has support for running LMTP
-over a pipe to a local process -- see chapter <<CHAPLMTP>>.
-
-
-oindex:[%retry_include_ip_address%]
-`..'=
-%retry_include_ip_address%, Use: 'smtp', Type: 'boolean', Default: 'true'
-===
-
-Exim normally includes both the host name and the IP address in the key it
-constructs for indexing retry data after a temporary delivery failure. This
-means that when one of several IP addresses for a host is failing, it gets
-tried periodically (controlled by the retry rules), but use of the other IP
-addresses is not affected.
-
-However, in some dialup environments hosts are assigned a different IP address
-each time they connect. In this situation the use of the IP address as part of
-the retry key leads to undesirable behaviour. Setting this option false causes
-Exim to use only the host name. This should normally be done on a separate
-instance of the ^smtp^ transport, set up specially to handle the dialup hosts.
-
-
-oindex:[%serialize_hosts%]
-`..'=
-%serialize_hosts%, Use: 'smtp', Type: 'host list'!!, Default: 'unset'
-===
-
-cindex:[serializing connections]
-cindex:[host,serializing connections]
-Because Exim operates in a distributed manner, if several messages for the same
-host arrive at around the same time, more than one simultaneous connection to
-the remote host can occur. This is not usually a problem except when there is a
-slow link between the hosts. In that situation it may be helpful to restrict
-Exim to one connection at a time. This can be done by setting
-%serialize_hosts% to match the relevant hosts.
-
-cindex:[hints database,serializing deliveries to a host]
-Exim implements serialization by means of a hints database in which a record is
-written whenever a process connects to one of the restricted hosts. The record
-is deleted when the connection is completed. Obviously there is scope for
-records to get left lying around if there is a system or program crash. To
-guard against this, Exim ignores any records that are more than six hours old.
-
-If you set up this kind of serialization, you should also arrange to delete the
-relevant hints database whenever your system reboots. The names of the files
-start with _misc_ and they are kept in the _spool/db_ directory. There
-may be one or two files, depending on the type of DBM in use. The same files
-are used for ETRN serialization.
-
-
-oindex:[%size_addition%]
-`..'=
-%size_addition%, Use: 'smtp', Type: 'integer', Default: '1024'
-===
-
-cindex:[SMTP,SIZE]
-cindex:[message,size issue for transport filter]
-cindex:[size,of message]
-cindex:[transport,filter]
-cindex:[filter,transport filter]
-If a remote SMTP server indicates that it supports the SIZE option of the
-MAIL command, Exim uses this to pass over the message size at the start of
-an SMTP transaction. It adds the value of %size_addition% to the value it
-sends, to allow for headers and other text that may be added during delivery by
-configuration options or in a transport filter. It may be necessary to increase
-this if a lot of text is added to messages.
-
-Alternatively, if the value of %size_addition% is set negative, it disables
-the use of the SIZE option altogether.
-
-
-oindex:[%tls_certificate%]
-`..'=
-%tls_certificate%, Use: 'smtp', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[TLS client certificate, location of]
-cindex:[certificate for client, location of]
-cindex:[$host$]
-cindex:[$host_address$]
-The value of this option must be the absolute path to a file which contains the
-client's certificate, for use when sending a message over an encrypted
-connection. The values of $host$ and $host_address$ are set to the name
-and address of the server during the expansion. See chapter <<CHAPTLS>> for
-details of TLS.
-
-*Note*: This option must be set if you want Exim to use TLS when sending
-messages as a client. The global option of the same name specifies the
-certificate for Exim as a server; it is not automatically assumed that the same
-certificate should be used when Exim is operating as a client.
-
-
-oindex:[%tls_crl%]
-`..'=
-%tls_crl%, Use: 'smtp', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[TLS,client certificate revocation list]
-cindex:[certificate,revocation list for client]
-This option specifies a certificate revocation list. The expanded value must
-be the name of a file that contains a CRL in PEM format.
-
-
-oindex:[%tls_privatekey%]
-`..'=
-%tls_privatekey%, Use: 'smtp', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[TLS client private key, location of]
-cindex:[$host$]
-cindex:[$host_address$]
-The value of this option must be the absolute path to a file which contains the
-client's private key, for use when sending a message over an encrypted
-connection. The values of $host$ and $host_address$ are set to the name
-and address of the server during the expansion.
-If this option is unset, the private key is assumed to be in the same file as
-the certificate.
-See chapter <<CHAPTLS>> for details of TLS.
-
-
-oindex:[%tls_require_ciphers%]
-`..'=
-%tls_require_ciphers%, Use: 'smtp', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[TLS,requiring specific ciphers]
-cindex:[cipher,requiring specific]
-cindex:[$host$]
-cindex:[$host_address$]
-The value of this option must be a list of permitted cipher suites, for use
-when setting up an outgoing encrypted connection. (There is a global option of
-the same name for controlling incoming connections.) The values of $host$ and
-$host_address$ are set to the name and address of the server during the
-expansion. See chapter <<CHAPTLS>> for details of TLS; note that this option is
-used in different ways by OpenSSL and GnuTLS (see sections <<SECTreqciphssl>>
-and <<SECTreqciphgnu>>). For GnuTLS, the order of the ciphers is a preference
-order.
-
-
-
-oindex:[%tls_tempfail_tryclear%]
-`..'=
-%tls_tempfail_tryclear%, Use: 'smtp', Type: 'boolean', Default: 'true'
-===
-
-When the server host is not in %hosts_require_tls%, and there is a problem in
-setting up a TLS session, this option determines whether or not Exim should try
-to deliver the message unencrypted. If it is set false, delivery to the
-current host is deferred; if there are other hosts, they are tried. If this
-option is set true, Exim attempts to deliver unencrypted after a 4##'xx'
-response to STARTTLS. Also, if STARTTLS is accepted, but the subsequent
-TLS negotiation fails, Exim closes the current connection (because it is in an
-unknown state), opens a new one to the same host, and then tries the delivery
-in clear.
-
-
-oindex:[%tls_verify_certificates%]
-`..'=
-%tls_verify_certificates%, Use: 'smtp', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[TLS,server certificate verification]
-cindex:[certificate,verification of server]
-cindex:[$host$]
-cindex:[$host_address$]
-The value of this option must be the absolute path to a file containing
-permitted server certificates, for use when setting up an encrypted connection.
-Alternatively, if you are using OpenSSL, you can set
-%tls_verify_certificates% to the name of a directory containing certificate
-files. This does not work with GnuTLS; the option must be set to the name of a
-single file if you are using GnuTLS. The values of $host$ and
-$host_address$ are set to the name and address of the server during the
-expansion of this option. See chapter <<CHAPTLS>> for details of TLS.
-
-
-
-
-[[SECTvalhosmax]]
-How the limits for the number of hosts to try are used
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[host,maximum number to try]
-cindex:[limit,hosts; maximum number tried]
-There are two options that are concerned with the number of hosts that are
-tried when an SMTP delivery takes place. They are %hosts_max_try% and
-%hosts_max_try_hardlimit%.
-
-
-The %hosts_max_try% option limits the number of hosts that are tried
-for a single delivery. However, despite the term ``host'' in its name, the option
-actually applies to each IP address independently. In other words, a multihomed
-host is treated as several independent hosts, just as it is for retrying.
-
-Many of the larger ISPs have multiple MX records which often point to
-multihomed hosts. As a result, a list of a dozen or more IP addresses may be
-created as a result of routing one of these domains.
-
-Trying every single IP address on such a long list does not seem sensible; if
-several at the top of the list fail, it is reasonable to assume there is some
-problem that is likely to affect all of them. Roughly speaking, the value of
-%hosts_max_try% is the maximum number that are tried before deferring the
-delivery. However, the logic cannot be quite that simple.
-
-Firstly, IP addresses that are skipped because their retry times have not
-arrived do not count, and in addition, addresses that are past their retry
-limits are also not counted, even when they are tried. This means that when
-some IP addresses are past their retry limits, more than the value of
-%hosts_max_retry% may be tried. The reason for this behaviour is to ensure
-that all IP addresses are considered before timing out an email address (but
-see below for an exception).
-
-Secondly, when the %hosts_max_try% limit is reached, Exim looks down the host
-list to see if there is a subsequent host with a different (higher valued) MX.
-If there is, that host is considered next, and the current IP address is used
-but not counted. This behaviour helps in the case of a domain with a retry rule
-that hardly ever delays any hosts, as is now explained:
-
-Consider the case of a long list of hosts with one MX value, and a few with a
-higher MX value. If %hosts_max_try% is small (the default is 5) only a few
-hosts at the top of the list are tried at first. With the default retry rule,
-which specifies increasing retry times, the higher MX hosts are eventually
-tried when those at the top of the list are skipped because they have not
-reached their retry times.
-
-However, it is common practice to put a fixed short retry time on domains for
-large ISPs, on the grounds that their servers are rarely down for very long.
-Unfortunately, these are exactly the domains that tend to resolve to long lists
-of hosts. The short retry time means that the lowest MX hosts are tried every
-time. The attempts may be in a different order because of random sorting, but
-without the special MX check, the higher MX hosts would never be tried
-
-until all the lower MX hosts had timed out (which might be several days),
-because there are always some lower MX hosts that have reached their retry
-times. With the special check, Exim considers at least one IP address from each
-MX value at every delivery attempt, even if the %hosts_max_try% limit has
-already been reached.
-
-The above logic means that %hosts_max_try% is not a hard limit, and in
-particular, Exim normally eventually tries all the IP addresses before timing
-out an email address. When %hosts_max_try% was implemented, this seemed a
-reasonable thing to do. Recently, however, some lunatic DNS configurations have
-been set up with hundreds of IP addresses for some domains. It can
-take a very long time indeed for an address to time out in these cases.
-
-The %hosts_max_try_hardlimit% option was added to help with this problem.
-Exim never tries more than this number of IP addresses; if it hits this limit
-and they are all timed out, the email address is bounced, even though not all
-possible IP addresses have been tried.
-
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPrewrite]]
-Address rewriting
------------------
-cindex:[rewriting,addresses]
-There are some circumstances in which Exim automatically rewrites domains in
-addresses. The two most common are when an address is given without a domain
-(referred to as an ``unqualified address'') or when an address contains an
-abbreviated domain that is expanded by DNS lookup.
-
-Unqualified envelope addresses are accepted only for locally submitted
-messages, or messages from hosts that match %sender_unqualified_hosts% or
-%recipient_unqualified_hosts%, respectively. Unqualified addresses in header
-lines are qualified if they are in locally submitted messages, or messages from
-hosts that are permitted to send unqualified envelope addresses. Otherwise,
-unqualified addresses in header lines are neither qualified nor rewritten.
-
-One situation in which Exim does 'not' automatically rewrite a domain is
-when it is the name of a CNAME record in the DNS. The older RFCs suggest that
-such a domain should be rewritten using the ``canonical'' name, and some MTAs do
-this. The new RFCs do not contain this suggestion.
-
-
-Explicitly configured address rewriting
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-This chapter describes the rewriting rules that can be used in the
-main rewrite section of the configuration file, and also in the generic
-%headers_rewrite% option that can be set on any transport.
-
-Some people believe that configured address rewriting is a Mortal Sin.
-Others believe that life is not possible without it. Exim provides the
-facility; you do not have to use it.
-
-The main rewriting rules that appear in the ``rewrite'' section of the
-configuration file are applied to addresses in incoming messages, both envelope
-addresses and addresses in header lines. Each rule specifies the types of
-address to which it applies.
-
-Rewriting of addresses in header lines applies only to those headers that
-were received with the message, and, in the case of transport rewriting, those
-that were added by a system filter. That is, it applies only to those headers
-that are common to all copies of the message. Header lines that are added by
-individual routers or transports (and which are therefore specific to
-individual recipient addresses) are not rewritten.
-
-In general, rewriting addresses from your own system or domain has some
-legitimacy. Rewriting other addresses should be done only with great care and
-in special circumstances. The author of Exim believes that rewriting should be
-used sparingly, and mainly for ``regularizing'' addresses in your own domains.
-Although it can sometimes be used as a routing tool, this is very strongly
-discouraged.
-
-There are two commonly encountered circumstances where rewriting is used, as
-illustrated by these examples:
-
-- The company whose domain is 'hitch.fict.example' has a number of hosts that
-exchange mail with each other behind a firewall, but there is only a single
-gateway to the outer world. The gateway rewrites '*.hitch.fict.example' as
-'hitch.fict.example' when sending mail off-site.
-
-- A host rewrites the local parts of its own users so that, for example,
-'fp42@hitch.fict.example' becomes 'Ford.Prefect@hitch.fict.example'.
-
-
-
-When does rewriting happen?
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[rewriting,timing of]
-cindex:[{ACL},rewriting addresses in]
-Configured address rewriting can take place at several different stages of a
-message's processing.
-
-cindex:[$sender_address$]
-At the start of an ACL for MAIL, the sender address may have been rewritten
-by a special SMTP-time rewrite rule (see section <<SECTrewriteS>>), but no
-ordinary rewrite rules have yet been applied. If, however, the sender address
-is verified in the ACL, it is rewritten before verification, and remains
-rewritten thereafter. The subsequent value of $sender_address$ is the
-rewritten address. This also applies if sender verification happens in a
-RCPT ACL. Otherwise, when the sender address is not verified, it is
-rewritten as soon as a message's header lines have been received.
-
-cindex:[$domain$]
-cindex:[$local_part$]
-Similarly, at the start of an ACL for RCPT, the current recipient's address
-may have been rewritten by a special SMTP-time rewrite rule, but no ordinary
-rewrite rules have yet been applied to it. However, the behaviour is different
-from the sender address when a recipient is verified. The address is rewritten
-for the verification, but the rewriting is not remembered at this stage. The
-value of $local_part$ and $domain$ after verification are always the same
-as they were before (that is, they contain the unrewritten -- except for
-SMTP-time rewriting -- address).
-
-Once a message's header lines have been received, all the envelope recipient
-addresses are permanently rewritten, and rewriting is also applied to the
-addresses in the header lines (if configured).
-cindex:['local_scan()' function,address rewriting; timing of]
-Thus, all the rewriting is completed before the DATA ACL and
-'local_scan()' functions are run.
-
-When an address is being routed, either for delivery or for verification,
-rewriting is applied immediately to child addresses that are generated by
-redirection, unless %no_rewrite% is set on the router.
-
-cindex:[envelope sender, rewriting]
-cindex:[rewriting,at transport time]
-At transport time, additional rewriting of addresses in header lines can be
-specified by setting the generic %headers_rewrite% option on a transport. This
-option contains rules that are identical in form to those in the rewrite
-section of the configuration file. In addition, the outgoing envelope sender
-can be rewritten by means of the %return_path% transport option. However, it
-is not possible to rewrite envelope recipients at transport time.
-
-
-
-
-Testing the rewriting rules that apply on input
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[rewriting,testing]
-cindex:[testing,rewriting]
-Exim's input rewriting configuration appears in a part of the run time
-configuration file headed by ``begin rewrite''. It can be tested by the %-brw%
-command line option. This takes an address (which can be a full RFC 2822
-address) as its argument. The output is a list of how the address would be
-transformed by the rewriting rules for each of the different places it might
-appear in an incoming message, that is, for each different header and for the
-envelope sender and recipient fields. For example,
-
- exim -brw ph10@exim.workshop.example
-
-might produce the output
-
- sender: Philip.Hazel@exim.workshop.example
- from: Philip.Hazel@exim.workshop.example
- to: ph10@exim.workshop.example
- cc: ph10@exim.workshop.example
- bcc: ph10@exim.workshop.example
- reply-to: Philip.Hazel@exim.workshop.example
- env-from: Philip.Hazel@exim.workshop.example
- env-to: ph10@exim.workshop.example
-
-which shows that rewriting has been set up for that address when used in any of
-the source fields, but not when it appears as a recipient address. At the
-present time, there is no equivalent way of testing rewriting rules that are
-set for a particular transport.
-
-
-Rewriting rules
-~~~~~~~~~~~~~~~
-cindex:[rewriting,rules]
-The rewrite section of the configuration file consists of lines of rewriting
-rules in the form
-
- <source pattern> <replacement> <flags>
-
-Rewriting rules that are specified for the %headers_rewrite% generic transport
-option are given as a colon-separated list. Each item in the list takes the
-same form as a line in the main rewriting configuration
-(except that any colons must be doubled, of course).
-
-The formats of source patterns and replacement strings are described below.
-Each is terminated by white space, unless enclosed in double quotes, in which
-case normal quoting conventions apply inside the quotes. The flags are single
-characters which may appear in any order. Spaces and tabs between them are
-ignored.
-
-For each address that could potentially be rewritten, the rules are scanned in
-order, and replacements for the address from earlier rules can themselves be
-replaced by later rules (but see the ``q'' and ``R'' flags).
-
-The order in which addresses are rewritten is undefined, may change between
-releases, and must not be relied on, with one exception: when a message is
-received, the envelope sender is always rewritten first, before any header
-lines are rewritten. For example, the replacement string for a rewrite of an
-address in 'To:' must not assume that the message's address in 'From:' has (or
-has not) already been rewritten. However, a rewrite of 'From:' may assume that
-the envelope sender has already been rewritten.
-
-cindex:[$domain$]
-cindex:[$local_part$]
-The variables $local_part$ and $domain$ can be used in the replacement
-string to refer to the address that is being rewritten. Note that lookup-driven
-rewriting can be done by a rule of the form
-
- *@* ${lookup ...
-
-where the lookup key uses $1$ and $2$ or $local_part$ and $domain$ to
-refer to the address that is being rewritten.
-
-
-Rewriting patterns
-~~~~~~~~~~~~~~~~~~
-cindex:[rewriting,patterns]
-cindex:[address list,in a rewriting pattern]
-The source pattern in a rewriting rule is any item which may appear in an
-address list (see section <<SECTaddresslist>>). It is in fact processed as a
-single-item address list, which means that it is expanded before being tested
-against the address. As always, if you use a regular expression as a pattern,
-you must take care to escape dollar and backslash characters, or use the `\N`
-facility to suppress string expansion within the regular expression.
-
-Domains in patterns should be given in lower case. Local parts in patterns are
-case-sensitive. If you want to do case-insensitive matching of local parts, you
-can use a regular expression that starts with `^(?i)`.
-
-cindex:[numerical variables ($1$ $2$ etc),in rewriting rules]
-After matching, the numerical variables $1$, $2$, etc. may be set,
-depending on the type of match which occurred. These can be used in the
-replacement string to insert portions of the incoming address. $0$ always
-refers to the complete incoming address. When a regular expression is used, the
-numerical variables are set from its capturing subexpressions. For other types
-of pattern they are set as follows:
-
-- If a local part or domain starts with an asterisk, the numerical variables
-refer to the character strings matched by asterisks, with $1$ associated with
-the first asterisk, and $2$ with the second, if present. For example, if the
-pattern
-
- *queen@*.fict.example
-+
-is matched against the address 'hearts-queen@wonderland.fict.example' then
-
- $0 = hearts-queen@wonderland.fict.example
- $1 = hearts-
- $2 = wonderland
-+
-Note that if the local part does not start with an asterisk, but the domain
-does, it is $1$ that contains the wild part of the domain.
-
-- If the domain part of the pattern is a partial lookup, the wild and fixed parts
-of the domain are placed in the next available numerical variables. Suppose,
-for example, that the address 'foo@bar.baz.example' is processed by a
-rewriting rule of the form
-
- *@partial-dbm;/some/dbm/file <replacement string>
-+
-and the key in the file that matches the domain is `*.baz.example`. Then
-
- $1 = foo
- $2 = bar
- $3 = baz.example
-+
-If the address 'foo@baz.example' is looked up, this matches the same
-wildcard file entry, and in this case $2$ is set to the empty string, but
-$3$ is still set to 'baz.example'. If a non-wild key is matched in a
-partial lookup, $2$ is again set to the empty string and $3$ is set to the
-whole domain. For non-partial domain lookups, no numerical variables are set.
-
-
-
-Rewriting replacements
-~~~~~~~~~~~~~~~~~~~~~~
-cindex:[rewriting,replacements]
-If the replacement string for a rule is a single asterisk, addresses that
-match the pattern and the flags are 'not' rewritten, and no subsequent
-rewriting rules are scanned. For example,
-
- hatta@lookingglass.fict.example * f
-
-specifies that 'hatta@lookingglass.fict.example' is never to be rewritten in
-'From:' headers.
-
-cindex:[$domain$]
-cindex:[$local_part$]
-If the replacement string is not a single asterisk, it is expanded, and must
-yield a fully qualified address. Within the expansion, the variables
-$local_part$ and $domain$ refer to the address that is being rewritten.
-Any letters they contain retain their original case -- they are not lower
-cased. The numerical variables are set up according to the type of pattern that
-matched the address, as described above. If the expansion is forced to fail by
-the presence of ``fail'' in a conditional or lookup item, rewriting by the
-current rule is abandoned, but subsequent rules may take effect. Any other
-expansion failure causes the entire rewriting operation to be abandoned, and an
-entry written to the panic log.
-
-
-
-Rewriting flags
-~~~~~~~~~~~~~~~
-There are three different kinds of flag that may appear on rewriting rules:
-
-- Flags that specify which headers and envelope addresses to rewrite: E, F, T, b,
-c, f, h, r, s, t.
-
-- A flag that specifies rewriting at SMTP time: S.
-
-- Flags that control the rewriting process: Q, q, R, w.
-
-For rules that are part of the %headers_rewrite% generic transport option,
-E, F, T, and S are not permitted.
-
-
-
-Flags specifying which headers and envelope addresses to rewrite
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[rewriting,flags]
-If none of the following flag letters, nor the ``S'' flag (see section
-<<SECTrewriteS>>) are present, a main rewriting rule applies to all headers and
-to both the sender and recipient fields of the envelope, whereas a
-transport-time rewriting rule just applies to all headers. Otherwise, the
-rewriting rule is skipped unless the relevant addresses are being processed.
-
-&&&
-`E` rewrite all envelope fields
-`F` rewrite the envelope From field
-`T` rewrite the envelope To field
-`b` rewrite the 'Bcc:' header
-`c` rewrite the 'Cc:' header
-`f` rewrite the 'From:' header
-`h` rewrite all headers
-`r` rewrite the 'Reply-To:' header
-`s` rewrite the 'Sender:' header
-`t` rewrite the 'To:' header
-&&&
-
-You should be particularly careful about rewriting 'Sender:' headers, and
-restrict this to special known cases in your own domains.
-
-
-[[SECTrewriteS]]
-The SMTP-time rewriting flag
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[SMTP,rewriting malformed addresses]
-cindex:[RCPT,rewriting argument of]
-cindex:[MAIL,rewriting argument of]
-The rewrite flag ``S'' specifies a rewrite of incoming envelope addresses at SMTP
-time, as soon as an address is received in a MAIL or RCPT command, and
-before any other processing; even before syntax checking. The pattern is
-required to be a regular expression, and it is matched against the whole of the
-data for the command, including any surrounding angle brackets.
-
-cindex:[$domain$]
-cindex:[$local_part$]
-This form of rewrite rule allows for the handling of addresses that are not
-compliant with RFCs 2821 and 2822 (for example, ``bang paths'' in batched SMTP
-input). Because the input is not required to be a syntactically valid address,
-the variables $local_part$ and $domain$ are not available during the
-expansion of the replacement string. The result of rewriting replaces the
-original address in the MAIL or RCPT command.
-
-
-Flags controlling the rewriting process
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-There are four flags which control the way the rewriting process works. These
-take effect only when a rule is invoked, that is, when the address is of the
-correct type (matches the flags) and matches the pattern:
-
-- If the ``Q'' flag is set on a rule, the rewritten address is permitted to be an
-unqualified local part. It is qualified with %qualify_recipient%. In the
-absence of ``Q'' the rewritten address must always include a domain.
-
-- If the ``q'' flag is set on a rule, no further rewriting rules are considered,
-even if no rewriting actually takes place because of a ``fail'' in the expansion.
-The ``q'' flag is not effective if the address is of the wrong type (does not
-match the flags) or does not match the pattern.
-
-- The ``R'' flag causes a successful rewriting rule to be re-applied to the new
-address, up to ten times. It can be combined with the ``q'' flag, to stop
-rewriting once it fails to match (after at least one successful rewrite).
-
-- cindex:[rewriting,whole addresses]
-When an address in a header is rewritten, the rewriting normally applies only
-to the working part of the address, with any comments and RFC 2822 ``phrase''
-left unchanged. For example, rewriting might change
-
- From: Ford Prefect <fp42@restaurant.hitch.fict.example>
-+
-into
-
- From: Ford Prefect <prefectf@hitch.fict.example>
-+
-cindex:[RFC 2047]
-Sometimes there is a need to replace the whole address item, and this can be
-done by adding the flag letter ``w'' to a rule. If this is set on a rule that
-causes an address in a header line to be rewritten, the entire address is
-replaced, not just the working part. The replacement must be a complete RFC
-2822 address, including the angle brackets if necessary. If text outside angle
-brackets contains a character whose value is greater than 126 or less than 32
-(except for tab), the text is encoded according to RFC 2047. The character set
-is taken from %headers_charset%, which defaults to ISO-8859-1.
-+
-When the ``w'' flag is set on a rule that causes an envelope address to be
-rewritten, all but the working part of the replacement address is discarded.
-
-
-
-Rewriting examples
-~~~~~~~~~~~~~~~~~~
-Here is an example of the two common rewriting paradigms:
-
-....
-*@*.hitch.fict.example $1@hitch.fict.example
-*@hitch.fict.example ${lookup{$1}dbm{/etc/realnames}\
- {$value}fail}@hitch.fict.example bctfrF
-....
-
-Note the use of ``fail'' in the lookup expansion in the second rule, forcing
-the string expansion to fail if the lookup does not succeed. In this context it
-has the effect of leaving the original address unchanged, but Exim goes on to
-consider subsequent rewriting rules, if any, because the ``q'' flag is not
-present in that rule. An alternative to ``fail'' would be to supply $1$
-explicitly, which would cause the rewritten address to be the same as before,
-at the cost of a small bit of processing. Not supplying either of these is an
-error, since the rewritten address would then contain no local part.
-
-The first example above replaces the domain with a superior, more general
-domain. This may not be desirable for certain local parts. If the rule
-
- root@*.hitch.fict.example *
-
-were inserted before the first rule, rewriting would be suppressed for the
-local part 'root' at any domain ending in 'hitch.fict.example'.
-
-Rewriting can be made conditional on a number of tests, by making use of
-$\{if$ in the expansion item. For example, to apply a rewriting rule only to
-messages that originate outside the local host:
-
-....
-*@*.hitch.fict.example "${if !eq {$sender_host_address}{}\
- {$1@hitch.fict.example}fail}"
-....
-
-The replacement string is quoted in this example because it contains white
-space.
-
-cindex:[rewriting,bang paths]
-cindex:[bang paths,rewriting]
-Exim does not handle addresses in the form of ``bang paths''. If it sees such an
-address it treats it as an unqualified local part which it qualifies with the
-local qualification domain (if the source of the message is local or if the
-remote host is permitted to send unqualified addresses). Rewriting can
-sometimes be used to handle simple bang paths with a fixed number of
-components. For example, the rule
-
- \N^([^!]+)!(.*)@your.domain.example$\N $2@$1
-
-rewrites a two-component bang path 'host.name!user' as the domain address
-'user@host.name'. However, there is a security implication in using this as
-a global rewriting rule for envelope addresses. It can provide a backdoor
-method for using your system as a relay, because the incoming addresses appear
-to be local. If the bang path addresses are received via SMTP, it is safer to
-use the ``S'' flag to rewrite them as they are received, so that relay checking
-can be done on the rewritten addresses.
-
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPretry]]
-Retry configuration
--------------------
-cindex:[retry configuration, description of]
-cindex:[configuration file,retry section]
-The ``retry'' section of the run time configuration file contains a list of retry
-rules which control how often Exim tries to deliver messages that cannot be
-delivered at the first attempt. If there are no retry rules, temporary errors
-are treated as permanent. The %-brt% command line option can be used to test
-which retry rule will be used for a given address or domain.
-
-The most common cause of retries is temporary failure to deliver to a remote
-host because the host is down, or inaccessible because of a network problem.
-Exim's retry processing in this case is applied on a per-host (strictly, per IP
-address) basis, not on a per-message basis. Thus, if one message has recently
-been delayed, delivery of a new message to the same host is not immediately
-tried, but waits for the host's retry time to arrive. If the %retry_defer% log
-selector is set, the message
-cindex:[retry,time not reached]
-``retry time not reached'' is written to the main log whenever a delivery is
-skipped for this reason. Section <<SECToutSMTPerr>> contains more details of the
-handling of errors during remote deliveries.
-
-Retry processing applies to routing as well as to delivering, except as covered
-in the next paragraph. The retry rules do not distinguish between these
-actions. It is not possible, for example, to specify different behaviour for
-failures to route the domain 'snark.fict.example' and failures to deliver to
-the host 'snark.fict.example'. I didn't think anyone would ever need this
-added complication, so did not implement it. However, although they share the
-same retry rule, the actual retry times for routing and transporting a given
-domain are maintained independently.
-
-When a delivery is not part of a queue run (typically an immediate delivery on
-receipt of a message), the routers are always run, and local deliveries are
-always attempted, even if retry times are set for them. This makes for better
-behaviour if one particular message is causing problems (for example, causing
-quota overflow, or provoking an error in a filter file). If such a delivery
-suffers a temporary failure, the retry data is updated as normal, and
-subsequent delivery attempts from queue runs occur only when the retry time for
-the local address is reached.
-
-
-
-Retry rules
-~~~~~~~~~~~
-cindex:[retry,rules]
-Each retry rule occupies one line and consists of three or four parts,
-separated by white space: a pattern, an error name, an optional list of sender
-addresses, and a list of retry parameters. The pattern and sender lists must be
-enclosed in double quotes if they contain white space. The rules are searched in
-order until one is found where the pattern, error name, and sender list (if
-present) match the failing host or address, the error that occurred, and the
-message's sender, respectively.
-
-
-The pattern is any single item that may appear in an address list (see section
-<<SECTaddresslist>>). It is in fact processed as a one-item address list, which
-means that it is expanded before being tested against the address that has
-been delayed. Address list processing treats a plain domain name as if it were
-preceded by ``\*@'', which makes it possible for many retry rules to start with
-just a domain. For example,
-
- lookingglass.fict.example * F,24h,30m;
-
-provides a rule for any address in the 'lookingglass.fict.example' domain,
-whereas
-
- alice@lookingglass.fict.example * F,24h,30m;
-
-applies only to temporary failures involving the local part %alice%.
-In practice, almost all rules start with a domain name pattern without a local
-part.
-
-cindex:[regular expressions,in retry rules]
-*Warning*: If you use a regular expression in a routing rule pattern, it
-must match a complete address, not just a domain, because that is how regular
-expressions work in address lists.
-
-&&&
-`\^\Nxyz\d+\.abc\.example\\$\N \* G,1h,10m,2` %Wrong%
-`\^\N[^@]+@xyz\d+\.abc\.example\\$\N \* G,1h,10m,2` %Right%
-&&&
-
-
-
-Choosing which retry rule to use for address errors
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-When Exim is looking for a retry rule after a routing attempt has failed (for
-example, after a DNS timeout), each line in the retry configuration is tested
-against the complete address only if %retry_use_local_part% is set for the
-router. Otherwise, only the domain is used, except when matching against a
-regular expression, when the local part of the address is replaced with ``\*''.
-A domain on its own can match a domain pattern, or a pattern that starts with
-``\*@''. By default, %retry_use_local_part% is true for routers where
-%check_local_user% is true, and false for other routers.
-
-Similarly, when Exim is looking for a retry rule after a local delivery has
-failed (for example, after a mailbox full error), each line in the retry
-configuration is tested against the complete address only if
-%retry_use_local_part% is set for the transport (it defaults true for all
-local transports).
-
-When Exim is looking for a retry rule after a remote delivery attempt has
-failed, what happens depends on the type of failure. After a 4##'xx' SMTP
-response for a recipient address, the whole address is used when searching the
-retry rules. The rule that is found is used to create a retry time for the
-failing address.
-
-
-Choosing which retry rule to use for host errors
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-For a temporary error that is not related to an individual address (for
-example, a connection timeout), each line in the retry configuration is checked
-twice. First, the name of the remote host is used as a domain name (preceded by
-``\*@'' when matching a regular expression). If this does not match the line,
-the domain from the email address is tried in a similar fashion. For example,
-suppose the MX records for 'a.b.c.example' are
-
- a.b.c.example MX 5 x.y.z.example
- MX 6 p.q.r.example
- MX 7 m.n.o.example
-
-and the retry rules are
-
- p.q.r.example * F,24h,30m;
- a.b.c.example * F,4d,45m;
-
-and a delivery to the host 'x.y.z.example' suffers a connection failure. The
-first rule matches neither the host nor the domain, so Exim looks at the second
-rule. This does not match the host, but it does match the domain, so it is used
-to calculate the retry time for the host 'x.y.z.example'. Meanwhile, Exim tries
-to deliver to 'p.q.r.example'. If this also suffers a host error, the first
-retry rule is used, because it matches the host.
-
-In other words, temporary failures to deliver to host 'p.q.r.example' use the
-first rule to determine retry times, but for all the other hosts for the domain
-'a.b.c.example', the second rule is used. The second rule is also used if
-routing to 'a.b.c.example' suffers a temporary failure.
-
-[revisionflag="changed"]
-*Note*: the host name is used when matching the patterns, not its IP address.
-However, if a message is routed directly to an IP address without the use of a
-host name, for example, if a ^manualroute^ router contains a setting such as:
-
- route_list = *.a.example 192.168.34.23
-
-then the ``host name'' that is used when searching for a retry rule is the
-textual form of the IP address.
-
-
-Retry rules for specific errors
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[retry,specific errors; specifying]
-The second field in a retry rule is the name of a particular error, or an
-asterisk, which matches any error. The errors that can be tested for are:
-
-%auth_failed%::
-Authentication failed when trying to send to a host in the %hosts_require_auth%
-list in an ^smtp^ transport.
-
-%rcpt_4xx%::
-A 4##'xx' error was received for an outgoing RCPT command. Either the first or
-both of the x's can be given as specific digits, for example: `rcpt_45x` or
-`rcpt_436`. For example, to recognize 452 errors given to RCPT commands by a
-particular host, and have retries every ten minutes and a one-hour timeout, you
-could set up a retry rule of this form:
-
- the.host.name rcpt_452 F,1h,10m
-+
-These errors apply to both outgoing SMTP (the ^smtp^ transport) and outgoing
-LMTP (either the ^lmtp^ transport, or the ^smtp^ transport in LMTP mode).
-Note, however, that they apply only to responses to RCPT commands.
-
-%refused_MX%::
-A connection to a host obtained from an MX record was refused.
-
-%refused_A%::
-A connection to a host not obtained from an MX record was refused.
-
-%refused%::
-A connection was refused.
-
-%timeout_connect_MX%::
-A connection attempt to a host obtained from an MX record timed out.
-
-%timeout_connect_A%::
-A connection attempt to a host not obtained from an MX record timed out.
-
-%timeout_connect%::
-A connection attempt timed out.
-
-%timeout_MX%::
-There was a timeout while connecting or during an SMTP session with a host
-obtained from an MX record.
-
-%timeout_A%::
-There was a timeout while connecting or during an SMTP session with a host not
-obtained from an MX record.
-
-%timeout%::
-There was a timeout while connecting or during an SMTP session.
-
-%quota%::
-A mailbox quota was exceeded in a local delivery by the ^appendfile^ transport.
-
-%quota_%<'time'>::
-cindex:[quota,error testing in retry rule]
-cindex:[retry,quota error testing]
-A mailbox quota was exceeded in a local delivery by the ^appendfile^ transport,
-and the mailbox has not been accessed for <'time'>. For example, 'quota_4d'
-applies to a quota error when the mailbox has not been accessed for four days.
-
-///
-End of list
-///
-
-cindex:[mailbox,time of last read]
-The idea of %quota_%<'time'> is to make it possible to have shorter timeouts
-when the mailbox is full and is not being read by its owner. Ideally, it should
-be based on the last time that the user accessed the mailbox. However, it is
-not always possible to determine this. Exim uses the following heuristic rules:
-
-- If the mailbox is a single file, the time of last access (the ``atime'') is used.
-As no new messages are being delivered (because the mailbox is over quota),
-Exim does not access the file, so this is the time of last user access.
-
-- cindex:[maildir format,time of last read]
-For a maildir delivery, the time of last modification of the _new_
-subdirectory is used. As the mailbox is over quota, no new files are created in
-the _new_ subdirectory, because no new messages are being delivered. Any
-change to the _new_ subdirectory is therefore assumed to be the result of an
-MUA moving a new message to the _cur_ directory when it is first read. The
-time that is used is therefore the last time that the user read a new message.
-
-- For other kinds of multi-file mailbox, the time of last access cannot be
-obtained, so a retry rule that uses this type of error field is never matched.
-
-The quota errors apply both to system-enforced quotas and to Exim's own quota
-mechanism in the ^appendfile^ transport. The 'quota' error also applies
-when a local delivery is deferred because a partition is full (the ENOSPC
-error).
-
-
-
-Retry rules for specified senders
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[retry,rules; sender-specific]
-You can specify retry rules that apply only when the failing message has a
-specific sender. In particular, this can be used to define retry rules that
-apply only to bounce messages. The third item in a retry rule can be of this
-form:
-
- senders=<address list>
-
-The retry timings themselves are then the fourth item. For example:
-
-....
-* rcpt_4xx senders=: F,1h,30m
-....
-
-matches 4##'xx' errors for bounce messages sent to any host. If the address
-list contains white space, it must be enclosed in quotes. For example:
-
- a.domain auth_failed senders="xb.dom : yc.dom" G,8h,10m,1.5
-
-[revisionflag="changed"]
-*Warning*: This facility can be unhelpful if it is used for host errors (those
-that do not depend on the recipient). The reason is that the sender is used
-only to match the retry rule. Once the rule has been found for a host error,
-its contents are used to set a retry time for the host, and this will apply to
-all messages, not just those with specific senders.
-
-When testing retry rules using %-brt%, you can supply a sender using the %-f%
-command line option, like this:
-
- exim -f "" -brt user@dom.ain
-
-If you do not set %-f% with %-brt%, a retry rule that contains a senders list
-is never matched.
-
-
-
-
-
-Retry parameters
-~~~~~~~~~~~~~~~~
-cindex:[retry,parameters in rules]
-The third (or fourth, if a senders list is present) field in a retry rule is a
-sequence of retry parameter sets, separated by semicolons. Each set consists of
-
- <letter>,<cutoff time>,<arguments>
-
-The letter identifies the algorithm for computing a new retry time; the cutoff
-time is the time beyond which this algorithm no longer applies, and the
-arguments vary the algorithm's action. The cutoff time is measured from the
-time that the first failure for the domain (combined with the local part if
-relevant) was detected, not from the time the message was received.
-
-cindex:[retry,algorithms]
-cindex:[retry,fixed intervals]
-cindex:[retry,increasing intervals]
-cindex:[retry,random intervals]
-The available algorithms are:
-
-- 'F': retry at fixed intervals. There is a single time parameter specifying
-the interval.
-
-- 'G': retry at geometrically increasing intervals. The first argument
-specifies a starting value for the interval, and the second a multiplier, which
-is used to increase the size of the interval at each retry.
-
-[revisionflag="changed"]
-- 'H': retry at randomized intervals. The arguments are as for 'G'. For each
-retry, the previous interval is multiplied by the factor in order to get a
-maximum for the next interval. The mininum interval is the first argument of
-the parameter, and an actual interval is chosen randomly between them. Such a
-rule has been found to be helpful in cluster configurations when all the
-members of the cluster restart at once, and may therefore synchronize their
-queue processing times.
-
-When computing the next retry time, the algorithm definitions are scanned in
-order until one whose cutoff time has not yet passed is reached. This is then
-used to compute a new retry time that is later than the current time. In the
-case of fixed interval retries, this simply means adding the interval to the
-current time. For geometrically increasing intervals, retry intervals are
-computed from the rule's parameters until one that is greater than the previous
-interval is found. The main configuration variable
-cindex:[limit,retry interval]
-cindex:[retry interval, maximum]
-cindex:[%retry_interval_max%]
-%retry_interval_max% limits the maximum interval between retries.
-
-A single remote domain may have a number of hosts associated with it, and each
-host may have more than one IP address. Retry algorithms are selected on the
-basis of the domain name, but are applied to each IP address independently. If,
-for example, a host has two IP addresses and one is unusable, Exim will
-generate retry times for it and will not try to use it until its next retry
-time comes. Thus the good IP address is likely to be tried first most of the
-time.
-
-cindex:[hints database,use for retrying]
-Retry times are hints rather than promises. Exim does not make any attempt to
-run deliveries exactly at the computed times. Instead, a queue runner process
-starts delivery processes for delayed messages periodically, and these attempt
-new deliveries only for those addresses that have passed their next retry time.
-If a new message arrives for a deferred address, an immediate delivery attempt
-occurs only if the address has passed its retry time. In the absence of new
-messages, the minimum time between retries is the interval between queue runner
-processes. There is not much point in setting retry times of five minutes if
-your queue runners happen only once an hour, unless there are a significant
-number of incoming messages (which might be the case on a system that is
-sending everything to a smart host, for example).
-
-The data in the retry hints database can be inspected by using the
-'exim_dumpdb' or 'exim_fixdb' utility programs (see chapter <<CHAPutils>>). The
-latter utility can also be used to change the data. The 'exinext' utility
-script can be used to find out what the next retry times are for the hosts
-associated with a particular mail domain, and also for local deliveries that
-have been deferred.
-
-
-Retry rule examples
-~~~~~~~~~~~~~~~~~~~
-Here are some example retry rules:
-
- alice@wonderland.fict.example quota_5d F,7d,3h
- wonderland.fict.example quota_5d
- wonderland.fict.example * F,1h,15m; G,2d,1h,2;
- lookingglass.fict.example * F,24h,30m;
- * refused_A F,2h,20m;
- * * F,2h,15m; G,16h,1h,1.5; F,5d,8h
-
-The first rule sets up special handling for mail to
-'alice@wonderland.fict.example' when there is an over-quota error and the
-mailbox has not been read for at least 5 days. Retries continue every three
-hours for 7 days. The second rule handles over-quota errors for all other local
-parts at 'wonderland.fict.example'; the absence of a local part has the same
-effect as supplying ``\*@''. As no retry algorithms are supplied, messages that
-fail are bounced immediately if the mailbox has not been read for at least 5
-days.
-
-The third rule handles all other errors at 'wonderland.fict.example'; retries
-happen every 15 minutes for an hour, then with geometrically increasing
-intervals until two days have passed since a delivery first failed. After the
-first hour there is a delay of one hour, then two hours, then four hours, and
-so on (this is a rather extreme example).
-
-The fourth rule controls retries for the domain 'lookingglass.fict.example'.
-They happen every 30 minutes for 24 hours only. The remaining two rules handle
-all other domains, with special action for connection refusal from hosts that
-were not obtained from an MX record.
-
-The final rule in a retry configuration should always have asterisks in the
-first two fields so as to provide a general catch-all for any addresses that do
-not have their own special handling. This example tries every 15 minutes for 2
-hours, then with intervals starting at one hour and increasing by a factor of
-1.5 up to 16 hours, then every 8 hours up to 5 days.
-
-
-
-Timeout of retry data
-~~~~~~~~~~~~~~~~~~~~~
-cindex:[timeout,of retry data]
-cindex:[%retry_data_expire%]
-cindex:[hints database,data expiry]
-cindex:[retry,timeout of data]
-Exim timestamps the data that it writes to its retry hints database. When it
-consults the data during a delivery it ignores any that is older than the value
-set in %retry_data_expire% (default 7 days). If, for example, a host hasn't
-been tried for 7 days, Exim will try to deliver to it immediately a message
-arrives, and if that fails, it will calculate a retry time as if it were
-failing for the first time.
-
-This improves the behaviour for messages routed to rarely-used hosts such as MX
-backups. If such a host was down at one time, and happens to be down again when
-Exim tries a month later, using the old retry data would imply that it had been
-down all the time, which is not a justified assumption.
-
-If a host really is permanently dead, this behaviour causes a burst of retries
-every now and again, but only if messages routed to it are rare. It there is a
-message at least once every 7 days the retry data never expires.
-
-
-
-
-Long-term failures
-~~~~~~~~~~~~~~~~~~
-cindex:[delivery failure, long-term]
-cindex:[retry,after long-term failure]
-Special processing happens when an email address has been failing for so long
-that the cutoff time for the last algorithm is reached. For example, using the
-default retry rule:
-
-....
-* * F,2h,15m; G,16h,1h,1.5; F,4d,6h
-....
-
-the cutoff time is four days. Reaching the retry cutoff is independent of how
-long any specific message has been failing; it is the length of continuous
-failure for the recipient address that counts.
-
-When the cutoff time is reached for a local delivery, or for all the IP
-addresses associated with a remote delivery, a subsequent delivery failure
-causes Exim to give up on the address, and a bounce message is generated.
-In order to cater for new messages that use the failing address, a next retry
-time is still computed from the final algorithm, and is used as follows:
-
-For local deliveries, one delivery attempt is always made for any subsequent
-messages. If this delivery fails, the address fails immediately. The
-post-cutoff retry time is not used.
-
-If the delivery is remote, there are two possibilities, controlled by the
-cindex:[%delay_after_cutoff%]
-%delay_after_cutoff% option of the ^smtp^ transport. The option is true by
-default. Until the post-cutoff retry time for one of the IP addresses is
-reached, the failing email address is bounced immediately, without a delivery
-attempt taking place. After that time, one new delivery attempt is made to
-those IP addresses that are past their retry times, and if that still fails,
-the address is bounced and new retry times are computed.
-
-In other words, when all the hosts for a given email address have been failing
-for a long time, Exim bounces rather then defers until one of the hosts' retry
-times is reached. Then it tries once, and bounces if that attempt fails. This
-behaviour ensures that few resources are wasted in repeatedly trying to deliver
-to a broken destination, but if the host does recover, Exim will eventually
-notice.
-
-If %delay_after_cutoff% is set false, Exim behaves differently. If all IP
-addresses are past their final cutoff time, Exim tries to deliver to those IP
-addresses that have not been tried since the message arrived. If there are
-no suitable IP addresses, or if they all fail, the address is bounced. In other
-words, it does not delay when a new message arrives, but tries the expired
-addresses immediately, unless they have been tried since the message arrived.
-If there is a continuous stream of messages for the failing domains, setting
-%delay_after_cutoff% false means that there will be many more attempts to
-deliver to permanently failing IP addresses than when %delay_after_cutoff% is
-true.
-
-
-Ultimate address timeout
-~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[retry,ultimate address timeout]
-An additional rule is needed to cope with cases where a host is intermittently
-available, or when a message has some attribute that prevents its delivery when
-others to the same address get through. In this situation, because some
-messages are successfully delivered, the ``retry clock'' for the address keeps
-getting restarted, and so a message could remain on the queue for ever. To
-prevent this, if a message has been on the queue for longer than the cutoff
-time of any applicable retry rule for a given address, a delivery is attempted
-for that address, even if it is not yet time, and if this delivery fails, the
-address is timed out. A new retry time is not computed in this case, so that
-other messages for the same address are considered immediately.
-
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPSMTPAUTH]]
-SMTP authentication
--------------------
-cindex:[SMTP,authentication configuration]
-cindex:[authentication]
-The ``authenticators'' section of Exim's run time configuration is concerned with
-SMTP authentication. This facility is an extension to the SMTP protocol,
-described in RFC 2554, which allows a client SMTP host to authenticate itself
-to a server. This is a common way for a server to recognize clients that
-are permitted to use it as a relay. SMTP authentication is not of relevance to
-the transfer of mail between servers that have no managerial connection with
-each other.
-
-cindex:[AUTH,description of]
-Very briefly, the way SMTP authentication works is as follows:
-
-- The server advertises a number of authentication 'mechanisms' in response to
-the client's EHLO command.
-
-- The client issues an AUTH command, naming a specific mechanism. The command
-may, optionally, contain some authentication data.
-
-- The server may issue one or more 'challenges', to which the client must send
-appropriate responses. In simple authentication mechanisms, the challenges are
-just prompts for user names and passwords. The server does not have to issue
-any challenges -- in some mechanisms the relevant data may all be transmitted
-with the AUTH command.
-
-- The server either accepts or denies authentication.
-
-- If authentication succeeds, the client may optionally make use of the AUTH
-option on the MAIL command to pass an authenticated sender in subsequent
-mail transactions. Authentication lasts for the remainder of the SMTP
-connection.
-
-- If authentication fails, the client may give up, or it may try a different
-authentication mechanism, or it may try transferring mail over the
-unauthenticated connection.
-
-If you are setting up a client, and want to know which authentication
-mechanisms the server supports, you can use Telnet to connect to port 25 (the
-SMTP port) on the server, and issue an EHLO command. The response to this
-includes the list of supported mechanisms. For example:
-
-&&&
-`\$ `##*`telnet server.example 25`*
-`Trying 192.168.34.25...`
-`Connected to server.example.`
-`Escape character is \'^]\'.`
-`220 server.example ESMTP Exim 4.20 ...`
-*`ehlo client.example`*
-`250-server.example Hello client.example [10.8.4.5]`
-`250-SIZE 52428800`
-`250-PIPELINING`
-`250-AUTH PLAIN`
-`250 HELP`
-&&&
-
-The second-last line of this example output shows that the server supports
-authentication using the PLAIN mechanism. In Exim, the different authentication
-mechanisms are configured by specifying 'authenticator' drivers. Like the
-routers and transports, which authenticators are included in the binary is
-controlled by build-time definitions. The following are currently available,
-included by setting
-
- AUTH_CRAM_MD5=yes
- AUTH_CYRUS_SASL=yes
- AUTH_PLAINTEXT=yes
- AUTH_SPA=yes
-
-in _Local/Makefile_, respectively. The first of these supports the CRAM-MD5
-authentication mechanism (RFC 2195), and the second provides an interface to
-the Cyrus SASL authentication library. The third can be configured to support
-the PLAIN authentication mechanism (RFC 2595) or the LOGIN mechanism, which is
-not formally documented, but used by several MUAs. The fourth authenticator
-supports Microsoft's 'Secure Password Authentication' mechanism.
-
-The authenticators are configured using the same syntax as other drivers (see
-section <<SECTfordricon>>). If no authenticators are required, no authentication
-section need be present in the configuration file. Each authenticator can in
-principle have both server and client functions. When Exim is receiving SMTP
-mail, it is acting as a server; when it is sending out messages over SMTP, it
-is acting as a client. Authenticator configuration options are provided for use
-in both these circumstances.
-
-To make it clear which options apply to which situation, the prefixes
-%server_% and %client_% are used on option names that are specific to either
-the server or the client function, respectively. Server and client functions
-are disabled if none of their options are set. If an authenticator is to be
-used for both server and client functions, a single definition, using both sets
-of options, is required. For example:
-
- cram:
- driver = cram_md5
- public_name = CRAM-MD5
- server_secret = ${if eq{$1}{ph10}{secret1}fail}
- client_name = ph10
- client_secret = secret2
-
-The %server_% option is used when Exim is acting as a server, and the
-%client_% options when it is acting as a client.
-
-Descriptions of the individual authenticators are given in subsequent chapters.
-The remainder of this chapter covers the generic options for the
-authenticators, followed by general discussion of the way authentication works
-in Exim.
-
-
-
-Generic options for authenticators
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[authentication,generic options]
-cindex:[options,generic; for authenticators]
-
-
-oindex:[%driver%]
-`..'=
-%driver%, Use: 'authenticators', Type: 'string', Default: 'unset'
-===
-
-This option must always be set. It specifies which of the available
-authenticators is to be used.
-
-
-oindex:[%public_name%]
-`..'=
-%public_name%, Use: 'authenticators', Type: 'string', Default: 'unset'
-===
-
-This option specifies the name of the authentication mechanism that the driver
-implements, and by which it is known to the outside world. These names should
-contain only upper case letters, digits, underscores, and hyphens (RFC 2222),
-but Exim in fact matches them caselessly. If %public_name% is not set, it
-defaults to the driver's instance name.
-
-
-oindex:[%server_advertise_condition%]
-`..'=
-%server_advertise_condition%, Use: 'authenticators', Type: 'string'!!, Default: 'unset'
-===
-
-When a server is about to advertise an authentication mechanism, the condition
-is expanded. If it yields the empty string, ``0'', ``no'', or ``false'', the
-mechanism is not advertised.
-If the expansion fails, the mechanism is not advertised. If the failure was not
-forced, and was not caused by a lookup defer, the incident is logged.
-See section <<SECTauthexiser>> below for further discussion.
-
-
-oindex:[%server_debug_print%]
-`..'=
-%server_debug_print%, Use: 'authenticators', Type: 'string'!!, Default: 'unset'
-===
-
-If this option is set and authentication debugging is enabled (see the %-d%
-command line option), the string is expanded and included in the debugging
-output when the authenticator is run as a server. This can help with checking
-out the values of variables.
-If expansion of the string fails, the error message is written to the debugging
-output, and Exim carries on processing.
-
-
-oindex:[%server_set_id%]
-`..'=
-%server_set_id%, Use: 'authenticators', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[$authenticated_id$]
-When an Exim server successfully authenticates a client, this string is
-expanded using data from the authentication, and preserved for any incoming
-messages in the variable $authenticated_id$. It is also included in the log
-lines for incoming messages. For example, a user/password authenticator
-configuration might preserve the user name that was used to authenticate, and
-refer to it subsequently during delivery of the message.
-If expansion fails, the option is ignored.
-
-
-oindex:[%server_mail_auth_condition%]
-`..'=
-%server_mail_auth_condition%, Use: 'authenticators', Type: 'string'!!, Default: 'unset'
-===
-
-This option allows a server to discard authenticated sender addresses supplied
-as part of MAIL commands in SMTP connections that are authenticated by the
-driver on which %server_mail_auth_condition% is set. The option is not used
-as part of the authentication process; instead its (unexpanded) value is
-remembered for later use.
-How it is used is described in the following section.
-
-
-
-
-
-[[SECTauthparamail]]
-The AUTH parameter on MAIL commands
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[authentication,sender; authenticated]
-cindex:[AUTH,on MAIL command]
-When a client supplied an AUTH= item on a MAIL command, Exim applies
-the following checks before accepting it as the authenticated sender of the
-message:
-
-- If the connection is not using extended SMTP (that is, HELO was used rather
-than EHLO), the use of AUTH= is a syntax error.
-
-- If the value of the AUTH= parameter is ``<>'', it is ignored.
-
-- cindex:[$authenticated_sender$]
-If %acl_smtp_mailauth% is defined, the ACL it specifies is run. While it is
-running, the value of $authenticated_sender$ is set to the value obtained from
-the AUTH= parameter. If the ACL does not yield ``accept'', the value of
-$authenticated_sender$ is deleted. The %acl_smtp_mailauth% ACL may not return
-``drop'' or ``discard''. If it defers, a temporary error code (451) is given
-for the MAIL command.
-
-- If %acl_smtp_mailauth% is not defined, the value of the AUTH= parameter
-is accepted and placed in $authenticated_sender$ only if the client has
-authenticated.
-
-- If the AUTH= value was accepted by either of the two previous rules, and
-the client has authenticated, and the authenticator has a setting for the
-%server_mail_auth_condition%, the condition is checked at this point. The
-valued that was saved from the authenticator is expanded. If the expansion
-fails, or yields an empty string, ``0'', ``no'', or ``false'', the value of
-$authenticated_sender$ is deleted. If the expansion yields any other value,
-the value of $authenticated_sender$ is retained and passed on with the
-message.
-
-
-When $authenticated_sender$ is set for a message, it is passed on to other
-hosts to which Exim authenticates as a client. Do not confuse this value with
-$authenticated_id$, which is a string obtained from the authentication
-process, and which is not usually a complete email address.
-
-cindex:[$sender_address$]
-Whenever an AUTH= value is ignored, the incident is logged. The ACL for
-MAIL, if defined, is run after AUTH= is accepted or ignored. It can
-therefore make use of $authenticated_sender$. The converse is not true: the
-value of $sender_address$ is not yet set up when the %acl_smtp_mailauth%
-ACL is run.
-
-
-
-[[SECTauthexiser]]
-Authentication on an Exim server
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[authentication,on an Exim server]
-When Exim receives an EHLO command, it advertises the public names of those
-authenticators that are configured as servers, subject to the following
-conditions:
-
-- The client host must match %auth_advertise_hosts% (default \*).
-
-- It the %server_advertise_condition% option is set, its expansion must not
-yield the empty string, ``0'', ``no'', or ``false''.
-
-The order in which the authenticators are defined controls the order in which
-the mechanisms are advertised.
-
-Some mail clients (for example, some versions of Netscape) require the user to
-provide a name and password for authentication whenever AUTH is advertised,
-even though authentication may not in fact be needed (for example, Exim may be
-set up to allow unconditional relaying from the client by an IP address check).
-You can make such clients more friendly by not advertising AUTH to them.
-For example, if clients on the 10.9.8.0/24 network are permitted (by the ACL
-that runs for RCPT) to relay without authentication, you should set
-
- auth_advertise_hosts = ! 10.9.8.0/24
-
-so that no authentication mechanisms are advertised to them.
-
-The %server_advertise_condition% controls the advertisement of individual
-authentication mechanisms. For example, it can be used to restrict the
-advertisement of a patricular mechanism to encrypted connections, by a setting
-such as:
-
- server_advertise_condition = ${if eq{$tls_cipher}{}{no}{yes}}
-
-cindex:[$tls_cipher$]
-If the session is encrypted, $tls_cipher$ is not empty, and so the expansion
-yields ``yes'', which allows the advertisement to happen.
-
-When an Exim server receives an AUTH command from a client, it rejects it
-immediately if AUTH was not advertised in response to an earlier EHLO
-command. This is the case if
-
-- The client host does not match %auth_advertise_hosts%; or
-
-- No authenticators are configured with server options; or
-
-- Expansion of %server_advertise_condition% blocked the advertising of all the
-server authenticators.
-
-
-Otherwise, Exim runs the ACL specified by %acl_smtp_auth% in order
-to decide whether to accept the command. If %acl_smtp_auth% is not set,
-AUTH is accepted from any client host.
-
-If AUTH is not rejected by the ACL, Exim searches its configuration for a
-server authentication mechanism that was advertised in response to EHLO and
-that matches the one named in the AUTH command. If it finds one, it runs
-the appropriate authentication protocol, and authentication either succeeds or
-fails. If there is no matching advertised mechanism, the AUTH command is
-rejected with a 504 error.
-
-cindex:[$received_protocol$]
-cindex:[$sender_host_authenticated$]
-When a message is received from an authenticated host, the value of
-$received_protocol$ is set to ``esmtpa'' or ``esmtpsa'' instead of ``esmtp'' or
-``esmtps'', and $sender_host_authenticated$ contains the name (not the public
-name) of the authenticator driver that successfully authenticated the client
-from which the message was received. This variable is empty if there was no
-successful authentication.
-
-
-
-
-Testing server authentication
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[authentication,testing a server]
-cindex:[AUTH,testing a server]
-cindex:[base64 encoding,creating authentication test data]
-Exim's %-bh% option can be useful for testing server authentication
-configurations. The data for the AUTH command has to be sent using base64
-encoding. A quick way to produce such data for testing is the following Perl
-script:
-
- use MIME::Base64;
- printf ("%s", encode_base64(eval "\"$ARGV[0]\""));
-
-cindex:[binary zero,in authentication data]
-This interprets its argument as a Perl string, and then encodes it. The
-interpretation as a Perl string allows binary zeros, which are required for
-some kinds of authentication, to be included in the data. For example, a
-command line to run this script on such data might be
-
- encode '\0user\0password'
-
-Note the use of single quotes to prevent the shell interpreting the
-backslashes, so that they can be interpreted by Perl to specify characters
-whose code value is zero.
-
-*Warning 1*: If either of the user or password strings starts with an octal
-digit, you must use three zeros instead of one after the leading backslash. If
-you do not, the octal digit that starts your string will be incorrectly
-interpreted as part of the code for the first character.
-
-*Warning 2*: If there are characters in the strings that Perl interprets
-specially, you must use a Perl escape to prevent them being misinterpreted. For
-example, a command such as
-
- encode '\0user@domain.com\0pas$$word'
-
-gives an incorrect answer because of the unescaped ``@'' and ``\$'' characters.
-
-If you have the %mimencode% command installed, another way to do produce
-base64-encoded strings is to run the command
-
- echo -e -n `\0user\0password' | mimencode
-
-The %-e% option of %echo% enables the interpretation of backslash escapes in
-the argument, and the %-n% option specifies no newline at the end of its
-output. However, not all versions of %echo% recognize these options, so you
-should check your version before relying on this suggestion.
-
-
-
-Authentication by an Exim client
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[authentication,on an Exim client]
-The ^smtp^ transport has two options called %hosts_require_auth% and
-%hosts_try_auth%. When the ^smtp^ transport connects to a server that
-announces support for authentication, and the host matches an entry in either
-of these options, Exim (as a client) tries to authenticate as follows:
-
-- For each authenticator that is configured as a client, it searches the
-authentication mechanisms announced by the server for one whose name
-matches the public name of the authenticator.
-
-- cindex:[$host$]
-cindex:[$host_address$]
-When it finds one that matches, it runs the authenticator's client code.
-The variables $host$ and $host_address$ are available for any string
-expansions that the client might do. They are set to the server's name and
-IP address. If any expansion is forced to fail, the authentication attempt
-is abandoned,
-and Exim moves on to the next authenticator.
-Otherwise an expansion failure causes delivery to be
-deferred.
-
-- If the result of the authentication attempt is a temporary error or a timeout,
-Exim abandons trying to send the message to the host for the moment. It will
-try again later. If there are any backup hosts available, they are tried in the
-usual way.
-
-- If the response to authentication is a permanent error (5xx code), Exim carries
-on searching the list of authenticators and tries another one if possible. If
-all authentication attempts give permanent errors, or if there are no attempts
-because no mechanisms match
-(or option expansions force failure),
-what happens depends on whether the host matches %hosts_require_auth% or
-%hosts_try_auth%. In the first case, a temporary error is generated, and
-delivery is deferred. The error can be detected in the retry rules, and thereby
-turned into a permanent error if you wish. In the second case, Exim tries to
-deliver the message unauthenticated.
-
-cindex:[AUTH,on MAIL command]
-When Exim has authenticated itself to a remote server, it adds the AUTH
-parameter to the MAIL commands it sends, if it has an authenticated sender
-for the message.
-If the message came from a remote host, the authenticated sender is the one
-that was receiving on an incoming MAIL command, provided that the incoming
-connection was authenticated and the %server_mail_auth% condition allowed the
-authenticated sender to be retained. If a local process calls Exim to send a
-message, the sender address that is built from the login name and
-%qualify_domain% is treated as authenticated. However, if the
-%authenticated_sender% option is set on the ^smtp^ transport, it overrides
-the authenticated sender that was received with the message.
-
-
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPplaintext]]
-The plaintext authenticator
----------------------------
-cindex:[^plaintext^ authenticator]
-cindex:[authenticators,^plaintext^]
-The ^plaintext^ authenticator can be configured to support the PLAIN and
-LOGIN authentication mechanisms, both of which transfer authentication data as
-plain (unencrypted) text (though base64 encoded). The use of plain text is a
-security risk. If you use one of these mechanisms without also making use of
-SMTP encryption (see chapter <<CHAPTLS>>) you should not use the same passwords
-for SMTP connections as you do for login accounts.
-
-
-Using plaintext in a server
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[options,^plaintext^ authenticator (server)]
-When running as a server, ^plaintext^ performs the authentication test by
-expanding a string. It has the following options:
-
-oindex:[%server_prompts%]
-`..'=
-%server_prompts%, Use: 'plaintext', Type: 'string'!!, Default: 'unset'
-===
-
-The contents of this option, after expansion, must be a colon-separated list of
-prompt strings. If expansion fails, a temporary authentication rejection is
-given.
-
-oindex:[%server_condition%]
-`..'=
-%server_condition%, Use: 'plaintext', Type: 'string'!!, Default: 'unset'
-===
-
-This option must be set in order to configure the driver as a server. Its use
-is described below.
-
-cindex:[AUTH,in ^plaintext^ authenticator]
-cindex:[binary zero,in ^plaintext^ authenticator]
-cindex:[numerical variables ($1$ $2$ etc),in ^plaintext^ authenticator]
-cindex:[base64 encoding,in ^plaintext^ authenticator]
-The data sent by the client with the AUTH command, or in response to
-subsequent prompts, is base64 encoded, and so may contain any byte values
-when decoded. If any data is supplied with the command, it is treated as a
-list of strings, separated by NULs (binary zeros), which are placed in the
-expansion variables $1$, $2$, etc. If there are more strings in
-%server_prompts% than the number of strings supplied with the AUTH
-command, the remaining prompts are used to obtain more data. Each response from
-the client may be a list of NUL-separated strings.
-
-cindex:[$authenticated_id$]
-Once a sufficient number of data strings have been received, %server_condition%
-is expanded. If the expansion is forced to fail, authentication fails. Any
-other expansion failure causes a temporary error code to be returned. If the
-result of a successful expansion is an empty string, ``0'', ``no'', or
-``false'', authentication fails. If the result of the expansion is ``1'',
-``yes'', or ``true'', authentication succeeds and the generic %server_set_id%
-option is expanded and saved in $authenticated_id$. For any other result, a
-temporary error code is returned, with the expanded string as the error text.
-
-*Warning*: If you use a lookup in the expansion to find the user's
-password, be sure to make the authentication fail if the user is unknown.
-There are good and bad examples at the end of the next section.
-
-
-
-The PLAIN authentication mechanism
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[PLAIN authentication mechanism]
-cindex:[authentication,PLAIN mechanism]
-cindex:[binary zero,in ^plaintext^ authenticator]
-The PLAIN authentication mechanism (RFC 2595) specifies that three strings be
-sent as one item of data (that is, one combined string containing two NUL
-separators). The data is sent either as part of the AUTH command, or
-subsequently in response to an empty prompt from the server.
-
-The second and third strings are a user name and a corresponding password.
-Using a single fixed user name and password as an example, this could be
-configured as follows:
-
-....
-fixed_plain:
- driver = plaintext
- public_name = PLAIN
- server_prompts = :
- server_condition = \
- ${if and {{eq{$2}{username}}{eq{$3}{mysecret}}}{yes}{no}}
- server_set_id = $2
-....
-
-The %server_prompts% setting specifies a single, empty prompt (empty items at
-the end of a string list are ignored). If all the data comes as part of the
-AUTH command, as is commonly the case, the prompt is not used. This
-authenticator is advertised in the response to EHLO as
-
- 250-AUTH PLAIN
-
-and a client host can authenticate itself by sending the command
-
- AUTH PLAIN AHVzZXJuYW1lAG15c2VjcmV0
-
-As this contains three strings (more than the number of prompts), no further
-data is required from the client. Alternatively, the client may just send
-
- AUTH PLAIN
-
-to initiate authentication, in which case the server replies with an empty
-prompt. The client must respond with the combined data string.
-
-The data string is base64 encoded, as required by the RFC. This example,
-when decoded, is <'NUL'>`username`<'NUL'>`mysecret`, where <'NUL'> represents a
-zero byte. This is split up into three strings, the first of which is empty.
-The %server_condition% option in the authenticator checks that the second two
-are `username` and `mysecret` respectively.
-
-Having just one fixed user name and password, as in this example, is not very
-realistic, though for a small organization with only a handful of
-authenticating clients it could make sense.
-
-A more sophisticated instance of this authenticator could use the user name in
-$2$ to look up a password in a file or database, and maybe do an encrypted
-comparison (see %crypteq% in chapter <<CHAPexpand>>). Here is a example of this
-approach, where the passwords are looked up in a DBM file. *Warning*: This
-is an incorrect example:
-
-....
-server_condition = \
- ${if eq{$3}{${lookup{$2}dbm{/etc/authpwd}}}{yes}{no}}
-....
-
-The expansion uses the user name ($2$) as the key to look up a password,
-which it then compares to the supplied password ($3$). Why is this example
-incorrect? It works fine for existing users, but consider what happens if a
-non-existent user name is given. The lookup fails, but as no success/failure
-strings are given for the lookup, it yields an empty string. Thus, to defeat
-the authentication, all a client has to do is to supply a non-existent user
-name and an empty password. The correct way of writing this test is:
-
-....
-server_condition = ${lookup{$2}dbm{/etc/authpwd}\
- {${if eq{$value}{$3}{yes}{no}}}{no}}
-....
-
-In this case, if the lookup succeeds, the result is checked; if the lookup
-fails, authentication fails. If %crypteq% is being used instead of %eq%, the
-first example is in fact safe, because %crypteq% always fails if its second
-argument is empty. However, the second way of writing the test makes the logic
-clearer.
-
-
-
-The LOGIN authentication mechanism
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[LOGIN authentication mechanism]
-cindex:[authentication,LOGIN mechanism]
-The LOGIN authentication mechanism is not documented in any RFC, but is in use
-in a number of programs. No data is sent with the AUTH command. Instead, a
-user name and password are supplied separately, in response to prompts. The
-plaintext authenticator can be configured to support this as in this example:
-
-....
-fixed_login:
- driver = plaintext
- public_name = LOGIN
- server_prompts = User Name : Password
- server_condition = \
- ${if and {{eq{$1}{username}}{eq{$2}{mysecret}}}{yes}{no}}
- server_set_id = $1
-....
-
-Because of the way plaintext operates, this authenticator accepts data supplied
-with the AUTH command (in contravention of the specification of LOGIN), but
-if the client does not supply it (as is the case for LOGIN clients), the prompt
-strings are used to obtain two data items.
-
-Some clients are very particular about the precise text of the prompts. For
-example, Outlook Express is reported to recognize only ``Username:'' and
-``Password:''. Here is an example of a LOGIN authenticator which uses those
-strings, and which uses the %ldapauth% expansion condition to check the user
-name and password by binding to an LDAP server:
-
-....
-login:
- driver = plaintext
- public_name = LOGIN
- server_prompts = Username:: : Password::
- server_condition = ${if ldapauth \
- {user="cn=${quote_ldap_dn:$1},ou=people,o=example.org" \
- pass=${quote:$2} \
- ldap://ldap.example.org/}{yes}{no}}
- server_set_id = uid=$1,ou=people,o=example.org
-....
-
-Note the use of the %quote_ldap_dn% operator to correctly quote the DN for
-authentication. However, the basic %quote% operator, rather than any of the
-LDAP quoting operators, is the correct one to use for the password, because
-quoting is needed only to make the password conform to the Exim syntax. At the
-LDAP level, the password is an uninterpreted string.
-
-
-
-Support for different kinds of authentication
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-A number of string expansion features are provided for the purpose of
-interfacing to different ways of user authentication. These include checking
-traditionally encrypted passwords from _/etc/passwd_ (or equivalent), PAM,
-Radius, %ldapauth%, and 'pwcheck'. For details see section <<SECTexpcond>>.
-
-
-
-
-Using plaintext in a client
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[options,^plaintext^ authenticator (client)]
-The ^plaintext^ authenticator has just one client option:
-
-
-
-oindex:[%client_send%]
-`..'=
-%client_send%, Use: 'plaintext', Type: 'string'!!, Default: 'unset'
-===
-
-The string is a colon-separated list of authentication data strings. Each
-string is independently expanded before being sent to the server. The first
-string is sent with the AUTH command; any more strings are sent in response
-to prompts from the server.
-
-*Note*: you cannot use expansion to create multiple strings, because
-splitting takes priority and happens first.
-
-Because the PLAIN authentication mechanism requires NUL (binary zero) bytes in
-the data, further processing is applied to each string before it is sent. If
-there are any single circumflex characters in the string, they are converted to
-NULs. Should an actual circumflex be required as data, it must be doubled in
-the string.
-
-This is an example of a client configuration that implements the PLAIN
-authentication mechanism with a fixed user name and password:
-
- fixed_plain:
- driver = plaintext
- public_name = PLAIN
- client_send = ^username^mysecret
-
-The lack of colons means that the entire text is sent with the AUTH
-command, with the circumflex characters converted to NULs. A similar example
-that uses the LOGIN mechanism is:
-
- fixed_login:
- driver = plaintext
- public_name = LOGIN
- client_send = : username : mysecret
-
-The initial colon means that the first string is empty, so no data is sent with
-the AUTH command itself. The remaining strings are sent in response to
-prompts.
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-The cram_md5 authenticator
---------------------------
-cindex:[^cram_md5^ authenticator]
-cindex:[authenticators,^cram_md5^]
-cindex:[CRAM-MD5 authentication mechanism]
-cindex:[authentication,CRAM-MD5 mechanism]
-The CRAM-MD5 authentication mechanism is described in RFC 2195. The server
-sends a challenge string to the client, and the response consists of a user
-name and the CRAM-MD5 digest of the challenge string combined with a secret
-string (password) which is known to both server and client. Thus, the secret
-is not sent over the network as plain text, which makes this authenticator more
-secure than ^plaintext^. However, the downside is that the secret has to be
-available in plain text at either end.
-
-
-Using cram_md5 as a server
-~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[options,^cram_md5^ authenticator (server)]
-This authenticator has one server option, which must be set to configure the
-authenticator as a server:
-
-oindex:[%server_secret%]
-`..'=
-%server_secret%, Use: 'cram_md5', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[numerical variables ($1$ $2$ etc),in ^cram_md5^ authenticator]
-When the server receives the client's response, the user name is placed in
-the expansion variable $1$, and %server_secret% is expanded to obtain the
-password for that user. The server then computes the CRAM-MD5 digest that the
-client should have sent, and checks that it received the correct string. If the
-expansion of %server_secret% is forced to fail, authentication fails. If the
-expansion fails for some other reason, a temporary error code is returned to
-the client.
-
-For example, the following authenticator checks that the user name given by the
-client is ``ph10'', and if so, uses ``secret'' as the password. For any other user
-name, authentication fails.
-
- fixed_cram:
- driver = cram_md5
- public_name = CRAM-MD5
- server_secret = ${if eq{$1}{ph10}{secret}fail}
- server_set_id = $1
-
-cindex:[$authenticated_id$]
-If authentication succeeds, the setting of %server_set_id% preserves the user
-name in $authenticated_id$. A more tyical configuration might look up the
-secret string in a file, using the user name as the key. For example:
-
- lookup_cram:
- driver = cram_md5
- public_name = CRAM-MD5
- server_secret = ${lookup{$1}lsearch{/etc/authpwd}{$value}fail}
- server_set_id = $1
-
-Note that this expansion explicitly forces failure if the lookup fails
-because $1$ contains an unknown user name.
-
-
-Using cram_md5 as a client
-~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[options,^cram_md5^ authenticator (client)]
-When used as a client, the ^cram_md5^ authenticator has two options:
-
-
-
-oindex:[%client_name%]
-`..'=
-%client_name%, Use: 'cram_md5', Type: 'string'!!, Default: 'the primary host name'
-===
-
-This string is expanded, and the result used as the user name data when
-computing the response to the server's challenge.
-
-
-oindex:[%client_secret%]
-`..'=
-%client_secret%, Use: 'cram_md5', Type: 'string'!!, Default: 'unset'
-===
-
-This option must be set for the authenticator to work as a client. Its value is
-expanded and the result used as the secret string when computing the response.
-
-
-cindex:[$host$]
-cindex:[$host_address$]
-Different user names and secrets can be used for different servers by referring
-to $host$ or $host_address$ in the options.
-
-Forced failure of either expansion string is treated as an indication that this
-authenticator is not prepared to handle this case. Exim moves on to the next
-configured client authenticator. Any other expansion failure causes Exim to
-give up trying to send the message to the current server.
-
-A simple example configuration of a ^cram_md5^ authenticator, using fixed
-strings, is:
-
- fixed_cram:
- driver = cram_md5
- public_name = CRAM-MD5
- client_name = ph10
- client_secret = secret
-
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-The cyrus_sasl authenticator
-----------------------------
-cindex:[^cyrus_sasl^ authenticator]
-cindex:[authenticators,^cyrus_sasl^]
-cindex:[Cyrus, SASL library]
-The code for this authenticator was provided by Matthew Byng-Maddick of A L
-Digital Ltd (*http://www.aldigital.co.uk[]*).
-
-The ^cyrus_sasl^ authenticator provides server support for the Cyrus SASL
-library implementation of the RFC 2222 (``Simple Authentication and Security
-Layer''). This library supports a number of authentication mechanisms, including
-PLAIN and LOGIN, but also several others that Exim does not support directly.
-In particular, there is support for Kerberos authentication.
-
-The ^cyrus_sasl^ authenticator provides a gatewaying mechanism directly to
-the Cyrus interface, so if your Cyrus library can do, for example, CRAM-MD5,
-then so can the ^cyrus_sasl^ authenticator. By default it uses the public
-name of the driver to determine which mechanism to support.
-
-Where access to some kind of secret file is required, for example in GSSAPI
-or CRAM-MD5, it is worth noting that the authenticator runs as the 'exim'
-user, and that the Cyrus SASL library has no way of escalating privileges
-by default. You may also find you need to set environment variables,
-depending on the driver you are using.
-
-
-Using cyrus_sasl as a server
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The ^cyrus_sasl^ authenticator has four private options. It puts the
-username (on a successful authentication) into $1$.
-
-oindex:[%server_hostname%]
-`..'=
-%server_hostname%, Use: 'cyrus_sasl', Type: 'string'!!, Default: `$primary_hostname`
-===
-
-This option selects the hostname that is used when communicating with
-the library. It is up to the underlying SASL plug-in what it does with
-this data.
-
-
-oindex:[%server_mech%]
-`..'=
-%server_mech%, Use: 'cyrus_sasl', Type: 'string', Default: `public_name`
-===
-
-This option selects the authentication mechanism this driver should
-use. It allows you to use a different underlying mechanism from the
-advertised name. For example:
-
- sasl:
- driver = cyrus_sasl
- public_name = X-ANYTHING
- server_mech = CRAM-MD5
- server_set_id = $1
-
-
-
-oindex:[%server_realm%]
-`..'=
-%server_realm%, Use: 'cyrus_sasl', Type: 'string', Default: 'unset'
-===
-
-This specifies the SASL realm that the server claims to be in.
-
-
-oindex:[%server_service%]
-`..'=
-%server_service%, Use: 'cyrus_sasl', Type: 'string', Default: `smtp`
-===
-
-This is the SASL service that the server claims to implement.
-
-
-For straightforward cases, you do not need to set any of the authenticator's
-private options. All you need to do is to specify an appropriate mechanism as
-the public name. Thus, if you have a SASL library that supports CRAM-MD5 and
-PLAIN, you could have two authenticators as follows:
-
- sasl_cram_md5:
- driver = cyrus_sasl
- public_name = CRAM-MD5
- server_set_id = $1
-
- sasl_plain:
- driver = cyrus_sasl
- public_name = PLAIN
- server_set_id = $1
-
-
-Cyrus SASL does implement the LOGIN authentication method, even though it is
-not a standard method. It is disabled by default in the source distribution,
-but it is present in many binary distributions.
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-The spa authenticator
----------------------
-cindex:[^spa^ authenticator]
-cindex:[authenticators,^spa^]
-cindex:[authentication,Microsoft Secure Password]
-cindex:[authentication,NTLM]
-cindex:[Microsoft Secure Password Authentication]
-cindex:[NTLM authentication]
-The ^spa^ authenticator provides client support for Microsoft's 'Secure
-Password Authentication' mechanism,
-which is also sometimes known as NTLM (NT LanMan). The code for client side of
-this authenticator was contributed by Marc Prud'hommeaux, and much of it is
-taken from the Samba project (*http://www.samba.org[]*). The code for the
-server side was subsequently contributed by Tom Kistner. The mechanism works as
-follows:
-
-- After the AUTH command has been accepted, the client sends an SPA
-authentication request based on the user name and optional domain.
-
-- The server sends back a challenge.
-
-- The client builds a challenge response which makes use of the user's password
-and sends it to the server, which then accepts or rejects it.
-
-Encryption is used to protect the password in transit.
-
-
-
-Using spa as a server
-~~~~~~~~~~~~~~~~~~~~~
-cindex:[options,^spa^ authenticator (server)]
-The ^spa^ authenticator has just one server option:
-
-oindex:[%server_password%]
-`..'=
-%server_password%, Use: 'spa', Type: 'string'!!, Default: 'unset'
-===
-
-cindex:[numerical variables ($1$ $2$ etc),in ^spa^ authenticator]
-This option is expanded, and the result must be the cleartext password for the
-authenticating user, whose name is at this point in $1$. For example:
-
-....
-spa:
- driver = spa
- public_name = NTLM
- server_password = ${lookup{$1}lsearch{/etc/exim/spa_clearpass}\
- {$value}fail}
-....
-
-If the expansion is forced to fail, authentication fails. Any other expansion
-failure causes a temporary error code to be returned.
-
-
-
-
-
-Using spa as a client
-~~~~~~~~~~~~~~~~~~~~~
-cindex:[options,^spa^ authenticator (client)]
-The ^spa^ authenticator has the following client options:
-
-
-
-oindex:[%client_domain%]
-`..'=
-%client_domain%, Use: 'spa', Type: 'string'!!, Default: 'unset'
-===
-
-This option specifies an optional domain for the authentication.
-
-
-oindex:[%client_password%]
-`..'=
-%client_password%, Use: 'spa', Type: 'string'!!, Default: 'unset'
-===
-
-This option specifies the user's password, and must be set.
-
-
-oindex:[%client_username%]
-`..'=
-%client_username%, Use: 'spa', Type: 'string'!!, Default: 'unset'
-===
-
-This option specifies the user name, and must be set.
-
-
-Here is an example of a configuration of this authenticator for use with the
-mail servers at 'msn.com':
-
- msn:
- driver = spa
- public_name = MSN
- client_username = msn/msn_username
- client_password = msn_plaintext_password
- client_domain = DOMAIN_OR_UNSET
-
-
-
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPTLS]]
-[titleabbrev="Encrypted SMTP connections"]
-Encrypted SMTP connections using TLS/SSL
-----------------------------------------
-cindex:[encryption,on SMTP connection]
-cindex:[SMTP,encryption]
-cindex:[TLS,on SMTP connection]
-cindex:[OpenSSL]
-cindex:[GnuTLS]
-Support for TLS (Transport Layer Security), formerly known as SSL (Secure
-Sockets Layer), is implemented by making use of the OpenSSL library or the
-GnuTLS library (Exim requires GnuTLS release 1.0 or later). There is no
-cryptographic code in the Exim distribution itself for implementing TLS. In
-order to use this feature you must install OpenSSL or GnuTLS, and then build a
-version of Exim that includes TLS support (see section <<SECTinctlsssl>>). You
-also need to understand the basic concepts of encryption at a managerial level,
-and in particular, the way that public keys, private keys, and certificates are
-used.
-
-RFC 3207 defines how SMTP connections can make use of encryption. Once a
-connection is established, the client issues a STARTTLS command. If the
-server accepts this, the client and the server negotiate an encryption
-mechanism. If the negotiation succeeds, the data that subsequently passes
-between them is encrypted.
-
-Exim's ACLs can detect whether the current SMTP session is encrypted or not,
-and if so, what cipher suite is in use, whether the client supplied a
-certificate, and whether or not that certificate was verified. This makes it
-possible for an Exim server to deny or accept certain commands based on the
-encryption state.
-
-*Warning*: certain types of firewall and certain anti-virus products can
-disrupt TLS connections. You need to turn off SMTP scanning for these products
-in order to get TLS to work.
-
-
-
-Support for the legacy ``ssmtp'' (aka ``smtps'') protocol
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[ssmtp protocol]
-cindex:[smtps protocol]
-cindex:[SMTP,ssmtp protocol]
-cindex:[SMTP,smtps protocol]
-Early implementations of encrypted SMTP used a different TCP port from normal
-SMTP, and expected an encryption negotiation to start immediately, instead of
-waiting for a STARTTLS command from the client using the standard SMTP
-port. The protocol was called ``ssmtp'' or ``smtps'', and port 465 was allocated
-for this purpose.
-
-This approach was abandoned when encrypted SMTP was standardised, but there are
-still some legacy clients that use it. Exim supports these clients by means of
-the %tls_on_connect_ports% global option. Its value must be a list of port
-numbers; the most common use is expected to be:
-
- tls_on_connect_ports = 465
-
-The port numbers specified by this option apply to all SMTP connections, both
-via the daemon and via 'inetd'. You still need to specify all the ports that
-the daemon uses (by setting %daemon_smtp_ports% or %local_interfaces% or the
-%-oX% command line option) because %tls_on_connect_ports% does not add an
-extra port -- rather, it specifies different behaviour on a port that is
-defined elsewhere.
-
-There is also a %-tls-on-connect% command line option. This overrides
-%tls_on_connect_ports%; it forces the legacy behaviour for all ports.
-
-
-
-
-
-
-[[SECTopenvsgnu]]
-OpenSSL vs GnuTLS
-~~~~~~~~~~~~~~~~~
-cindex:[TLS,OpenSSL 'vs' GnuTLS]
-The first TLS support in Exim was implemented using OpenSSL. Support for GnuTLS
-followed later, when the first versions of GnuTLS were released. To build Exim
-to use GnuTLS, you need to set
-
- USE_GNUTLS=yes
-
-in Local/Makefile, in addition to
-
- SUPPORT_TLS=yes
-
-You must also set TLS_LIBS and TLS_INCLUDE appropriately, so that the
-include files and libraries for GnuTLS can be found.
-
-There are some differences in usage when using GnuTLS instead of OpenSSL:
-
-- The %tls_verify_certificates% option must contain the name of a file, not the
-name of a directory (for OpenSSL it can be either).
-
-- The %tls_dhparam% option is ignored, because early versions of GnuTLS had no
-facility for varying its Diffie-Hellman parameters. I understand that this has
-changed, but Exim has not been updated to provide this facility.
-
-- cindex:[$tls_peerdn$]
-Distinguished Name (DN) strings reported by the OpenSSL library use a slash for
-separating fields; GnuTLS uses commas, in accordance with RFC 2253. This
-affects the value of the $tls_peerdn$ variable.
-
-- OpenSSL identifies cipher suites using hyphens as separators, for example:
-DES-CBC3-SHA. GnuTLS uses underscores, for example: RSA_ARCFOUR_SHA. What is
-more, OpenSSL complains if underscores are present in a cipher list. To make
-life simpler, Exim changes underscores to hyhens for OpenSSL and hyphens to
-underscores for GnuTLS when processing lists of cipher suites in the
-%tls_require_ciphers% options (the global option and the ^smtp^ transport
-option).
-
-- The %tls_require_ciphers% options operate differently, as described in the
-sections <<SECTreqciphssl>> and <<SECTreqciphgnu>>.
-
-
-GnuTLS parameter computation
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-GnuTLS uses RSA and D-H parameters that take a substantial amount of time to
-compute. It is unreasonable to re-compute them for every TLS session.
-Therefore, Exim keeps this data in a file in its spool directory, called
-_gnutls-params_. The file is owned by the Exim user and is readable only by its
-owner. Every Exim process that start up GnuTLS reads the RSA and D-H parameters
-from this file. If the file does not exist, the first Exim process that needs
-it computes the data and writes it to a temporary file which is renamed once it
-is complete. It does not matter if several Exim processes do this
-simultaneously (apart from wasting a few resources). Once a file is in place,
-new Exim processes immediately start using it.
-
-[revisionflag="changed"]
-For maximum security, the parameters that are stored in this file should be
-recalculated periodically, the frequency depending on your paranoia level.
-Arranging this is easy in principle; just delete the file when you want new
-values to be computed. However, there may be a problem. The calculation of new
-parameters needs random numbers, and these are obtained from _/dev/random_. If
-the system is not very active, _/dev/random_ may delay returning data until
-enough randomness (entropy) is available. This may cause Exim to hang for a
-substantial amount of time, causing timeouts on incoming connections.
-
-[revisionflag="changed"]
-The solution is to generate the parameters externally to Exim. They are stored
-in _gnutls-params_ in PEM format, which means that they can be generated
-externally using the ^certtool^ command that is part of GnuTLS.
-
-[revisionflag="changed"]
-To replace the parameters with new ones, instead of deleting the file
-and letting Exim re-create it, you can generate new parameters using
-^certtool^ and, when this has been done, replace Exim's cache file by
-renaming. The relevant commands are something like this:
-
-[revisionflag="changed"]
-....
-# rm -f new-params
-# touch new-params
-# chown exim:exim new-params
-# chmod 0400 new-params
-# certtool --generate-privkey --bits 512 >new-params
-# echo "" >>new-params
-# certtool --generate-dh-params --bits 1024 >> new-params
-# mv new-params gnutls-params
-....
-
-[revisionflag="changed"]
-If Exim never has to generate the parameters itself, the possibility of
-stalling is removed.
-
-
-
-[[SECTreqciphssl]]
-Requiring specific ciphers in OpenSSL
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[TLS,requiring specific ciphers (OpenSSL)]
-cindex:[%tls_require_ciphers%,OpenSSL]
-There is a function in the OpenSSL library that can be passed a list of cipher
-suites before the cipher negotiation takes place. This specifies which ciphers
-are acceptable. The list is colon separated and may contain names like
-DES-CBC3-SHA. Exim passes the expanded value of %tls_require_ciphers%
-directly to this function call. The following quotation from the OpenSSL
-documentation specifies what forms of item are allowed in the cipher string:
-
-- It can consist of a single cipher suite such as RC4-SHA.
-
-- It can represent a list of cipher suites containing a certain algorithm,
-or cipher suites of a certain type. For example SHA1 represents all
-ciphers suites using the digest algorithm SHA1 and SSLv3 represents all
-SSL v3 algorithms.
-
-- Lists of cipher suites can be combined in a single cipher string using
-the + character. This is used as a logical and operation. For example
-SHA1+DES represents all cipher suites containing the SHA1 and the DES
-algorithms.
-
-- Each cipher string can be optionally preceded by the characters `!`, `-` or
-`+`.
-+
-If `!` is used then the ciphers are permanently deleted from the list. The
-ciphers deleted can never reappear in the list even if they are explicitly
-stated.
-+
-If `-` is used then the ciphers are deleted from the list, but some or all
-of the ciphers can be added again by later options.
-+
-If `+` is used then the ciphers are moved to the end of the list. This
-option doesn't add any new ciphers it just moves matching existing ones.
-+
-If none of these characters is present then the string is just interpreted as
-a list of ciphers to be appended to the current preference list. If the list
-includes any ciphers already present they will be ignored: that is, they will
-not moved to the end of the list.
-
-
-
-
-[[SECTreqciphgnu]]
-Requiring specific ciphers in GnuTLS
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[TLS,requiring specific ciphers (GnuTLS)]
-cindex:[%tls_require_ciphers%,GnuTLS]
-The GnuTLS library does not have a combined function like OpenSSL. Instead,
-it allows the caller to specify separate lists of key-exchange methods,
-main cipher algorithms, and MAC algorithms. Unfortunately, these lists are
-numerical, and the library does not have a function for turning names into
-numbers. Consequently, the list of recognized names has to be built into
-the application.
-
-At present, Exim permits only the list of main cipher algorithms to be
-changed. The %tls_require_ciphers% option is in the same format as for
-OpenSSL. Exim searches each item for the name of available algorithm. For
-example, if the list contains RSA_AES_SHA then AES is recognized.
-
-The cipher algorithms list starts out with a default set of algorithms. If
-the first item in %tls_require_ciphers% does 'not' start with an
-exclamation mark, all the default items are deleted. Thus, only those specified
-can be used. If the first item in %tls_require_ciphers% 'does' start with
-an exclamation mark, the defaults are left on the list.
-
-Then, any item that starts with an exclamation mark causes the relevent
-algorithms to be removed from the list, and any item that does not start
-with an exclamation mark causes the relevant algorithms to be added to the
-list. Thus,
-
- tls_require_ciphers = !RSA_ARCFOUR_SHA
-
-allows all the defaults except those that use ARCFOUR, whereas
-
- tls_require_ciphers = AES : 3DES
-
-allows only cipher suites that use AES and 3DES. The currently recognized
-algorithms are: AES_256, AES_128, AES (both of the preceding), 3DES, and
-ARCFOUR_128. Unrecognized algorithms are ignored. In a server, the order of the
-list is unimportant; the server will advertise the availability of all the
-relevant cipher suites. However, in a client, the order of the list specifies a
-preference order for the algorithms. The first one in the client's list that is
-also advertised by the server is tried first. The default order is as listed
-above.
-
-
-
-
-Configuring an Exim server to use TLS
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[TLS,configuring an Exim server]
-When Exim has been built with TLS support, it advertises the availability of
-the STARTTLS command to client hosts that match %tls_advertise_hosts%,
-but not to any others. The default value of this option is unset, which means
-that STARTTLS is not advertised at all. This default is chosen because you
-need to set some other options in order to make TLS avaliable, and also it is
-sensible for systems that want to use TLS only as a client.
-
-If a client issues a STARTTLS command and there is some configuration
-problem in the server, the command is rejected with a 454 error. If the client
-persists in trying to issue SMTP commands, all except QUIT are rejected
-with the error
-
- 554 Security failure
-
-If a STARTTLS command is issued within an existing TLS session, it is
-rejected with a 554 error code.
-
-To enable TLS operations on a server, you must set %tls_advertise_hosts% to
-match some hosts. You can, of course, set it to \* to match all hosts.
-However, this is not all you need to do. TLS sessions to a server won't work
-without some further configuration at the server end.
-
-It is rumoured that all existing clients that support TLS/SSL use RSA
-encryption. To make this work you need to set, in the server,
-
- tls_certificate = /some/file/name
- tls_privatekey = /some/file/name
-
-The first file contains the server's X509 certificate, and the second contains
-the private key that goes with it. These files need to be readable by the Exim
-user, and must always be given as full path names. They can be the same file if
-both the certificate and the key are contained within it. If %tls_privatekey%
-is not set, this is assumed to be the case. The certificate file may also
-contain intermediate certificates that need to be sent to the client to enable
-it to authenticate the server's certificate.
-
-If you do not understand about certificates and keys, please try to find a
-source of this background information, which is not Exim-specific. (There are a
-few comments below in section <<SECTcerandall>>.)
-
-*Note*: These options do not apply when Exim is operating as a client --
-they apply only in the case of a server. For a client, you must set the options
-of the same name in an ^smtp^ transport.
-
-With just these options, Exim will work as a server with clients such as
-Netscape. It does not require the client to have a certificate (but see below
-for how to insist on this). There is one other option that may be needed in
-other situations. If
-
- tls_dhparam = /some/file/name
-
-is set, the SSL library is initialized for the use of Diffie-Hellman ciphers
-with the parameters contained in the file. This increases the set of cipher
-suites that the server supports. See the command
-
- openssl dhparam
-
-for a way of generating this data.
-At present, %tls_dhparam% is used only when Exim is linked with OpenSSL. It is
-ignored if GnuTLS is being used.
-
-The strings supplied for these three options are expanded every time a client
-host connects. It is therefore possible to use different certificates and keys
-for different hosts, if you so wish, by making use of the client's IP address
-in $sender_host_address$ to control the expansion. If a string expansion is
-forced to fail, Exim behaves as if the option is not set.
-
-cindex:[cipher,logging]
-cindex:[log,TLS cipher]
-cindex:[$tls_cipher$]
-The variable $tls_cipher$ is set to the cipher suite that was negotiated for
-an incoming TLS connection. It is included in the 'Received:' header of an
-incoming message (by default -- you can, of course, change this), and it is
-also included in the log line that records a message's arrival, keyed by ``X='',
-unless the %tls_cipher% log selector is turned off.
-The %encrypted% condition can be used to test for specific cipher suites in
-ACLs.
-
-The ACLs that run for subsequent SMTP commands can check the name of the cipher
-suite and vary their actions accordingly. The cipher suite names are those used
-by OpenSSL. These may differ from the names used elsewhere. For example,
-OpenSSL uses the name DES-CBC3-SHA for the cipher suite which in other contexts
-is known as TLS_RSA_WITH_3DES_EDE_CBC_SHA. Check the OpenSSL
-documentation for more details.
-
-
-
-Requesting and verifying client certificates
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[certificate,verification of client]
-cindex:[TLS,client certificate verification]
-If you want an Exim server to request a certificate when negotiating a TLS
-session with a client, you must set either %tls_verify_hosts% or
-%tls_try_verify_hosts%. You can, of course, set either of them to \* to
-apply to all TLS connections. For any host that matches one of these options,
-Exim requests a certificate as part of the setup of the TLS session. The
-contents of the certificate are verified by comparing it with a list of
-expected certificates. These must be available in a file or,
-for OpenSSL only (not GnuTLS), a directory, identified by
-%tls_verify_certificates%.
-
-A file can contain multiple certificates, concatenated end to end. If a
-directory is used
-(OpenSSL only),
-each certificate must be in a separate file, with a name (or a symbolic link)
-of the form <'hash'>.0, where <'hash'> is a hash value constructed from the
-certificate. You can compute the relevant hash by running the command
-
- openssl x509 -hash -noout -in /cert/file
-
-where _/cert/file_ contains a single certificate.
-
-The difference between %tls_verify_hosts% and %tls_try_verify_hosts% is
-what happens if the client does not supply a certificate, or if the certificate
-does not match any of the certificates in the collection named by
-%tls_verify_certificates%. If the client matches %tls_verify_hosts%, the
-attempt to set up a TLS session is aborted, and the incoming connection is
-dropped. If the client matches %tls_try_verify_hosts%, the (encrypted) SMTP
-session continues. ACLs that run for subsequent SMTP commands can detect the
-fact that no certificate was verified, and vary their actions accordingly. For
-example, you can insist on a certificate before accepting a message for
-relaying, but not when the message is destined for local delivery.
-
-cindex:[$tls_peerdn$]
-When a client supplies a certificate (whether it verifies or not), the value of
-the Distinguished Name of the certificate is made available in the variable
-$tls_peerdn$ during subsequent processing of the message.
-
-cindex:[log,distinguished name]
-Because it is often a long text string, it is not included in the log line or
-'Received:' header by default. You can arrange for it to be logged, keyed by
-``DN='', by setting the %tls_peerdn% log selector, and you can use
-%received_header_text% to change the 'Received:' header. When no certificate
-is supplied, $tls_peerdn$ is empty.
-
-
-Revoked certificates
-~~~~~~~~~~~~~~~~~~~~
-cindex:[TLS,revoked certificates]
-cindex:[revocation list]
-cindex:[certificate,revocation list]
-Certificate issuing authorities issue Certificate Revocation Lists (CRLs) when
-certificates are revoked. If you have such a list, you can pass it to an Exim
-server using the global option called %tls_crl% and to an Exim client using an
-identically named option for the ^smtp^ transport. In each case, the value of
-the option is expanded and must then be the name of a file that contains a CRL
-in PEM format.
-
-
-Configuring an Exim client to use TLS
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[cipher,logging]
-cindex:[log,TLS cipher]
-cindex:[log,distinguished name]
-cindex:[TLS,configuring an Exim client]
-The %tls_cipher% and %tls_peerdn% log selectors apply to outgoing SMTP
-deliveries as well as to incoming, the latter one causing logging of the
-server certificate's DN. The remaining client configuration for TLS is all
-within the ^smtp^ transport.
-
-It is not necessary to set any options to have TLS work in the ^smtp^
-transport. If Exim is built with TLS support, and TLS is advertised by a
-server, the ^smtp^ transport always tries to start a TLS session. However,
-this can be prevented by setting %hosts_avoid_tls% (an option of the
-transport) to a list of server hosts for which TLS should not be used.
-
-If you do not want Exim to attempt to send messages unencrypted when an attempt
-to set up an encrypted connection fails in any way, you can set
-%hosts_require_tls% to a list of hosts for which encryption is mandatory. For
-those hosts, delivery is always deferred if an encrypted connection cannot be
-set up. If there are any other hosts for the address, they are tried in the
-usual way.
-
-When the server host is not in %hosts_require_tls%, Exim may try to deliver
-the message unencrypted. It always does this if the response to STARTTLS is
-a 5##'xx' code. For a temporary error code, or for a failure to negotiate a TLS
-session after a success response code, what happens is controlled by the
-%tls_tempfail_tryclear% option of the ^smtp^ transport. If it is false,
-delivery to this host is deferred, and other hosts (if available) are tried. If
-it is true, Exim attempts to deliver unencrypted after a 4##'xx' response to
-STARTTLS, and if STARTTLS is accepted, but the subsequent TLS
-negotiation fails, Exim closes the current connection (because it is in an
-unknown state), opens a new one to the same host, and then tries the delivery
-unencrypted.
-
-
-The %tls_certificate% and %tls_privatekey% options of the ^smtp^ transport
-provide the client with a certificate, which is passed to the server if it
-requests it. If the server is Exim, it will request a certificate only if
-%tls_verify_hosts% or %tls_try_verify_hosts% matches the client.
-*Note*: these options must be set in the ^smtp^ transport for Exim to use
-TLS when it is operating as a client. Exim does not assume that a server
-certificate (set by the global options of the same name) should also be used
-when operating as a client.
-
-If %tls_verify_certificates% is set, it must name a file or,
-for OpenSSL only (not GnuTLS), a directory, that contains a collection of
-expected server certificates. The client verifies the server's certificate
-against this collection, taking into account any revoked certificates that are
-in the list defined by %tls_crl%.
-
-If
-%tls_require_ciphers% is set on the ^smtp^ transport, it must contain a
-list of permitted cipher suites. If either of these checks fails, delivery to
-the current host is abandoned, and the ^smtp^ transport tries to deliver to
-alternative hosts, if any.
-
-cindex:[$host$]
-cindex:[$host_address$]
-All the TLS options in the ^smtp^ transport are expanded before use, with
-$host$ and $host_address$ containing the name and address of the server to
-which the client is connected. Forced failure of an expansion causes Exim to
-behave as if the relevant option were unset.
-
-
-
-[[SECTmulmessam]]
-Multiple messages on the same encrypted TCP/IP connection
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[multiple SMTP deliveries with TLS]
-cindex:[TLS,multiple message deliveries]
-Exim sends multiple messages down the same TCP/IP connection by starting up
-an entirely new delivery process for each message, passing the socket from
-one process to the next. This implementation does not fit well with the use
-of TLS, because there is quite a lot of state information associated with a TLS
-connection, not just a socket identification. Passing all the state information
-to a new process is not feasible. Consequently, Exim shuts down an existing TLS
-session before passing the socket to a new process. The new process may then
-try to start a new TLS session, and if successful, may try to re-authenticate
-if AUTH is in use, before sending the next message.
-
-The RFC is not clear as to whether or not an SMTP session continues in clear
-after TLS has been shut down, or whether TLS may be restarted again later, as
-just described. However, if the server is Exim, this shutdown and
-reinitialization works. It is not known which (if any) other servers operate
-successfully if the client closes a TLS session and continues with unencrypted
-SMTP, but there are certainly some that do not work. For such servers, Exim
-should not pass the socket to another process, because the failure of the
-subsequent attempt to use it would cause Exim to record a temporary host error,
-and delay other deliveries to that host.
-
-To test for this case, Exim sends an EHLO command to the server after
-closing down the TLS session. If this fails in any way, the connection is
-closed instead of being passed to a new delivery process, but no retry
-information is recorded.
-
-There is also a manual override; you can set %hosts_nopass_tls% on the
-^smtp^ transport to match those hosts for which Exim should not pass
-connections to new processes if TLS has been used.
-
-
-
-
-[[SECTcerandall]]
-Certificates and all that
-~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[certificate,references to discussion]
-In order to understand fully how TLS works, you need to know about
-certificates, certificate signing, and certificate authorities. This is not the
-place to give a tutorial, especially as I do not know very much about it
-myself. Some helpful introduction can be found in the FAQ for the SSL addition
-to Apache, currently at
-
-&&&
-*http://www.modssl.org/docs/2.7/ssl_faq.html#ToC24[]*
-&&&
-
-Other parts of the 'modssl' documentation are also helpful, and have
-links to further files.
-Eric Rescorla's book, 'SSL and TLS', published by Addison-Wesley (ISBN
-0-201-61598-3), contains both introductory and more in-depth descriptions.
-Some sample programs taken from the book are available from
-
-&&&
-*http://www.rtfm.com/openssl-examples/[]*
-&&&
-
-
-
-Certificate chains
-~~~~~~~~~~~~~~~~~~
-The file named by %tls_certificate% may contain more than one
-certificate. This is useful in the case where the certificate that is being
-sent is validated by an intermediate certificate which the other end does
-not have. Multiple certificates must be in the correct order in the file.
-First the host's certificate itself, then the first intermediate
-certificate to validate the issuer of the host certificate, then the next
-intermediate certificate to validate the issuer of the first intermediate
-certificate, and so on, until finally (optionally) the root certificate.
-The root certificate must already be trusted by the recipient for
-validation to succeed, of course, but if it's not preinstalled, sending the
-root certificate along with the rest makes it available for the user to
-install if the receiving end is a client MUA that can interact with a user.
-
-
-Self-signed certificates
-~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[certificate,self-signed]
-You can create a self-signed certificate using the 'req' command provided
-with OpenSSL, like this:
-
-....
-openssl req -x509 -newkey rsa:1024 -keyout file1 -out file2 \
- -days 9999 -nodes
-....
-
-_file1_ and _file2_ can be the same file; the key and the certificate are
-delimited and so can be identified independently. The %-days% option
-specifies a period for which the certificate is valid. The %-nodes% option is
-important: if you do not set it, the key is encrypted with a passphrase
-that you are prompted for, and any use that is made of the key causes more
-prompting for the passphrase. This is not helpful if you are going to use
-this certificate and key in an MTA, where prompting is not possible.
-
-A self-signed certificate made in this way is sufficient for testing, and
-may be adequate for all your requirements if you are mainly interested in
-encrypting transfers, and not in secure identification.
-
-However, many clients require that the certificate presented by the server be a
-user (also called ``leaf'' or ``site'') certificate, and not a self-signed
-certificate. In this situation, the self-signed certificate described above
-must be installed on the client host as a trusted root 'certification
-authority' (CA), and the certificate used by Exim must be a user certificate
-signed with that self-signed certificate.
-
-For information on creating self-signed CA certificates and using them to sign
-user certificates, see the 'General implementation overview' chapter of the
-Open-source PKI book, available online at *http://ospkibook.sourceforge.net/[]*.
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPACL]]
-Access control lists
---------------------
-cindex:[{ACL},description]
-cindex:[control of incoming mail]
-cindex:[message,controlling incoming]
-cindex:[policy control,access control lists]
-Access Control Lists (ACLs) are defined in a separate section of the run time
-configuration file, headed by ``begin acl''. Each ACL definition starts with a
-name, terminated by a colon. Here is a complete ACL section that contains just
-one very small ACL:
-
- begin acl
-
- small_acl:
- accept hosts = one.host.only
-
-You can have as many lists as you like in the ACL section, and the order in
-which they appear does not matter. The lists are self-terminating.
-
-The majority of ACLs are used to control Exim's behaviour when it receives
-certain SMTP commands. This applies both to incoming TCP/IP connections, and
-when a local process submits a message using SMTP by specifying the %-bs%
-option. The most common use is for controlling which recipients are accepted
-in incoming messages. In addition, you can define an ACL that is used to check
-local non-SMTP messages. The default configuration file contains an example of
-a realistic ACL for checking RCPT commands. This is discussed in chapter
-<<CHAPdefconfil>>.
-
-
-Testing ACLs
-~~~~~~~~~~~~
-The %-bh% command line option provides a way of testing your ACL configuration
-locally by running a fake SMTP session with which you interact. The host
-'relay-test.mail-abuse.org' provides a service for checking your relaying
-configuration (see section <<SECTcheralcon>> for more details).
-
-
-
-Specifying when ACLs are used
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[{ACL},options for specifying]
-In order to cause an ACL to be used, you have to name it in one of the relevant
-options in the main part of the configuration. These options are:
-cindex:[AUTH,ACL for]
-cindex:[DATA, ACLs for]
-cindex:[ETRN,ACL for]
-cindex:[EXPN,ACL for]
-cindex:[HELO,ACL for]
-cindex:[EHLO,ACL for]
-cindex:[MAIL,ACL for]
-cindex:[QUIT, ACL for]
-cindex:[RCPT,ACL for]
-cindex:[STARTTLS, ACL for]
-cindex:[VRFY,ACL for]
-cindex:[SMTP connection, ACL for]
-cindex:[non-smtp message, ACL for]
-
-[frame="none"]
-`--`--------------------`---------------------------------------
- %acl_not_smtp% ACL for non-SMTP messages
- %acl_smtp_auth% ACL for AUTH
- %acl_smtp_connect% ACL for start of SMTP connection
- %acl_smtp_data% ACL after DATA is complete
- %acl_smtp_etrn% ACL for ETRN
- %acl_smtp_expn% ACL for EXPN
- %acl_smtp_helo% ACL for HELO or EHLO
- %acl_smtp_mail% ACL for MAIL
- %acl_smtp_mailauth% ACL for the AUTH parameter of MAIL
- %acl_smtp_mime% ACL for content-scanning MIME parts
- %acl_smtp_predata% ACL at start of DATA command
- %acl_smtp_quit% ACL for QUIT
- %acl_smtp_rcpt% ACL for RCPT
- %acl_smtp_starttls% ACL for STARTTLS
- %acl_smtp_vrfy% ACL for VRFY
-----------------------------------------------------------------
-
-For example, if you set
-
- acl_smtp_rcpt = small_acl
-
-the little ACL defined above is used whenever Exim receives a RCPT command
-in an SMTP dialogue. The majority of policy tests on incoming messages can be
-done when RCPT commands arrive. A rejection of RCPT should cause the
-sending MTA to give up on the recipient address contained in the RCPT
-command, whereas rejection at other times may cause the client MTA to keep on
-trying to deliver the message. It is therefore recommended that you do as much
-testing as possible at RCPT time.
-
-
-The non-SMTP ACL
-~~~~~~~~~~~~~~~~
-cindex:[non-smtp message, ACL for]
-The non-SMTP ACL applies to all non-interactive incoming messages, that is, it
-applies to batch SMTP as well as to non-SMTP messages. (Batch SMTP is not
-really SMTP.) This ACL is run just before the 'local_scan()' function. Any
-kind of rejection is treated as permanent, because there is no way of sending a
-temporary error for these kinds of message. Many of the ACL conditions (for
-example, host tests, and tests on the state of the SMTP connection such as
-encryption and authentication) are not relevant and are forbidden in this ACL.
-
-
-The connect ACL
-~~~~~~~~~~~~~~~
-cindex:[SMTP connection, ACL for]
-The ACL test specified by %acl_smtp_connect% happens after the test specified
-by %host_reject_connection% (which is now an anomaly) and any TCP Wrappers
-testing (if configured).
-
-
-The DATA ACLs
-~~~~~~~~~~~~~
-cindex:[DATA, ACLs for]
-Two ACLs are associated with the DATA command, because it is two-stage
-command, with two responses being sent to the client.
-When the DATA command is received, the ACL defined by %acl_smtp_predata%
-is obeyed. This gives you control after all the RCPT commands, but before
-the message itself is received. It offers the opportunity to give a negative
-response to the DATA command before the data is transmitted. Header lines
-added by MAIL or RCPT ACLs are not visible at this time, but any that
-are defined here are visible when the %acl_smtp_data% ACL is run.
-
-You cannot test the contents of the message, for example, to verify addresses
-in the headers, at RCPT time or when the DATA command is received. Such
-tests have to appear in the ACL that is run after the message itself has been
-received, before the final response to the DATA command is sent. This is
-the ACL specified by %acl_smtp_data%, which is the second ACL that is
-associated with the DATA command.
-
-For both of these ACLs, it is not possible to reject individual recipients. An
-error response rejects the entire message. Unfortunately, it is known that some
-MTAs do not treat hard (5##'xx') responses to the DATA command (either
-before or after the data) correctly -- they keep the message on their queues
-and try again later, but that is their problem, though it does waste some of
-your resources.
-
-
-The MIME ACL
-~~~~~~~~~~~~
-The %acl_smtp_mime% option is available only when Exim is compiled with the
-content-scanning extension. For details, see chapter <<CHAPexiscan>>.
-
-
-[[SECTQUITACL]]
-The QUIT ACL
-~~~~~~~~~~~~
-cindex:[QUIT, ACL for]
-The ACL for the SMTP QUIT command is anomalous, in that the outcome of the ACL
-does not affect the response code to QUIT, which is always 221. Thus, the ACL
-does not in fact control any access. For this reason, the only verbs that are
-permitted are %accept% and %warn%.
-
-This ACL can be used for tasks such as custom logging at the end of an SMTP
-session. For example, you can use ACL variables in other ACLs to count
-messages, recipients, etc., and log the totals at QUIT time using one or
-more %logwrite% modifiers on a %warn% verb.
-
-[revisionflag="changed"]
-*Warning*: only the $acl_c$'x' variables can be used for this, because the
-$acl_m$'x' variables are reset at the end of each incoming message.
-
-You do not need to have a final %accept%, but if you do, you can use a
-%message% modifier to specify custom text that is sent as part of the 221
-response to QUIT.
-
-This ACL is run only for a ``normal'' QUIT. For certain kinds of disastrous
-failure (for example, failure to open a log file, or when Exim is bombing out
-because it has detected an unrecoverable error), all SMTP commands from the
-client are given temporary error responses until QUIT is received or the
-connection is closed. In these special cases, the QUIT ACL does not run.
-
-
-
-Finding an ACL to use
-~~~~~~~~~~~~~~~~~~~~~
-cindex:[{ACL},finding which to use]
-The value of an %acl_smtp_'xxx'% option is expanded before use, so you can
-use different ACLs in different circumstances. The resulting string does not
-have to be the name of an ACL in the configuration file; there are other
-possibilities. Having expanded the string, Exim searches for an ACL as follows:
-
-- If the string begins with a slash, Exim uses it as a file name, and reads its
-contents as an ACL. The lines are processed in the same way as lines in the
-Exim configuration file. In particular, continuation lines are supported, blank
-lines are ignored, as are lines whose first non-whitespace character is ``#''.
-If the file does not exist or cannot be read, an error occurs (typically
-causing a temporary failure of whatever caused the ACL to be run). For example:
-+
-....
-acl_smtp_data = /etc/acls/\
- ${lookup{$sender_host_address}lsearch\
- {/etc/acllist}{$value}{default}}
-....
-+
-This looks up an ACL file to use on the basis of the host's IP address, falling
-back to a default if the lookup fails. If an ACL is successfully read from a
-file, it is retained in memory for the duration of the Exim process, so that it
-can be re-used without having to re-read the file.
-
-- If the string does not start with a slash, and does not contain any spaces,
-Exim searches the ACL section of the configuration for an ACL whose name
-matches the string.
-
-- If no named ACL is found, or if the string contains spaces, Exim parses
-the string as an inline ACL. This can save typing in cases where you just
-want to have something like
-+
- acl_smtp_vrfy = accept
-+
-in order to allow free use of the VRFY command. Such a string may contain
-newlines; it is processed in the same way as an ACL that is read from a file.
-
-
-
-
-ACL return codes
-~~~~~~~~~~~~~~~~
-cindex:[{ACL},return codes]
-Except for the QUIT ACL, which does not affect the SMTP return code (see
-section <<SECTQUITACL>> above), the
-
-result of running an ACL is either ``accept'' or ``deny'', or, if some test
-cannot be completed (for example, if a database is down), ``defer''. These
-results cause 2##'xx', 5##'xx', and 4##'xx' return codes, respectively, to be
-used in the SMTP dialogue. A fourth return, ``error'', occurs when there is an
-error such as invalid syntax in the ACL. This also causes a 4'##xx' return
-code.
-
-For the non-SMTP ACL, ``defer'' and ``error'' are treated in the same way as
-``deny'', because there is no mechanism for passing temporary errors to the
-submitters of non-SMTP messages.
-
-
-ACLs that are relevant to message reception may also return ``discard''. This
-has the effect of ``accept'', but causes either the entire message or an
-individual recipient address to be discarded. In other words, it is a
-blackholing facility. Use it with care.
-
-If the ACL for MAIL returns ``discard'', all recipients are discarded, and no
-ACL is run for subsequent RCPT commands. The effect of ``discard'' in a
-RCPT ACL is to discard just the one recipient address. If there are no
-recipients left when the message's data is received, the DATA ACL is not
-run. A ``discard'' return from the DATA or the non-SMTP ACL discards all the
-remaining recipients.
-
-The ``discard'' return is not permitted for the %acl_smtp_predata% ACL.
-
-
-cindex:['local_scan()' function,when all recipients discarded]
-The 'local_scan()' function is always run, even if there are no remaining
-recipients; it may create new recipients.
-
-
-
-Unset ACL options
-~~~~~~~~~~~~~~~~~
-cindex:[{ACL},unset options]
-The default actions when any of the %acl_'xxx'% options are unset are not
-all the same. *Note*: These defaults apply only when the relevant ACL is
-not defined at all. For any defined ACL, the default action when control reaches
-the end of the ACL statements is ``deny''.
-
-For %acl_not_smtp%, %acl_smtp_auth%, %acl_smtp_connect%, %acl_smtp_data%,
-%acl_smtp_helo%, %acl_smtp_mail%, %acl_smtp_mailauth%, %acl_smtp_mime%,
-%acl_smtp_predata%, %acl_smtp_quit%, and %acl_smtp_starttls%, the action when
-the ACL is not defined is ``accept''.
-
-For the others (%acl_smtp_etrn%, %acl_smtp_expn%, %acl_smtp_rcpt%, and
-%acl_smtp_vrfy%), the action when the ACL is not defined is ``deny''.
-This means that %acl_smtp_rcpt% must be defined in order to receive any
-messages over an SMTP connection. For an example, see the ACL in the default
-configuration file.
-
-
-
-
-Data for message ACLs
-~~~~~~~~~~~~~~~~~~~~~
-cindex:[{ACL},data for message ACL]
-cindex:[$domain$]
-cindex:[$local_part$]
-cindex:[$sender_address$]
-cindex:[$sender_host_address$]
-When a MAIL or RCPT ACL, or either of the DATA ACLs, is running, the variables
-that contain information about the host and the message's sender (for example,
-$sender_host_address$ and $sender_address$) are set, and can be used in ACL
-statements. In the case of RCPT (but not MAIL or DATA), $domain$ and
-$local_part$ are set from the argument address.
-
-When an ACL for the AUTH parameter of MAIL is running, the variables that
-contain information about the host are set, but $sender_address$ is not yet
-set. Section <<SECTauthparamail>> contains a discussion of this parameter and
-how it is used.
-
-cindex:[$message_size$]
-The $message_size$ variable is set to the value of the SIZE parameter on
-the MAIL command at MAIL, RCPT and pre-data time, or to -1 if
-that parameter is not given. The value is updated to the true message size by
-the time the final DATA ACL is run (after the message data has been
-received).
-
-cindex:[$rcpt_count$]
-cindex:[$recipients_count$]
-The $rcpt_count$ variable increases by one for each RCPT command received. The
-$recipients_count$ variable increases by one each time a RCPT command is
-accepted, so while an ACL for RCPT is being processed, it contains the number
-of previously accepted recipients. At DATA time (for both the DATA ACLs),
-$rcpt_count$ contains the total number of RCPT commands, and $recipients_count$
-contains the total number of accepted recipients.
-
-
-
-
-
-[[SECTdatfornon]]
-Data for non-message ACLs
-~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[{ACL},data for non-message ACL]
-cindex:[$smtp_command_argument$]
-When an ACL is being run for AUTH, EHLO, ETRN, EXPN, HELO, STARTTLS, or VRFY,
-the remainder of the SMTP command line is placed in $smtp_command_argument$.
-This can be tested using a %condition% condition. For example, here is an ACL
-for use with AUTH, which insists that either the session is encrypted, or the
-CRAM-MD5 authentication method is used. In other words, it does not permit
-authentication methods that use cleartext passwords on unencrypted connections.
-
-....
-acl_check_auth:
- accept encrypted = *
- accept condition = ${if eq{${uc:$smtp_command_argument}}\
- {CRAM-MD5}}
- deny message = TLS encryption or CRAM-MD5 required
-....
-
-(Another way of applying this restriction is to arrange for the authenticators
-that use cleartext passwords not to be advertised when the connection is not
-encrypted. You can use the generic %server_advertise_condition% authenticator
-option to do this.)
-
-
-
-Format of an ACL
-~~~~~~~~~~~~~~~~
-cindex:[{ACL},format of]
-cindex:[{ACL},verbs; definition of]
-An individual ACL consists of a number of statements. Each statement starts
-with a verb, optionally followed by a number of conditions and ``modifiers''.
-Modifiers can change the way the verb operates, define error and log messages,
-set variables, insert delays, and vary the processing of accepted messages.
-
-If all the conditions are met, the verb is obeyed. The same condition may be
-used (with different arguments) more than once in the same statement. This
-provides a means of specifying an ``and'' conjunction between conditions. For
-example:
-
- deny dnslists = list1.example
- dnslists = list2.example
-
-If there are no conditions, the verb is always obeyed. Exim stops evaluating
-the conditions and modifiers when it reaches a condition that fails. What
-happens then depends on the verb (and in one case, on a special modifier). Not
-all the conditions make sense at every testing point. For example, you cannot
-test a sender address in the ACL that is run for a VRFY command.
-
-
-ACL verbs
-~~~~~~~~~
-The ACL verbs are as follows:
-
-- cindex:[%accept%, ACL verb]
-%accept%: If all the conditions are met, the ACL returns ``accept''. If any of
-the conditions are not met, what happens depends on whether %endpass% appears
-among the conditions (for syntax see below). If the failing condition is before
-%endpass%, control is passed to the next ACL statement; if it is after
-%endpass%, the ACL returns ``deny''. Consider this statement, used to check a
-RCPT command:
-
- accept domains = +local_domains
- endpass
- verify = recipient
-+
-If the recipient domain does not match the %domains% condition, control passes
-to the next statement. If it does match, the recipient is verified, and the
-command is accepted if verification succeeds. However, if verification fails,
-the ACL yields ``deny'', because the failing condition is after %endpass%.
-
-- cindex:[%defer%, ACL verb]
-%defer%: If all the conditions are met, the ACL returns ``defer'' which, in an
-SMTP session, causes a 4##'xx' response to be given. For a non-SMTP ACL,
-%defer% is the same as %deny%, because there is no way of sending a temporary
-error. For a RCPT command, %defer% is much the same as using a
-^redirect^ router and `:defer:` while verifying, but the %defer% verb can
-be used in any ACL, and even for a recipient it might be a simpler approach.
-
-- cindex:[%deny%, ACL verb]
-%deny%: If all the conditions are met, the ACL returns ``deny''. If any of the
-conditions are not met, control is passed to the next ACL statement. For
-example,
-
- deny dnslists = blackholes.mail-abuse.org
-+
-rejects commands from hosts that are on a DNS black list.
-
-- cindex:[%discard%, ACL verb]
-%discard%: This verb behaves like %accept%, except that it returns ``discard''
-from the ACL instead of ``accept''. It is permitted only on ACLs that are
-concerned with receiving messages, and it causes recipients to be discarded.
-If the %log_message% modifier is set when %discard% operates, its contents are
-added to the line that is automatically written to the log.
-+
-If %discard% is used in an ACL for RCPT, just the one recipient is
-discarded; if used for MAIL, DATA or in the non-SMTP ACL, all the
-message's recipients are discarded. Recipients that are discarded before
-DATA do not appear in the log line when the %log_recipients% log selector
-is set.
-
-- cindex:[%drop%, ACL verb]
-%drop%: This verb behaves like %deny%, except that an SMTP connection is
-forcibly closed after the 5##'xx' error message has been sent. For example:
-
- drop message = I don't take more than 20 RCPTs
-
- condition = ${if > {$rcpt_count}{20}}
-+
-There is no difference between %deny% and %drop% for the connect-time ACL. The
-connection is always dropped after sending a 550 response.
-
-- cindex:[%require%, ACL verb]
-%require%: If all the conditions are met, control is passed to the next ACL
-statement. If any of the conditions are not met, the ACL returns ``deny''. For
-example, when checking a RCPT command,
-
- require verify = sender
-+
-passes control to subsequent statements only if the message's sender can be
-verified. Otherwise, it rejects the command.
-
-- cindex:[%warn%, ACL verb]
-%warn%: If all the conditions are met, a header line is added to an incoming
-message and/or a line is written to Exim's main log. In all cases, control
-passes to the next ACL statement. The text of the added header line and the log
-line are specified by modifiers; if they are not present, a %warn% verb just
-checks its conditions and obeys any ``immediate'' modifiers such as %set% and
-%logwrite%. There is more about adding header lines in section
-<<SECTaddheadwarn>>.
-+
-If any condition on a %warn% statement cannot be completed (that is, there is
-some sort of defer), no header lines are added and the configured log line is
-not written. No further conditions or modifiers in the %warn% statement are
-processed. The incident is logged, but the ACL continues to be processed, from
-the next statement onwards.
-+
-If a %message% modifier is present on a %warn% verb in an ACL that is not
-testing an incoming message, it is ignored, and the incident is logged.
-+
-A %warn% statement may use the %log_message% modifier to cause a line to be
-written to the main log when the statement's conditions are true.
-If an identical log line is requested several times in the same message, only
-one copy is actually written to the log. If you want to force duplicates to be
-written, use the %logwrite% modifier instead.
-+
-cindex:[$acl_verify_message$]
-When one of the %warn% conditions is an address verification that fails, the
-text of the verification failure message is in $acl_verify_message$. If you
-want this logged, you must set it up explicitly. For example:
-
- warn !verify = sender
- log_message = sender verify failed: $acl_verify_message
-
-At the end of each ACL there is an implicit unconditional %deny%.
-
-As you can see from the examples above, the conditions and modifiers are
-written one to a line, with the first one on the same line as the verb, and
-subsequent ones on following lines. If you have a very long condition, you can
-continue it onto several physical lines by the usual backslash continuation
-mechanism. It is conventional to align the conditions vertically.
-
-
-
-[[SECTaclvariables]]
-ACL variables
-~~~~~~~~~~~~~
-cindex:[{ACL},variables]
-There are some special variables that can be set during ACL processing. They
-can be used to pass information between different ACLs, different invocations
-of the same ACL in the same SMTP connection, and between ACLs and the routers,
-transports, and filters that are used to deliver a message. There are two sets
-of these variables:
-
-- The values of $acl_c0$ to $acl_c9$ persist throughout an SMTP connection.
-They are never reset. Thus, a value that is set while receiving one message is
-still available when receiving the next message on the same SMTP connection.
-
-- The values of $acl_m0$ to $acl_m9$ persist only while a message is being
-received. They are reset afterwards. They are also reset by MAIL, RSET,
-EHLO, HELO, and after starting up a TLS session.
-
-When a message is accepted, the current values of all the ACL variables are
-preserved with the message and are subsequently made available at delivery
-time. The ACL variables are set by modifier called %set%. For example:
-
- accept hosts = whatever
- set acl_m4 = some value
-
-*Note*: a leading dollar sign is not used when naming a variable that is to
-be set. If you want to set a variable without taking any action, you can use a
-%warn% verb without any other modifiers or conditions.
-
-
-
-Condition and modifier processing
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[{ACL},conditions; processing]
-cindex:[{ACL},modifiers; processing]
-An exclamation mark preceding a condition negates its result. For example:
-
- deny domains = *.dom.example
- !verify = recipient
-
-[revisionflag="changed"]
-causes the ACL to return ``deny'' if the recipient domain ends in 'dom.example'
-and the recipient address cannot be verified. Sometimes negation can be used on
-the right-hand side of a condition. For example, these two statements are
-equivalent:
-
-[revisionflag="changed"]
-....
-deny hosts = !192.168.3.4
-deny !hosts = 192.168.3.4
-....
-
-[revisionflag="changed"]
-However, for many conditions (%verify% being a good example), only left-hand
-side negation of the whole condition is possible.
-
-The arguments of conditions and modifiers are expanded. A forced failure
-of an expansion causes a condition to be ignored, that is, it behaves as if the
-condition is true. Consider these two statements:
-
-....
-accept senders = ${lookup{$host_name}lsearch\
- {/some/file}{$value}fail}
-accept senders = ${lookup{$host_name}lsearch\
- {/some/file}{$value}{}}
-....
-
-Each attempts to look up a list of acceptable senders. If the lookup succeeds,
-the returned list is searched, but if the lookup fails the behaviour is
-different in the two cases. The %fail% in the first statement causes the
-condition to be ignored, leaving no further conditions. The %accept% verb
-therefore succeeds. The second statement, however, generates an empty list when
-the lookup fails. No sender can match an empty list, so the condition fails,
-and therefore the %accept% also fails.
-
-ACL modifiers appear mixed in with conditions in ACL statements. Some of them
-specify actions that are taken as the conditions for a statement are checked;
-others specify text for messages that are used when access is denied or a
-warning is generated. The %control% modifier affects the way an incoming
-message is handled.
-
-The positioning of the modifiers in an ACL statement important, because the
-processing of a verb ceases as soon as its outcome is known. Only those
-modifiers that have already been encountered will take effect. For example,
-consider this use of the %message% modifier:
-
- require message = Can't verify sender
- verify = sender
- message = Can't verify recipient
- verify = recipient
- message = This message cannot be used
-
-If sender verification fails, Exim knows that the result of the statement is
-``deny'', so it goes no further. The first %message% modifier has been seen, so
-its text is used as the error message. If sender verification succeeds, but
-recipient verification fails, the second message is used. If recipient
-verification succeeds, the third message becomes ``current'', but is never used
-because there are no more conditions to cause failure.
-
-For the %deny% verb, on the other hand, it is always the last %message%
-modifier that is used, because all the conditions must be true for rejection to
-happen. Specifying more than one %message% modifier does not make sense, and
-the message can even be specified after all the conditions. For example:
-
- deny hosts = ...
- !senders = *@my.domain.example
- message = Invalid sender from client host
-
-The ``deny'' result does not happen until the end of the statement is reached,
-by which time Exim has set up the message.
-
-
-
-[[SECTACLmodi]]
-ACL modifiers
-~~~~~~~~~~~~~
-cindex:[{ACL},modifiers; list of]
-The ACL modifiers are as follows:
-
-*control*~=~<'text'>::
-cindex:[%control%, ACL modifier]
-This modifier affects the subsequent processing of the SMTP connection or of an
-incoming message that is accepted. The effect of the first type of control
-lasts for the duration of the connection, whereas the effect of the second type
-lasts only until the current message has been received. The message-specific
-controls always apply to the whole message, not to individual recipients,
-even if the %control% modifier appears in a RCPT ACL.
-+
-As there are now quite a few controls that can be applied, they are described
-separately in section <<SECTcontrols>>. The %control% modifier can be used in
-several different ways. For example:
-+
-- It can be at the end of an %accept% statement:
-+
-....
- accept ...some conditions
- control = queue_only
-....
-+
-In this case, the control is applied when this statement yields ``accept'', in
-other words, when the conditions are all true.
-
-- It can be in the middle of an %accept% statement:
-+
-....
- accept ...some conditions...
- control = queue_only
- ...some more conditions...
-....
-+
-If the first set of conditions are true, the control is applied, even if the
-statement does not accept because one of the second set of conditions is false.
-In this case, some subsequent statement must yield ``accept'' for the control to
-be relevant.
-
-- It can be used with %warn% to apply the control, leaving the
-decision about accepting or denying to a subsequent verb. For
-example:
-+
-....
- warn ...some conditions...
- control = freeze
- accept ...
-....
-+
-This example of %warn% does not contain %message%, %log_message%, or
-%logwrite%, so it does not add anything to the message and does not write a log
-entry.
-
-- If you want to apply a control unconditionally, you can use it with a
-%require% verb. For example:
-+
-....
- require control = no_multiline_response
-....
-
-///
-End of bulleted list, continue with variable list
-///
-
-
-*delay*~=~<'time'>::
-cindex:[%delay%, ACL modifier]
-cindex:[%-bh% option]
-This modifier causes Exim to wait for the time interval before proceeding. The
-time is given in the usual Exim notation. This modifier may appear in any ACL.
-The delay happens as soon as the modifier is processed. However, when testing
-Exim using the %-bh% option, the delay is not actually imposed (an appropriate
-message is output instead).
-+
-Like %control%, %delay% can be used with %accept% or
-%deny%, for example:
-
- deny ...some conditions...
- delay = 30s
-+
-The delay happens if all the conditions are true, before the statement returns
-``deny''. Compare this with:
-
- deny delay = 30s
- ...some conditions...
-+
-which waits for 30s before processing the conditions. The %delay% modifier can
-also be used with %warn% and together with %control%:
-
- warn ...some conditions...
- delay = 2m
- control = freeze
- accept ...
-
-*endpass*::
-cindex:[%endpass%, ACL modifier]
-This modifier, which has no argument, is recognized only in %accept%
-statements. It marks the boundary between the conditions whose failure causes
-control to pass to the next statement, and the conditions whose failure causes
-the ACL to return ``deny''. See the description of %accept% above.
-
-*log_message*~=~<'text'>::
-cindex:[%log_message%, ACL modifier]
-This modifier sets up a message that is used as part of the log message if the
-ACL denies access or a %warn% statement's conditions are true. For example:
-
- require log_message = wrong cipher suite $tls_cipher
- encrypted = DES-CBC3-SHA
-+
-%log_message% adds to any underlying error message that may exist because of
-the condition failure. For example, while verifying a recipient address, a
-':fail:' redirection might have already set up a message. Although the message
-is usually defined before the conditions to which it applies, the expansion
-does not happen until Exim decides that access is to be denied. This means that
-any variables that are set by the condition are available for inclusion in the
-message. For example, the $dnslist_$<'xxx'> variables are set after a DNS
-black list lookup succeeds. If the expansion of %log_message% fails, or if the
-result is an empty string, the modifier is ignored.
-+
-cindex:[$acl_verify_message$]
-If you want to use a %warn% statement to log the result of an address
-verification, you can use $acl_verify_message$ to include the verification
-error message.
-+
-If %log_message% is used with a %warn% statement, ``Warning:'' is added to the
-start of the logged message. If the same warning log message is requested more
-than once while receiving a single email message, only one copy is actually
-logged. If you want to log multiple copies, use %logwrite% instead of
-%log_message%. In the absence of %log_message% and %logwrite%, nothing is
-logged for a succesful %warn% statement.
-+
-If %log_message% is not present and there is no underlying error message (for
-example, from the failure of address verification), but %message% is present,
-the %message% text is used for logging rejections. However, if any text for
-logging contains newlines, only the first line is logged. In the absence of
-both %log_message% and %message%, a default built-in message is used for
-logging rejections.
-
-*logwrite*~=~<'text'>::
-cindex:[%logwrite%, ACL modifier]
-cindex:[logging in ACL, immediate]
-This modifier writes a message to a log file as soon as it is encountered when
-processing an ACL. (Compare %log_message%, which, except in the case of
-%warn%, is used only if the ACL statement denies access.) The %logwrite%
-modifier can be used to log special incidents in ACLs. For example:
-
- accept <some special conditions>
- control = freeze
- logwrite = froze message because ...
-+
-By default, the message is written to the main log. However, it may begin
-with a colon, followed by a comma-separated list of log names, and then
-another colon, to specify exactly which logs are to be written. For
-example:
-
- logwrite = :main,reject: text for main and reject logs
- logwrite = :panic: text for panic log only
-
-*message*~=~<'text'>::
-cindex:[%message%, ACL modifier]
-This modifier sets up a text string that is expanded and used as an error
-message if the current statement causes the ACL to deny access. The expansion
-happens at the time Exim decides that access is to be denied, not at the time
-it processes %message%. If the expansion fails, or generates an empty string,
-the modifier is ignored. For ACLs that are triggered by SMTP commands, the
-message is returned as part of the SMTP error response.
-+
-The %message% modifier is also used with the %warn% verb to specify one or more
-header lines to be added to an incoming message when all the conditions are
-true. See section <<SECTaddheadwarn>> for more details. If %message% is used
-with %warn% in an ACL that is not concerned with receiving a message, it has no
-effect.
-+
-The text is literal; any quotes are taken as literals, but because the string
-is expanded, backslash escapes are processed anyway. If the message contains
-newlines, this gives rise to a multi-line SMTP response. Like %log_message%,
-the contents of %message% are not expanded until after a condition has failed.
-+
-cindex:[$acl_verify_message$]
-If %message% is used on a statement that verifies an address, the message
-specified overrides any message that is generated by the verification process.
-However, the original message is available in the variable
-$acl_verify_message$, so you can incorporate it into your message if you wish.
-In particular, if you want the text from %:fail:% items in ^redirect^ routers
-to be passed back as part of the SMTP response, you should either not use a
-%message% modifier, or make use of $acl_verify_message$.
-
-*set*~<'acl_name'>~=~<'value'>::
-cindex:[%set%, ACL modifier]
-This modifier puts a value into one of the ACL variables (see section
-<<SECTaclvariables>>).
-
-
-
-[[SECTcontrols]]
-Use of the control modifier
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[%control%, ACL modifier]
-The %control% modifier supports the following settings:
-
-*control~=~caseful_local_part*::
-See below.
-
-*control~=~caselower_local_part*::
-cindex:[{ACL},case of local part in]
-cindex:[case of local parts]
-cindex:[$local_part$]
-These two controls are permitted only in the ACL specified by %acl_smtp_rcpt%
-(that is, during RCPT processing). By default, the contents of $local_part$ are
-lower cased before ACL processing. If ``caseful_local_part'' is specified, any
-uppercase letters in the original local part are restored in $local_part$ for
-the rest of the ACL, or until a control that sets ``caselower_local_part'' is
-encountered.
-+
-These controls affect only the current recipient. Moreover, they apply only to
-local part handling that takes place directly in the ACL (for example, as a key
-in lookups). If a test to verify the recipient is obeyed, the case-related
-handling of the local part during the verification is controlled by the router
-configuration (see the %caseful_local_part% generic router option).
-+
-This facility could be used, for example, to add a spam score to local parts
-containing upper case letters. For example, using $acl_m4$ to accumulate the
-spam score:
-+
-....
-warn control = caseful_local_part
- set acl_m4 = ${eval:\
- $acl_m4 + \
- ${if match{$local_part}{[A-Z]}{1}{0}}\
- }
- control = caselower_local_part
-....
-+
-Notice that we put back the lower cased version afterwards, assuming that
-is what is wanted for subsequent tests.
-
-*control~=~enforce_sync*::
-See below.
-
-*control~=~no_enforce_sync*::
-cindex:[SMTP,synchronization checking]
-cindex:[synchronization checking in SMTP]
-These controls make it possible to be selective about when SMTP synchronization
-is enforced. The global option %smtp_enforce_sync% specifies the initial
-state of the switch (it is true by default). See the description of this option
-in chapter <<CHAPmainconfig>> for details of SMTP synchronization checking.
-+
-The effect of these two controls lasts for the remainder of the SMTP
-connection. They can appear in any ACL except the one for the non-SMTP
-messages. The most straightforward place to put them is in the ACL defined by
-%acl_smtp_connect%, which is run at the start of an incoming SMTP connection,
-before the first synchronization check. The expected use is to turn off the
-synchronization checks for badly-behaved hosts that you nevertheless need to
-work with.
-
-
-[revisionflag="changed"]
-*control~=~fakedefer/*<'message'>::
-cindex:[fake defer]
-cindex:[defer,fake]
-This control works in exactly the same way as %fakereject% (described below)
-except that it causes an SMTP 450 response after the message data instead of a
-550 response. You must take care when using %fakedefer% because it causes the
-messages to be duplicated when the sender retries. Therefore, you should not
-use %fakedefer% if the message is to be delivered normally.
-
-
-*control~=~fakereject/*<'message'>::
-cindex:[fake rejection]
-cindex:[rejection, fake]
-This control is permitted only for the MAIL, RCPT, and DATA ACLs, in other
-words, only when an SMTP message is being received. If Exim accepts the
-message, instead the final 250 response, a 550 rejection message is sent.
-However, Exim proceeds to deliver the message as normal. The control applies
-only to the current message, not to any subsequent ones that may be received in
-the same SMTP connection.
-+
-The text for the 550 response is taken from the %control% modifier. If no
-message is supplied, the following is used:
-
- 550-Your message has been rejected but is being
- 550-kept for evaluation.
- 550-If it was a legitimate message, it may still be
- 550 delivered to the target recipient(s).
-+
-This facilty should be used with extreme caution.
-
-*control~=~freeze*::
-cindex:[frozen messages,forcing in ACL]
-This control is permitted only for the MAIL, RCPT, DATA, and non-SMTP ACLs, in
-other words, only when a message is being received. If the message is accepted,
-it is placed on Exim's queue and frozen. The control applies only to the
-current message, not to any subsequent ones that may be received in the same
-SMTP connection.
-
-*control~=~no_mbox_unspool*::
-This control is available when Exim is compiled with the content scanning
-extension. Content scanning may require a copy of the current message, or parts
-of it, to be written in ``mbox format'' to a spool file, for passing to a virus
-or spam scanner. Normally, such copies are deleted when they are no longer
-needed. If this control is set, the copies are not deleted. The control applies
-only to the current message, not to any subsequent ones that may be received in
-the same SMTP connection. It is provided for debugging purposes and is unlikely
-to be useful in production.
-
-*control~=~no_multiline_response*::
-cindex:[multiline responses, suppressing]
-This control is permitted for any ACL except the one for non-SMTP messages.
-It seems that there are broken clients in use that cannot handle multiline
-SMTP responses, despite the fact that RFC 821 defined them over 20 years ago.
-+
-If this control is set, multiline SMTP responses from ACL rejections are
-suppressed. One way of doing this would have been to put out these responses as
-one long line. However, RFC 2821 specifies a maximum of 512 bytes per response
-(``use multiline responses for more'' it says -- ha!), and some of the responses
-might get close to that. So this facility, which is after all only a sop to
-broken clients, is implemented by doing two very easy things:
-+
---
-. Extra information that is normally output as part of a rejection caused by
-sender verification failure is omitted. Only the final line (typically ``sender
-verification failed'') is sent.
-
-. If a %message% modifier supplies a multiline response, only the first
-line is output.
---
-+
-The setting of the switch can, of course, be made conditional on the
-calling host. Its effect lasts until the end of the SMTP connection.
-
-*control~=~queue_only*::
-cindex:[%queue_only%]
-cindex:[queueing incoming messages]
-This control is permitted only for the MAIL, RCPT, DATA, and non-SMTP ACLs, in
-other words, only when a message is being received. If the message is accepted,
-it is placed on Exim's queue and left there for delivery by a subsequent queue
-runner. No immediate delivery process is started. In other words, it has the
-effect as the %queue_only% global option. However, the control applies only to
-the current message, not to any subsequent ones that may be received in the
-same SMTP connection.
-
-*control~=~submission/*<'options'>::
-cindex:[message,submission]
-cindex:[submission mode]
-This control is permitted only for the MAIL, RCPT, and start of data ACLs (the
-latter is the one defined by %acl_smtp_predata%). Setting it tells Exim that
-the current message is a submission from a local MUA. In this case, Exim
-operates in ``submission mode'', and applies certain fixups to the message if
-necessary. For example, it add a 'Date:' header line if one is not present.
-This control is not permitted in the %acl_smtp_data% ACL, because that is too
-late (the message has already been created).
-+
-Chapter <<CHAPmsgproc>> describes the processing that Exim applies to messages.
-Section <<SECTsubmodnon>> covers the processing that happens in submission mode;
-the available options for this control are described there. The control applies
-only to the current message, not to any subsequent ones that may be received in
-the same SMTP connection.
-
-[revisionflag="changed"]
-*control~=~suppress_local_fixups*::
-cindex:[submission fixups,suppressing]
-This control applies to locally submitted (non TCP/IP) messages, and is the
-complement of `control = submission`. It disables the fixups that are normally
-applied to locally-submitted messages. Specifically:
-+
---
-[revisionflag="changed"]
-- Any 'Sender:' header line is left alone (in this respect, it is a
-dynamic version of %local_sender_retain%).
-
-[revisionflag="changed"]
-- No 'Message-ID:', 'From:', or 'Date:' header lines are added.
-
-[revisionflag="changed"]
-- There is no check that 'From:' corresponds to the actual sender.
---
-+
-[revisionflag="changed"]
-This feature may be useful when a remotely-originated message is accepted,
-passed to some scanning program, and then re-submitted for delivery.
-
-[revisionflag="changed"]
-All four possibilities for message fixups can be specified:
-
-[revisionflag="changed"]
-- Locally submitted, fixups applied: the default.
-
-[revisionflag="changed"]
-- Locally submitted, no fixups applied: use `control = suppress_local_fixups`.
-
-[revisionflag="changed"]
-- Remotely submitted, no fixups applied: the default.
-
-[revisionflag="changed"]
-- Remotely submitted, fixups applied: use `control = submission`.
-
-
-
-
-
-[[SECTaddheadwarn]]
-Adding header lines with the warn verb
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[header lines,adding in an ACL]
-cindex:[header lines,position of added lines]
-cindex:[%warn%, ACL verb]
-cindex:[%message%, ACL modifier]
-The %message% modifier can be used on a %warn% statement to add an extra header
-line to an incoming message, as in this example:
-
-....
-warn message = X-blacklisted-at: $dnslist_domain
- dnslists = sbl.spamhaus.org : \
- dialup.mail-abuse.org
-....
-
-If an identical header line is requested several times (provoked, for example,
-by multiple RCPT commands), only one copy is actually added to the message.
-If the text of the %message% modifier contains one or more newlines that are
-not followed by a space or a tab, it is assumed to contain multiple header
-lines. Each one is checked for valid syntax; `X-ACL-Warn:` is added to the
-front of any line that is not a valid header line.
-
-By default, new lines are added at the end of the existing header lines.
-However, you can specify that any particular header line should be added right
-at the start (before all the 'Received:' lines), immediately after the first
-block of 'Received:' lines, or immediately before any line that is not a
-'Received:' or 'Resent-something:' header.
-
-This is done by specifying ``:at_start:'', ``:after_received:'', or
-``:at_start_rfc:'' (or, for completeness, ``:at_end:'') before the text of the
-header line, respectively. (Header text cannot start with a colon, as there has
-to be a header name first.) For example:
-
- warn message = :after_received:X-My-Header: something or other...
-
-
-If more than one header is supplied in a single warn statement, each one is
-treated independently and can therefore be placed differently. If you add
-more than one line at the start, or after the Received: block, they will
-end up in reverse order.
-
-*Warning*: This facility currently applies only to header lines that are
-added in an ACL. It does NOT work for header lines that are added in a
-system filter or in a router or transport.
-
-[revisionflag="changed"]
-cindex:[header lines,added; visibility of]
-Header lines that are added by an ACL at MAIL or RCPT time are not visible in
-string expansions in ACLs for subsequent RCPT commands or in the
-%acl_smtp_predata% ACL. However, they are visible in string expansions in the
-ACL that is run after DATA is complete (the %acl_smtp_data% ACL). This is also
-true for header lines that are added in the %acl_smtp_predata% ACL. However,
-header lines that are added in the %acl_smtp_data% itself are not visible
-during that ACL. If a message is rejected after DATA, all added header lines
-are included in the entry that is written to the reject log.
-
-If you want to preserve data between MAIL, RCPT, and the
-%acl_smtp_predata% ACLs, you can use ACL variables, as described in section
-<<SECTaclvariables>>.
-
-
-
-
-
-[[SECTaclconditions]]
-ACL conditions
-~~~~~~~~~~~~~~
-cindex:[{ACL},conditions; list of]
-Some of conditions listed in this section are available only when Exim is
-compiled with the content-scanning extension. They are included here briefly
-for completeness. More detailed descriptions can be found in the discussion on
-content scanning in chapter <<CHAPexiscan>>.
-
-Not all conditions are relevant in all circumstances. For example, testing
-senders and recipients does not make sense in an ACL that is being run as the
-result of the arrival of an ETRN command, and checks on message headers can be
-done only in the ACLs specified by %acl_smtp_data% and %acl_not_smtp%. You can
-use the same condition (with different parameters) more than once in the same
-ACL statement. This provides a way of specifying an ``and'' conjunction. The
-conditions are as follows:
-
-
-*acl~=~*<'name~of~acl~or~ACL~string~or~file~name~'>::
-cindex:[{ACL},nested]
-cindex:[{ACL},indirect]
-cindex:[%acl%, ACL condition]
-The possible values of the argument are the same as for the %acl_smtp_%##'xxx'
-options. The named or inline ACL is run. If it returns ``accept'' the condition
-is true; if it returns ``deny'' the condition is false. If it returns
-``defer'', the current ACL returns ``defer'' unless the condition is on a
-%warn% verb. In that case, a ``defer'' return makes the condition false. This
-means that further processing of the %warn% verb ceases, but processing of the
-ACL continues.
-+
-If the nested %acl% returns ``drop'' and the outer condition denies access, the
-connection is dropped. If it returns ``discard'', the verb must be %accept% or
-%discard%, and the action is taken immediately -- no further conditions are
-tested.
-+
-ACLs may be nested up to 20 deep; the limit exists purely to catch runaway
-loops. This condition allows you to use different ACLs in different
-circumstances. For example, different ACLs can be used to handle RCPT commands
-for different local users or different local domains.
-
-*authenticated~=~*<'string~list'>::
-cindex:[%authenticated%, ACL condition]
-cindex:[authentication,ACL checking]
-cindex:[{ACL},testing for authentication]
-If the SMTP connection is not authenticated, the condition is false. Otherwise,
-the name of the authenticator is tested against the list. To test for
-authentication by any authenticator, you can set
-
- authenticated = *
-
-*condition~=~*<'string'>::
-cindex:[%condition%, ACL condition]
-cindex:[customizing,ACL condition]
-cindex:[{ACL},customized test]
-cindex:[{ACL},testing; customized]
-This feature allows you to make up custom conditions. If the result of
-expanding the string is an empty string, the number zero, or one of the strings
-``no'' or ``false'', the condition is false. If the result is any non-zero
-number, or one of the strings ``yes'' or ``true'', the condition is true. For
-any other values, some error is assumed to have occured, and the ACL returns
-``defer''.
-
-*decode~=~*<'location'>::
-cindex:[%decode%, ACL condition]
-This condition is available only when Exim is compiled with the
-content-scanning extension, and it is allowed only the the ACL defined by
-%acl_smtp_mime%. It causes the current MIME part to be decoded into a file. For
-details, see chapter <<CHAPexiscan>>.
-
-*demime~=~*<'extension~list'>::
-cindex:[%demime%, ACL condition]
-This condition is available only when Exim is compiled with the
-content-scanning extension. Its use is described in section <<SECTdemimecond>>.
-
-*dnslists~=~*<'list~of~domain~names~and~other~data'>::
-cindex:[%dnslists%, ACL condition]
-cindex:[DNS list,in ACL]
-cindex:[black list (DNS)]
-cindex:[{ACL},testing a DNS list]
-This condition checks for entries in DNS black lists. These are also known as
-``RBL lists'', after the original Realtime Blackhole List, but note that the
-use of the lists at 'mail-abuse.org' now carries a charge. There are too many
-different variants of this condition to describe briefly here. See sections
-<<SECTmorednslists>>--<<SECTmorednslistslast>> for details.
-
-*domains~=~*<'domain~list'>::
-cindex:[%domains%, ACL condition]
-cindex:[domain,ACL checking]
-cindex:[{ACL},testing a recipient domain]
-cindex:[$domain_data$]
-This condition is relevant only after a RCPT command. It checks that the domain
-of the recipient address is in the domain list. If percent-hack processing is
-enabled, it is done before this test is done. If the check succeeds with a
-lookup, the result of the lookup is placed in $domain_data$ until the next
-%domains% test.
-
-*encrypted~=~*<'string~list'>::
-cindex:[%encrypted%, ACL condition]
-cindex:[encryption,checking in an ACL]
-cindex:[{ACL},testing for encryption]
-If the SMTP connection is not encrypted, the condition is false. Otherwise, the
-name of the cipher suite in use is tested against the list. To test for
-encryption without testing for any specific cipher suite(s), set
-
- encrypted = *
-
-*hosts~=~*<'~host~list'>::
-cindex:[%hosts%, ACL condition]
-cindex:[host,ACL checking]
-cindex:[{ACL},testing the client host]
-This condition tests that the calling host matches the host list. If you have
-name lookups or wildcarded host names and IP addresses in the same host list,
-you should normally put the IP addresses first. For example, you could have:
-
- accept hosts = 10.9.8.7 : dbm;/etc/friendly/hosts
-+
-The reason for this lies in the left-to-right way that Exim processes lists.
-It can test IP addresses without doing any DNS lookups, but when it reaches an
-item that requires a host name, it fails if it cannot find a host name to
-compare with the pattern. If the above list is given in the opposite order, the
-%accept% statement fails for a host whose name cannot be found, even if its
-IP address is 10.9.8.7.
-+
-If you really do want to do the name check first, and still recognize the IP
-address even if the name lookup fails, you can rewrite the ACL like this:
-
- accept hosts = dbm;/etc/friendly/hosts
- accept hosts = 10.9.8.7
-+
-The default action on failing to find the host name is to assume that the host
-is not in the list, so the first %accept% statement fails. The second statement
-can then check the IP address.
-+
-cindex:[$host_data$]
-If a %hosts% condition is satisfied by means of a lookup, the result
-of the lookup is made available in the $host_data$ variable. This
-allows you, for example, to set up a statement like this:
-
- deny hosts = net-lsearch;/some/file
- message = $host_data
-+
-which gives a custom error message for each denied host.
-
-*local_parts~=~*<'local~part~list'>::
-cindex:[%local_parts%, ACL condition]
-cindex:[local part,ACL checking]
-cindex:[{ACL},testing a local part]
-cindex:[$local_part_data$]
-This condition is relevant only after a RCPT command. It checks that the local
-part of the recipient address is in the list. If percent-hack processing is
-enabled, it is done before this test. If the check succeeds with a lookup, the
-result of the lookup is placed in $local_part_data$, which remains set until
-the next %local_parts% test.
-
-*malware~=~*<'option'>::
-cindex:[%malware%, ACL condition]
-cindex:[{ACL},virus scanning]
-cindex:[{ACL},scanning for viruses]
-This condition is available only when Exim is compiled with the
-content-scanning extension. It causes the incoming message to be scanned for
-viruses. For details, see chapter <<CHAPexiscan>>.
-
-*mime_regex~=~*<'list~of~regular~expressions'>::
-cindex:[%mime_regex%, ACL condition]
-cindex:[{ACL},testing by regex matching]
-This condition is available only when Exim is compiled with the
-content-scanning extension, and it is allowed only the the ACL defined by
-%acl_smtp_mime%. It causes the current MIME part to be scanned for a match with
-any of the regular expressions. For details, see chapter <<CHAPexiscan>>.
-
-[revisionflag="changed"]
-*ratelimit~=~*<'parameters'>::
-cindex:[rate limiting]
-This condition can be used to limit the rate at which a user or host submits
-messages. Details are given in section <<SECTratelimiting>>.
-
-*recipients~=~*<'address~list'>::
-cindex:[%recipients%, ACL condition]
-cindex:[recipient,ACL checking]
-cindex:[{ACL},testing a recipient]
-This condition is relevant only after a RCPT command. It checks the entire
-recipient address against a list of recipients.
-
-*regex~=~*<'list~of~regular~expressions'>::
-cindex:[%regex%, ACL condition]
-cindex:[{ACL},testing by regex matching]
-This condition is available only when Exim is compiled with the
-content-scanning extension, and is available only in the DATA, MIME, and
-non-SMTP ACLs. It causes the incoming message to be scanned for a match with
-any of the regular expressions. For details, see chapter <<CHAPexiscan>>.
-
-*sender_domains~=~*<'domain~list'>::
-cindex:[%sender_domains%, ACL condition]
-cindex:[sender,ACL checking]
-cindex:[{ACL},testing a sender domain]
-cindex:[$domain$]
-cindex:[$sender_address_domain$]
-This condition tests the domain of the sender of the message against the given
-domain list. *Note*: the domain of the sender address is in
-$sender_address_domain$. It is 'not' put in $domain$ during the testing of this
-condition. This is an exception to the general rule for testing domain lists.
-It is done this way so that, if this condition is used in an ACL for a RCPT
-command, the recipient's domain (which is in $domain$) can be used to influence
-the sender checking.
-+
-[revisionflag="changed"]
-*Note*: it is a bad idea to use this condition on its own as a control on
-relaying, because sender addresses are easily, and commonly, forged.
-
-*senders~=~*<'address~list'>::
-cindex:[%senders%, ACL condition]
-cindex:[sender,ACL checking]
-cindex:[{ACL},testing a sender]
-This condition tests the sender of the message against the given list. To test
-for a bounce message, which has an empty sender, set
-
- senders = :
-+
-[revisionflag="changed"]
-*Note*: it is a bad idea to use this condition on its own as a control on
-relaying, because sender addresses are easily, and commonly, forged.
-
-*spam~=~*<'username'>::
-cindex:[%spam%, ACL condition]
-cindex:[{ACL},scanning for spam]
-This condition is available only when Exim is compiled with the
-content-scanning extension. It causes the incoming message to be scanned by
-SpamAssassin. For details, see chapter <<CHAPexiscan>>.
-
-*verify~=~certificate*::
-cindex:[%verify%, ACL condition]
-cindex:[TLS,client certificate verification]
-cindex:[certificate,verification of client]
-cindex:[{ACL},certificate verification]
-cindex:[{ACL},testing a TLS certificate]
-This condition is true in an SMTP session if the session is encrypted, and a
-certificate was received from the client, and the certificate was verified. The
-server requests a certificate only if the client matches %tls_verify_hosts% or
-%tls_try_verify_hosts% (see chapter <<CHAPTLS>>).
-
-[revisionflag="changed"]
-*verify~=~csa*::
-cindex:[CSA verification]
-This condition checks whether the sending host (the client) is authorized to
-send email. Details of how this works are given in section
-<<SECTverifyCSA>>.
-
-*verify~=~header_sender/*<'options'>::
-cindex:[%verify%, ACL condition]
-cindex:[{ACL},verifying sender in the header]
-cindex:[header lines,verifying the sender in]
-cindex:[sender,verifying in header]
-cindex:[verifying,sender in header]
-This condition is relevant only in an ACL that is run after a message has been
-received, that is, in an ACL specified by %acl_smtp_data% or %acl_not_smtp%. It
-checks that there is a verifiable address in at least one of the 'Sender:',
-'Reply-To:', or 'From:' header lines. Such an address is loosely thought of as
-a ``sender'' address (hence the name of the test). However, an address that
-appears in one of these headers need not be an address that accepts bounce
-messages; only sender addresses in envelopes are required to accept bounces.
-Therefore, if you use the callout option on this check, you might want to
-arrange for a non-empty address in the MAIL command.
-+
-Details of address verification and the options are given later, starting at
-section <<SECTaddressverification>> (callouts are described in section
-<<SECTcallver>>). You can combine this condition with the %senders% condition to
-restrict it to bounce messages only:
-
- deny senders = :
- message = A valid sender header is required for bounces
- !verify = header_sender
-
-*verify~=~header_syntax*::
-cindex:[%verify%, ACL condition]
-cindex:[{ACL},verifying header syntax]
-cindex:[header lines,verifying syntax]
-cindex:[verifying,header syntax]
-This condition is relevant only in an ACL that is run after a message has been
-received, that is, in an ACL specified by %acl_smtp_data% or %acl_not_smtp%. It
-checks the syntax of all header lines that can contain lists of addresses
-('Sender:', 'From:', 'Reply-To:', 'To:', 'Cc:', and 'Bcc:'). Unqualified
-addresses (local parts without domains) are permitted only in locally generated
-messages and from hosts that match %sender_unqualified_hosts% or
-%recipient_unqualified_hosts%, as appropriate.
-+
-Note that this condition is a syntax check only. However, a common spamming
-ploy used to be to send syntactically invalid headers such as
-
- To: @
-+
-and this condition can be used to reject such messages, though they are not as
-common as they used to be.
-
-[revisionflag="changed"]
-*verify~=~helo*::
-cindex:[%verify%, ACL condition]
-cindex:[{ACL},verifying HELO/EHLO]
-cindex:[HELO,verifying]
-cindex:[EHLO,verifying]
-cindex:[verifying,EHLO]
-cindex:[verifying,HELO]
-This condition is true if a HELO or EHLO command has been received from the
-client host, and its contents have been verified. It there has been no previous
-attempt to verify the the HELO/EHLO contents, it is carried out when this
-condition is encountered. See the description of the %helo_verify_hosts% and
-%helo_try_verify_hosts% options for details of how to request verification
-independently of this condition.
-
-[revisionflag="changed"]
-*verify~=~not_blind*::
-cindex:[verifying,not blind]
-cindex:[bcc recipients,verifying none]
-This condition checks that there are no blind (bcc) recipients in the message.
-Every envelope recipient must appear either in a 'To:' header line or in a
-'Cc:' header line for this condition to be true. Local parts are checked
-case-sensitively; domains are checked case-insensitively. If 'Resent-To:' or
-'Resent-Cc:' header lines exist, they are also checked. This condition can be
-used only in a DATA or non-SMTP ACL.
-+
-[revisionflag="changed"]
-There are, of course, many legitimate messages that make use of blind
-(bcc) recipients. This check should not be used on its own for blocking
-messages.
-
-
-
-*verify~=~recipient/*<'options'>::
-cindex:[%verify%, ACL condition]
-cindex:[{ACL},verifying recipient]
-cindex:[recipient,verifying]
-cindex:[verifying,recipient]
-cindex:[$address_data$]
-This condition is relevant only after a RCPT command. It verifies the current
-recipient. Details of address verification are given later, starting at section
-<<SECTaddressverification>>. After a recipient has been verified, the value of
-$address_data$ is the last value that was set while routing the address. This
-applies even if the verification fails. When an address that is being verified
-is redirected to a single address, verification continues with the new address,
-and in that case, the subsequent value of $address_data$ is the value for the
-child address.
-
-*verify~=~reverse_host_lookup*::
-cindex:[%verify%, ACL condition]
-cindex:[{ACL},verifying host reverse lookup]
-cindex:[host,verifying reverse lookup]
-This condition ensures that a verified host name has been looked up from the IP
-address of the client host. (This may have happened already if the host name
-was needed for checking a host list, or if the host matched %host_lookup%.)
-Verification ensures that the host name obtained from a reverse DNS lookup, or
-one of its aliases, does, when it is itself looked up in the DNS, yield the
-original IP address.
-+
-If this condition is used for a locally generated message (that is, when there
-is no client host involved), it always succeeds.
-
-*verify~=~sender/*<'options'>::
-cindex:[%verify%, ACL condition]
-cindex:[{ACL},verifying sender]
-cindex:[sender,verifying]
-cindex:[verifying,sender]
-This condition is relevant only after a MAIL or RCPT command, or after a
-message has been received (the %acl_smtp_data% or %acl_not_smtp% ACLs). If the
-message's sender is empty (that is, this is a bounce message), the condition is
-true. Otherwise, the sender address is verified.
-+
-cindex:[$address_data$]
-cindex:[$sender_address_data$]
-If there is data in the $address_data$ variable at the end of routing, its
-value is placed in $sender_address_data$ at the end of verification. This
-value can be used in subsequent conditions and modifiers in the same ACL
-statement. It does not persist after the end of the current statement. If you
-want to preserve the value for longer, you can save it in an ACL variable.
-+
-Details of verification are given later, starting at section
-<<SECTaddressverification>>. Exim caches the result of sender verification, to
-avoid doing it more than once per message.
-
-*verify~=~sender=*<'address'>*/*<'options'>::
-cindex:[%verify%, ACL condition]
-This is a variation of the previous option, in which a modified address is
-verified as a sender.
-
-
-
-[[SECTmorednslists]]
-Using DNS lists
-~~~~~~~~~~~~~~~
-cindex:[DNS list,in ACL]
-cindex:[black list (DNS)]
-cindex:[{ACL},testing a DNS list]
-In its simplest form, the %dnslists% condition tests whether the calling host
-is on at least one of a number of DNS lists by looking up the inverted IP
-address in one or more DNS domains. For example, if the calling host's IP
-address is 192.168.62.43, and the ACL statement is
-
-....
-deny dnslists = blackholes.mail-abuse.org : \
- dialups.mail-abuse.org
-....
-
-the following records are looked up:
-
- 43.62.168.192.blackholes.mail-abuse.org
- 43.62.168.192.dialups.mail-abuse.org
-
-As soon as Exim finds an existing DNS record, processing of the list stops.
-Thus, multiple entries on the list provide an ``or'' conjunction. If you want to
-test that a host is on more than one list (an ``and'' conjunction), you can use
-two separate conditions:
-
- deny dnslists = blackholes.mail-abuse.org
- dnslists = dialups.mail-abuse.org
-
-If a DNS lookup times out or otherwise fails to give a decisive answer, Exim
-behaves as if the host does not match the list item, that is, as if the DNS
-record does not exist. If there are further items in the DNS list, they are
-processed.
-
-This is usually the required action when %dnslists% is used with %deny% (which
-is the most common usage), because it prevents a DNS failure from blocking
-mail. However, you can change this behaviour by putting one of the following
-special items in the list:
-
-cindex:[`+include_unknown`]
-cindex:[`+exclude_unknown`]
-cindex:[`+defer_unknown`]
-&&&
-`+include_unknown ` behave as if the item is on the list
-`+exclude_unknown ` behave as if the item is not on the list (default)
-`+defer_unknown ` give a temporary error
-&&&
-Each of these applies to any subsequent items on the list. For example:
-
- deny dnslists = +defer_unknown : foo.bar.example
-
-
-Testing the list of domains stops as soon as a match is found. If you want to
-warn for one list and block for another, you can use two different statements:
-
- deny dnslists = blackholes.mail-abuse.org
- warn message = X-Warn: sending host is on dialups list
- dnslists = dialups.mail-abuse.org
-
-
-DNS list lookups are cached by Exim for the duration of the SMTP session,
-so a lookup based on the IP address is done at most once for any incoming
-connection. Exim does not share information between multiple incoming
-connections (but your local name server cache should be active).
-
-
-
-Specifying the IP address for a DNS list lookup
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[DNS list,keyed by explicit IP address]
-By default, the IP address that is used in a DNS list lookup is the IP address
-of the calling host. However, you can specify another IP address by listing it
-after the domain name, introduced by a slash. For example:
-
- deny dnslists = black.list.tld/192.168.1.2
-
-This feature is not very helpful with explicit IP addresses; it is intended for
-use with IP addresses that are looked up, for example, the IP addresses of the
-MX hosts or nameservers of an email sender address. For an example, see section
-<<SECTmulkeyfor>> below.
-
-
-
-
-DNS lists keyed on domain names
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[DNS list,keyed by domain name]
-There are some lists that are keyed on domain names rather than inverted IP
-addresses (see for example the 'domain based zones' link at
-*http://www.rfc-ignorant.org/[]*). No reversing of components is used with
-these lists. You can change the name that is looked up in a DNS list by listing
-it after the domain name, introduced by a slash. For example,
-
- deny message = Sender's domain is listed at $dnslist_domain
- dnslists = dsn.rfc-ignorant.org/$sender_address_domain
-
-This particular example is useful only in ACLs that are obeyed after the
-RCPT or DATA commands, when a sender address is available. If (for
-example) the message's sender is 'user@tld.example' the name that is looked
-up by this example is
-
- tld.example.dsn.rfc-ignorant.org
-
-A single %dnslists% condition can contain entries for both names and IP
-addresses. For example:
-
-....
-deny dnslists = sbl.spamhaus.org : \
- dsn.rfc-ignorant.org/$sender_address_domain
-....
-
-The first item checks the sending host's IP address; the second checks a domain
-name. The whole condition is true if either of the DNS lookups succeeds.
-
-
-
-
-[[SECTmulkeyfor]]
-Multiple explicit keys for a DNS list
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[DNS list,multiple keys for]
-The syntax described above for looking up explicitly-defined values (either
-names or IP addresses) in a DNS blacklist is a simplification. After the domain
-name for the DNS list, what follows the slash can in fact be a list of items.
-As with all lists in Exim, the default separator is a colon. However, because
-this is a sublist within the list of DNS blacklist domains, it is necessary
-either to double the separators like this:
-
- dnslists = black.list.tld/name.1::name.2
-
-or to change the separator character, like this:
-
- dnslists = black.list.tld/<;name.1;name.2
-
-If an item in the list is an IP address, it is inverted before the DNS
-blacklist domain is appended. If it is not an IP address, no inversion
-occurs. Consider this condition:
-
- dnslists = black.list.tld/<;192.168.1.2;a.domain
-
-The DNS lookups that occur are:
-
- 2.1.168.192.black.list.tld
- a.domain.black.list.tld
-
-Once a DNS record has been found (that matches a specific IP return
-address, if specified -- see section <<SECTaddmatcon>>), no further lookups are
-done. If there is a temporary DNS error, the rest of the sublist of domains or
-IP addresses is tried. A temporary error for the whole dnslists item occurs
-only if no other DNS lookup in this sublist succeeds. In other words, a
-successful lookup for any of the items in the sublist overrides a temporary
-error for a previous item.
-
-The ability to supply a list of items after the slash is in some sense just a
-syntactic convenience. These two examples have the same effect:
-
- dnslists = black.list.tld/a.domain : black.list.tld/b.domain
- dnslists = black.list.tld/a.domain::b.domain
-
-However, when the data for the list is obtained from a lookup, the second form
-is usually much more convenient. Consider this example:
-
-....
-deny message = The mail servers for the domain \
- $sender_address_domain \
- are listed at $dnslist_domain ($dnslist_value); \
- see $dnslist_text.
- dnslists = sbl.spamhaus.org/<|${lookup dnsdb {>|a=<|\
- ${lookup dnsdb {>|mxh=\
- $sender_address_domain} }} }
-....
-
-Note the use of `>|` in the dnsdb lookup to specify the separator for
-multiple DNS records. The inner dnsdb lookup produces a list of MX hosts
-and the outer dnsdb lookup finds the IP addresses for these hosts. The result
-of expanding the condition might be something like this:
-
- dnslists = sbl.spahmaus.org/<|192.168.2.3|192.168.5.6|...
-
-Thus, this example checks whether or not the IP addresses of the sender
-domain's mail servers are on the Spamhaus black list.
-
-
-
-
-
-Data returned by DNS lists
-~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[DNS list,data returned from]
-DNS lists are constructed using address records in the DNS. The original RBL
-just used the address 127.0.0.1 on the right hand side of each record, but the
-RBL+ list and some other lists use a number of values with different meanings.
-The values used on the RBL+ list are:
-
-&&&
-127.1.0.1 RBL
-127.1.0.2 DUL
-127.1.0.3 DUL and RBL
-127.1.0.4 RSS
-127.1.0.5 RSS and RBL
-127.1.0.6 RSS and DUL
-127.1.0.7 RSS and DUL and RBL
-&&&
-
-Some DNS lists may return more than one address record.
-
-
-Variables set from DNS lists
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[DNS list,variables set from]
-cindex:[$dnslist_domain$]
-cindex:[$dnslist_text$]
-cindex:[$dnslist_value$]
-When an entry is found in a DNS list, the variable $dnslist_domain$
-contains the name of the domain that matched, $dnslist_value$ contains the
-data from the entry, and $dnslist_text$ contains the contents of any
-associated TXT record. If more than one address record is returned by the DNS
-lookup, all the IP addresses are included in $dnslist_value$, separated by
-commas and spaces.
-
-You can use these variables in %message% or %log_message% modifiers --
-although these appear before the condition in the ACL, they are not expanded
-until after it has failed. For example:
-
-....
-deny hosts = !+local_networks
- message = $sender_host_address is listed \
- at $dnslist_domain
- dnslists = rbl-plus.mail-abuse.example
-....
-
-
-
-
-[[SECTaddmatcon]]
-Additional matching conditions for DNS lists
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[DNS list,matching specific returned data]
-You can add an equals sign and an IP address after a %dnslists% domain name in
-order to restrict its action to DNS records with a matching right hand side.
-For example,
-
- deny dnslists = rblplus.mail-abuse.org=127.0.0.2
-
-rejects only those hosts that yield 127.0.0.2. Without this additional data,
-any address record is considered to be a match. If more than one address record
-is found on the list, they are all checked for a matching right-hand side.
-
-More than one IP address may be given for checking, using a comma as a
-separator. These are alternatives -- if any one of them matches, the %dnslists%
-condition is true. For example:
-
- deny dnslists = a.b.c=127.0.0.2,127.0.0.3
-
-
-If you want to specify a constraining address list and also specify names or IP
-addresses to be looked up, the constraining address list must be specified
-first. For example:
-
-....
-deny dnslists = dsn.rfc-ignorant.org\
- =127.0.0.2/$sender_address_domain
-....
-
-
-If the character ``&'' is used instead of ``='', the comparison for each listed
-IP address is done by a bitwise ``and'' instead of by an equality test. In
-other words, the listed addresses are used as bit masks. The comparison is
-true if all the bits in the mask are present in the address that is being
-tested. For example:
-
- dnslists = a.b.c&0.0.0.3
-
-matches if the address is 'x.x.x.'3, 'x.x.x.'7, 'x.x.x.'11, etc. If you
-want to test whether one bit or another bit is present (as opposed to both
-being present), you must use multiple values. For example:
-
- dnslists = a.b.c&0.0.0.1,0.0.0.2
-
-matches if the final component of the address is an odd number or two times
-an odd number.
-
-
-
-Negated DNS matching conditions
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-You can supply a negative list of IP addresses as part of a %dnslists%
-condition. Whereas
-
- deny dnslists = a.b.c=127.0.0.2,127.0.0.3
-
-means ``deny if the host is in the black list at the domain 'a.b.c' and the IP
-address yielded by the list is either 127.0.0.2 or 127.0.0.3'',
-
- deny dnslists = a.b.c!=127.0.0.2,127.0.0.3
-
-means ``deny if the host is in the black list at the domain 'a.b.c' and the IP
-address yielded by the list is not 127.0.0.2 and not 127.0.0.3''. In other
-words, the result of the test is inverted if an exclamation mark appears before
-the ``='' (or the ``&'') sign.
-
-*Note*: this kind of negation is not the same as negation in a domain,
-host, or address list (which is why the syntax is different).
-
-If you are using just one list, the negation syntax does not gain you much. The
-previous example is precisely equivalent to
-
- deny dnslists = a.b.c
- !dnslists = a.b.c=127.0.0.2,127.0.0.3
-
-However, if you are using multiple lists, the negation syntax is clearer.
-Consider this example:
-
-....
-deny dnslists = sbl.spamhaus.org : \
- list.dsbl.org : \
- dnsbl.njabl.org!=127.0.0.3 : \
- relays.ordb.org
-....
-
-Using only positive lists, this would have to be:
-
-....
-deny dnslists = sbl.spamhaus.org : \
- list.dsbl.org
-deny dnslists = dnsbl.njabl.org
- !dnslists = dnsbl.njabl.org=127.0.0.3
-deny dnslists = relays.ordb.org
-....
-
-which is less clear, and harder to maintain.
-
-
-
-
-[[SECTmorednslistslast]]
-DNS lists and IPv6
-~~~~~~~~~~~~~~~~~~
-cindex:[IPv6,DNS black lists]
-cindex:[DNS list,IPv6 usage]
-If Exim is asked to do a dnslist lookup for an IPv6 address, it inverts it
-nibble by nibble. For example, if the calling host's IP address is
-3ffe:ffff:836f:0a00:000a:0800:200a:c031, Exim might look up
-
- 1.3.0.c.a.0.0.2.0.0.8.0.a.0.0.0.0.0.a.0.f.6.3.8.
- f.f.f.f.e.f.f.3.blackholes.mail-abuse.org
-
-(split over two lines here to fit on the page). Unfortunately, some of the DNS
-lists contain wildcard records, intended for IPv4, that interact badly with
-IPv6. For example, the DNS entry
-
- *.3.some.list.example. A 127.0.0.1
-
-is probably intended to put the entire 3.0.0.0/8 IPv4 network on the list.
-Unfortunately, it also matches the entire 3::/4 IPv6 network.
-
-You can exclude IPv6 addresses from DNS lookups by making use of a suitable
-%condition% condition, as in this example:
-
- deny condition = ${if isip4{$sender_host_address}}
- dnslists = some.list.example
-
-
-
-[[SECTratelimiting]]
-Rate limiting senders
-~~~~~~~~~~~~~~~~~~~~~
-[revisionflag="changed"]
-cindex:[rate limiting,client sending]
-cindex:[limiting client sending rates]
-oindex:[%smpt_ratelimit_*%]
-The %ratelimit% ACL condition can be used to measure and control the rate at
-which clients can send email. This is more powerful than the %smtp_ratelimit_*%
-options, because those options control the rate of commands in a single SMTP
-session only, whereas the %ratelimit% condition works across all connections
-(concurrent and sequential) from the same client host. There's a script in
-_util/ratelimit.pl_ which extracts sending rates from log files, to assist with
-choosing appropriate settings when deploying the %ratelimit% ACL condition.
-The syntax of the %ratelimit% condition is:
-
-[revisionflag="changed"]
-&&&
-`ratelimit =` <'m'> `/` <'p'> `/` <'options'> `/` <'key'>
-&&&
-
-[revisionflag="changed"]
-If the average client sending rate is less than 'm' messages per time
-period 'p' then the condition is false; otherwise it is true.
-
-[revisionflag="changed"]
-The parameter 'p' is the smoothing time constant, in the form of an Exim
-time interval, for example, `8h` for eight hours. A larger time constant means
-that it takes Exim longer to forget a client's past behaviour. The parameter
-'m' is the maximum number of messages that a client is permitted to send in a
-fast burst. By increasing both 'm' and 'p' but keeping 'm/p' constant, you can
-allow a client to send more messages in a burst without changing its overall
-sending rate limit. Conversely, if 'm' and 'p' are both small, messages must be
-sent at an even rate.
-
-[revisionflag="changed"]
-The key is used to look up the data for calculating the client's average
-sending rate. This data is stored in a database maintained by Exim in its spool
-directory, alongside the retry and other hints databases. You can limit the
-sending rate of each authenticated user, independent of the computer they are
-sending from, by setting the key to $authenticated_id$. The default key is
-$sender_host_address$, which applies the limit to the client host, independent
-of the sender.
-
-[revisionflag="changed"]
-Internally, Exim includes the smoothing constant 'p' and the options in the
-lookup key because they alter the meaning of the stored data. This is not true
-for the limit 'm', so you can alter the configured maximum rate and Exim will
-still remember clients' past behaviour, but if you alter the other ratelimit
-parameters Exim forgets past behaviour.
-
-[revisionflag="changed"]
-Each %ratelimit% condition can have up to two options. The first option
-specifies what Exim measures the rate of, and the second specifies how Exim
-handles excessively fast clients. The options are separated by a slash, like
-the other parameters.
-
-[revisionflag="changed"]
-The %per_conn% option limits the client's connection rate. The %per_mail%
-option limits the client's rate of sending messages. This is the default if
-none of the %per_*% options is specified.
-
-[revisionflag="changed"]
-The %per_byte% option limits the sender's email bandwidth. Note that it is best
-to use this option in the DATA ACL; if it is used in an earlier ACL it relies
-on the SIZE parameter on the MAIL command, which may be inaccurate or
-completely missing. You can follow the limit 'm' in the configuration with K,
-M, or G to specify limits in kilobytes, megabytes, or gigabytes, respectively.
-
-[revisionflag="changed"]
-The %per_cmd% option causes Exim to recompute the rate every time the condition
-is processed. This can be used to limit the SMTP command rate. The alias
-%per_rcpt% is provided for use in the RCPT ACL instead of %per_cmd% to make it
-clear that the effect is to limit the rate at which recipients are accepted.
-Note that in this case the rate limiting engine will see a message with many
-recipients as a large high-speed burst.
-
-[revisionflag="changed"]
-If a client's average rate is greater than the maximum, the rate limiting
-engine can react in two possible ways, depending on the presence of the
-%strict% or %leaky% options. This is independent of the other counter-measures
-(such as rejecting the message) that may be specified by the rest of the ACL.
-The default mode is leaky, which avoids a sender's over-aggressive retry rate
-preventing it from getting any email through.
-
-[revisionflag="changed"]
-The %strict% option means that the client's recorded rate is always updated.
-The effect of this is that Exim measures the client's average rate of attempts
-to send email, which can be much higher than the maximum. If the client is over
-the limit it will be subjected to counter-measures until it slows down below
-the maximum rate. The smoothing period determines the time it takes for a high
-sending rate to decay exponentially to 37% of its peak value, which means that
-you can work out the time (the number of smoothing periods) that a client is
-subjected to counter-measures after an over-limit burst with this formula:
-
- ln(peakrate/maxrate)
-
-[revisionflag="changed"]
-The %leaky% option means that the client's recorded rate is not updated if it
-is above the limit. The effect of this is that Exim measures the client's
-average rate of successfully sent email, which cannot be greater than the
-maximum. If the client is over the limit it will suffer some counter-measures,
-but it will still be able to send email at the configured maximum rate,
-whatever the rate of its attempts.
-
-[revisionflag="changed"]
-As a side-effect, the %ratelimit% condition sets the expansion variable
-$sender_rate$ to the client's computed rate, $sender_rate_limit$ to the
-configured value of 'm', and $sender_rate_period$ to the configured value of
-'p'.
-
-[revisionflag="changed"]
-Exim's other ACL facilities are used to define what counter-measures are taken
-when the rate limit is exceeded. This might be anything from logging a warning
-(for example, while measuring existing sending rates in order to define
-policy), through time delays to slow down fast senders, up to rejecting the
-message. For example:
-
-[revisionflag="changed"]
-....
-# Log all senders' rates
-warn
- ratelimit = 0 / 1h / strict
- log_message = Sender rate $sender_rate / $sender_rate_period
-
-# Slow down fast senders
-warn
- ratelimit = 100 / 1h / per_rcpt / strict
- delay = ${eval: $sender_rate - $sender_rate_limit }s
-
-# Keep authenticated users under control
-deny
- ratelimit = 100 / 1d / strict / $authenticated_id
-
-# System-wide rate limit
-defer
- message = Sorry, too busy. Try again later.
- ratelimit = 10 / 1s / $primary_hostname
-
-# Restrict incoming rate from each host, with a default
-# set using a macro and special cases looked up in a table.
-defer
- message = Sender rate exceeds $sender_rate_limit \
- messages per $sender_rate_period
- ratelimit = ${lookup {$sender_host_address} \
- cdb {DB/ratelimits.cdb} \
- {$value} {RATELIMIT} }
-....
-
-[revisionflag="changed"]
-*Warning*: if you have a busy server with a lot of %ratelimit% tests,
-especially with the %per_rcpt% option, you may suffer from a performance
-bottleneck caused by locking on the ratelimit hints database. Apart from
-making your ACLs less complicated, you can reduce the problem by using a
-RAM disk for Exim's hints directory (usually _/var/spool/exim/db/_). However
-this means that Exim will lose its hints data after a reboot (including retry
-hints, the callout cache, and ratelimit data).
-
-
-
-[[SECTaddressverification]]
-Address verification
-~~~~~~~~~~~~~~~~~~~~
-cindex:[verifying address, options for]
-cindex:[policy control,address verification]
-Several of the %verify% conditions described in section <<SECTaclconditions>>
-cause addresses to be verified. These conditions can be followed by options
-that modify the verification process. The options are separated from the
-keyword and from each other by slashes, and some of them contain parameters.
-For example:
-
- verify = sender/callout
- verify = recipient/defer_ok/callout=10s,defer_ok
-
-The first stage of address verification, which always happens, is to run the
-address through the routers, in ``verify mode''. Routers can detect the
-difference between verification and routing for delivery, and their actions can
-be varied by a number of generic options such as %verify% and %verify_only%
-(see chapter <<CHAProutergeneric>>). If routing fails, verification fails.
-The available options are as follows:
-
-- If the %callout% option is specified, successful routing to one or more remote
-hosts is followed by a ``callout'' to those hosts as an additional check.
-Callouts and their sub-options are discussed in the next section.
-
-- If there is a defer error while doing verification routing, the ACL
-normally returns ``defer''. However, if you include %defer_ok% in the options,
-the condition is forced to be true instead. Note that this is a main
-verification option as well as a suboption for callouts.
-
-- The %no_details% option is covered in section <<SECTsenaddver>>, which
-discusses the reporting of sender address verification failures.
-
-[revisionflag="changed"]
-- The %success_on_redirect% option causes verification always to succeed
-immediately after a successful redirection. By default, if a redirection
-generates just one address, that address is also verified. See further
-discussion in section <<SECTredirwhilveri>>.
-
-[revisionflag="changed"]
-cindex:[verifying address, differentiating failures]
-cindex:[$recipient_verify_failure$]
-cindex:[$sender_verify_failure$]
-cindex:[$acl_verify_message$]
-After an address verification failure, $acl_verify_message$ contains the error
-message that is associated with the failure. It can be preserved by coding like
-this:
-
- warn !verify = sender
- set acl_m0 = $acl_verify_message
-
-[revisionflag="changed"]
-If you are writing your own custom rejection message or log message when
-denying access, you can use this variable to include information about the
-verification failure.
-
-In addition, $sender_verify_failure$ or $recipient_verify_failure$ (as
-appropriate) contains one of the following words:
-
-- %qualify%: The address was unqualified (no domain), and the message
-was neither local nor came from an exempted host.
-
-- %route%: Routing failed.
-
-- %mail%: Routing succeeded, and a callout was attempted; rejection
-occurred at or before the MAIL command (that is, on initial
-connection, HELO, or MAIL).
-
-- %recipient%: The RCPT command in a callout was rejected.
-
-- %postmaster%: The postmaster check in a callout was rejected.
-
-The main use of these variables is expected to be to distinguish between
-rejections of MAIL and rejections of RCPT in callouts.
-
-
-
-
-[[SECTcallver]]
-Callout verification
-~~~~~~~~~~~~~~~~~~~~
-[revisionflag="changed"]
-cindex:[verifying address, by callout]
-cindex:[callout,verification]
-cindex:[SMTP,callout verification]
-For non-local addresses, routing verifies the domain, but is unable to do any
-checking of the local part. There are situations where some means of verifying
-the local part is desirable. One way this can be done is to make an SMTP
-'callback' to a delivery host for the sender address or a 'callforward' to a
-subsequent host for a recipient address, to see if the host accepts the
-address. We use the term 'callout' to cover both cases. Note that for a sender
-address, the callback is not to the client host that is trying to deliver the
-message, but to one of the hosts that accepts incoming mail for the sender's
-domain.
-
-[revisionflag="changed"]
-Exim does not do callouts by default. If you want them to happen, you must
-request them by setting appropriate options on the %verify% condition, as
-described below. This facility should be used with care, because it can add a
-lot of resource usage to the cost of verifying an address. However, Exim does
-cache the results of callouts, which helps to reduce the cost. Details of
-caching are in section <<SECTcallvercache>>.
-
-Recipient callouts are usually used only between hosts that are controlled by
-the same administration. For example, a corporate gateway host could use
-callouts to check for valid recipients on an internal mailserver. A successful
-callout does not guarantee that a real delivery to the address would succeed;
-on the other hand, a failing callout does guarantee that a delivery would fail.
-
-If the %callout% option is present on a condition that verifies an address, a
-second stage of verification occurs if the address is successfully routed to
-one or more remote hosts. The usual case is routing by a ^dnslookup^ or a
-^manualroute^ router, where the router specifies the hosts. However, if a
-router that does not set up hosts routes to an ^smtp^ transport with a
-%hosts% setting, the transport's hosts are used. If an ^smtp^ transport has
-%hosts_override% set, its hosts are always used, whether or not the router
-supplies a host list.
-
-The port that is used is taken from the transport, if it is specified and is a
-remote transport. (For routers that do verification only, no transport need be
-specified.) Otherwise, the default SMTP port is used. If a remote transport
-specifies an outgoing interface, this is used; otherwise the interface is not
-specified.
-
-For a sender callout check, Exim makes SMTP connections to the remote hosts, to
-test whether a bounce message could be delivered to the sender address. The
-following SMTP commands are sent:
-
-&&&
-`HELO `<'smtp active host name'>
-`MAIL FROM:<>`
-`RCPT TO:`<'the address to be tested'>
-`QUIT`
-&&&
-
-LHLO is used instead of HELO if the transport's %protocol% option is
-set to ``lmtp''.
-
-A recipient callout check is similar. By default, it also uses an empty address
-for the sender. This default is chosen because most hosts do not make use of
-the sender address when verifying a recipient. Using the same address means
-that a single cache entry can be used for each recipient. Some sites, however,
-do make use of the sender address when verifying. These are catered for by the
-%use_sender% and %use_postmaster% options, described in the next section.
-
-If the response to the RCPT command is a 2'##xx' code, the verification
-succeeds. If it is 5##'xx', the verification fails. For any other condition,
-Exim tries the next host, if any. If there is a problem with all the remote
-hosts, the ACL yields ``defer'', unless the %defer_ok% parameter of the
-%callout% option is given, in which case the condition is forced to succeed.
-
-
-
-
-
-[[CALLaddparcall]]
-Additional parameters for callouts
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[callout,additional parameters for]
-The %callout% option can be followed by an equals sign and a number of optional
-parameters, separated by commas. For example:
-
- verify = recipient/callout=10s,defer_ok
-
-The old syntax, which had %callout_defer_ok% and %check_postmaster% as
-separate verify options, is retained for backwards compatibility, but is now
-deprecated. The additional parameters for %callout% are as follows:
-
-
-<'a~time~interval'>::
-cindex:[callout timeout, specifying]
-This specifies the timeout that applies for the callout attempt to each host.
-For example:
-
- verify = sender/callout=5s
-+
-The default is 30 seconds. The timeout is used for each response from the
-remote host. It is also used for the intial connection, unless overridden by
-the %connect% parameter.
-
-
-*connect~=~*<'time~interval'>::
-cindex:[callout connection timeout, specifying]
-This parameter makes it possible to set a different (usually smaller) timeout
-for making the SMTP connection. For example:
-
- verify = sender/callout=5s,connect=1s
-+
-If not specified, this timeout defaults to the general timeout value.
-
-*defer_ok*::
-cindex:[callout defer, action on]
-When this parameter is present, failure to contact any host, or any other kind
-of temporary error, is treated as success by the ACL. However, the cache is not
-updated in this circumstance.
-
-[revisionflag="changed"]
-*fullpostmaster*::
-cindex:[callout,full postmaster check]
-This operates like the %postmaster% option (see below), but if the check for
-'postmaster@domain' fails, it tries just 'postmaster', without a domain, in
-accordance with the specification in RFC 2821. The RFC states that the
-unqualified address 'postmaster' should be accepted.
-
-
-
-*mailfrom~=~*<'email~address'>::
-cindex:[callout,sender when verifying header]
-When verifying addresses in header lines using the %header_sender% verification
-option, Exim behaves by default as if the addresses are envelope sender
-addresses from a message. Callout verification therefore tests to see whether a
-bounce message could be delivered, by using an empty address in the MAIL
-command. However, it is arguable that these addresses might never be used as
-envelope senders, and could therefore justifiably reject bounce messages (empty
-senders). The %mailfrom% callout parameter allows you to specify what address
-to use in the MAIL command. For example:
-
- require verify = header_sender/callout=mailfrom=abcd@x.y.z
-+
-This parameter is available only for the %header_sender% verification option.
-
-
-*maxwait~=~*<'time~interval'>::
-cindex:[callout overall timeout, specifying]
-This parameter sets an overall timeout for performing a callout verification.
-For example:
-
- verify = sender/callout=5s,maxwait=30s
-+
-This timeout defaults to four times the callout timeout for individual SMTP
-commands. The overall timeout applies when there is more than one host that can
-be tried. The timeout is checked before trying the next host. This prevents
-very long delays if there are a large number of hosts and all are timing out
-(for example, when network connections are timing out).
-
-
-*no_cache*::
-cindex:[callout cache, suppressing]
-cindex:[caching callout, suppressing]
-When this parameter is given, the callout cache is neither read nor updated.
-
-*postmaster*::
-cindex:[callout,postmaster; checking]
-When this parameter is set, a sucessful callout check is followed by a similar
-check for the local part 'postmaster' at the same domain. If this address is
-rejected, the callout fails (but see %fullpostmaster% above). The result of the
-postmaster check is recorded in a cache record; if it is a failure, this is
-used to fail subsequent callouts for the domain without a connection being
-made, until the cache record expires.
-
-*postmaster_mailfrom~=~*<'email~address'>::
-The postmaster check uses an empty sender in the MAIL command by default.
-You can use this parameter to do a postmaster check using a different address.
-For example:
-
- require verify = sender/callout=postmaster_mailfrom=abc@x.y.z
-+
-If both %postmaster% and %postmaster_mailfrom% are present, the rightmost one
-overrides. The %postmaster% parameter is equivalent to this example:
-
- require verify = sender/callout=postmaster_mailfrom=
-+
-*Warning*: The caching arrangements for postmaster checking do not take
-account of the sender address. It is assumed that either the empty address or
-a fixed non-empty address will be used. All that Exim remembers is that the
-postmaster check for the domain succeeded or failed.
-
-
-*random*::
-cindex:[callout,``random'' check]
-When this parameter is set, before doing the normal callout check, Exim does a
-check for a ``random'' local part at the same domain. The local part is not
-really random -- it is defined by the expansion of the option
-%callout_random_local_part%, which defaults to
-
- $primary_host_name-$tod_epoch-testing
-+
-The idea here is to try to determine whether the remote host accepts all local
-parts without checking. If it does, there is no point in doing callouts for
-specific local parts. If the ``random'' check succeeds, the result is saved in
-a cache record, and used to force the current and subsequent callout checks to
-succeed without a connection being made, until the cache record expires.
-
-*use_postmaster*::
-cindex:[callout,sender for recipient check]
-This parameter applies to recipient callouts only. For example:
-
- deny !verify = recipient/callout=use_postmaster
-+
-[revisionflag="changed"]
-cindex:[$qualify_domain$]
-It causes a non-empty postmaster address to be used in the MAIL command when
-performing the callout for the recipient, and also for a ``random'' check if
-that is configured. The local part of the address is `postmaster` and the
-domain is the contents of $qualify_domain$.
-
-*use_sender*::
-This option applies to recipient callouts only. For example:
-
- require verify = recipient/callout=use_sender
-+
-It causes the message's actual sender address to be used in the MAIL
-command when performing the callout, instead of an empty address. There is no
-need to use this option unless you know that the called hosts make use of the
-sender when checking recipients. If used indiscriminately, it reduces the
-usefulness of callout caching.
-
-///
-End of list
-///
-
-If you use any of the parameters that set a non-empty sender for the MAIL
-command (%mailfrom%, %postmaster_mailfrom%, %use_postmaster%, or
-%use_sender%), you should think about possible loops. Recipient checking is
-usually done between two hosts that are under the same management, and the host
-that receives the callouts is not normally configured to do callouts itself.
-Therefore, it is normally safe to use %use_postmaster% or %use_sender% in
-these circumstances.
-
-However, if you use a non-empty sender address for a callout to an arbitrary
-host, there is the likelihood that the remote host will itself initiate a
-callout check back to your host. As it is checking what appears to be a message
-sender, it is likely to use an empty address in MAIL, thus avoiding a
-callout loop. However, to be on the safe side it would be best to set up your
-own ACLs so that they do not do sender verification checks when the recipient
-is the address you use for header sender or postmaster callout checking.
-
-Another issue to think about when using non-empty senders for callouts is
-caching. When you set %mailfrom% or %use_sender%, the cache record is keyed by
-the sender/recipient combination; thus, for any given recipient, many more
-actual callouts are performed than when an empty sender or postmaster is used.
-
-
-
-
-[[SECTcallvercache]]
-Callout caching
-~~~~~~~~~~~~~~~
-cindex:[hints database,callout cache]
-cindex:[callout,caching]
-cindex:[caching,callout]
-Exim caches the results of callouts in order to reduce the amount of resources
-used, unless you specify the %no_cache% parameter with the %callout% option.
-A hints database called ``callout'' is used for the cache. Two different record
-types are used: one records the result of a callout check for a specific
-address, and the other records information that applies to the entire domain
-(for example, that it accepts the local part 'postmaster').
-
-When an original callout fails, a detailed SMTP error message is given about
-the failure. However, for subsequent failures use the cache data, this message
-is not available.
-
-The expiry times for negative and positive address cache records are
-independent, and can be set by the global options %callout_negative_expire%
-(default 2h) and %callout_positive_expire% (default 24h), respectively.
-
-If a host gives a negative response to an SMTP connection, or rejects any
-commands up to and including
-
- MAIL FROM:<>
-
-(but not including the MAIL command with a non-empty address),
-any callout attempt is bound to fail. Exim remembers such failures in a
-domain cache record, which it uses to fail callouts for the domain without
-making new connections, until the domain record times out. There are two
-separate expiry times for domain cache records:
-%callout_domain_negative_expire% (default 3h) and
-%callout_domain_positive_expire% (default 7d).
-
-Domain records expire when the negative expiry time is reached if callouts
-cannot be made for the domain, or if the postmaster check failed.
-Otherwise, they expire when the positive expiry time is reached. This
-ensures that, for example, a host that stops accepting ``random'' local parts
-will eventually be noticed.
-
-The callout caching mechanism is based on the domain of the address that is
-being tested. If the domain routes to several hosts, it is assumed that their
-behaviour will be the same.
-
-
-
-[[SECTsenaddver]]
-Sender address verification reporting
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[verifying,suppressing error details]
-When sender verification fails in an ACL, the details of the failure are
-given as additional output lines before the 550 response to the relevant
-SMTP command (RCPT or DATA). For example, if sender callout is in use,
-you might see:
-
- MAIL FROM:<xyz@abc.example>
- 250 OK
- RCPT TO:<pqr@def.example>
- 550-Verification failed for <xyz@abc.example>
- 550-Called: 192.168.34.43
- 550-Sent: RCPT TO:<xyz@abc.example>
- 550-Response: 550 Unknown local part xyz in <xyz@abc.example>
- 550 Sender verification failed
-
-If more than one RCPT command fails in the same way, the details are given
-only for the first of them. However, some administrators do not want to send
-out this much information. You can suppress the details by adding
-``/no_details'' to the ACL statement that requests sender verification. For
-example:
-
- verify = sender/no_details
-
-
-
-[[SECTredirwhilveri]]
-Redirection while verifying
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[verifying,redirection while]
-cindex:[address redirection,while verifying]
-A dilemma arises when a local address is redirected by aliasing or forwarding
-during verification: should the generated addresses themselves be verified,
-or should the successful expansion of the original address be enough to verify
-it? By default, Exim takes the following pragmatic approach:
-
-- When an incoming address is redirected to just one child address, verification
-continues with the child address, and if that fails to verify, the original
-verification also fails.
-
-- When an incoming address is redirected to more than one child address,
-verification does not continue. A success result is returned.
-
-This seems the most reasonable behaviour for the common use of aliasing as a
-way of redirecting different local parts to the same mailbox. It means, for
-example, that a pair of alias entries of the form
-
- A.Wol: aw123
- aw123: :fail: Gone away, no forwarding address
-
-work as expected, with both local parts causing verification failure. When a
-redirection generates more than one address, the behaviour is more like a
-mailing list, where the existence of the alias itself is sufficient for
-verification to succeed.
-
-[revisionflag="changed"]
-It is possible, however, to change the default behaviour so that all successful
-redirections count as successful verifications, however many new addresses are
-generated. This is specified by the %success_on_redirect% verification option.
-For example:
-
-[revisionflag="changed"]
- require verify = recipient/success_on_redirect/callout=10s
-
-[revisionflag="changed"]
-In this example, verification succeeds if a router generates a new address, and
-the callout does not occur, because no address was routed to a remote host.
-
-
-
-
-
-[[SECTverifyCSA]]
-Client SMTP authorization (CSA)
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-[revisionflag="changed"]
-cindex:[CSA,verifying]
-Client SMTP Authorization is a system that allows a site to advertise
-which machines are and are not permitted to send email. This is done by placing
-special SRV records in the DNS; these are looked up using the client's HELO
-domain. At the time of writing, CSA is still an Internet Draft. Client SMTP
-Authorization checks in Exim are performed by the ACL condition:
-
- verify = csa
-
-[revisionflag="changed"]
-This fails if the client is not authorized. If there is a DNS problem, or if no
-valid CSA SRV record is found, or if the client is authorized, the condition
-succeeds. These three cases can be distinguished using the expansion variable
-$csa_status$, which can take one of the values ``fail'', ``defer'',
-``unknown'', or ``ok''. The condition does not itself defer because that would
-be likely to cause problems for legitimate email.
-
-[revisionflag="changed"]
-The error messages produced by the CSA code include slightly more
-detail. If $csa_status$ is ``defer'', this may be because of problems
-looking up the CSA SRV record, or problems looking up the CSA target
-address record. There are four reasons for $csa_status$ being ``fail'':
-
-[revisionflag="changed"]
-- The client's host name is explicitly not authorized.
-
-[revisionflag="changed"]
-- The client's IP address does not match any of the CSA target IP addresses.
-
-[revisionflag="changed"]
-- The client's host name is authorized but it has no valid target IP addresses
-(for example, the target's addresses are IPv6 and the client is using IPv4).
-
-[revisionflag="changed"]
-- The client's host name has no CSA SRV record but a parent domain has asserted
-that all subdomains must be explicitly authorized.
-
-[revisionflag="changed"]
-The %csa% verification condition can take an argument which is the domain to
-use for the DNS query. The default is:
-
- verify = csa/$sender_helo_name
-
-[revisionflag="changed"]
-This implementation includes an extension to CSA. If the query domain
-is an address literal such as [192.0.2.95], or if it is a bare IP
-address, Exim searches for CSA SRV records in the reverse DNS as if
-the HELO domain was (for example) '95.2.0.192.in-addr.arpa'. Therefore it is
-meaningful to say:
-
- verify = csa/$sender_host_address
-
-[revisionflag="changed"]
-In fact, this is the check that Exim performs if the client does not say HELO.
-This extension can be turned off by setting the main configuration option
-%dns_csa_use_reverse% to be false.
-
-[revisionflag="changed"]
-If a CSA SRV record is not found for the domain itself, a search
-is performed through its parent domains for a record which might be
-making assertions about subdomains. The maximum depth of this search is limited
-using the main configuration option %dns_csa_search_limit%, which is 5 by
-default. Exim does not look for CSA SRV records in a top level domain, so the
-default settings handle HELO domains as long as seven
-('hostname.five.four.three.two.one.com'). This encompasses the vast majority of
-legitimate HELO domains.
-
-[revisionflag="changed"]
-The 'dnsdb' lookup also has support for CSA. Although 'dnsdb' also supports
-direct SRV lookups, this is not sufficient because of the extra parent domain
-search behaviour of CSA, and (as with PTR lookups) 'dnsdb' also turns IP
-addresses into lookups in the reverse DNS space. The result of a successful
-lookup such as:
-
-[revisionflag="changed"]
-....
-${lookup dnsdb {csa=$sender_helo_name}}
-....
-
-[revisionflag="changed"]
-has two space-separated fields: an authorization code and a target host name.
-The authorization code can be ``Y'' for yes, ``N'' for no, ``X'' for explicit
-authorization required but absent, or ``?'' for unknown.
-
-
-
-
-[[SECTverifyPRVS]]
-Bounce address tag validation
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-[revisionflag="changed"]
-cindex:[BATV,verifying]
-Bounce address tag validation (BATV) is a scheme whereby the envelope senders
-of outgoing messages have a cryptographic, timestamped ``tag'' added to them.
-Genuine incoming bounce messages should therefore always be addressed to
-recipients that have a valid tag. This scheme is a way of detecting unwanted
-bounce messages caused by sender address forgeries (often called ``collateral
-spam''), because the recipients of such messages will not include valid tags.
-
-[revisionflag="changed"]
-There are two expansion items to help with the implementation of the BATV
-``prvs'' (private signature) scheme in an Exim configuration. This scheme signs
-the original envelope sender address by using a simple shared key to add a hash
-of the address and some time-based randomizing information. The %prvs%
-expansion item creates a signed address, and the %prvscheck% expansion item
-checks one. The syntax of these expansion items is described in section
-<<SECTexpansionitems>>.
-
-[revisionflag="changed"]
-As an example, suppose the secret per-address keys are stored in an MySQL
-database. A query to look up the key for an address could be defined as a macro
-like this:
-
-[revisionflag="changed"]
-....
-PRVSCHECK_SQL = ${lookup mysql{SELECT secret FROM batv_prvs \
- WHERE sender='${quote_mysql:$prvscheck_address}'\
- }{$value}}
-....
-
-[revisionflag="changed"]
-Suppose also that the senders who make use of BATV are defined by an address
-list called %batv_senders%. Then, in the ACL for RCPT commands, you could
-use this:
-
-[revisionflag="changed"]
-....
-# Bounces: drop unsigned addresses for BATV senders
-deny message = This address does not send an unsigned reverse path.
- senders = :
- recipients = +batv_senders
-
-# Bounces: In case of prvs-signed address, check signature.
-deny message = Invalid reverse path signature.
- senders = :
- condition = ${prvscheck {$local_part@$domain}\
- {PRVSCHECK_SQL}{1}}
- !condition = $prvscheck_result
-....
-
-[revisionflag="changed"]
-The first statement rejects recipients for bounce messages that are addressed
-to plain BATV sender addresses, because it is known that BATV senders do not
-send out messages with plain sender addresses. The second statement rejects
-recipients that are prvs-signed, but with invalid signatures (either because
-the key is wrong, or the signature has timed out).
-
-[revisionflag="changed"]
-A non-prvs-signed address is not rejected by the second statement, because the
-%prvscheck% expansion yields an empty string if its first argument is not a
-prvs-signed address, thus causing the %condition% condition to be false. If the
-first argument is a syntactically valid prvs-signed address, the yield is the
-third string (in this case ``1''), whether or not the cryptographic and timeout
-checks succeed. The $prvscheck_result$ variable contains the result of the
-checks (empty for failure, ``1'' for success).
-
-[revisionflag="changed"]
-Of course, when you accept a prvs-signed address, you have to ensure that the
-routers accept it and deliver it correctly. The easiest way to handle this is
-to use a ^redirect^ router to remove the signature with a configuration along
-these lines:
-
-[revisionflag="changed"]
-....
-batv_redirect:
- driver = redirect
- data = ${prvscheck {$local_part@$domain}{PRVSCHECK_SQL}}
-....
-
-[revisionflag="changed"]
-This works because, if the third argument of %prvscheck% is empty, the result
-of the expansion of a prvs-signed address is the decoded value of the original
-address. This router should probably be the first of your routers that handles
-local addresses.
-
-[revisionflag="changed"]
-To create BATV-signed addresses in the first place, a transport of this form
-can be used:
-
-[revisionflag="changed"]
-....
-external_smtp_batv:
- driver = smtp
- return_path = ${prvs {$return_path} \
- {${lookup mysql{SELECT \
- secret FROM batv_prvs WHERE \
- sender='${quote_mysql:$sender_address}'} \
- {$value}fail}}}
-....
-
-[revisionflag="changed"]
-If no key can be found for the existing return path, no signing takes place.
-
-
-
-
-[[SECTrelaycontrol]]
-Using an ACL to control relaying
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[{ACL},relay control]
-cindex:[relaying,control by ACL]
-cindex:[policy control,relay control]
-An MTA is said to 'relay' a message if it receives it from some host and
-delivers it directly to another host as a result of a remote address contained
-within it. Redirecting a local address via an alias or forward file and then
-passing the message on to another host is not relaying,
-cindex:[``percent hack'']
-but a redirection as a result of the ``percent hack'' is.
-
-Two kinds of relaying exist, which are termed ``incoming'' and ``outgoing''.
-A host which is acting as a gateway or an MX backup is concerned with incoming
-relaying from arbitrary hosts to a specific set of domains. On the other hand,
-a host which is acting as a smart host for a number of clients is concerned
-with outgoing relaying from those clients to the Internet at large. Often the
-same host is fulfilling both functions,
-///
-as illustrated in the diagram below,
-///
-but in principle these two kinds of relaying are entirely independent. What is
-not wanted is the transmission of mail from arbitrary remote hosts through your
-system to arbitrary domains.
-
-
-You can implement relay control by means of suitable statements in the ACL that
-runs for each RCPT command. For convenience, it is often easiest to use
-Exim's named list facility to define the domains and hosts involved. For
-example, suppose you want to do the following:
-
-- Deliver a number of domains to mailboxes on the local host (or process them
-locally in some other way). Let's say these are 'my.dom1.example' and
-'my.dom2.example'.
-
-- Relay mail for a number of other domains for which you are the secondary MX.
-These might be 'friend1.example' and 'friend2.example'.
-
-- Relay mail from the hosts on your local LAN, to whatever domains are involved.
-Suppose your LAN is 192.168.45.0/24.
-
-
-In the main part of the configuration, you put the following definitions:
-
- domainlist local_domains = my.dom1.example : my.dom2.example
- domainlist relay_domains = friend1.example : friend2.example
- hostlist relay_hosts = 192.168.45.0/24
-
-Now you can use these definitions in the ACL that is run for every RCPT
-command:
-
- acl_check_rcpt:
- accept domains = +local_domains : +relay_domains
- accept hosts = +relay_hosts
-
-The first statement accepts any RCPT command that contains an address in
-the local or relay domains. For any other domain, control passes to the second
-statement, which accepts the command only if it comes from one of the relay
-hosts. In practice, you will probably want to make your ACL more sophisticated
-than this, for example, by including sender and recipient verification. The
-default configuration includes a more comprehensive example, which is described
-in chapter <<CHAPdefconfil>>.
-
-
-
-[[SECTcheralcon]]
-Checking a relay configuration
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[relaying,checking control of]
-You can check the relay characteristics of your configuration in the same way
-that you can test any ACL behaviour for an incoming SMTP connection, by using
-the %-bh% option to run a fake SMTP session with which you interact.
-
-For specifically testing for unwanted relaying, the host
-'relay-test.mail-abuse.org' provides a useful service. If you telnet to this
-host from the host on which Exim is running, using the normal telnet port, you
-will see a normal telnet connection message and then quite a long delay. Be
-patient. The remote host is making an SMTP connection back to your host, and
-trying a number of common probes to test for open relay vulnerability. The
-results of the tests will eventually appear on your terminal.
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPexiscan]]
-Content scanning at ACL time
-----------------------------
-cindex:[content scanning,at ACL time]
-The extension of Exim to include content scanning at ACL time, formerly known
-as ``exiscan'', was originally implemented as a patch by Tom Kistner. The code
-was integrated into the main source for Exim release 4.50, and Tom continues to
-maintain it. Most of the wording of this chapter is taken from Tom's
-specification.
-
-[revisionflag="changed"]
-It is also possible to scan the content of messages at other times. The
-'local_scan()' function (see chapter <<CHAPlocalscan>>) allows for content
-scanning after all the ACLs have run. A transport filter can be used to scan
-messages at delivery time (see the %transport_filter% option, described in
-chapter <<CHAPtransportgeneric>>).
-
-If you want to include the ACL-time content-scanning features when you compile
-Exim, you need to arrange for WITH_CONTENT_SCAN to be defined in your
-_Local/Makefile_. When you do that, the Exim binary is built with:
-
-[revisionflag="changed"]
-- Two additional ACLs (%acl_smtp_mime% and %acl_not_smtp_mime%) that are run for
-all MIME parts for SMTP and non-SMTP messages, respectively.
-
-- Additional ACL conditions and modifiers: %decode%, %malware%, %mime_regex%,
-%regex%, and %spam%. These can be used in the ACL that is run at the end of
-message reception (the %acl_smtp_data% ACL).
-
-- An additional control feature (``no_mbox_unspool'') that saves spooled copies
-of messages, or parts of messages, for debugging purposes.
-
-- Additional expansion variables that are set in the new ACL and by the new
-conditions.
-
-- Two new main configuration options: %av_scanner% and %spamd_address%.
-
-There is another content-scanning configuration option for _Local/Makefile_,
-called WITH_OLD_DEMIME. If this is set, the old, deprecated %demime% ACL
-condition is compiled, in addition to all the other content-scanning features.
-
-Content-scanning is continually evolving, and new features are still being
-added. While such features are still unstable and liable to incompatible
-changes, they are made available in Exim by setting options whose names begin
-EXPERIMENTAL_ in _Local/Makefile_. Such features are not documented in
-this manual. You can find out about them by reading the file called
-_doc/experimental.txt_.
-
-All the content-scanning facilites work on a MBOX copy of the message that is
-temporarily created in a file called:
-
- <spool_directory>/scan/<message_id>/<message_id>.eml
-
-The _.eml_ extension is a friendly hint to virus scanners that they can
-expect an MBOX-like structure inside that file. The file is created when the
-first content scanning facility is called. Subsequent calls to content
-scanning conditions open the same file again. The directory is recursively
-removed when the %acl_smtp_data% ACL has finished running, unless
-
- control = no_mbox_unspool
-
-has been encountered. When the MIME ACL decodes files, they are put into the
-same directory by default.
-
-
-
-[[SECTscanvirus]]
-Scanning for viruses
-~~~~~~~~~~~~~~~~~~~~
-cindex:[virus scanning]
-cindex:[content scanning,for viruses]
-cindex:[content scanning,the %malware% condition]
-The %malware% ACL condition lets you connect virus scanner software to Exim. It
-supports a ``generic'' interface to scanners called via the shell, and
-specialized interfaces for ``daemon'' type virus scanners, which are resident in
-memory and thus are much faster.
-
-cindex:[%av_scanner%]
-You can set the %av_scanner% option in first part of the Exim configuration
-file to specify which scanner to use, together with any additional options that
-are needed. The basic syntax is as follows:
-
- av_scanner = <scanner-type>:<option1>:<option2>:[...]
-
-If you do not set %av_scanner%, it defaults to
-
- av_scanner = sophie:/var/run/sophie
-
-If the value of %av_scanner% starts with dollar character, it is expanded
-before use.
-
-The following scanner types are supported in this release:
-
-%aveserver%::
-cindex:[virus scanners,Kaspersky]
-This is the scanner daemon of Kaspersky Version 5. You can get a trial version
-at *http://www.kaspersky.com[]*. This scanner type takes one option, which is
-the path to the daemon's UNIX socket. The default is shown in this example:
-
- av_scanner = aveserver:/var/run/aveserver
-
-%clamd%::
-cindex:[virus scanners,clamd]
-This daemon-type scanner is GPL and free. You can get it at
-*http://www.clamav.net/[]*. Some older versions of clamd do not seem to unpack
-MIME containers, so it used to be recommended to unpack MIME attachments in the
-MIME ACL. This no longer believed to be necessary. One option is required:
-either the path and name of a UNIX socket file, or a hostname or IP number, and
-a port, separated by space, as in the second of these examples:
-
- av_scanner = clamd:/opt/clamd/socket
- av_scanner = clamd:192.168.2.100 1234
-+
-If the option is unset, the default is _/tmp/clamd_. Thanks to David Saez for
-contributing the code for this scanner.
-
-%cmdline%::
-cindex:[virus scanners,command line interface]
-This is the keyword for the generic command line scanner interface. It can be
-used to attach virus scanners that are invoked from the shell. This scanner
-type takes 3 mandatory options:
-+
---
-. The full path and name of the scanner binary, with all command line options,
-and a placeholder (%s) for the directory to scan.
-
-. A regular expression to match against the STDOUT and STDERR output of the
-virus scanner. If the expression matches, a virus was found. You must make
-absolutely sure that this expression matches on ``virus found''. This is called
-the ``trigger'' expression.
-
-. Another regular expression, containing exactly one pair of parentheses, to
-match the name of the virus found in the scanners output. This is called the
-``name'' expression.
---
-+
-For example, Sophos Sweep reports a virus on a line like this:
-
- Virus 'W32/Magistr-B' found in file ./those.bat
-+
-For the trigger expression, we can just match the word ``found''. For the name
-expression, we want to extract the W32/Magistr-B string, so we can match for
-the single quotes left and right of it. Altogether, this makes the
-configuration setting:
-+
-....
-av_scanner = cmdline:\
- /path/to/sweep -all -rec -archive %s:\
- found:'(.+)'
-....
-
-
-%drweb%::
-cindex:[virus scanners,DrWeb]
-The DrWeb daemon scanner (*http://www.sald.com/[]*) interface takes one
-argument, either a full path to a UNIX socket, or an IP address and port
-separated by white space, as in these examples:
-
- av_scanner = drweb:/var/run/drwebd.sock
- av_scanner = drweb:192.168.2.20 31337
-+
-If you omit the argument, the default path _/usr/local/drweb/run/drwebd.sock_
-is used. Thanks to Alex Miller for contributing the code for this scanner.
-
-%fsecure%::
-cindex:[virus scanners,F-Secure]
-The F-Secure daemon scanner (*http://www.f-secure.com[]*) takes one argument
-which is the path to a UNIX socket. For example:
-
- av_scanner = fsecure:/path/to/.fsav
-+
-If no argument is given, the default is _/var/run/.fsav_. Thanks to Johan
-Thelmen for contributing the code for this scanner.
-
-%kavdaemon%::
-cindex:[virus scanners,Kaspersky]
-This is the scanner daemon of Kaspersky Version 4. This version of the
-Kaspersky scanner is outdated. Please upgrade (see %aveserver% above). This
-scanner type takes one option, which is the path to the daemon's UNIX socket.
-For example:
-
- av_scanner = kavdaemon:/opt/AVP/AvpCtl
-+
-The default path is _/var/run/AvpCtl_.
-
-%mksd%::
-cindex:[virus scanners,mksd]
-This is a daemon type scanner that is aimed mainly at Polish users, though some
-parts of documentation are now available in English. You can get it at
-*http://linux.mks.com.pl/[]*. The only option for this scanner type is the
-maximum number of processes used simultaneously to scan the attachments,
-provided that the demime facility is employed and also provided that mksd has
-been run with at least the same number of child processes. For example:
-
- av_scanner = mksd:2
-+
-You can safely omit this option (the default value is 1).
-
-%sophie%::
-cindex:[virus scanners,Sophos and Sophie]
-Sophie is a daemon that uses Sophos' %libsavi% library to scan for viruses. You
-can get Sophie at *http://www.vanja.com/tools/sophie/[]*. The only option for
-this scanner type is the path to the UNIX socket that Sophie uses for client
-communication. For example:
-
- av_scanner = sophie:/tmp/sophie
-+
-The default path is _/var/run/sophie_, so if you are using this, you can omit
-the option.
-
-///
-End of list
-///
-
-[revisionflag="changed"]
-When %av_scanner% is correctly set, you can use the %malware% condition in the
-DATA ACL. *Note*: you cannot use the %malware% condition in the MIME ACL.
-
-The %av_scanner% option is expanded each time %malware% is called. This makes
-it possible to use different scanners. See further below for an example. The
-%malware% condition caches its results, so when you use it multiple times for
-the same message, the actual scanning process is only carried out once.
-However, using expandable items in %av_scanner% disables this caching, in which
-case each use of the %malware% condition causes a new scan of the message.
-
-The %malware% condition takes a right-hand argument that is expanded before
-use. It can then be one of
-
-- ``true'', ``\*'', or ``1'', in which case the message is scanned for viruses.
-The condition succeeds if a virus was found, and fail otherwise. This is the
-recommended usage.
-
-- ``false'' or ``0'', in which case no scanning is done and the condition fails
-immediately.
-
-- A regular expression, in which case the message is scanned for viruses. The
-condition succeeds if a virus is found and its name matches the regular
-expression. This allows you to take special actions on certain types of virus.
-
-You can append `/defer_ok` to the %malware% condition to accept messages even
-if there is a problem with the virus scanner.
-
-cindex:[$malware_name$]
-When a virus is found, the condition sets up an expansion variable called
-$malware_name$ that contains the name of the virus. You can use it in a
-%message% modifier that specifies the error returned to the sender, and/or in
-logging data.
-
-If your virus scanner cannot unpack MIME and TNEF containers itself, you should
-use the %demime% condition (see section <<SECTdemimecond>>) before the %malware%
-condition.
-
-Here is a very simple scanning example:
-
- deny message = This message contains malware ($malware_name)
- demime = *
- malware = *
-
-The next example accepts messages when there is a problem with the scanner:
-
- deny message = This message contains malware ($malware_name)
- demime = *
- malware = */defer_ok
-
-The next example shows how to use an ACL variable to scan with both sophie and
-aveserver. It assumes you have set:
-
- av_scanner = $acl_m0
-
-in the main Exim configuration.
-
- deny message = This message contains malware ($malware_name)
- set acl_m0 = sophie
- malware = *
-
- deny message = This message contains malware ($malware_name)
- set acl_m0 = aveserver
- malware = *
-
-
-
-
-[[SECTscanspamass]]
-Scanning with SpamAssassin
-~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[content scanning,for spam]
-cindex:[spam scanning]
-cindex:[SpamAssassin, scanning with]
-The %spam% ACL condition calls SpamAssassin's %spamd% daemon to get a spam
-score and a report for the message. You can get SpamAssassin at
-*http://www.spamassassin.org[]*, or, if you have a working Perl installation,
-you can use CPAN by running:
-
- perl -MCPAN -e 'install Mail::SpamAssassin'
-
-SpamAssassin has its own set of configuration files. Please review its
-documentation to see how you can tweak it. The default installation should work
-nicely, however.
-
-cindex:[%spamd_address%]
-After having installed and configured SpamAssassin, start the %spamd% daemon.
-By default, it listens on 127.0.0.1, TCP port 783. If you use another host or
-port for %spamd%, you must set the %spamd_address% option in the global part
-of the Exim configuration as follows (example):
-
- spamd_address = 192.168.99.45 387
-
-You do not need to set this option if you use the default. As of version 2.60,
-%spamd% also supports communication over UNIX sockets. If you want to use
-these, supply %spamd_address% with an absolute file name instead of a
-address/port pair:
-
- spamd_address = /var/run/spamd_socket
-
-You can have multiple %spamd% servers to improve scalability. These can reside
-on other hardware reachable over the network. To specify multiple %spamd%
-servers, put multiple address/port pairs in the %spamd_address% option,
-separated with colons:
-
-....
-spamd_address = 192.168.2.10 783 : \
- 192.168.2.11 783 : \
- 192.168.2.12 783
-....
-
-Up to 32 %spamd% servers are supported. The servers are queried in a random
-fashion. When a server fails to respond to the connection attempt, all other
-servers are tried until one succeeds. If no server responds, the %spam%
-condition defers.
-
-*Warning*: It is not possible to use the UNIX socket connection method with
-multiple %spamd% servers.
-
-
-Calling SpamAssassin from an Exim ACL
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Here is a simple example of the use of the %spam% condition in a DATA ACL:
-
- deny message = This message was classified as SPAM
- spam = joe
-
-The right-hand side of the %spam% condition specifies the username that
-SpamAssassin should scan for. If you do not want to scan for a particular user,
-but rather use the SpamAssassin system-wide default profile, you can scan for
-an unknown user, or simply use ``nobody''. However, you must put something on
-the right-hand side.
-
-The username allows you to use per-domain or per-user antispam profiles. The
-right-hand side is expanded before being used, so you can put lookups or
-conditions there. When the right-hand side evaluates to ``0'' or ``false'', no
-scanning is done and the condition fails immediately.
-
-[revisionflag="changed"]
-Scanning with SpamAssassin uses a lot of resources. If you scan every message,
-large ones may cause significant performance degredation. As most spam messages
-are quite small, it is recommended that you do not scan the big ones. For
-example:
-
-[revisionflag="changed"]
-....
-deny message = This message was classified as SPAM
- condition = ${if < {$message_size}{10K}}
- spam = nobody
-....
-
-The %spam% condition returns true if the threshold specified in the user's
-SpamAssassin profile has been matched or exceeded. If you want to use the
-%spam% condition for its side effects (see the variables below), you can make
-it always return ``true'' by appending `:true` to the username.
-
-cindex:[spam scanning,returned variables]
-When the %spam% condition is run, it sets up the following expansion
-variables:
-
-$spam_score$::
-The spam score of the message, for example ``3.4'' or ``30.5''. This is useful
-for inclusion in log or reject messages.
-
-$spam_score_int$::
-The spam score of the message, multiplied by ten, as an integer value. For
-example ``34'' or ``305''. This is useful for numeric comparisons in
-conditions. This variable is special; it is saved with the message, and written
-to Exim's spool file. This means that it can be used during the whole life of
-the message on your Exim system, in particular, in routers or transports during
-the later delivery phase.
-
-$spam_bar$::
-A string consisting of a number of ``+'' or ``-'' characters, representing the
-integer part of the spam score value. A spam score of 4.4 would have a
-$spam_bar$ value of ``++++''. This is useful for inclusion in warning headers,
-since MUAs can match on such strings.
-
-$spam_report$::
-A multiline text table, containing the full SpamAssassin report for the
-message. Useful for inclusion in headers or reject messages.
-
-///
-End of list
-///
-
-The %spam% condition caches its results. If you call it again with the same
-user name, it does not scan again, but rather returns the same values as
-before.
-
-The %spam% condition returns DEFER if there is any error while running the
-message through SpamAssassin. If you want to treat DEFER as FAIL (to pass on to
-the next ACL statement block), append `/defer_ok` to the right-hand side of
-the spam condition, like this:
-
- deny message = This message was classified as SPAM
- spam = joe/defer_ok
-
-This causes messages to be accepted even if there is a
-problem with %spamd%.
-
-Here is a longer, commented example of the use of the %spam%
-condition:
-
- # put headers in all messages (no matter if spam or not)
- warn message = X-Spam-Score: $spam_score ($spam_bar)
- spam = nobody:true
- warn message = X-Spam-Report: $spam_report
- spam = nobody:true
-
- # add second subject line with *SPAM* marker when message
- # is over threshold
- warn message = Subject: *SPAM* $h_Subject:
- spam = nobody
-
- # reject spam at high scores (> 12)
- deny message = This message scored $spam_score spam points.
- spam = nobody:true
- condition = ${if >{$spam_score_int}{120}{1}{0}}
-
-
-
-
-
-[[SECTscanmimepart]]
-Scanning MIME parts
-~~~~~~~~~~~~~~~~~~~
-[revisionflag="changed"]
-cindex:[content scanning,MIME parts]
-cindex:[MIME content scanning]
-cindex:[%acl_smtp_mime%]
-The %acl_smtp_mime% global option specifies an ACL that is called once for each
-MIME part of an SMTP message, including multipart types, in the sequence of
-their position in the message. Similarly, the %acl_not_smtp_mime% option
-specifies an ACL that is used for the MIME parts of non-SMTP messages. These
-options may both refer to the same ACL if you want the same processing in both
-cases.
-
-[revisionflag="changed"]
-These ACLs are called (possibly many times) just before the %acl_smtp_data% ACL
-in the case of an SMTP message, or just before a non-SMTP message is accepted.
-However, a MIME ACL is called only if the message contains a 'MIME-Version:'
-header line. When a call to a MIME ACL does not yield ``accept'', ACL
-processing is aborted and the appropriate result code is sent to the client. In
-the case of an SMTP message, the %acl_smtp_data% ACL is not called when this
-happens.
-
-[revisionflag="changed"]
-You cannot use the %malware% or %spam% conditions in a MIME ACL; these can only
-be used in the DATA or non-SMTP ACLs. However, you can use the %regex%
-condition to match against the raw MIME part. You can also use the %mime_regex%
-condition to match against the decoded MIME part (see section
-<<SECTscanregex>>).
-
-At the start of a MIME ACL, a number of variables are set from the header
-information for the relevant MIME part. These are described below. The contents
-of the MIME part are not by default decoded into a disk file except for MIME
-parts whose content-type is ``message/rfc822''. If you want to decode a MIME
-part into a disk file, you can use the %decode% modifier. The general syntax
-is:
-
- decode = [/<path>/]<filename>
-
-The right hand side is expanded before use. After expansion,
-the value can be:
-
-. ``0'' or ``false'', in which case no decoding is done.
-
-. The string ``default''. In that case, the file is put in the temporary
-``default'' directory <'spool_directory'>_/scan/_<'message_id'>_/_ with a
-sequential file name consisting of the message id and a sequence number. The
-full path and name is available in $mime_decoded_filename$ after decoding.
-
-. A full path name starting with a slash. If the full name is an existing
-directory, it is used as a replacement for the default directory. The filename
-is then sequentially assigned. If the path does not exist, it is used as
-the full path and file name.
-
-. If the string does not start with a slash, it is used as the
-filename, and the default path is then used.
-
-///
-End of list
-///
-
-You can easily decode a file with its original, proposed filename using
-
- decode = $mime_filename
-
-However, you should keep in mind that $mime_filename$ might contain
-anything. If you place files outside of the default path, they are not
-automatically unlinked.
-
-For RFC822 attachments (these are messages attached to messages, with a
-content-type of ``message/rfc822''), the ACL is called again in the same manner
-as for the primary message, only that the $mime_is_rfc822$ expansion
-variable is set (see below). Attached messages are always decoded to disk
-before being checked, and the files are unlinked once the check is done.
-
-The MIME ACL supports the %regex% and %mime_regex% conditions. These can be
-used to match regular expressions against raw and decoded MIME parts,
-respectively. They are described in section <<SECTscanregex>>.
-
-cindex:[MIME content scanning,returned variables]
-The following list describes all expansion variables that are
-available in the MIME ACL:
-
-$mime_boundary$::
-If the current part is a multipart (see $mime_is_multipart$) below, it should
-have a boundary string, which is stored in this variable. If the current part
-has no boundary parameter in the 'Content-Type:' header, this variable contains
-the empty string.
-
-$mime_charset$::
-This variable contains the character set identifier, if one was found in the
-'Content-Type:' header. Examples for charset identifiers are:
-
- us-ascii
- gb2312 (Chinese)
- iso-8859-1
-+
-Please note that this value is not normalized, so you should do matches
-case-insensitively.
-
-$mime_content_description$::
-This variable contains the normalized content of the 'Content-Description:'
-header. It can contain a human-readable description of the parts content. Some
-implementations repeat the filename for attachments here, but they are usually
-only used for display purposes.
-
-$mime_content_disposition$::
-This variable contains the normalized content of the 'Content-Disposition:'
-header. You can expect strings like ``attachment'' or ``inline'' here.
-
-$mime_content_id$::
-This variable contains the normalized content of the 'Content-ID:' header.
-This is a unique ID that can be used to reference a part from another part.
-
-$mime_content_size$::
-This variable is set only after the %decode% modifier (see above) has been
-successfully run. It contains the size of the decoded part in kilobytes. The
-size is always rounded up to full kilobytes, so only a completely empty part
-has a $mime_content_size$ of zero.
-
-$mime_content_transfer_encoding$::
-This variable contains the normalized content of the
-'Content-transfer-encoding:' header. This is a symbolic name for an encoding
-type. Typical values are ``base64'' and ``quoted-printable''.
-
-$mime_content_type$::
-If the MIME part has a 'Content-Type:' header, this variable contains its
-value, lowercased, and without any options (like ``name'' or ``charset''). Here
-are some examples of popular MIME types, as they may appear in this variable:
-
- text/plain
- text/html
- application/octet-stream
- image/jpeg
- audio/midi
-+
-If the MIME part has no 'Content-Type:' header, this variable contains the
-empty string.
-
-$mime_decoded_filename$::
-This variable is set only after the %decode% modifier (see above) has been
-successfully run. It contains the full path and file name of the file
-containing the decoded data.
-
-cindex:[RFC 2047]
-$mime_filename$::
-This is perhaps the most important of the MIME variables. It contains a
-proposed filename for an attachment, if one was found in either the
-'Content-Type:' or 'Content-Disposition:' headers. The filename will be RFC2047
-decoded, but no additional sanity checks are done. If no filename was found,
-this variable contains the empty string.
-
-$mime_is_coverletter$::
-This variable attempts to differentiate the ``cover letter'' of an e-mail from
-attached data. It can be used to clamp down on flashy or unneccessarily encoded
-content in the cover letter, while not restricting attachments at all.
-+
-The variable contains 1 (true) for a MIME part believed to be part of the
-cover letter, and 0 (false) for an attachment. At present, the algorithm is as
-follows:
-+
---
-. The outermost MIME part of a message is always a cover letter.
-
-. If a multipart/alternative or multipart/related MIME part is a cover letter,
-so are all MIME subparts within that multipart.
-
-. If any other multipart is a cover letter, the first subpart is a cover letter,
-and the rest are attachments.
-
-. All parts contained within an attachment multipart are attachments.
---
-+
-As an example, the following will ban ``HTML mail'' (including that sent with
-alternative plain text), while allowing HTML files to be attached. HTML
-coverletter mail attached to non-HMTL coverletter mail will also be allowed:
-
- deny message = HTML mail is not accepted here
- !condition = $mime_is_rfc822
- condition = $mime_is_coverletter
- condition = ${if eq{$mime_content_type}{text/html}{1}{0}}
-
-$mime_is_multipart$::
-This variable has the value 1 (true) when the current part has the main type
-``multipart'', for example ``multipart/alternative'' or ``multipart/mixed''.
-Since multipart entities only serve as containers for other parts, you may not
-want to carry out specific actions on them.
-
-$mime_is_rfc822$::
-This variable has the value 1 (true) if the current part is not a part of the
-checked message itself, but part of an attached message. Attached message
-decoding is fully recursive.
-
-$mime_part_count$::
-This variable is a counter that is raised for each processed MIME part. It
-starts at zero for the very first part (which is usually a multipart). The
-counter is per-message, so it is reset when processing RFC822 attachments (see
-$mime_is_rfc822$). The counter stays set after %acl_smtp_mime% is
-complete, so you can use it in the DATA ACL to determine the number of MIME
-parts of a message. For non-MIME messages, this variable contains the value -1.
-
-
-
-[[SECTscanregex]]
-Scanning with regular expressions
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[content scanning,with regular expressions]
-cindex:[regular expressions,content scanning with]
-You can specify your own custom regular expression matches on the full body of
-the message, or on individual MIME parts.
-
-The %regex% condition takes one or more regular expressions as arguments and
-matches them against the full message (when called in the DATA ACL) or a raw
-MIME part (when called in the MIME ACL). The %regex% condition matches
-linewise, with a maximum line length of 32K characters. That means you cannot
-have multiline matches with the %regex% condition.
-
-The %mime_regex% condition can be called only in the MIME ACL. It matches up
-to 32K of decoded content (the whole content at once, not linewise). If the
-part has not been decoded with the %decode% modifier earlier in the ACL, it is
-decoded automatically when %mime_regex% is executed (using default path and
-filename values). If the decoded data is larger than 32K, only the first 32K
-characters are checked.
-
-The regular expressions are passed as a colon-separated list. To include a
-literal colon, you must double it. Since the whole right-hand side string is
-expanded before being used, you must also escape dollar signs and backslashes
-with more backslashes, or use the `\N` facility to disable expansion.
-Here is a simple example that contains two regular expressions:
-
- deny message = contains blacklisted regex ($regex_match_string)
- regex = [Mm]ortgage : URGENT BUSINESS PROPOSAL
-
-The conditions returns true if any one of the regular expressions matches. The
-$regex_match_string$ expansion variable is then set up and contains the
-matching regular expression.
-
-*Warning*: With large messages, these conditions can be fairly
-CPU-intensive.
-
-
-
-
-[[SECTdemimecond]]
-The demime condition
-~~~~~~~~~~~~~~~~~~~~
-cindex:[content scanning,MIME checking]
-cindex:[MIME content scanning]
-The %demime% ACL condition provides MIME unpacking, sanity checking and file
-extension blocking. It is usable only in the DATA and non-SMTP ACLs. The
-%demime% condition uses a simpler interface to MIME decoding than the MIME ACL
-functionality, but provides no additional facilities. Please note that this
-condition is deprecated and kept only for backward compatibility. You must set
-the WITH_OLD_DEMIME option in _Local/Makefile_ at build time to be able to use
-the %demime% condition.
-
-The %demime% condition unpacks MIME containers in the message. It detects
-errors in MIME containers and can match file extensions found in the message
-against a list. Using this facility produces files containing the unpacked MIME
-parts of the message in the temporary scan directory. If you do antivirus
-scanning, it is recommened that you use the %demime% condition before the
-antivirus (%malware%) condition.
-
-On the right-hand side of the %demime% condition you can pass a colon-separated
-list of file extensions that it should match against. For example:
-
- deny message = Found blacklisted file attachment
- demime = vbs:com:bat:pif:prf:lnk
-
-If one of the file extensions is found, the condition is true, otherwise it is
-false. If there is a temporary error while demimeing (for example, ``disk
-full''), the condition defers, and the message is temporarily rejected (unless
-the condition is on a %warn% verb).
-
-The right-hand side is expanded before being treated as a list, so you can have
-conditions and lookups there. If it expands to an empty string, ``false'', or
-zero (``0''), no demimeing is done and the condition is false.
-
-The %demime% condition set the following variables:
-
-$demime_errorlevel$::
-cindex:[$demime_errorlevel$]
-When an error is detected in a MIME container, this variable contains the
-severity of the error, as an integer number. The higher the value, the more
-severe the error (the current maximum value is 3). If this variable is unset or
-zero, no error occurred.
-
-$demime_reason$::
-cindex:[$demime_reason$]
-When $demime_errorlevel$ is greater than zero, this variable contains a
-human-readable text string describing the MIME error that occurred.
-
-cindex:[$found_extension$]
-$found_extension$::
-When the %demime% condition is true, this variable contains the file extension
-it found.
-
-///
-End of list
-///
-
-Both $demime_errorlevel$ and $demime_reason$ are set by the first call of
-the %demime% condition, and are not changed on subsequent calls.
-
-If you do not want to check for file extensions, but rather use the %demime%
-condition for unpacking or error checking purposes, pass ``\*'' as the
-right-hand side value. Here is a more elaborate example of how to use this
-facility:
-
- # Reject messages with serious MIME container errors
- deny message = Found MIME error ($demime_reason).
- demime = *
- condition = ${if >{$demime_errorlevel}{2}{1}{0}}
-
- # Reject known virus spreading file extensions.
- # Accepting these is pretty much braindead.
- deny message = contains $found_extension file (blacklisted).
- demime = com:vbs:bat:pif:scr
-
- # Freeze .exe and .doc files. Postmaster can
- # examine them and eventually thaw them.
- deny log_message = Another $found_extension file.
- demime = exe:doc
- control = freeze
-
-
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPlocalscan]]
-[titleabbrev="Local scan function"]
-Adding a local scan function to Exim
-------------------------------------
-cindex:['local_scan()' function,description of]
-cindex:[customizing,input scan using C function]
-cindex:[policy control,by local scan function]
-In these days of email worms, viruses, and ever-increasing spam, some sites
-want to apply a lot of checking to messages before accepting them.
-
-The content scanning extension (chapter <<CHAPexiscan>>) has facilities for
-passing messages to external virus and spam scanning software. You can also do
-
-a certain amount in Exim itself through string expansions and the %condition%
-condition in the ACL that runs after the SMTP DATA command or the ACL for
-non-SMTP messages (see chapter <<CHAPACL>>), but this has its limitations.
-
-To allow for further customization to a site's own requirements, there is the
-possibility of linking Exim with a private message scanning function, written
-in C. If you want to run code that is written in something other than C, you
-can of course use a little C stub to call it.
-
-The local scan function is run once for every incoming message, at the point
-when Exim is just about to accept the message.
-It can therefore be used to control non-SMTP messages from local processes as
-well as messages arriving via SMTP.
-
-Exim applies a timeout to calls of the local scan function, and there is an
-option called %local_scan_timeout% for setting it. The default is 5 minutes.
-Zero means ``no timeout''.
-Exim also sets up signal handlers for SIGSEGV, SIGILL, SIGFPE, and SIGBUS
-before calling the local scan function, so that the most common types of crash
-are caught. If the timeout is exceeded or one of those signals is caught, the
-incoming message is rejected with a temporary error if it is an SMTP message.
-For a non-SMTP message, the message is dropped and Exim ends with a non-zero
-code. The incident is logged on the main and reject logs.
-
-
-
-Building Exim to use a local scan function
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:['local_scan()' function,building Exim to use]
-To make use of the local scan function feature, you must tell Exim where your
-function is before building Exim, by setting LOCAL_SCAN_SOURCE in your
-_Local/Makefile_. A recommended place to put it is in the _Local_
-directory, so you might set
-
- LOCAL_SCAN_SOURCE=Local/local_scan.c
-
-for example. The function must be called 'local_scan()'. It is called by
-Exim after it has received a message, when the success return code is about to
-be sent. This is after all the ACLs have been run. The return code from your
-function controls whether the message is actually accepted or not. There is a
-commented template function (that just accepts the message) in the file
-_src/local_scan.c_.
-
-If you want to make use of Exim's run time configuration file to set options
-for your 'local_scan()' function, you must also set
-
- LOCAL_SCAN_HAS_OPTIONS=yes
-
-in _Local/Makefile_ (see section <<SECTconoptloc>> below).
-
-
-
-
-[[SECTapiforloc]]
-API for local_scan()
-~~~~~~~~~~~~~~~~~~~~
-cindex:['local_scan()' function,API description]
-You must include this line near the start of your code:
-
- #include "local_scan.h"
-
-This header file defines a number of variables and other values, and the
-prototype for the function itself. Exim is coded to use unsigned char values
-almost exclusively, and one of the things this header defines is a shorthand
-for `unsigned char` called `uschar`.
-It also contains the following macro definitions, to simplify casting character
-strings and pointers to character strings:
-
- #define CS (char *)
- #define CCS (const char *)
- #define CSS (char **)
- #define US (unsigned char *)
- #define CUS (const unsigned char *)
- #define USS (unsigned char **)
-
-
-The function prototype for 'local_scan()' is:
-
- extern int local_scan(int fd, uschar **return_text);
-
-The arguments are as follows:
-
-- %fd% is a file descriptor for the file that contains the body of the message
-(the -D file). The file is open for reading and writing, but updating it is not
-recommended. *Warning*: You must 'not' close this file descriptor.
-+
-The descriptor is positioned at character 19 of the file, which is the first
-character of the body itself, because the first 19 characters are the message
-id followed by `-D` and a newline. If you rewind the file, you should use the
-macro SPOOL_DATA_START_OFFSET to reset to the start of the data, just in
-case this changes in some future version.
-
-- %return_text% is an address which you can use to return a pointer to a text
-string at the end of the function. The value it points to on entry is NULL.
-
-The function must return an %int% value which is one of the following macros:
-
-`LOCAL_SCAN_ACCEPT`::
-cindex:[$local_scan_data$]
-The message is accepted. If you pass back a string of text, it is saved with
-the message, and made available in the variable $local_scan_data$. No
-newlines are permitted (if there are any, they are turned into spaces) and the
-maximum length of text is 1000 characters.
-
-`LOCAL_SCAN_ACCEPT_FREEZE`::
-This behaves as LOCAL_SCAN_ACCEPT, except that the accepted message is
-queued without immediate delivery, and is frozen.
-
-`LOCAL_SCAN_ACCEPT_QUEUE`::
-This behaves as LOCAL_SCAN_ACCEPT, except that the accepted message is
-queued without immediate delivery.
-
-`LOCAL_SCAN_REJECT`::
-The message is rejected; the returned text is used as an error message which is
-passed back to the sender and which is also logged. Newlines are permitted --
-they cause a multiline response for SMTP rejections, but are converted to `\n`
-in log lines. If no message is given, ``Administrative prohibition'' is used.
-
-`LOCAL_SCAN_TEMPREJECT`::
-The message is temporarily rejected; the returned text is used as an error
-message as for LOCAL_SCAN_REJECT. If no message is given, ``Temporary local
-problem'' is used.
-
-`LOCAL_SCAN_REJECT_NOLOGHDR`::
-This behaves as LOCAL_SCAN_REJECT, except that the header of the rejected
-message is not written to the reject log. It has the effect of unsetting the
-%rejected_header% log selector for just this rejection. If %rejected_header%
-is already unset (see the discussion of the %log_selection% option in section
-<<SECTlogselector>>), this code is the same as LOCAL_SCAN_REJECT.
-
-`LOCAL_SCAN_TEMPREJECT_NOLOGHDR`::
-This code is a variation of LOCAL_SCAN_TEMPREJECT in the same way that
-LOCAL_SCAN_REJECT_NOLOGHDR is a variation of LOCAL_SCAN_REJECT.
-
-///
-End of list
-///
-
-If the message is not being received by interactive SMTP, rejections are
-reported by writing to %stderr% or by sending an email, as configured by the
-%-oe% command line options.
-
-
-
-[[SECTconoptloc]]
-Configuration options for local_scan()
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:['local_scan()' function,configuration options]
-It is possible to have option settings in the main configuration file
-that set values in static variables in the 'local_scan()' module. If you
-want to do this, you must have the line
-
- LOCAL_SCAN_HAS_OPTIONS=yes
-
-in your _Local/Makefile_ when you build Exim. (This line is in
-_OS/Makefile-Default_, commented out). Then, in the 'local_scan()' source
-file, you must define static variables to hold the option values, and a table to
-define them.
-
-The table must be a vector called %local_scan_options%, of type
-`optionlist`. Each entry is a triplet, consisting of a name, an option type,
-and a pointer to the variable that holds the value. The entries must appear in
-alphabetical order. Following %local_scan_options% you must also define a
-variable called %local_scan_options_count% that contains the number of
-entries in the table. Here is a short example, showing two kinds of option:
-
- static int my_integer_option = 42;
- static uschar *my_string_option = US"a default string";
-
- optionlist local_scan_options[] = {
- { "my_integer", opt_int, &my_integer_option },
- { "my_string", opt_stringptr, &my_string_option }
- };
- int local_scan_options_count =
- sizeof(local_scan_options)/sizeof(optionlist);
-
-The values of the variables can now be changed from Exim's runtime
-configuration file by including a local scan section as in this example:
-
- begin local_scan
- my_integer = 99
- my_string = some string of text...
-
-The available types of option data are as follows:
-
-*opt_bool*::
-This specifies a boolean (true/false) option. The address should point to a
-variable of type `BOOL`, which will be set to TRUE or FALSE, which are macros
-that are defined as ``1'' and ``0'', respectively. If you want to detect
-whether such a variable has been set at all, you can initialize it to
-TRUE_UNSET. (BOOL variables are integers underneath, so can hold more than two
-values.)
-
-*opt_fixed*::
-This specifies a fixed point number, such as is used for load averages.
-The address should point to a variable of type `int`. The value is stored
-multiplied by 1000, so, for example, 1.4142 is truncated and stored as 1414.
-
-*opt_int*::
-This specifies an integer; the address should point to a variable of type
-`int`. The value may be specified in any of the integer formats accepted by
-Exim.
-
-*opt_mkint*::
-This is the same as %opt_int%, except that when such a value is output in a
-%-bP% listing, if it is an exact number of kilobytes or megabytes, it is
-printed with the suffix K or M.
-
-*opt_octint*::
-This also specifies an integer, but the value is always interpeted as an
-octal integer, whether or not it starts with the digit zero, and it is
-always output in octal.
-
-*opt_stringptr*::
-This specifies a string value; the address must be a pointer to a
-variable that points to a string (for example, of type `uschar \*`).
-
-*opt_time*::
-This specifies a time interval value. The address must point to a variable of
-type `int`. The value that is placed there is a number of seconds.
-
-///
-End of list
-///
-
-If the %-bP% command line option is followed by `local_scan`, Exim prints
-out the values of all the 'local_scan()' options.
-
-
-
-Available Exim variables
-~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:['local_scan()' function,available Exim variables]
-The header _local_scan.h_ gives you access to a number of C variables. These
-are the only ones that are guaranteed to be maintained from release to release.
-Note, however, that you can obtain the value of any Exim variable by calling
-'expand_string()'. The exported variables are as follows:
-
-*unsigned~int~debug_selector*::
-This variable is set to zero when no debugging is taking place. Otherwise, it
-is a bitmap of debugging selectors. Two bits are identified for use in
-'local_scan()'; they are defined as macros:
-+
---
-- The `D_v` bit is set when %-v% was present on the command line. This is a
-testing option that is not privileged -- any caller may set it. All the
-other selector bits can be set only by admin users.
-
-- The `D_local_scan` bit is provided for use by 'local_scan()'; it is set
-by the `+local_scan` debug selector. It is not included in the default set
-of debugging bits.
---
-+
-Thus, to write to the debugging output only when `+local_scan` has been
-selected, you should use code like this:
-
- if ((debug_selector & D_local_scan) != 0)
- debug_printf("xxx", ...);
-
-
-*uschar~\*expand_string_message*::
-After a failing call to 'expand_string()' (returned value NULL), the
-variable %expand_string_message% contains the error message, zero-terminated.
-
-*header_line~\*header_list*::
-A pointer to a chain of header lines. The %header_line% structure is discussed
-below.
-
-*header_line~\*header_last*::
-A pointer to the last of the header lines.
-
-*uschar~\*headers_charset*::
-The value of the %headers_charset% configuration option.
-
-*BOOL~host_checking*::
-This variable is TRUE during a host checking session that is initiated by the
-%-bh% command line option.
-
-*uschar~\*interface_address*::
-The IP address of the interface that received the message, as a string. This
-is NULL for locally submitted messages.
-
-*int~interface_port*::
-The port on which this message was received.
-
-*uschar~\*message_id*::
-This variable contains Exim's message id for the incoming message (the value of
-$message_exim_id$) as a zero-terminated string.
-
-*uschar~\*received_protocol*::
-The name of the protocol by which the message was received.
-
-*int~recipients_count*::
-The number of accepted recipients.
-
-*recipient_item~\*recipients_list*::
-cindex:[recipient,adding in local scan]
-cindex:[recipient,removing in local scan]
-The list of accepted recipients, held in a vector of length %recipients_count%.
-The %recipient_item% structure is discussed below. You can add additional
-recipients by calling 'receive_add_recipient()' (see below). You can delete
-recipients by removing them from the vector and adusting the value in
-%recipients_count%. In particular, by setting %recipients_count% to zero you
-remove all recipients. If you then return the value `LOCAL_SCAN_ACCEPT`, the
-message is accepted, but immediately blackholed. To replace the recipients, set
-%recipients_count% to zero and then call 'receive_add_recipient()' as often as
-needed.
-
-*uschar~\*sender_address*::
-The envelope sender address. For bounce messages this is the empty string.
-
-*uschar~\*sender_host_address*::
-The IP address of the sending host, as a string. This is NULL for
-locally-submitted messages.
-
-*uschar~\*sender_host_authenticated*::
-The name of the authentication mechanism that was used, or NULL if the message
-was not received over an authenticated SMTP connection.
-
-*uschar~\*sender_host_name*::
-The name of the sending host, if known.
-
-*int~sender_host_port*::
-The port on the sending host.
-
-*BOOL~smtp_input*::
-This variable is TRUE for all SMTP input, including BSMTP.
-
-*BOOL~smtp_batched_input*::
-This variable is TRUE for BSMTP input.
-
-*int~store_pool*::
-The contents of this variable control which pool of memory is used for new
-requests. See section <<SECTmemhanloc>> for details.
-
-///
-End of list
-///
-
-
-
-Structure of header lines
-~~~~~~~~~~~~~~~~~~~~~~~~~
-The %header_line% structure contains the members listed below.
-You can add additional header lines by calling the 'header_add()' function
-(see below). You can cause header lines to be ignored (deleted) by setting
-their type to \*.
-
-
-*struct~header_line~\*next*::
-A pointer to the next header line, or NULL for the last line.
-
-*int~type*::
-A code identifying certain headers that Exim recognizes. The codes are printing
-characters, and are documented in chapter <<CHAPspool>> of this manual. Notice
-in particular that any header line whose type is \* is not transmitted with the
-message. This flagging is used for header lines that have been rewritten, or
-are to be removed (for example, 'Envelope-sender:' header lines.) Effectively,
-\* means ``deleted''.
-
-*int~slen*::
-The number of characters in the header line, including the terminating and any
-internal newlines.
-
-*uschar~\*text*::
-A pointer to the text of the header. It always ends with a newline, followed by
-a zero byte. Internal newlines are preserved.
-
-
-
-Structure of recipient items
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The %recipient_item% structure contains these members:
-
-*uschar~\*address*::
-This is a pointer to the recipient address as it was received.
-
-*int~pno*::
-This is used in later Exim processing when top level addresses are created by
-the %one_time% option. It is not relevant at the time 'local_scan()' is run and
-must always contain -1 at this stage.
-
-*uschar~\*errors_to*::
-If this value is not NULL, bounce messages caused by failing to deliver to the
-recipient are sent to the address it contains. In other words, it overrides the
-envelope sender for this one recipient. (Compare the %errors_to% generic router
-option.) If a 'local_scan()' function sets an %errors_to% field to an
-unqualified address, Exim qualifies it using the domain from
-%qualify_recipient%. When 'local_scan()' is called, the %errors_to% field is
-NULL for all recipients.
-
-
-
-Available Exim functions
-~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:['local_scan()' function,available Exim functions]
-The header _local_scan.h_ gives you access to a number of Exim functions.
-These are the only ones that are guaranteed to be maintained from release to
-release:
-
-*pid_t~child_open(uschar~{star}{star}argv,~uschar~{star}{star}envp,~int~newumask,~int~{star}infdptr,~int~{star}outfdptr,~BOOL~make_leader)*::
-
-This function creates a child process that runs the command specified by
-%argv%. The environment for the process is specified by %envp%, which can be
-NULL if no environment variables are to be passed. A new umask is supplied for
-the process in %newumask%.
-+
-Pipes to the standard input and output of the new process are set up
-and returned to the caller via the %infdptr% and %outfdptr% arguments. The
-standard error is cloned to the standard output. If there are any file
-descriptors ``in the way'' in the new process, they are closed. If the final
-argument is TRUE, the new process is made into a process group leader.
-+
-The function returns the pid of the new process, or -1 if things go wrong.
-
-*int~child_close(pid_t~pid,~int~timeout)*::
-This function waits for a child process to terminate, or for a timeout (in
-seconds) to expire. A timeout value of zero means wait as long as it takes. The
-return value is as follows:
-+
-- >= 0
-+
-The process terminated by a normal exit and the value is the process ending
-status.
-
-- < 0 and > --256
-+
-The process was terminated by a signal and the value is the negation of the
-signal number.
-
-- --256
-+
-The process timed out.
-
-- --257
-+
-The was some other error in wait(); %errno% is still set.
-
-
-*pid_t~child_open_exim(int~{star}fd)*::
-This function provide you with a means of submitting a new message to
-Exim. (Of course, you can also call _/usr/sbin/sendmail_ yourself if you
-want, but this packages it all up for you.) The function creates a pipe,
-forks a subprocess that is running
-
- exim -t -oem -oi -f <>
-+
-and returns to you (via the `int *` argument) a file descriptor for the pipe
-that is connected to the standard input. The yield of the function is the PID
-of the subprocess. You can then write a message to the file descriptor, with
-recipients in 'To:', 'Cc:', and/or 'Bcc:' header lines.
-+
-When you have finished, call 'child_close()' to wait for the process to
-finish and to collect its ending status. A timeout value of zero is usually
-fine in this circumstance. Unless you have made a mistake with the recipient
-addresses, you should get a return code of zero.
-
-*void~debug_printf(char~{star},~...)*::
-This is Exim's debugging function, with arguments as for '(printf()'. The
-output is written to the standard error stream. If no debugging is selected,
-calls to 'debug_printf()' have no effect. Normally, you should make calls
-conditional on the `local_scan` debug selector by coding like this:
-
- if ((debug_selector & D_local_scan) != 0)
- debug_printf("xxx", ...);
-
-*uschar~{star}expand_string(uschar~{star}string)*::
-This is an interface to Exim's string expansion code. The return value is the
-expanded string, or NULL if there was an expansion failure.
-The C variable %expand_string_message% contains an error message after an
-expansion failure. If expansion does not change the string, the return value is
-the pointer to the input string. Otherwise, the return value points to a new
-block of memory that was obtained by a call to 'store_get()'. See section
-<<SECTmemhanloc>> below for a discussion of memory handling.
-
-*void~header_add(int~type,~char~{star}format,~...)*::
-This function allows you to an add additional header line at the end of the
-existing ones. The first argument is the type, and should normally be a space
-character. The second argument is a format string and any number of
-substitution arguments as for 'sprintf()'. You may include internal newlines if
-you want, and you must ensure that the string ends with a newline.
-
-*void~header_add_at_position(BOOL~after,~uschar~{star}name,~BOOL~topnot,~int~type,~char~{star}format,~...)*::
-This function adds a new header line at a specified point in the header
-chain. The header itself is specified as for 'header_add()'.
-+
-If %name% is NULL, the new header is added at the end of the chain if %after%
-is true, or at the start if %after% is false. If %name% is not NULL, the header
-lines are searched for the first non-deleted header that matches the name. If
-one is found, the new header is added before it if %after% is false. If %after%
-is true, the new header is added after the found header and any adjacent
-subsequent ones with the same name (even if marked ``deleted''). If no matching
-non-deleted header is found, the %topnot% option controls where the header is
-added. If it is true, addition is at the top; otherwise at the bottom. Thus, to
-add a header after all the 'Received:' headers, or at the top if there are no
-'Received:' headers, you could use
-
- header_add_at_position(TRUE, US"Received", TRUE,
- ' ', "X-xxx: ...");
-+
-Normally, there is always at least one non-deleted 'Received:' header, but
-there may not be if %received_header_text% expands to an empty string.
-
-
-*void~header_remove(int~occurrence,~uschar~{star}name)*::
-This function removes header lines. If %occurrence% is zero or negative, all
-occurrences of the header are removed. If occurrence is greater than zero, that
-particular instance of the header is removed. If no header(s) can be found that
-match the specification, the function does nothing.
-
-
-*BOOL~header_testname(header_line~{star}hdr,~uschar~{star}name,~int~length,~BOOL~notdel)*::
-This function tests whether the given header has the given name. It is not just
-a string comparison, because white space is permitted between the name and the
-colon. If the %notdel% argument is true, a false return is forced for all
-``deleted'' headers; otherwise they are not treated specially. For example:
-
- if (header_testname(h, US"X-Spam", 6, TRUE)) ...
-
-
-*uschar~{star}lss_b64encode(uschar~{star}cleartext,~int~length)*::
-cindex:[base64 encoding,functions for 'local_scan()' use]
-This function base64-encodes a string, which is passed by address and length.
-The text may contain bytes of any value, including zero. The result is passed
-back in dynamic memory that is obtained by calling 'store_get()'. It is
-zero-terminated.
-
-*int~lss_b64decode(uschar~{star}codetext,~uschar~{star}{star}cleartext)*::
-This function decodes a base64-encoded string. Its arguments are a
-zero-terminated base64-encoded string and the address of a variable that is set
-to point to the result, which is in dynamic memory. The length of the decoded
-string is the yield of the function. If the input is invalid base64 data, the
-yield is -1. A zero byte is added to the end of the output string to make it
-easy to interpret as a C string (assuming it contains no zeros of its own). The
-added zero byte is not included in the returned count.
-
-*int~lss_match_domain(uschar~{star}domain,~uschar~{star}list)*::
-This function checks for a match in a domain list. Domains are always
-matched caselessly. The return value is one of the following:
-+
-&&&
-`OK ` match succeeded
-`FAIL ` match failed
-`DEFER ` match deferred
-&&&
-+
-DEFER is usually caused by some kind of lookup defer, such as the
-inability to contact a database.
-
-*int~lss_match_local_part(uschar~{star}localpart,~uschar~{star}list,~BOOL~caseless)*::
-This function checks for a match in a local part list. The third argument
-controls case-sensitivity. The return values are as for
-'lss_match_domain()'.
-
-*int~lss_match_address(uschar~{star}address,~uschar~{star}list,~BOOL~caseless)*::
-This function checks for a match in an address list. The third argument
-controls the case-sensitivity of the local part match. The domain is always
-matched caselessly. The return values are as for 'lss_match_domain()'.
-
-*int~lss_match_host(uschar~{star}host_name,~uschar~{star}host_address,~uschar~{star}list)*::
-This function checks for a match in a host list. The most common usage is
-expected to be
-
- lss_match_host(sender_host_name, sender_host_address, ...)
-+
-cindex:[$sender_host_address$]
-An empty address field matches an empty item in the host list. If the host name
-is NULL, the name corresponding to $sender_host_address$ is automatically
-looked up if a host name is required to match an item in the list. The return
-values are as for 'lss_match_domain()', but in addition, 'lss_match_host()'
-returns ERROR in the case when it had to look up a host name, but the lookup
-failed.
-
-*void~log_write(unsigned~int~selector,~int~which,~char~{star}format,~...)*::
-This function writes to Exim's log files. The first argument should be zero (it
-is concerned with %log_selector%). The second argument can be `LOG_MAIN` or
-`LOG_REJECT` or `LOG_PANIC` or the inclusive ``or'' of any combination of them.
-It specifies to which log or logs the message is written. The remaining
-arguments are a format and relevant insertion arguments. The string should not
-contain any newlines, not even at the end.
-
-
-*void~receive_add_recipient(uschar~{star}address,~int~pno)*::
-This function adds an additional recipient to the message. The first argument
-is the recipient address. If it is unqualified (has no domain), it is qualified
-with the %qualify_recipient% domain. The second argument must always be -1.
-+
-This function does not allow you to specify a private %errors_to% address (as
-described with the structure of %recipient_item% above), because it pre-dates
-the addition of that field to the structure. However, it is easy to add such a
-value afterwards. For example:
-
- receive_add_recipient(US"monitor@mydom.example", -1);
- recipients_list[recipients_count-1].errors_to =
- US"postmaster@mydom.example";
-
-*BOOL~receive_remove_recipient(uschar~{star}recipient)*::
-This is a convenience function to remove a named recipient from the list of
-recipients. It returns true if a recipient was removed, and false if no
-matching recipient could be found. The argument must be a complete email
-address.
-
-
-cindex:[RFC 2047]
-*uschar~*rfc2047_decode(uschar~{star}string,~BOOL~lencheck,~uschar~{star}target,~int~zeroval,~int~{star}lenptr,~uschar~{star}{star}error)*::
-This function decodes strings that are encoded according to RFC 2047. Typically
-these are the contents of header lines. First, each ``encoded word'' is decoded
-from the Q or B encoding into a byte-string. Then, if provided with the name of
-a charset encoding, and if the 'iconv()' function is available, an attempt is
-made to translate the result to the named character set. If this fails, the
-binary string is returned with an error message.
-+
-The first argument is the string to be decoded. If %lencheck% is TRUE, the
-maximum MIME word length is enforced. The third argument is the target
-encoding, or NULL if no translation is wanted.
-+
-cindex:[binary zero,in RFC 2047 decoding]
-cindex:[RFC 2047,binary zero in]
-If a binary zero is encountered in the decoded string, it is replaced by the
-contents of the %zeroval% argument. For use with Exim headers, the value must
-not be 0 because header lines are handled as zero-terminated strings.
-+
-The function returns the result of processing the string, zero-terminated; if
-%lenptr% is not NULL, the length of the result is set in the variable to which
-it points. When %zeroval% is 0, %lenptr% should not be NULL.
-+
-If an error is encountered, the function returns NULL and uses the %error%
-argument to return an error message. The variable pointed to by %error% is set
-to NULL if there is no error; it may be set non-NULL even when the function
-returns a non-NULL value if decoding was successful, but there was a problem
-with translation.
-
-
-*int~smtp_fflush(void)*::
-This function is used in conjunction with 'smtp_printf()', as described
-below.
-
-*void~smtp_printf(char~{star},~...)*::
-The arguments of this function are like 'printf()'; it writes to the SMTP
-output stream. You should use this function only when there is an SMTP output
-stream, that is, when the incoming message is being received via interactive
-SMTP. This is the case when %smtp_input% is TRUE and %smtp_batched_input% is
-FALSE. If you want to test for an incoming message from another host (as
-opposed to a local process that used the %-bs% command line option), you can
-test the value of %sender_host_address%, which is non-NULL when a remote host
-is involved.
-+
-If an SMTP TLS connection is established, 'smtp_printf()' uses the TLS
-output function, so it can be used for all forms of SMTP connection.
-+
-Strings that are written by 'smtp_printf()' from within 'local_scan()'
-must start with an appropriate response code: 550 if you are going to return
-LOCAL_SCAN_REJECT, 451 if you are going to return
-LOCAL_SCAN_TEMPREJECT, and 250 otherwise. Because you are writing the
-initial lines of a multi-line response, the code must be followed by a hyphen
-to indicate that the line is not the final response line. You must also ensure
-that the lines you write terminate with CRLF. For example:
-
- smtp_printf("550-this is some extra info\r\n");
- return LOCAL_SCAN_REJECT;
-+
-Note that you can also create multi-line responses by including newlines in
-the data returned via the %return_text% argument. The added value of using
-'smtp_printf()' is that, for instance, you could introduce delays between
-multiple output lines.
-+
-The 'smtp_printf()' function does not return any error indication, because it
-does not automatically flush pending output, and therefore does not test
-the state of the stream. (In the main code of Exim, flushing and error
-detection is done when Exim is ready for the next SMTP input command.) If
-you want to flush the output and check for an error (for example, the
-dropping of a TCP/IP connection), you can call 'smtp_fflush()', which has no
-arguments. It flushes the output stream, and returns a non-zero value if there
-is an error.
-
-*void~{star}store_get(int)*::
-This function accesses Exim's internal store (memory) manager. It gets a new
-chunk of memory whose size is given by the argument. Exim bombs out if it ever
-runs out of memory. See the next section for a discussion of memory handling.
-
-*void~{star}store_get_perm(int)*::
-This function is like 'store_get()', but it always gets memory from the
-permanent pool. See the next section for a discussion of memory handling.
-
-*uschar~{star}string_copy(uschar~{star}string)*::
-See below.
-
-*uschar~{star}string_copyn(uschar~{star}string,~int~length)*::
-See below.
-
-*uschar~{star}string_sprintf(char~{star}format,~...)*::
-These three functions create strings using Exim's dynamic memory facilities.
-The first makes a copy of an entire string. The second copies up to a maximum
-number of characters, indicated by the second argument. The third uses a format
-and insertion arguments to create a new string. In each case, the result is a
-pointer to a new string in the current memory pool. See the next section for
-more discussion.
-
-///
-End of list
-///
-
-
-
-
-[[SECTmemhanloc]]
-More about Exim's memory handling
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:['local_scan()' function,memory handling]
-No function is provided for freeing memory, because that is never needed.
-The dynamic memory that Exim uses when receiving a message is automatically
-recycled if another message is received by the same process (this applies only
-to incoming SMTP connections -- other input methods can supply only one message
-at a time). After receiving the last message, a reception process terminates.
-
-Because it is recycled, the normal dynamic memory cannot be used for holding
-data that must be preserved over a number of incoming messages on the same SMTP
-connection. However, Exim in fact uses two pools of dynamic memory; the second
-one is not recycled, and can be used for this purpose.
-
-If you want to allocate memory that remains available for subsequent messages
-in the same SMTP connection, you should set
-
- store_pool = POOL_PERM
-
-before calling the function that does the allocation. There is no need to
-restore the value if you do not need to; however, if you do want to revert to
-the normal pool, you can either restore the previous value of %store_pool% or
-set it explicitly to POOL_MAIN.
-
-The pool setting applies to all functions that get dynamic memory, including
-'expand_string()', 'store_get()', and the 'string_xxx()' functions.
-There is also a convenience function called 'store_get_perm()' that gets a
-block of memory from the permanent pool while preserving the value of
-%store_pool%.
-
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPsystemfilter]]
-System-wide message filtering
------------------------------
-cindex:[filter,system filter]
-cindex:[filtering all mail]
-cindex:[system filter]
-The previous chapters (on ACLs and the local scan function) describe checks
-that can be applied to messages before they are accepted by a host. There is
-also a mechanism for checking messages once they have been received, but before
-they are delivered. This is called the 'system filter'.
-
-The system filter operates in a similar manner to users' filter files, but it
-is run just once per message (however many recipients the message has).
-It should not normally be used as a substitute for routing, because %deliver%
-commands in a system router provide new envelope recipient addresses.
-The system filter must be an Exim filter. It cannot be a Sieve filter.
-
-The system filter is run at the start of a delivery attempt, before any routing
-is done. If a message fails to be completely delivered at the first attempt,
-the system filter is run again at the start of every retry.
-If you want your filter to do something only once per message, you can make use
-of the %first_delivery% condition in an %if% command in the filter to prevent
-it happening on retries.
-
-cindex:[$domain$]
-cindex:[$local_part$]
-*Warning*: Because the system filter runs just once, variables that are
-specific to individual recipient addresses, such as $local_part$ and
-$domain$, are not set, and the ``personal'' condition is not meaningful. If you
-want to run a centrally-specified filter for each recipient address
-independently, you can do so by setting up a suitable ^redirect^ router, as
-described in section <<SECTperaddfil>> below.
-
-
-Specifying a system filter
-~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[uid (user id),system filter]
-cindex:[gid (group id),system filter]
-The name of the file that contains the system filter must be specified by
-setting %system_filter%. If you want the filter to run under a uid and gid
-other than root, you must also set %system_filter_user% and
-%system_filter_group% as appropriate. For example:
-
- system_filter = /etc/mail/exim.filter
- system_filter_user = exim
-
-If a system filter generates any deliveries directly to files or pipes (via the
-%save% or %pipe% commands), transports to handle these deliveries must be
-specified by setting %system_filter_file_transport% and
-%system_filter_pipe_transport%, respectively. Similarly,
-%system_filter_reply_transport% must be set to handle any messages generated
-by the %reply% command.
-
-
-Testing a system filter
-~~~~~~~~~~~~~~~~~~~~~~~
-You can run simple tests of a system filter in the same way as for a user
-filter, but you should use %-bF% rather than %-bf%, so that features that
-are permitted only in system filters are recognized.
-
-If you want to test the combined effect of a system filter and a user filter,
-you can use both %-bF% and %-bf% on the same command line.
-
-
-
-Contents of a system filter
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The language used to specify system filters is the same as for users' filter
-files. It is described in the separate end-user document 'Exim's interface to
-mail filtering'. However, there are some additional features that are
-available only in system filters; these are described in subsequent sections.
-If they are encountered in a user's filter file or when testing with %-bf%,
-they cause errors.
-
-cindex:[frozen messages,manual thaw; testing in filter]
-There are two special conditions which, though available in users' filter
-files, are designed for use in system filters. The condition %first_delivery%
-is true only for the first attempt at delivering a message, and
-%manually_thawed% is true only if the message has been frozen, and
-subsequently thawed by an admin user. An explicit forced delivery counts as a
-manual thaw, but thawing as a result of the %auto_thaw% setting does not.
-
-*Warning*: If a system filter uses the %first_delivery% condition to
-specify an ``unseen'' (non-significant) delivery, and that delivery does not
-succeed, it will not be tried again.
-If you want Exim to retry an unseen delivery until it succeeds, you should
-arrange to set it up every time the filter runs.
-
-When a system filter finishes running, the values of the variables $n0$ --
-$n9$ are copied into $sn0$ -- $sn9$ and are thereby made available to
-users' filter files. Thus a system filter can, for example, set up ``scores'' to
-which users' filter files can refer.
-
-
-
-Additional variable for system filters
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[$recipients$]
-The expansion variable $recipients$, containing a list of all the recipients
-of the message (separated by commas and white space), is available in system
-filters. It is not available in users' filters for privacy reasons.
-
-
-
-Defer, freeze, and fail commands for system filters
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[freezing messages]
-cindex:[message,freezing]
-cindex:[message,forced failure]
-cindex:[%fail%,in system filter]
-cindex:[%freeze% in system filter]
-cindex:[%defer% in system filter]
-There are three extra commands (%defer%, %freeze% and %fail%) which are always
-available in system filters, but are not normally enabled in users' filters.
-(See the %allow_defer%,
-%allow_freeze% and %allow_fail% options for the ^redirect^ router.) These
-commands can optionally be followed by the word %text% and a string containing
-an error message, for example:
-
- fail text "this message looks like spam to me"
-
-The keyword %text% is optional if the next character is a double quote.
-
-The %defer% command defers delivery of the original recipients of the message.
-The %fail% command causes all the original recipients to be failed, and a
-bounce message to be created. The %freeze% command suspends all delivery
-attempts for the original recipients. In all cases, any new deliveries that are
-specified by the filter are attempted as normal after the filter has run.
-
-The %freeze% command is ignored if the message has been manually unfrozen and
-not manually frozen since. This means that automatic freezing by a system
-filter can be used as a way of checking out suspicious messages. If a message
-is found to be all right, manually unfreezing it allows it to be delivered.
-
-cindex:[log,%fail% command log line]
-cindex:[%fail%,log line; reducing]
-The text given with a fail command is used as part of the bounce message as
-well as being written to the log. If the message is quite long, this can fill
-up a lot of log space when such failures are common. To reduce the size of the
-log message, Exim interprets the text in a special way if it starts with the
-two characters `<<` and contains `>>` later. The text between these two
-strings is written to the log, and the rest of the text is used in the bounce
-message. For example:
-
-....
-fail "<<filter test 1>>Your message is rejected \
- because it contains attachments that we are \
- not prepared to receive."
-....
-
-
-cindex:[loop,caused by %fail%]
-Take great care with the %fail% command when basing the decision to fail on the
-contents of the message, because the bounce message will of course include the
-contents of the original message and will therefore trigger the %fail% command
-again (causing a mail loop) unless steps are taken to prevent this. Testing the
-%error_message% condition is one way to prevent this. You could use, for
-example
-
- if $message_body contains "this is spam" and not error_message
- then fail text "spam is not wanted here" endif
-
-though of course that might let through unwanted bounce messages. The
-alternative is clever checking of the body and/or headers to detect bounces
-generated by the filter.
-
-The interpretation of a system filter file ceases after a
-%defer%,
-%freeze%, or %fail% command is obeyed. However, any deliveries that were set up
-earlier in the filter file are honoured, so you can use a sequence such as
-
- mail ...
- freeze
-
-to send a specified message when the system filter is freezing (or deferring or
-failing) a message. The normal deliveries for the message do not, of course,
-take place.
-
-
-
-[[SECTaddremheasys]]
-Adding and removing headers in a system filter
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[header lines,adding; in system filter]
-cindex:[header lines,removing; in system filter]
-cindex:[filter,header lines; adding/removing]
-Two filter commands that are available only in system filters are:
-
- headers add <string>
- headers remove <string>
-
-The argument for the %headers add% is a string that is expanded and then added
-to the end of the message's headers. It is the responsibility of the filter
-maintainer to make sure it conforms to RFC 2822 syntax. Leading white space is
-ignored, and if the string is otherwise empty, or if the expansion is forced to
-fail, the command has no effect.
-
-You can use ``\n'' within the string, followed by white space, to specify
-continued header lines. More than one header may be added in one command by
-including ``\n'' within the string without any following white space. For
-example:
-
-....
-headers add "X-header-1: ....\n \
- continuation of X-header-1 ...\n\
- X-header-2: ...."
-....
-
-Note that the header line continuation white space after the first newline must
-be placed before the backslash that continues the input string, because white
-space after input continuations is ignored.
-
-The argument for %headers remove% is a colon-separated list of header names.
-This command applies only to those headers that are stored with the message;
-those that are added at delivery time (such as 'Envelope-To:' and
-'Return-Path:') cannot be removed by this means. If there is more than one
-header with the same name, they are all removed.
-
-The %headers% command in a system filter makes an immediate change to the set
-of header lines that was received with the message (with possible additions
-from ACL processing). Subsequent commands in the system filter operate on the
-modified set, which also forms the basis for subsequent message delivery.
-Unless further modified during routing or transporting, this set of headers is
-used for all recipients of the message.
-
-During routing and transporting, the variables that refer to the contents of
-header lines refer only to those lines that are in this set. Thus, header lines
-that are added by a system filter are visible to users' filter files and to all
-routers and transports. This contrasts with the manipulation of header lines by
-routers and transports, which is not immediate, but which instead is saved up
-until the message is actually being written (see section <<SECTheadersaddrem>>).
-
-If the message is not delivered at the first attempt, header lines that were
-added by the system filter are stored with the message, and so are still
-present at the next delivery attempt. Header lines that were removed are still
-present, but marked ``deleted'' so that they are not transported with the
-message. For this reason, it is usual to make the %headers% command conditional
-on %first_delivery% so that the set of header lines is not modified more than
-once.
-
-Because header modification in a system filter acts immediately, you have to
-use an indirect approach if you want to modify the contents of a header line.
-For example:
-
- headers add "Old-Subject: $h_subject:"
- headers remove "Subject"
- headers add "Subject: new subject (was: $h_old-subject:)"
- headers remove "Old-Subject"
-
-
-
-
-
-Setting an errors address in a system filter
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[envelope sender]
-In a system filter, if a %deliver% command is followed by
-
- errors_to <some address>
-
-in order to change the envelope sender (and hence the error reporting) for that
-delivery, any address may be specified. (In a user filter, only the current
-user's address can be set.) For example, if some mail is being monitored, you
-might use
-
- unseen deliver monitor@spying.example errors_to root@local.example
-
-to take a copy which would not be sent back to the normal error reporting
-address if its delivery failed.
-
-
-
-[[SECTperaddfil]]
-Per-address filtering
-~~~~~~~~~~~~~~~~~~~~~
-cindex:[$domain$]
-cindex:[$local_part$]
-In contrast to the system filter, which is run just once per message for each
-delivery attempt, it is also possible to set up a system-wide filtering
-operation that runs once for each recipient address. In this case, variables
-such as $local_part$ and $domain$ can be used, and indeed, the choice of
-filter file could be made dependent on them. This is an example of a router
-which implements such a filter:
-
- central_filter:
- check_local_user
- driver = redirect
- domains = +local_domains
- file = /central/filters/$local_part
- no_verify
- allow_filter
- allow_freeze
-
-The filter is run in a separate process under its own uid. Therefore, either
-%check_local_user% must be set (as above), in which case the filter is run as
-the local user, or the %user% option must be used to specify which user to use.
-If both are set, %user% overrides.
-
-Care should be taken to ensure that none of the commands in the filter file
-specify a significant delivery if the message is to go on to be delivered to
-its intended recipient. The router will not then claim to have dealt with the
-address, so it will be passed on to subsequent routers to be delivered in the
-normal way.
-
-
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPmsgproc]]
-Message processing
-------------------
-cindex:[message,general processing]
-Exim performs various transformations on the sender and recipient addresses of
-all messages that it handles, and also on the messages' header lines. Some of
-these are optional and configurable, while others always take place. All of
-this processing, except rewriting as a result of routing, and the addition or
-removal of header lines while delivering, happens when a message is received,
-before it is placed on Exim's queue.
-
-Some of the automatic processing takes place by default only for
-``locally-originated'' messages. This adjective is used to describe messages that
-are not received over TCP/IP, but instead are passed to an Exim process on its
-standard input. This includes the interactive ``local SMTP'' case that is set up
-by the %-bs% command line option.
-
-*Note*: messages received over TCP/IP on the loopback interface (127.0.0.1
-or ::1) are not considered to be locally-originated. Exim does not treat the
-loopback interface specially in any way.
-
-If you want the loopback interface to be treated specially, you must ensure
-that there are appropriate entries in your ACLs.
-
-
-
-
-[[SECTsubmodnon]]
-Submission mode for non-local messages
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-[revisionflag="changed"]
-cindex:[message,submission]
-cindex:[submission mode]
-Processing that happens automatically for locally-originated messages (unless
-%suppress_local_fixups% is set) can also be requested for messages that are
-received over TCP/IP. The term ``submission mode'' is used to describe this
-state. Submisssion mode is set by the modifier
-
- control = submission
-
-in a MAIL, RCPT, or pre-data ACL for an incoming message (see sections
-<<SECTACLmodi>> and <<SECTcontrols>>). This makes Exim treat the message as a
-local submission, and is normally used when the source of the message is known
-to be an MUA running on a client host (as opposed to an MTA). For example, to
-set submission mode for messages originating on the IPv4 loopback interface,
-you could include the following in the MAIL ACL:
-
- warn hosts = 127.0.0.1
- control = submission
-
-cindex:[%sender_retain%]
-There are some options that can be used when setting submission mode. A slash
-is used to separate options. For example:
-
- control = submission/sender_retain
-
-Specifying %sender_retain% has the effect of setting %local_sender_retain%
-true and %local_from_check% false for the current incoming message. The first
-of these allows an existing 'Sender:' header in the message to remain, and the
-second suppresses the check to ensure that 'From:' matches the authenticated
-sender. With this setting, Exim still fixes up messages by adding 'Date:' and
-'Message-ID:' header lines if they are missing, but makes no attempt to check
-sender authenticity in header lines.
-
-When %sender_retain% is not set, a submission mode setting may specify a domain
-to be used when generating a 'From:' or 'Sender:' header line. For example:
-
- control = submission/domain=some.domain
-
-[revisionflag="changed"]
-The domain may be empty. How this value is used is described in sections
-<<SECTthefrohea>> and <<SECTthesenhea>>. There is also a %name% option that
-allows you to specify the user's full name for inclusion in a created
-'Sender:' or 'From:' header line. For example:
-
-[revisionflag="changed"]
-....
-accept authenticated = *
- control = submission/domain=wonderland.example/\
- name=${lookup {$authenticated_id} \
- lsearch {/etc/exim/namelist}}
-....
-
-[revisionflag="changed"]
-Because the name may contain any characters, including slashes, the %name%
-option must be given last. The remainder of the string is used as the name. For
-the example above, if _/etc/exim/namelist_ contains:
-
-[revisionflag="changed"]
-....
-bigegg: Humpty Dumpty
-....
-
-[revisionflag="changed"]
-then when the sender has authenticated as 'bigegg', the generated 'Sender:'
-line would be:
-
-[revisionflag="changed"]
-....
-Sender: Humpty Dumpty <bigegg@wonderland.example>
-....
-
-[revisionflag="changed"]
-cindex:[return path,in submission mode]
-By default, submission mode forces the return path to the same address as is
-used to create the 'Sender:' header. However, if %sender_retain% is specified,
-the return path is also left unchanged.
-
-[revisionflag="changed"]
-*Note*: the changes caused by submission mode take effect after the predata
-ACL. This means that any sender checks performed before the fix-ups use the
-untrusted sender address specified by the user, not the trusted sender address
-specified by submission mode. Although this might be slightly unexpected, it
-does mean that you can configure ACL checks to spot that a user is trying to
-spoof another's address.
-
-
-[[SECTlineendings]]
-Line endings
-~~~~~~~~~~~~
-cindex:[line endings]
-cindex:[carriage return]
-cindex:[linefeed]
-RFC 2821 specifies that CRLF (two characters: carriage-return, followed by
-linefeed) is the line ending for messages transmitted over the Internet using
-SMTP over TCP/IP. However, within individual operating systems, different
-conventions are used. For example, Unix-like systems use just LF, but others
-use CRLF or just CR.
-
-Exim was designed for Unix-like systems, and internally, it stores messages
-using the system's convention of a single LF as a line terminator. When
-receiving a message, all line endings are translated to this standard format.
-Originally, it was thought that programs that passed messages directly to an
-MTA within an operating system would use that system's convention. Experience
-has shown that this is not the case; for example, there are Unix applications
-that use CRLF in this circumstance. For this reason, and for compatibility with
-other MTAs, the way Exim handles line endings for all messages is now as
-follows:
-
-- LF not preceded by CR is treated as a line ending.
-
-- CR is treated as a line ending; if it is immediately followed by LF, the LF
-is ignored.
-
-- The sequence ``CR, dot, CR'' does not terminate an incoming SMTP message,
-nor a local message in the state where a line containing only a dot is a
-terminator.
-
-- If a bare CR is encountered within a header line, an extra space is added after
-the line terminator so as not to end the header line. The reasoning behind this
-is that bare CRs in header lines are most likely either to be mistakes, or
-people trying to play silly games.
-
-- If the first header line received in a message ends with CRLF, a subsequent
-bare LF in a header line is treated in the same way as a bare CR in a header
-line.
-
-
-
-
-
-Unqualified addresses
-~~~~~~~~~~~~~~~~~~~~~
-cindex:[unqualified addresses]
-cindex:[address,qualification]
-By default, Exim expects every envelope address it receives from an external
-host to be fully qualified. Unqualified addresses cause negative responses to
-SMTP commands. However, because SMTP is used as a means of transporting
-messages from MUAs running on personal workstations, there is sometimes a
-requirement to accept unqualified addresses from specific hosts or IP networks.
-
-Exim has two options that separately control which hosts may send unqualified
-sender or receipient addresses in SMTP commands, namely
-%sender_unqualified_hosts% and %recipient_unqualified_hosts%. In both
-cases, if an unqualified address is accepted, it is qualified by adding the
-value of %qualify_domain% or %qualify_recipient%, as appropriate.
-
-cindex:[%qualify_domain%]
-cindex:[%qualify_recipient%]
-Unqualified addresses in header lines are automatically qualified for messages
-that are locally originated, unless the %-bnq% option is given on the command
-line. For messages received over SMTP, unqualified addresses in header lines
-are qualified only if unqualified addresses are permitted in SMTP commands. In
-other words, such qualification is also controlled by
-%sender_unqualified_hosts% and %recipient_unqualified_hosts%,
-
-
-
-
-The UUCP From line
-~~~~~~~~~~~~~~~~~~
-cindex:[``From'' line]
-cindex:[UUCP,``From'' line]
-cindex:[sender,address]
-cindex:[%uucp_from_pattern%]
-cindex:[%uucp_from_sender%]
-cindex:[envelope sender]
-cindex:[Sendmail compatibility,``From'' line]
-Messages that have come from UUCP (and some other applications) often begin
-with a line containing the envelope sender and a timestamp, following the word
-``From''. Examples of two common formats are:
-
- From a.oakley@berlin.mus Fri Jan 5 12:35 GMT 1996
- From f.butler@berlin.mus Fri, 7 Jan 97 14:00:00 GMT
-
-This line precedes the RFC 2822 header lines. For compatibility with Sendmail,
-Exim recognizes such lines at the start of messages that are submitted to it
-via the command line (that is, on the standard input). It does not recognize
-such lines in incoming SMTP messages, unless the sending host matches
-%ignore_fromline_hosts% or the %-bs% option was used for a local message and
-%ignore_fromline_local% is set. The recognition is controlled by a regular
-expression that is defined by the %uucp_from_pattern% option, whose default
-value matches the two common cases shown above and puts the address that
-follows ``From'' into $1$.
-
-cindex:[numerical variables ($1$ $2$ etc),in ``From '' line handling]
-When the caller of Exim for a non-SMTP message that contains a ``From'' line is a
-trusted user, the message's sender address is constructed by expanding the
-contents of %uucp_sender_address%, whose default value is ``\$1''. This is then
-parsed as an RFC 2822 address. If there is no domain, the local part is
-qualified with %qualify_domain% unless it is the empty string. However, if the
-command line %-f% option is used, it overrides the ``From'' line.
-
-If the caller of Exim is not trusted, the ``From'' line is recognized, but the
-sender address is not changed. This is also the case for incoming SMTP messages
-that are permitted to contain ``From'' lines.
-
-Only one ``From'' line is recognized. If there is more than one, the second is
-treated as a data line that starts the body of the message, as it is not valid
-as a header line. This also happens if a ``From'' line is present in an incoming
-SMTP message from a source that is not permitted to send them.
-
-
-
-Resent- header lines
-~~~~~~~~~~~~~~~~~~~~
-cindex:[%Resent-% header lines]
-RFC 2822 makes provision for sets of header lines starting with the string
-`Resent-` to be added to a message when it is resent by the original
-recipient to somebody else. These headers are 'Resent-Date:', 'Resent-From:',
-'Resent-Sender:', 'Resent-To:', 'Resent-Cc:', 'Resent-Bcc:' and
-'Resent-Message-ID:'. The RFC says:
-
-'Resent fields are strictly informational. They MUST NOT be used in the normal
-processing of replies or other such automatic actions on messages.'
-
-This leaves things a bit vague as far as other processing actions such as
-address rewriting are concerned. Exim treats %Resent-% header lines as
-follows:
-
-- A 'Resent-From:' line that just contains the login id of the submitting user
-is automatically rewritten in the same way as 'From:' (see below).
-
-- If there's a rewriting rule for a particular header line, it is also applied to
-%Resent-% header lines of the same type. For example, a rule that rewrites
-'From:' also rewrites 'Resent-From:'.
-
-- For local messages, if 'Sender:' is removed on input, 'Resent-Sender:' is also
-removed.
-
-- For a locally-submitted message,
-if there are any %Resent-% header lines but no 'Resent-Date:',
-'Resent-From:', or 'Resent-Message-Id:', they are added as necessary. It is
-the contents of 'Resent-Message-Id:' (rather than 'Message-Id:') which are
-included in log lines in this case.
-
-- The logic for adding 'Sender:' is duplicated for 'Resent-Sender:' when any
-%Resent-% header lines are present.
-
-
-
-
-The Auto-Submitted: header line
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Whenever Exim generates a bounce or a delay warning message, it includes the
-header line
-
- Auto-Submitted: auto-generated
-
-
-
-
-The Bcc: header line
-~~~~~~~~~~~~~~~~~~~~
-cindex:['Bcc:' header line]
-If Exim is called with the %-t% option, to take recipient addresses from a
-message's header, it removes any 'Bcc:' header line that may exist (after
-extracting its addresses). If %-t% is not present on the command line, any
-existing 'Bcc:' is not removed.
-
-
-The Date: header line
-~~~~~~~~~~~~~~~~~~~~~
-[revisionflag="changed"]
-cindex:['Date:' header line]
-If a locally-generated or submission-mode message has no 'Date:' header line,
-Exim adds one, using the current date and time, unless the
-%suppress_local_fixups% control has been specified.
-
-
-The Delivery-date: header line
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:['Delivery-date:' header line]
-cindex:[%delivery_date_remove%]
-'Delivery-date:' header lines are not part of the standard RFC 2822 header
-set. Exim can be configured to add them to the final delivery of messages. (See
-the generic %delivery_date_add% transport option.) They should not be present
-in messages in transit. If the %delivery_date_remove% configuration option is
-set (the default), Exim removes 'Delivery-date:' header lines from incoming
-messages.
-
-
-The Envelope-to: header line
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:['Envelope-to:' header line]
-cindex:[%envelope_to_remove%]
-'Envelope-to:' header lines are not part of the standard RFC 2822 header set.
-Exim can be configured to add them to the final delivery of messages. (See the
-generic %envelope_to_add% transport option.) They should not be present in
-messages in transit. If the %envelope_to_remove% configuration option is set
-(the default), Exim removes 'Envelope-to:' header lines from incoming
-messages.
-
-
-[[SECTthefrohea]]
-The From: header line
-~~~~~~~~~~~~~~~~~~~~~
-cindex:['From:' header line]
-cindex:[Sendmail compatibility,``From'' line]
-cindex:[message,submission]
-cindex:[submission mode]
-If a submission-mode message does not contain a 'From:' header line, Exim adds
-one if either of the following conditions is true:
-
-- The envelope sender address is not empty (that is, this is not a bounce
-message). The added header line copies the envelope sender address.
-
-- cindex:[$authenticated_id$]
-The SMTP session is authenticated and $authenticated_id$ is not empty.
-
-.. cindex:[$qualify_domain$]
-If no domain is specified by the submission control, the local part is
-$authenticated_id$ and the domain is $qualify_domain$.
-
-.. If a non-empty domain is specified by the submission control, the local
-part is $authenticated_id$, and the the domain is the specified domain.
-
-.. If an empty domain is specified by the submission control,
-$authenticated_id$ is assumed to be the complete address.
-
-A non-empty envelope sender takes precedence.
-
-[revisionflag="changed"]
-If a locally-generated incoming message does not contain a 'From:' header line,
-and the %suppress_local_fixups% control is not set, Exim adds one containing
-the sender's address. The calling user's login name and full name are used to
-construct the address, as described in section <<SECTconstr>>. They are
-obtained from the password data by calling 'getpwuid()' (but see the
-%unknown_login% configuration option). The address is qualified with
-%qualify_domain%.
-
-For compatibility with Sendmail, if an incoming, non-SMTP message has a
-'From:' header line containing just the unqualified login name of the calling
-user, this is replaced by an address containing the user's login name and full
-name as described in section <<SECTconstr>>.
-
-
-The Message-ID: header line
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
-[revisionflag="changed"]
-cindex:['Message-ID:' header line]
-cindex:[message,submission]
-cindex:[%message_id_header_text%]
-If a locally-generated or submission-mode incoming message does not contain a
-'Message-ID:' or 'Resent-Message-ID:' header line, and the
-%suppress_local_fixups% control is not set, Exim adds a suitable header line to
-the message. If there are any 'Resent-:' headers in the message, it creates
-'Resent-Message-ID:'. The id is constructed from Exim's internal message id,
-preceded by the letter E to ensure it starts with a letter, and followed by @
-and the primary host name. Additional information can be included in this
-header line by setting the %message_id_header_text% and/or
-%message_id_header_domain% options.
-
-
-
-The Received: header line
-~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:['Received:' header line]
-A 'Received:' header line is added at the start of every message. The contents
-are defined by the %received_header_text% configuration option, and Exim
-automatically adds a semicolon and a timestamp to the configured string.
-
-The 'Received:' header is generated as soon as the message's header lines have
-been received. At this stage, the timestamp in the 'Received:' header line is
-the time that the message started to be received. This is the value that is
-seen by the DATA ACL and by the 'local_scan()' function.
-
-Once a message is accepted, the timestamp in the 'Received:' header line is
-changed to the time of acceptance, which is (apart from a small delay while the
--H spool file is written) the earliest time at which delivery could start.
-
-
-
-The Return-path: header line
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:['Return-path:' header line]
-cindex:[%return_path_remove%]
-'Return-path:' header lines are defined as something an MTA may insert when
-it does the final delivery of messages. (See the generic %return_path_add%
-transport option.) Therefore, they should not be present in messages in
-transit. If the %return_path_remove% configuration option is set (the
-default), Exim removes 'Return-path:' header lines from incoming messages.
-
-
-
-[[SECTthesenhea]]
-The Sender: header line
-~~~~~~~~~~~~~~~~~~~~~~~
-[revisionflag="changed"]
-cindex:['Sender:' header line]
-cindex:[message,submission]
-For a locally-originated message from an untrusted user, Exim may remove an
-existing 'Sender:' header line, and it may add a new one. You can modify these
-actions by setting the %local_sender_retain% option true, the
-%local_from_check% option false, or by using the %suppress_local_fixups%
-control setting.
-
-[revisionflag="changed"]
-When a local message is received from an untrusted user and %local_from_check%
-is true (the default), and the %suppress_local_fixups% control has not been
-set, a check is made to see if the address given in the 'From:' header line is
-the correct (local) sender of the message. The address that is expected has the
-login name as the local part and the value of %qualify_domain% as the domain.
-Prefixes and suffixes for the local part can be permitted by setting
-%local_from_prefix% and %local_from_suffix% appropriately. If 'From:' does not
-contain the correct sender, a 'Sender:' line is added to the message.
-
-If you set %local_from_check% false, this checking does not occur. However,
-the removal of an existing 'Sender:' line still happens, unless you also set
-%local_sender_retain% to be true. It is not possible to set both of these
-options true at the same time.
-
-cindex:[submission mode]
-By default, no processing of 'Sender:' header lines is done for messages
-received over TCP/IP or for messages submitted by trusted users. However, when
-a message is received over TCP/IP in submission mode, and %sender_retain% is
-not specified on the submission control, the following processing takes place:
-
-cindex:[$authenticated_id$]
-First, any existing 'Sender:' lines are removed. Then, if the SMTP session is
-authenticated, and $authenticated_id$ is not empty, a sender address is
-created as follows:
-
-- cindex:[$qualify_domain$]
-If no domain is specified by the submission control, the local part is
-$authenticated_id$ and the domain is $qualify_domain$.
-
-- If a non-empty domain is specified by the submission control, the local part
-is $authenticated_id$, and the the domain is the specified domain.
-
-- If an empty domain is specified by the submission control,
-$authenticated_id$ is assumed to be the complete address.
-
-This address is compared with the address in the 'From:' header line. If they
-are different, a 'Sender:' header line containing the created address is
-added. Prefixes and suffixes for the local part in 'From:' can be permitted by
-setting %local_from_prefix% and %local_from_suffix% appropriately.
-
-[revisionflag="changed"]
-cindex:[return path,created from 'Sender:']
-*Note*: whenever a 'Sender:' header line is created, the return path for the
-message (the envelope sender address) is changed to be the same address, except
-in the case of submission mode when %sender_retain% is specified.
-
-
-
-
-[[SECTheadersaddrem]]
-Adding and removing header lines in routers and transports
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-[revisionflag="changed"]
-cindex:[header lines,adding; in router or transport]
-cindex:[header lines,removing; in router or transport]
-When a message is delivered, the addition and removal of header lines can be
-specified in a system filter, or on any of the routers and transports that
-process the message. Section <<SECTaddremheasys>> contains details about
-modifying headers in a system filter. Header lines can also be added in an ACL
-as a message is received (see section <<SECTaddheadwarn>>).
-
-In contrast to what happens in a system filter, header modifications that are
-specified on routers and transports apply only to the particular recipient
-addresses that are being processed by those routers and transports. These
-changes do not actually take place until a copy of the message is being
-transported. Therefore, they do not affect the basic set of header lines, and
-they do not affect the values of the variables that refer to header lines.
-
-[revisionflag="changed"]
-*Note*: in particular, this means that any expansions in the configuration of
-the transport cannot refer to the modified header lines, because such
-expansions all occur before the message is actually transported.
-
-For both routers and transports, the result of expanding a %headers_add%
-option must be in the form of one or more RFC 2822 header lines, separated by
-newlines (coded as ``\n''). For example:
-
-....
-headers_add = X-added-header: added by $primary_hostname\n\
- X-added-second: another added header line
-....
-
-Exim does not check the syntax of these added header lines.
-
-The result of expanding %headers_remove% must consist of a colon-separated
-list of header names. This is confusing, because header names themselves are
-often terminated by colons. In this case, the colons are the list separators,
-not part of the names. For example:
-
- headers_remove = return-receipt-to:acknowledge-to
-
-When %headers_add% or %headers_remove% is specified on a router, its value is
-expanded at routing time, and then associated with all addresses that are
-accepted by that router, and also with any new addresses that it generates. If
-an address passes through several routers as a result of aliasing or
-forwarding, the changes are cumulative.
-
-cindex:[%unseen% option]
-However, this does not apply to multiple routers that result from the use of
-the %unseen% option. Any header modifications that were specified by the
-``unseen'' router or its predecessors apply only to the ``unseen'' delivery.
-
-Addresses that end up with different %headers_add% or %headers_remove%
-settings cannot be delivered together in a batch, so a transport is always
-dealing with a set of addresses that have the same header-processing
-requirements.
-
-The transport starts by writing the original set of header lines that arrived
-with the message, possibly modified by the system filter. As it writes out
-these lines, it consults the list of header names that were attached to the
-recipient address(es) by %headers_remove% options in routers, and it also
-consults the transport's own %headers_remove% option. Header lines whose names
-are on either of these lists are not written out. If there are multiple
-instances of any listed header, they are all skipped.
-
-After the remaining original header lines have been written, new header
-lines that were specified by routers' %headers_add% options are written, in
-the order in which they were attached to the address. These are followed by any
-header lines specified by the transport's %headers_add% option.
-
-This way of handling header line modifications in routers and transports has
-the following consequences:
-
-- The original set of header lines, possibly modified by the system filter,
-remains ``visible'', in the sense that the $header_$'xxx' variables refer to
-it, at all times.
-
-- Header lines that are added by a router's
-%headers_add% option are not accessible by means of the $header_$'xxx'
-expansion syntax in subsequent routers or the transport.
-
-- Conversely, header lines that are specified for removal by %headers_remove% in
-a router remain visible to subsequent routers and the transport.
-
-- Headers added to an address by %headers_add% in a router cannot be removed by
-a later router or by a transport.
-
-- An added header can refer to the contents of an original header that is to be
-removed, even it has the same name as the added header. For example:
-
- headers_remove = subject
- headers_add = Subject: new subject (was: $h_subject:)
-
-
-*Warning*: The %headers_add% and %headers_remove% options cannot be used
-for a ^redirect^ router that has the %one_time% option set.
-
-
-
-
-
-[[SECTconstr]]
-Constructed addresses
-~~~~~~~~~~~~~~~~~~~~~
-cindex:[address,constructed]
-cindex:[constructed address]
-When Exim constructs a sender address for a locally-generated message, it uses
-the form
-
- <user name> <<login>@<qualify_domain>>
-
-For example:
-
- Zaphod Beeblebrox <zaphod@end.univ.example>
-
-The user name is obtained from the %-F% command line option if set, or
-otherwise by looking up the calling user by 'getpwuid()' and extracting the
-``gecos'' field from the password entry. If the ``gecos'' field contains an
-ampersand character, this is replaced by the login name with the first letter
-upper cased, as is conventional in a number of operating systems. See the
-%gecos_name% option for a way to tailor the handling of the ``gecos'' field. The
-%unknown_username% option can be used to specify user names in cases when
-there is no password file entry.
-
-cindex:[RFC 2047]
-In all cases, the user name is made to conform to RFC 2822 by quoting all or
-parts of it if necessary. In addition, if it contains any non-printing
-characters, it is encoded as described in RFC 2047, which defines a way of
-including non-ASCII characters in header lines. The value of the
-%headers_charset% option specifies the name of the encoding that is used (the
-characters are assumed to be in this encoding). The setting of
-%print_topbitchars% controls whether characters with the top bit set (that is,
-with codes greater than 127) count as printing characters or not.
-
-
-
-Case of local parts
-~~~~~~~~~~~~~~~~~~~
-cindex:[case of local parts]
-cindex:[local part,case of]
-RFC 2822 states that the case of letters in the local parts of addresses cannot
-be assumed to be non-significant. Exim preserves the case of local parts of
-addresses, but by default it uses a lower-cased form when it is routing,
-because on most Unix systems, usernames are in lower case and case-insensitive
-routing is required. However, any particular router can be made to use the
-original case for local parts by setting the %caseful_local_part% generic
-router option.
-
-cindex:[mixed-case login names]
-If you must have mixed-case user names on your system, the best way to proceed,
-assuming you want case-independent handling of incoming email, is to set up
-your first router to convert incoming local parts in your domains to the
-correct case by means of a file lookup. For example:
-
-....
-correct_case:
- driver = redirect
- domains = +local_domains
- data = ${lookup{$local_part}cdb\
- {/etc/usercased.cdb}{$value}fail}\
- @$domain
-....
-
-For this router, the local part is forced to lower case by the default action
-(%caseful_local_part% is not set). The lower-cased local part is used to look
-up a new local part in the correct case. If you then set %caseful_local_part%
-on any subsequent routers which process your domains, they will operate on
-local parts with the correct case in a case-sensitive manner.
-
-
-
-Dots in local parts
-~~~~~~~~~~~~~~~~~~~
-cindex:[dot,in local part]
-cindex:[local part,dots in]
-RFC 2822 forbids empty components in local parts. That is, an unquoted local
-part may not begin or end with a dot, nor have two consecutive dots in the
-middle. However, it seems that many MTAs do not enforce this, so Exim permits
-empty components for compatibility.
-
-
-
-Rewriting addresses
-~~~~~~~~~~~~~~~~~~~
-cindex:[rewriting,addresses]
-Rewriting of sender and recipient addresses, and addresses in headers, can
-happen automatically, or as the result of configuration options, as described
-in chapter <<CHAPrewrite>>. The headers that may be affected by this are 'Bcc:',
-'Cc:', 'From:', 'Reply-To:', 'Sender:', and 'To:'.
-
-Automatic rewriting includes qualification, as mentioned above. The other case
-in which it can happen is when an incomplete non-local domain is given. The
-routing process may cause this to be expanded into the full domain name. For
-example, a header such as
-
- To: hare@teaparty
-
-might get rewritten as
-
- To: hare@teaparty.wonderland.fict.example
-
-Rewriting as a result of routing is the one kind of message processing that
-does not happen at input time, as it cannot be done until the address has
-been routed.
-
-Strictly, one should not do 'any' deliveries of a message until all its
-addresses have been routed, in case any of the headers get changed as a
-result of routing. However, doing this in practice would hold up many
-deliveries for unreasonable amounts of time, just because one address could not
-immediately be routed. Exim therefore does not delay other deliveries when
-routing of one or more addresses is deferred.
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPSMTP]]
-SMTP processing
----------------
-cindex:[SMTP,processing details]
-cindex:[LMTP,processing details]
-Exim supports a number of different ways of using the SMTP protocol, and its
-LMTP variant, which is an interactive protocol for transferring messages into a
-closed mail store application. This chapter contains details of how SMTP is
-processed. For incoming mail, the following are available:
-
-- SMTP over TCP/IP (Exim daemon or 'inetd');
-
-- SMTP over the standard input and output (the %-bs% option);
-
-- Batched SMTP on the standard input (the %-bS% option).
-
-For mail delivery, the following are available:
-
-- SMTP over TCP/IP (the ^smtp^ transport);
-
-- LMTP over TCP/IP (the ^smtp^ transport with the %protocol% option set to
-``lmtp'');
-
-- LMTP over a pipe to a process running in the local host (the ^lmtp^
-transport);
-
-- Batched SMTP to a file or pipe (the ^appendfile^ and ^pipe^ transports with
-the %use_bsmtp% option set).
-
-'Batched SMTP' is the name for a process in which batches of messages are
-stored in or read from files (or pipes), in a format in which SMTP commands are
-used to contain the envelope information.
-
-
-
-[[SECToutSMTPTCP]]
-Outgoing SMTP and LMTP over TCP/IP
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[SMTP,outgoing over TCP/IP]
-cindex:[outgoing SMTP over TCP/IP]
-cindex:[LMTP,over TCP/IP]
-cindex:[outgoing LMTP over TCP/IP]
-cindex:[EHLO]
-cindex:[HELO]
-cindex:[SIZE option on MAIL command]
-Outgoing SMTP and LMTP over TCP/IP is implemented by the ^smtp^ transport.
-The %protocol% option selects which protocol is to be used, but the actual
-processing is the same in both cases.
-
-If, in response to its EHLO command, Exim is told that the SIZE
-parameter is supported, it adds SIZE=<'n'> to each subsequent MAIL
-command. The value of <'n'> is the message size plus the value of the
-%size_addition% option (default 1024) to allow for additions to the message
-such as per-transport header lines, or changes made in a
-cindex:[transport,filter]
-cindex:[filter,transport filter]
-transport filter. If %size_addition% is set negative, the use of SIZE is
-suppressed.
-
-If the remote server advertises support for PIPELINING, Exim uses the
-pipelining extension to SMTP (RFC 2197) to reduce the number of TCP/IP packets
-required for the transaction.
-
-If the remote server advertises support for the STARTTLS command, and Exim
-was built to support TLS encryption, it tries to start a TLS session unless the
-server matches %hosts_avoid_tls%. See chapter <<CHAPTLS>> for more details.
-
-If the remote server advertises support for the AUTH command, Exim scans
-the authenticators configuration for any suitable client settings, as described
-in chapter <<CHAPSMTPAUTH>>.
-
-cindex:[carriage return]
-cindex:[linefeed]
-Responses from the remote host are supposed to be terminated by CR followed by
-LF. However, there are known to be hosts that do not send CR characters, so in
-order to be able to interwork with such hosts, Exim treats LF on its own as a
-line terminator.
-
-If a message contains a number of different addresses, all those with the same
-characteristics (for example, the same envelope sender) that resolve to the
-same set of hosts, in the same order, are sent in a single SMTP transaction,
-even if they are for different domains, unless there are more than the setting
-of the %max_rcpts% option in the ^smtp^ transport allows, in which case they
-are split into groups containing no more than %max_rcpts% addresses each. If
-%remote_max_parallel% is greater than one, such groups may be sent in
-parallel sessions. The order of hosts with identical MX values is not
-significant when checking whether addresses can be batched in this way.
-
-When the ^smtp^ transport suffers a temporary failure that is not
-message-related, Exim updates its transport-specific database, which contains
-records indexed by host name that remember which messages are waiting for each
-particular host. It also updates the retry database with new retry times.
-
-cindex:[hints database,retry keys]
-Exim's retry hints are based on host name plus IP address, so if one address of
-a multi-homed host is broken, it will soon be skipped most of the time.
-See the next section for more detail about error handling.
-
-cindex:[SMTP,passed connection]
-cindex:[SMTP,batching over TCP/IP]
-When a message is successfully delivered over a TCP/IP SMTP connection, Exim
-looks in the hints database for the transport to see if there are any queued
-messages waiting for the host to which it is connected. If it finds one, it
-creates a new Exim process using the %-MC% option (which can only be used by a
-process running as root or the Exim user) and passes the TCP/IP socket to it so
-that it can deliver another message using the same socket. The new process does
-only those deliveries that are routed to the connected host, and may in turn
-pass the socket on to a third process, and so on.
-
-The %connection_max_messages% option of the ^smtp^ transport can be used to
-limit the number of messages sent down a single TCP/IP connection.
-
-cindex:[asterisk,after IP address]
-The second and subsequent messages delivered down an existing connection are
-identified in the main log by the addition of an asterisk after the closing
-square bracket of the IP address.
-
-
-
-
-[[SECToutSMTPerr]]
-Errors in outgoing SMTP
-~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[error,in outgoing SMTP]
-cindex:[SMTP,errors in outgoing]
-cindex:[host,error]
-Three different kinds of error are recognized for outgoing SMTP: host errors,
-message errors, and recipient errors.
-
-. A host error is not associated with a particular message or with a
-particular recipient of a message. The host errors are:
-+
---
-- Connection refused or timed out,
-
-- Any error response code on connection,
-
-- Any error response code to EHLO or HELO,
-
-- Loss of connection at any time, except after ``.'',
-
-- I/O errors at any time,
-
-- Timeouts during the session, other than in response to MAIL, RCPT or
-the ``.'' at the end of the data.
---
-+
-For a host error, a permanent error response on connection, or in response to
-EHLO, causes all addresses routed to the host to be failed. Any other host
-error causes all addresses to be deferred, and retry data to be created for the
-host. It is not tried again, for any message, until its retry time arrives. If
-the current set of addresses are not all delivered in this run (to some
-alternative host), the message is added to the list of those waiting for this
-host, so if it is still undelivered when a subsequent successful delivery is
-made to the host, it will be sent down the same SMTP connection.
-
-. cindex:[message,error]
-A message error is associated with a particular message when sent to a
-particular host, but not with a particular recipient of the message. The
-message errors are:
-+
---
-- Any error response code to MAIL, DATA, or the ``.'' that terminates
-the data,
-
-- Timeout after MAIL,
-
-- Timeout or loss of connection after the ``.'' that terminates the data. A
-timeout after the DATA command itself is treated as a host error, as is loss of
-connection at any other time.
---
-+
-For a message error, a permanent error response (5##'xx') causes all addresses
-to be failed, and a delivery error report to be returned to the sender. A
-temporary error response (4##'xx'), or one of the timeouts, causes all
-addresses to be deferred. Retry data is not created for the host, but instead,
-a retry record for the combination of host plus message id is created. The
-message is not added to the list of those waiting for this host. This ensures
-that the failing message will not be sent to this host again until the retry
-time arrives. However, other messages that are routed to the host are not
-affected, so if it is some property of the message that is causing the error,
-it will not stop the delivery of other mail.
-+
-If the remote host specified support for the SIZE parameter in its response
-to EHLO, Exim adds SIZE='nnn' to the MAIL command, so an
-over-large message will cause a message error because the error arrives as a
-response to MAIL.
-
-. cindex:[recipient,error]
-A recipient error is associated with a particular recipient of a message. The
-recipient errors are:
-+
---
-- Any error response to RCPT,
-
-- Timeout after RCPT.
---
-+
-For a recipient error, a permanent error response (5##'xx') causes the
-recipient address to be failed, and a bounce message to be returned to the
-sender. A temporary error response (4##'xx') or a timeout causes the failing
-address to be deferred, and routing retry data to be created for it. This is
-used to delay processing of the address in subsequent queue runs, until its
-routing retry time arrives. This applies to all messages, but because it
-operates only in queue runs, one attempt will be made to deliver a new message
-to the failing address before the delay starts to operate. This ensures that,
-if the failure is really related to the message rather than the recipient
-(``message too big for this recipient'' is a possible example), other messages
-have a chance of getting delivered. If a delivery to the address does succeed,
-the retry information gets cleared, so all stuck messages get tried again, and
-the retry clock is reset.
-+
-The message is not added to the list of those waiting for this host. Use of the
-host for other messages is unaffected, and except in the case of a timeout,
-other recipients are processed independently, and may be successfully delivered
-in the current SMTP session. After a timeout it is of course impossible to
-proceed with the session, so all addresses get deferred. However, those other
-than the one that failed do not suffer any subsequent retry delays. Therefore,
-if one recipient is causing trouble, the others have a chance of getting
-through when a subsequent delivery attempt occurs before the failing
-recipient's retry time.
-
-///
-End of list
-///
-
-In all cases, if there are other hosts (or IP addresses) available for the
-current set of addresses (for example, from multiple MX records), they are
-tried in this run for any undelivered addresses, subject of course to their
-own retry data. In other words, recipient error retry data does not take effect
-until the next delivery attempt.
-
-Some hosts have been observed to give temporary error responses to every
-MAIL command at certain times (``insufficient space'' has been seen). It
-would be nice if such circumstances could be recognized, and defer data for the
-host itself created, but this is not possible within the current Exim design.
-What actually happens is that retry data for every (host, message) combination
-is created.
-
-The reason that timeouts after MAIL and RCPT are treated specially is that
-these can sometimes arise as a result of the remote host's verification
-procedures. Exim makes this assumption, and treats them as if a temporary error
-response had been received. A timeout after ``.'' is treated specially because
-it is known that some broken implementations fail to recognize the end of the
-message if the last character of the last line is a binary zero. Thus, it is
-helpful to treat this case as a message error.
-
-Timeouts at other times are treated as host errors, assuming a problem with the
-host, or the connection to it. If a timeout after MAIL, RCPT,
-or ``.'' is really a connection problem, the assumption is that at the next try
-the timeout is likely to occur at some other point in the dialogue, causing it
-then to be treated as a host error.
-
-There is experimental evidence that some MTAs drop the connection after the
-terminating ``.'' if they do not like the contents of the message for some
-reason, in contravention of the RFC, which indicates that a 5##'xx' response
-should be given. That is why Exim treats this case as a message rather than a
-host error, in order not to delay other messages to the same host.
-
-
-
-
-
-Variable Envelope Return Paths (VERP)
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[VERP]
-cindex:[Variable Envelope Return Paths]
-cindex:[envelope sender]
-Variable Envelope Return Paths -- see
-*ftp://koobera.math.uic.edu/www/proto/verp.txt[]* -- can be supported in Exim
-by using the %return_path% generic transport option to rewrite the return path
-at transport time. For example, the following could be used on an ^smtp^
-transport:
-
-....
-return_path = \
- ${if match {$return_path}{^(.+?)-request@your.dom.example\$}\
- {$1-request=$local_part%$domain@your.dom.example}fail}
-....
-
-This has the effect of rewriting the return path (envelope sender) on all
-outgoing SMTP messages, if the local part of the original return path ends in
-``-request'', and the domain is 'your.dom.example'. The rewriting inserts the
-local part and domain of the recipient into the return path. Suppose, for
-example, that a message whose return path has been set to
-'somelist-request@your.dom.example' is sent to
-'subscriber@other.dom.example'. In the transport, the return path is
-rewritten as
-
- somelist-request=subscriber%other.dom.example@your.dom.example
-
-For this to work, you must arrange for outgoing messages that have ``-request''
-in their return paths to have just a single recipient. This can be done by
-setting
-
- max_rcpt = 1
-
-cindex:[$local_part$]
-in the ^smtp^ transport. Otherwise a single copy of a message might be
-addressed to several different recipients in the same domain, in which case
-$local_part$ is not available (because it is not unique). Of course, if you
-do start sending out messages with this kind of return path, you must also
-configure Exim to accept the bounce messages that come back to those paths.
-Typically this would be done by setting an %local_part_suffix% option for a
-suitable router.
-
-The overhead incurred in using VERP depends very much on the size of the
-message, the number of recipient addresses that resolve to the same remote
-host, and the speed of the connection over which the message is being sent. If
-a lot of addresses resolve to the same host and the connection is slow, sending
-a separate copy of the message for each address may take substantially longer
-than sending a single copy with many recipients (for which VERP cannot be
-used).
-
-
-
-Incoming SMTP messages over TCP/IP
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[SMTP,incoming over TCP/IP]
-cindex:[incoming SMTP over TCP/IP]
-cindex:[inetd]
-cindex:[daemon]
-Incoming SMTP messages can be accepted in one of two ways: by running a
-listening daemon, or by using 'inetd'. In the latter case, the entry in
-_/etc/inetd.conf_ should be like this:
-
- smtp stream tcp nowait exim /opt/exim/bin/exim in.exim -bs
-
-Exim distinguishes between this case and the case of a locally running user
-agent using the %-bs% option by checking whether or not the standard input is
-a socket. When it is, either the port must be privileged (less than 1024), or
-the caller must be root or the Exim user. If any other user passes a socket
-with an unprivileged port number, Exim prints a message on the standard error
-stream and exits with an error code.
-
-By default, Exim does not make a log entry when a remote host connects or
-disconnects (either via the daemon or 'inetd'), unless the disconnection is
-unexpected. It can be made to write such log entries by setting the
-%smtp_connection% log selector.
-
-cindex:[carriage return]
-cindex:[linefeed]
-Commands from the remote host are supposed to be terminated by CR followed by
-LF. However, there are known to be hosts that do not send CR characters. In
-order to be able to interwork with such hosts, Exim treats LF on its own as a
-line terminator.
-Furthermore, because common code is used for receiving messages from all
-sources, a CR on its own is also interpreted as a line terminator. However, the
-sequence ``CR, dot, CR'' does not terminate incoming SMTP data.
-
-cindex:[EHLO,invalid data]
-cindex:[HELO,invalid data]
-One area that sometimes gives rise to problems concerns the EHLO or
-HELO commands. Some clients send syntactically invalid versions of these
-commands, which Exim rejects by default. (This is nothing to do with verifying
-the data that is sent, so %helo_verify_hosts% is not relevant.) You can tell
-Exim not to apply a syntax check by setting %helo_accept_junk_hosts% to
-match the broken hosts that send invalid commands.
-
-cindex:[SIZE option on MAIL command]
-cindex:[MAIL,SIZE option]
-The amount of disk space available is checked whenever SIZE is received on
-a MAIL command, independently of whether %message_size_limit% or
-%check_spool_space% is configured, unless %smtp_check_spool_space% is set
-false. A temporary error is given if there is not enough space. If
-%check_spool_space% is set, the check is for that amount of space plus the
-value given with SIZE, that is, it checks that the addition of the incoming
-message will not reduce the space below the threshold.
-
-When a message is successfully received, Exim includes the local message id in
-its response to the final ``.'' that terminates the data. If the remote host logs
-this text it can help with tracing what has happened to a message.
-
-The Exim daemon can limit the number of simultaneous incoming connections it is
-prepared to handle (see the %smtp_accept_max% option). It can also limit the
-number of simultaneous incoming connections from a single remote host (see the
-%smtp_accept_max_per_host% option). Additional connection attempts are
-rejected using the SMTP temporary error code 421.
-
-The Exim daemon does not rely on the SIGCHLD signal to detect when a
-subprocess has finished, as this can get lost at busy times. Instead, it looks
-for completed subprocesses every time it wakes up. Provided there are other
-things happening (new incoming calls, starts of queue runs), completed
-processes will be noticed and tidied away. On very quiet systems you may
-sometimes see a ``defunct'' Exim process hanging about. This is not a problem; it
-will be noticed when the daemon next wakes up.
-
-When running as a daemon, Exim can reserve some SMTP slots for specific hosts,
-and can also be set up to reject SMTP calls from non-reserved hosts at times of
-high system load -- for details see the %smtp_accept_reserve%,
-%smtp_load_reserve%, and %smtp_reserve_hosts% options. The load check
-applies in both the daemon and 'inetd' cases.
-
-Exim normally starts a delivery process for each message received, though this
-can be varied by means of the %-odq% command line option and the
-%queue_only%, %queue_only_file%, and %queue_only_load% options. The number
-of simultaneously running delivery processes started in this way from SMTP
-input can be limited by the %smtp_accept_queue% and
-%smtp_accept_queue_per_connection% options. When either limit is reached,
-subsequently received messages are just put on the input queue without starting
-a delivery process.
-
-The controls that involve counts of incoming SMTP calls (%smtp_accept_max%,
-%smtp_accept_queue%, %smtp_accept_reserve%) are not available when Exim is
-started up from the 'inetd' daemon, because in that case each connection is
-handled by an entirely independent Exim process. Control by load average is,
-however, available with 'inetd'.
-
-Exim can be configured to verify addresses in incoming SMTP commands as they
-are received. See chapter <<CHAPACL>> for details. It can also be configured to
-rewrite addresses at this time -- before any syntax checking is done. See
-section <<SECTrewriteS>>.
-
-Exim can also be configured to limit the rate at which a client host submits
-MAIL and RCPT commands in a single SMTP session. See the
-%smtp_ratelimit_hosts% option.
-
-
-
-Unrecognized SMTP commands
-~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[SMTP,unrecognized commands]
-If Exim receives more than %smtp_max_unknown_commands% unrecognized SMTP
-commands during a single SMTP connection, it drops the connection after sending
-the error response to the last command. The default value for
-%smtp_max_unknown_commands% is 3. This is a defence against some kinds of
-abuse that subvert web servers into making connections to SMTP ports; in these
-circumstances, a number of non-SMTP lines are sent first.
-
-
-Syntax and protocol errors in SMTP commands
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[SMTP,syntax errors]
-cindex:[SMTP,protocol errors]
-A syntax error is detected if an SMTP command is recognized, but there is
-something syntactically wrong with its data, for example, a malformed email
-address in a RCPT command. Protocol errors include invalid command
-sequencing such as RCPT before MAIL. If Exim receives more than
-%smtp_max_synprot_errors% such commands during a single SMTP connection, it
-drops the connection after sending the error response to the last command. The
-default value for %smtp_max_synprot_errors% is 3. This is a defence against
-broken clients that loop sending bad commands (yes, it has been seen).
-
-
-
-Use of non-mail SMTP commands
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[SMTP,non-mail commands]
-The ``non-mail'' SMTP commands are those other than MAIL, RCPT, and
-DATA. Exim counts such commands, and drops the connection if there are too
-many of them in a single SMTP session. This action catches some
-denial-of-service attempts and things like repeated failing AUTHs, or a mad
-client looping sending EHLO. The global option %smtp_accept_max_nonmail%
-defines what ``too many'' means. Its default value is 10.
-
-When a new message is expected, one occurrence of RSET is not counted. This
-allows a client to send one RSET between messages (this is not necessary,
-but some clients do it). Exim also allows one uncounted occurence of HELO
-or EHLO, and one occurrence of STARTTLS between messages. After
-starting up a TLS session, another EHLO is expected, and so it too is not
-counted.
-
-The first occurrence of AUTH in a connection, or immediately following
-STARTTLS is also not counted. Otherwise, all commands other than MAIL,
-RCPT, DATA, and QUIT are counted.
-
-You can control which hosts are subject to the limit set by
-%smtp_accept_max_nonmail% by setting
-%smtp_accept_max_nonmail_hosts%. The default value is `\*`, which makes
-the limit apply to all hosts. This option means that you can exclude any
-specific badly-behaved hosts that you have to live with.
-
-
-
-
-The VRFY and EXPN commands
-~~~~~~~~~~~~~~~~~~~~~~~~~~
-When Exim receives a VRFY or EXPN command on a TCP/IP connection, it
-runs the ACL specified by %acl_smtp_vrfy% or %acl_smtp_expn% (as
-appropriate) in order to decide whether the command should be accepted or not.
-If no ACL is defined, the command is rejected.
-
-cindex:[VRFY,processing]
-When VRFY is accepted, it runs exactly the same code as when Exim is
-called with the %-bv% option.
-
-cindex:[EXPN,processing]
-When EXPN is accepted, a single-level expansion of the address is done.
-EXPN is treated as an ``address test'' (similar to the %-bt% option) rather
-than a verification (the %-bv% option). If an unqualified local part is given
-as the argument to EXPN, it is qualified with %qualify_domain%. Rejections
-of VRFY and EXPN commands are logged on the main and reject logs, and
-VRFY verification failures are logged on the main log for consistency with
-RCPT failures.
-
-
-
-[[SECTETRN]]
-The ETRN command
-~~~~~~~~~~~~~~~~
-cindex:[ETRN,processing]
-RFC 1985 describes an SMTP command called ETRN that is designed to
-overcome the security problems of the TURN command (which has fallen into
-disuse). When Exim receives an ETRN command on a TCP/IP connection, it runs
-the ACL specified by %acl_smtp_etrn% in order to decide whether the command
-should be accepted or not. If no ACL is defined, the command is rejected.
-
-The ETRN command is concerned with ``releasing'' messages that are awaiting
-delivery to certain hosts. As Exim does not organize its message queue by host,
-the only form of ETRN that is supported by default is the one where the
-text starts with the ``#'' prefix, in which case the remainder of the text is
-specific to the SMTP server. A valid ETRN command causes a run of Exim with
-the %-R% option to happen, with the remainder of the ETRN text as its
-argument. For example,
-
- ETRN #brigadoon
-
-runs the command
-
- exim -R brigadoon
-
-which causes a delivery attempt on all messages with undelivered addresses
-containing the text ``brigadoon''. When %smtp_etrn_serialize% is set (the
-default), Exim prevents the simultaneous execution of more than one queue run
-for the same argument string as a result of an ETRN command. This stops
-a misbehaving client from starting more than one queue runner at once.
-
-cindex:[hints database,ETRN serialization]
-Exim implements the serialization by means of a hints database in which a
-record is written whenever a process is started by ETRN, and deleted when
-the process completes. However, Exim does not keep the SMTP session waiting for
-the ETRN process to complete. Once ETRN is accepted, the client is sent
-a ``success'' return code. Obviously there is scope for hints records to get left
-lying around if there is a system or program crash. To guard against this, Exim
-ignores any records that are more than six hours old.
-
-cindex:[%smtp_etrn_command%]
-For more control over what ETRN does, the %smtp_etrn_command% option can
-used. This specifies a command that is run whenever ETRN is received,
-whatever the form of its argument. For
-example:
-
- smtp_etrn_command = /etc/etrn_command $domain $sender_host_address
-
-cindex:[$domain$]
-The string is split up into arguments which are independently expanded. The
-expansion variable $domain$ is set to the argument of the ETRN command,
-and no syntax checking is done on the contents of this argument. Exim does not
-wait for the command to complete, so its status code is not checked. Exim runs
-under its own uid and gid when receiving incoming SMTP, so it is not possible
-for it to change them before running the command.
-
-
-
-Incoming local SMTP
-~~~~~~~~~~~~~~~~~~~
-cindex:[SMTP,local incoming]
-Some user agents use SMTP to pass messages to their local MTA using the
-standard input and output, as opposed to passing the envelope on the command
-line and writing the message to the standard input. This is supported by the
-%-bs% option. This form of SMTP is handled in the same way as incoming
-messages over TCP/IP (including the use of ACLs), except that the envelope
-sender given in a MAIL command is ignored unless the caller is trusted. In
-an ACL you can detect this form of SMTP input by testing for an empty host
-identification. It is common to have this as the first line in the ACL that
-runs for RCPT commands:
-
- accept hosts = :
-
-This accepts SMTP messages from local processes without doing any other tests.
-
-
-
-[[SECTbatchSMTP]]
-Outgoing batched SMTP
-~~~~~~~~~~~~~~~~~~~~~
-cindex:[SMTP,batched outgoing]
-cindex:[batched SMTP output]
-Both the ^appendfile^ and ^pipe^ transports can be used for handling batched
-SMTP. Each has an option called %use_bsmtp% which causes messages to be output
-in BSMTP format. No SMTP responses are possible for this form of delivery. All
-it is doing is using SMTP commands as a way of transmitting the envelope along
-with the message.
-
-The message is written to the file or pipe preceded by the SMTP commands
-MAIL and RCPT, and followed by a line containing a single dot. Lines in
-the message that start with a dot have an extra dot added. The SMTP command
-HELO is not normally used. If it is required, the %message_prefix% option
-can be used to specify it.
-
-Because ^appendfile^ and ^pipe^ are both local transports, they accept only
-one recipient address at a time by default. However, you can arrange for them
-to handle several addresses at once by setting the %batch_max% option. When
-this is done for BSMTP, messages may contain multiple RCPT commands. See
-chapter <<CHAPbatching>> for more details.
-
-cindex:[$host$]
-When one or more addresses are routed to a BSMTP transport by a router that
-sets up a host list, the name of the first host on the list is available to the
-transport in the variable $host$. Here is an example of such a transport and
-router:
-
- begin routers
- route_append:
- driver = manualroute
- transport = smtp_appendfile
- route_list = domain.example batch.host.example
-
- begin transports
- smtp_appendfile:
- driver = appendfile
- directory = /var/bsmtp/$host
- batch_max = 1000
- use_bsmtp
- user = exim
-
-This causes messages addressed to 'domain.example' to be written in BSMTP
-format to _/var/bsmtp/batch.host.example_, with only a single copy of each
-message (unless there are more than 1000 recipients).
-
-
-
-[[SECTincomingbatchedSMTP]]
-Incoming batched SMTP
-~~~~~~~~~~~~~~~~~~~~~
-cindex:[SMTP,batched incoming]
-cindex:[batched SMTP input]
-The %-bS% command line option causes Exim to accept one or more messages by
-reading SMTP on the standard input, but to generate no responses. If the caller
-is trusted, the senders in the MAIL commands are believed; otherwise the
-sender is always the caller of Exim. Unqualified senders and receivers are not
-rejected (there seems little point) but instead just get qualified. HELO
-and EHLO act as RSET; VRFY, EXPN, ETRN and HELP, act
-as NOOP; QUIT quits.
-
-No policy checking is done for BSMTP input. That is, no ACL is run at anytime.
-In this respect it is like non-SMTP local input.
-
-If an error is detected while reading a message, including a missing ``.'' at
-the end, Exim gives up immediately. It writes details of the error to the
-standard output in a stylized way that the calling program should be able to
-make some use of automatically, for example:
-
- 554 Unexpected end of file
- Transaction started in line 10
- Error detected in line 14
-
-It writes a more verbose version, for human consumption, to the standard error
-file, for example:
-
- An error was detected while processing a file of BSMTP input.
- The error message was:
-
- 501 '>' missing at end of address
-
- The SMTP transaction started in line 10.
- The error was detected in line 12.
- The SMTP command at fault was:
-
- rcpt to:<malformed@in.com.plete
-
- 1 previous message was successfully processed.
- The rest of the batch was abandoned.
-
-The return code from Exim is zero only if there were no errors. It is 1 if some
-messages were accepted before an error was detected, and 2 if no messages were
-accepted.
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPemsgcust]]
-[titleabbrev="Customizing messages"]
-Customizing bounce and warning messages
----------------------------------------
-When a message fails to be delivered, or remains on the queue for more than a
-configured amount of time, Exim sends a message to the original sender, or
-to an alternative configured address. The text of these messages is built into
-the code of Exim, but it is possible to change it, either by adding a single
-string, or by replacing each of the paragraphs by text supplied in a file.
-
-The 'From:' and 'To:' header lines are automatically generated; you can cause
-a 'Reply-To:' line to be added by setting the %errors_reply_to% option. Exim
-also adds the line
-
- Auto-Submitted: auto-generated
-
-to all warning and bounce messages,
-
-
-Customizing bounce messages
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[customizing,bounce message]
-cindex:[bounce message,customizing]
-If %bounce_message_text% is set, its contents are included in the default
-message immediately after ``This message was created automatically by mail
-delivery software.'' The string is not expanded. It is not used if
-%bounce_message_file% is set.
-
-When %bounce_message_file% is set, it must point to a template file for
-constructing error messages. The file consists of a series of text items,
-separated by lines consisting of exactly four asterisks. If the file cannot be
-opened, default text is used and a message is written to the main and panic
-logs. If any text item in the file is empty, default text is used for that
-item.
-
-cindex:[$bounce_recipient$]
-cindex:[$bounce_return_size_limit$]
-Each item of text that is read from the file is expanded, and there are two
-expansion variables which can be of use here: $bounce_recipient$ is set to the
-recipient of an error message while it is being created, and
-$bounce_return_size_limit$ contains the value of the %return_size_limit%
-option, rounded to a whole number.
-
-The items must appear in the file in the following order:
-
-- The first item is included in the headers, and should include at least a
-'Subject:' header. Exim does not check the syntax of these headers.
-
-- The second item forms the start of the error message. After it, Exim lists the
-failing addresses with their error messages.
-
-- The third item is used to introduce any text from pipe transports that is to be
-returned to the sender. It is omitted if there is no such text.
-
-- The fourth item is used to introduce the copy of the message that is returned
-as part of the error report.
-
-- The fifth item is added after the fourth one if the returned message is
-truncated because it is bigger than %return_size_limit%.
-
-- The sixth item is added after the copy of the original message.
-
-The default state (%bounce_message_file% unset) is equivalent to the
-following file, in which the sixth item is empty. The 'Subject:' line has been
-split into two here in order to fit it on the page:
-
- Subject: Mail delivery failed
- ${if eq{$sender_address}{$bounce_recipient}{: returning message to sender}}
- ****
- This message was created automatically by mail delivery software.
-
- A message ${if eq{$sender_address}{$bounce_recipient}{that you sent }{sent by
-
- <$sender_address>
-
- }}could not be delivered to all of its recipients.
- The following address(es) failed:
- ****
- The following text was generated during the delivery attempt(s):
- ****
- ------ This is a copy of the message, including all the headers. ------
- ****
- ------ The body of the message is $message_size characters long; only the first
- ------ $bounce_return_size_limit or so are included here.
- ****
-
-
-[[SECTcustwarn]]
-Customizing warning messages
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[customizing,warning message]
-cindex:[warning of delay,customizing the message]
-The option %warn_message_file% can be pointed at a template file for use when
-warnings about message delays are created. In this case there are only three
-text sections:
-
-- The first item is included in the headers, and should include at least a
-'Subject:' header. Exim does not check the syntax of these headers.
-
-- The second item forms the start of the warning message. After it, Exim lists
-the delayed addresses.
-
-- The third item then ends the message.
-
-The default state is equivalent to the following file, except that the line
-starting ``A message'' has been split here, in order to fit it on the page:
-
- Subject: Warning: message $message_exim_id delayed $warn_message_delay
- ****
- This message was created automatically by mail delivery software.
-
- A message ${if eq{$sender_address}{$warn_message_recipients}
- {that you sent }{sent by
-
- <$sender_address>
-
- }}has not been delivered to all of its recipients after
- more than $warn_message_delay on the queue on $primary_hostname.
-
- The message identifier is: $message_exim_id
- The subject of the message is: $h_subject
- The date of the message is: $h_date
-
- The following address(es) have not yet been delivered:
- ****
- No action is required on your part. Delivery attempts will continue for
- some time, and this warning may be repeated at intervals if the message
- remains undelivered. Eventually the mail delivery software will give up,
- and when that happens, the message will be returned to you.
-+
-cindex:[$warn_message_delay$]
-cindex:[$warn_message_recipients$]
-except that in the default state the subject and date lines are omitted if no
-appropriate headers exist. During the expansion of this file,
-$warn_message_delay$ is set to the delay time in one of the forms ``<''n'>
-minutes' or ``<''n'> hours', and $warn_message_recipients$ contains a list of
-recipients for the warning message. There may be more than one if there are
-multiple addresses with different %errors_to% settings on the routers that
-handled them.
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPcomconreq]]
-[titleabbrev="Common configuration settings"]
-Some common configuration settings
-----------------------------------
-This chapter discusses some configuration settings that seem to be fairly
-common. More examples and discussion can be found in the Exim book.
-
-
-
-Sending mail to a smart host
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[smart host,example router]
-If you want to send all mail for non-local domains to a ``smart host'', you
-should replace the default ^dnslookup^ router with a router which does the
-routing explicitly:
-
- send_to_smart_host:
- driver = manualroute
- route_list = !+local_domains smart.host.name
- transport = remote_smtp
-
-You can use the smart host's IP address instead of the name if you wish.
-
-If you are using Exim only to submit messages to a smart host, and not for
-receiving incoming messages, you can arrange for it to do the submission
-synchronously by setting the %mua_wrapper% option (see chapter
-<<CHAPnonqueueing>>).
-
-
-
-
-[[SECTmailinglists]]
-Using Exim to handle mailing lists
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[mailing lists]
-Exim can be used to run simple mailing lists, but for large and/or complicated
-requirements, the use of additional specialized mailing list software such as
-Majordomo or Mailman is recommended.
-
-The ^redirect^ router can be used to handle mailing lists where each list
-is maintained in a separate file, which can therefore be managed by an
-independent manager. The %domains% router option can be used to run these
-lists in a separate domain from normal mail. For example:
-
- lists:
- driver = redirect
- domains = lists.example
- file = /usr/lists/$local_part
- forbid_pipe
- forbid_file
- errors_to = $local_part-request@lists.example
- no_more
-
-This router is skipped for domains other than 'lists.example'. For addresses
-in that domain, it looks for a file that matches the local part. If there is no
-such file, the router declines, but because %no_more% is set, no subsequent
-routers are tried, and so the whole delivery fails.
-
-The %forbid_pipe% and %forbid_file% options prevent a local part from being
-expanded into a file name or a pipe delivery, which is usually inappropriate in
-a mailing list.
-
-cindex:[%errors_to%]
-The %errors_to% option specifies that any delivery errors caused by addresses
-taken from a mailing list are to be sent to the given address rather than the
-original sender of the message. However, before acting on this, Exim verifies
-the error address, and ignores it if verification fails.
-
-For example, using the configuration above, mail sent to
-'dicts@lists.example' is passed on to those addresses contained in
-_/usr/lists/dicts_, with error reports directed to
-'dicts-request@lists.example', provided that this address can be verified.
-There could be a file called _/usr/lists/dicts-request_ containing
-the address(es) of this particular list's manager(s), but other approaches,
-such as setting up an earlier router (possibly using the %local_part_prefix%
-or %local_part_suffix% options) to handle addresses of the form %owner-xxx%
-or %xxx-request%, are also possible.
-
-
-
-Syntax errors in mailing lists
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[mailing lists,syntax errors in]
-If an entry in redirection data contains a syntax error, Exim normally defers
-delivery of the original address. That means that a syntax error in a mailing
-list holds up all deliveries to the list. This may not be appropriate when a
-list is being maintained automatically from data supplied by users, and the
-addresses are not rigorously checked.
-
-If the %skip_syntax_errors% option is set, the ^redirect^ router just skips
-entries that fail to parse, noting the incident in the log. If in addition
-%syntax_errors_to% is set to a verifiable address, a message is sent to it
-whenever a broken address is skipped. It is usually appropriate to set
-%syntax_errors_to% to the same address as %errors_to%.
-
-
-
-Re-expansion of mailing lists
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[mailing lists,re-expansion of]
-Exim remembers every individual address to which a message has been delivered,
-in order to avoid duplication, but it normally stores only the original
-recipient addresses with a message. If all the deliveries to a mailing list
-cannot be done at the first attempt, the mailing list is re-expanded when the
-delivery is next tried. This means that alterations to the list are taken into
-account at each delivery attempt, so addresses that have been added to
-the list since the message arrived will therefore receive a copy of the
-message, even though it pre-dates their subscription.
-
-If this behaviour is felt to be undesirable, the %one_time% option can be set
-on the ^redirect^ router. If this is done, any addresses generated by the
-router that fail to deliver at the first attempt are added to the message as
-``top level'' addresses, and the parent address that generated them is marked
-``delivered''. Thus, expansion of the mailing list does not happen again at the
-subsequent delivery attempts. The disadvantage of this is that if any of the
-failing addresses are incorrect, correcting them in the file has no effect on
-pre-existing messages.
-
-The original top-level address is remembered with each of the generated
-addresses, and is output in any log messages. However, any intermediate parent
-addresses are not recorded. This makes a difference to the log only if the
-%all_parents% selector is set, but for mailing lists there is normally only
-one level of expansion anyway.
-
-
-
-Closed mailing lists
-~~~~~~~~~~~~~~~~~~~~
-cindex:[mailing lists,closed]
-The examples so far have assumed open mailing lists, to which anybody may
-send mail. It is also possible to set up closed lists, where mail is accepted
-from specified senders only. This is done by making use of the generic
-%senders% option to restrict the router that handles the list.
-
-The following example uses the same file as a list of recipients and as a list
-of permitted senders. It requires three routers:
-
-....
-lists_request:
- driver = redirect
- domains = lists.example
- local_part_suffix = -request
- file = /usr/lists/$local_part$local_part_suffix
- no_more
-
-lists_post:
- driver = redirect
- domains = lists.example
- senders = ${if exists {/usr/lists/$local_part}\
- {lsearch;/usr/lists/$local_part}{*}}
- file = /usr/lists/$local_part
- forbid_pipe
- forbid_file
- errors_to = $local_part-request@lists.example
- no_more
-
-lists_closed:
- driver = redirect
- domains = lists.example
- allow_fail
- data = :fail: $local_part@lists.example is a closed mailing list
-....
-
-All three routers have the same %domains% setting, so for any other domains,
-they are all skipped. The first router runs only if the local part ends in
-%-request%. It handles messages to the list manager(s) by means of an open
-mailing list.
-
-The second router runs only if the %senders% precondition is satisfied. It
-checks for the existence of a list that corresponds to the local part, and then
-checks that the sender is on the list by means of a linear search. It is
-necessary to check for the existence of the file before trying to search it,
-because otherwise Exim thinks there is a configuration error. If the file does
-not exist, the expansion of %senders% is \*, which matches all senders. This
-means that the router runs, but because there is no list, declines, and
-%no_more% ensures that no further routers are run. The address fails with an
-``unrouteable address'' error.
-
-The third router runs only if the second router is skipped, which happens when
-a mailing list exists, but the sender is not on it. This router forcibly fails
-the address, giving a suitable error message.
-
-
-
-
-[[SECTvirtualdomains]]
-Virtual domains
-~~~~~~~~~~~~~~~
-cindex:[virtual domains]
-cindex:[domain,virtual]
-The phrase 'virtual domain' is unfortunately used with two rather different
-meanings:
-
-- A domain for which there are no real mailboxes; all valid local parts are
-aliases for other email addresses. Common examples are organizational
-top-level domains and ``vanity'' domains.
-
-- One of a number of independent domains that are all handled by the same host,
-with mailboxes on that host, but where the mailbox owners do not necessarily
-have login accounts on that host.
-
-The first usage is probably more common, and does seem more ``virtual'' than the
-second. This kind of domain can be handled in Exim with a straightforward
-aliasing router. One approach is to create a separate alias file for each
-virtual domain. Exim can test for the existence of the alias file to determine
-whether the domain exists. The ^dsearch^ lookup type is useful here, leading
-to a router of this form:
-
- virtual:
- driver = redirect
- domains = dsearch;/etc/mail/virtual
- data = ${lookup{$local_part}lsearch{/etc/mail/virtual/$domain}}
- no_more
-
-The %domains% option specifies that the router is to be skipped, unless there
-is a file in the _/etc/mail/virtual_ directory whose name is the same as the
-domain that is being processed. When the router runs, it looks up the local
-part in the file to find a new address (or list of addresses). The %no_more%
-setting ensures that if the lookup fails (leading to %data% being an empty
-string), Exim gives up on the address without trying any subsequent routers.
-
-This one router can handle all the virtual domains because the alias file names
-follow a fixed pattern. Permissions can be arranged so that appropriate people
-can edit the different alias files. A successful aliasing operation results in
-a new envelope recipient address, which is then routed from scratch.
-
-The other kind of ``virtual'' domain can also be handled in a straightforward
-way. One approach is to create a file for each domain containing a list of
-valid local parts, and use it in a router like this:
-
- my_domains:
- driver = accept
- domains = dsearch;/etc/mail/domains
- local_parts = lsearch;/etc/mail/domains/$domain
- transport = my_mailboxes
-
-The address is accepted if there is a file for the domain, and the local part
-can be found in the file. The %domains% option is used to check for the file's
-existence because %domains% is tested before the %local_parts% option (see
-section <<SECTrouprecon>>). You can't use %require_files%, because that option
-is tested after %local_parts%. The transport is as follows:
-
- my_mailboxes:
- driver = appendfile
- file = /var/mail/$domain/$local_part
- user = mail
-
-This uses a directory of mailboxes for each domain. The %user% setting is
-required, to specify which uid is to be used for writing to the mailboxes.
-
-The configuration shown here is just one example of how you might support this
-requirement. There are many other ways this kind of configuration can be set
-up, for example, by using a database instead of separate files to hold all the
-information about the domains.
-
-
-
-[[SECTmulbox]]
-Multiple user mailboxes
-~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[multiple mailboxes]
-cindex:[mailbox,multiple]
-cindex:[local part,prefix]
-cindex:[local part,suffix]
-Heavy email users often want to operate with multiple mailboxes, into which
-incoming mail is automatically sorted. A popular way of handling this is to
-allow users to use multiple sender addresses, so that replies can easily be
-identified. Users are permitted to add prefixes or suffixes to their local
-parts for this purpose. The wildcard facility of the generic router options
-%local_part_prefix% and %local_part_suffix% can be used for this. For
-example, consider this router:
-
- userforward:
- driver = redirect
- check_local_user
- file = $home/.forward
- local_part_suffix = -*
- local_part_suffix_optional
- allow_filter
-
-cindex:[$local_part_suffix$]
-It runs a user's _.forward_ file for all local parts of the form
-'username-\*'. Within the filter file the user can distinguish different
-cases by testing the variable $local_part_suffix$. For example:
-
- if $local_part_suffix contains -special then
- save /home/$local_part/Mail/special
- endif
-
-If the filter file does not exist, or does not deal with such addresses, they
-fall through to subsequent routers, and, assuming no subsequent use of the
-%local_part_suffix% option is made, they presumably fail. Thus, users have
-control over which suffixes are valid.
-
-Alternatively, a suffix can be used to trigger the use of a different
-_.forward_ file -- which is the way a similar facility is implemented in
-another MTA:
-
- userforward:
- driver = redirect
- check_local_user
- file = $home/.forward$local_part_suffix
- local_part_suffix = -*
- local_part_suffix_optional
- allow_filter
-
-If there is no suffix, _.forward_ is used; if the suffix is '-special', for
-example, _.forward-special_ is used. Once again, if the appropriate file
-does not exist, or does not deal with the address, it is passed on to
-subsequent routers, which could, if required, look for an unqualified
-_.forward_ file to use as a default.
-
-
-
-Simplified vacation processing
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[vacation processing]
-The traditional way of running the 'vacation' program is for a user to set up
-a pipe command in a _.forward_ file
-(see section <<SECTspecitredli>> for syntax details).
-This is prone to error by inexperienced users. There are two features of Exim
-that can be used to make this process simpler for users:
-
-- A local part prefix such as ``vacation-'' can be specified on a router which
-can cause the message to be delivered directly to the 'vacation' program, or
-alternatively can use Exim's ^autoreply^ transport. The contents of a user's
-_.forward_ file are then much simpler. For example:
-
- spqr, vacation-spqr
-
-- The %require_files% generic router option can be used to trigger a
-vacation delivery by checking for the existence of a certain file in the
-user's home directory. The %unseen% generic option should also be used, to
-ensure that the original delivery also proceeds. In this case, all the user has
-to do is to create a file called, say, _.vacation_, containing a vacation
-message.
-
-Another advantage of both these methods is that they both work even when the
-use of arbitrary pipes by users is locked out.
-
-
-
-Taking copies of mail
-~~~~~~~~~~~~~~~~~~~~~
-cindex:[message,copying every]
-Some installations have policies that require archive copies of all messages to
-be made. A single copy of each message can easily be taken by an appropriate
-command in a system filter, which could, for example, use a different file for
-each day's messages.
-
-There is also a shadow transport mechanism that can be used to take copies of
-messages that are successfully delivered by local transports, one copy per
-delivery. This could be used, 'inter alia', to implement automatic
-notification of delivery by sites that insist on doing such things.
-
-
-
-Intermittently connected hosts
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[intermittently connected hosts]
-It has become quite common (because it is cheaper) for hosts to connect to the
-Internet periodically rather than remain connected all the time. The normal
-arrangement is that mail for such hosts accumulates on a system that is
-permanently connected.
-
-Exim was designed for use on permanently connected hosts, and so it is not
-particularly well-suited to use in an intermittently connected environment.
-Nevertheless there are some features that can be used.
-
-
-Exim on the upstream server host
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-It is tempting to arrange for incoming mail for the intermittently connected
-host to remain on Exim's queue until the client connects. However, this
-approach does not scale very well. Two different kinds of waiting message are
-being mixed up in the same queue -- those that cannot be delivered because of
-some temporary problem, and those that are waiting for their destination host
-to connect. This makes it hard to manage the queue, as well as wasting
-resources, because each queue runner scans the entire queue.
-
-A better approach is to separate off those messages that are waiting for an
-intermittently connected host. This can be done by delivering these messages
-into local files in batch SMTP, ``mailstore'', or other envelope-preserving
-format, from where they are transmitted by other software when their
-destination connects. This makes it easy to collect all the mail for one host
-in a single directory, and to apply local timeout rules on a per-message basis
-if required.
-
-On a very small scale, leaving the mail on Exim's queue can be made to work. If
-you are doing this, you should configure Exim with a long retry period for the
-intermittent host. For example:
-
- cheshire.wonderland.fict.example * F,5d,24h
-
-This stops a lot of failed delivery attempts from occurring, but Exim remembers
-which messages it has queued up for that host. Once the intermittent host comes
-online, forcing delivery of one message (either by using the %-M% or %-R%
-options, or by using the ETRN SMTP command (see section <<SECTETRN>>)
-causes all the queued up messages to be delivered, often down a single SMTP
-connection. While the host remains connected, any new messages get delivered
-immediately.
-
-If the connecting hosts do not have fixed IP addresses, that is, if a host is
-issued with a different IP address each time it connects, Exim's retry
-mechanisms on the holding host get confused, because the IP address is normally
-used as part of the key string for holding retry information. This can be
-avoided by unsetting %retry_include_ip_address% on the ^smtp^ transport.
-Since this has disadvantages for permanently connected hosts, it is best to
-arrange a separate transport for the intermittently connected ones.
-
-
-
-Exim on the intermittently connected client host
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The value of %smtp_accept_queue_per_connection% should probably be
-increased, or even set to zero (that is, disabled) on the intermittently
-connected host, so that all incoming messages down a single connection get
-delivered immediately.
-
-cindex:[SMTP,passed connection]
-cindex:[SMTP,multiple deliveries]
-cindex:[multiple SMTP deliveries]
-Mail waiting to be sent from an intermittently connected host will probably
-not have been routed, because without a connection DNS lookups are not
-possible. This means that if a normal queue run is done at connection time,
-each message is likely to be sent in a separate SMTP session. This can be
-avoided by starting the queue run with a command line option beginning with
-%-qq% instead of %-q%. In this case, the queue is scanned twice. In the first
-pass, routing is done but no deliveries take place. The second pass is a normal
-queue run; since all the messages have been previously routed, those destined
-for the same host are likely to get sent as multiple deliveries in a single
-SMTP connection.
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPnonqueueing]]
-[titleabbrev="Exim as a non-queueing client"]
-Using Exim as a non-queueing client
------------------------------------
-cindex:[client, non-queueing]
-cindex:[smart host,queueing; suppressing]
-On a personal computer, it is a common requirement for all
-email to be sent to a ``smart host''. There are plenty of MUAs that can be
-configured to operate that way, for all the popular operating systems.
-However, there are some MUAs for Unix-like systems that cannot be so
-configured: they submit messages using the command line interface of
-_/usr/sbin/sendmail_. Furthermore, utility programs such as 'cron' submit
-messages this way.
-
-If the personal computer runs continuously, there is no problem, because it can
-run a conventional MTA that handles delivery to the smart host, and deal with
-any delays via its queueing mechanism. However, if the computer does not run
-continuously or runs different operating systems at different times, queueing
-email is not desirable.
-
-There is therefore a requirement for something that can provide the
-_/usr/sbin/sendmail_ interface but deliver messages to a smart host without
-any queueing or retrying facilities. Furthermore, the delivery to the smart
-host should be synchronous, so that if it fails, the sending MUA is immediately
-informed. In other words, we want something that extends an MUA that submits
-to a local MTA via the command line so that it behaves like one that submits
-to a remote smart host using TCP/SMTP.
-
-There are a number of applications (for example, there is one called 'ssmtp')
-that do this job. However, people have found them to be lacking in various
-ways. For instance, you might want to allow aliasing and forwarding to be done
-before sending a message to the smart host.
-
-Exim already had the necessary infrastructure for doing this job. Just a few
-tweaks were needed to make it behave as required, though it is somewhat of an
-overkill to use a fully-featured MTA for this purpose.
-
-cindex:[%mua_wrapper%]
-There is a Boolean global option called %mua_wrapper%, defaulting false.
-Setting %mua_wrapper% true causes Exim to run in a special mode where it
-assumes that it is being used to ``wrap'' a command-line MUA in the manner
-just described. As well as setting %mua_wrapper%, you also need to provide a
-compatible router and transport configuration. Typically there will be just one
-router and one transport, sending everything to a smart host.
-
-When run in MUA wrapping mode, the behaviour of Exim changes in the
-following ways:
-
-- A daemon cannot be run, nor will Exim accept incoming messages from 'inetd'.
-In other words, the only way to submit messages is via the command line.
-
-- Each message is synchonously delivered as soon as it is received (%-odi% is
-assumed). All queueing options (%queue_only%, %queue_smtp_domains%,
-%control% in an ACL, etc.) are quietly ignored. The Exim reception process does
-not finish until the delivery attempt is complete. If the delivery is
-successful, a zero return code is given.
-
-- Address redirection is permitted, but the final routing for all addresses must
-be to the same remote transport, and to the same list of hosts. Furthermore,
-the return address (envelope sender) must be the same for all recipients, as
-must any added or deleted header lines. In other words, it must be possible to
-deliver the message in a single SMTP transaction, however many recipients there
-are.
-
-- If these conditions are not met, or if routing any address results in a
-failure or defer status, or if Exim is unable to deliver all the recipients
-successfully to one of the smart hosts, delivery of the entire message fails.
-
-- Because no queueing is allowed, all failures are treated as permanent; there
-is no distinction between 4##'xx' and 5##'xx' SMTP response codes from the
-smart host. Furthermore, because only a single yes/no response can be given to
-the caller, it is not possible to deliver to some recipients and not others. If
-there is an error (temporary or permanent) for any recipient, all are failed.
-
-- If more than one smart host is listed, Exim will try another host after a
-connection failure or a timeout, in the normal way. However, if this kind of
-failure happens for all the hosts, the delivery fails.
-
-- When delivery fails, an error message is written to the standard error stream
-(as well as to Exim's log), and Exim exits to the caller with a return code
-value 1. The message is expunged from Exim's spool files. No bounce messages
-are ever generated.
-
-- No retry data is maintained, and any retry rules are ignored.
-
-- A number of Exim options are overridden: %deliver_drop_privilege% is forced
-true, %max_rcpt% in the smtp transport is forced to ``unlimited'',
-%remote_max_parallel% is forced to one, and fallback hosts are ignored.
-
-The overall effect is that Exim makes a single synchronous attempt to deliver
-the message, failing if there is any kind of problem. Because no local
-deliveries are done and no daemon can be run, Exim does not need root
-privilege. It should be possible to run it setuid to 'exim' instead of setuid
-to 'root'. See section <<SECTrunexiwitpri>> for a general discussion about the
-advantages and disadvantages of running without root privilege.
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPlog]]
-Log files
----------
-cindex:[log,types of]
-cindex:[log,general description]
-Exim writes three different logs, referred to as the main log, the reject log,
-and the panic log:
-
-- cindex:[main log]
-The main log records the arrival of each message and each delivery in a single
-line in each case. The format is as compact as possible, in an attempt to keep
-down the size of log files. Two-character flag sequences make it easy to pick
-out these lines. A number of other events are recorded in the main log. Some of
-them are optional, in which case the %log_selector% option controls whether
-they are included or not. A Perl script called 'eximstats', which does simple
-analysis of main log files, is provided in the Exim distribution (see section
-<<SECTmailstat>>).
-
-- cindex:[reject log]
-The reject log records information from messages that are rejected as a result
-of a configuration option (that is, for policy reasons).
-The first line of each rejection is a copy of the line that is also written to
-the main log. Then, if the message's header has been read at the time the log
-is written, its contents are written to this log. Only the original header
-lines are available; header lines added by ACLs are not logged. You can use the
-reject log to check that your policy controls are working correctly; on a busy
-host this may be easier than scanning the main log for rejection messages. You
-can suppress the writing of the reject log by setting %write_rejectlog% false.
-
-- cindex:[panic log]
-cindex:[system log]
-When certain serious errors occur, Exim writes entries to its panic log. If the
-error is sufficiently disastrous, Exim bombs out afterwards. Panic log entries
-are usually written to the main log as well, but can get lost amid the mass of
-other entries. The panic log should be empty under normal circumstances. It is
-therefore a good idea to check it (or to have a 'cron' script check it)
-regularly, in order to become aware of any problems. When Exim cannot open its
-panic log, it tries as a last resort to write to the system log (syslog). This
-is opened with LOG_PID+LOG_CONS and the facility code of LOG_MAIL. The
-message itself is written at priority LOG_CRIT.
-
-Every log line starts with a timestamp, in the format shown in this example:
-
- 2001-09-16 16:09:47 SMTP connection from [127.0.0.1] closed by QUIT
-
-By default, the timestamps are in the local timezone. There are two
-ways of changing this:
-
-- You can set the %timezone% option to a different time zone; in particular, if
-you set
-+
- timezone = UTC
-+
-the timestamps will be in UTC (aka GMT).
-
-- If you set %log_timezone% true, the time zone is added to the timestamp, for
-example:
-+
- 2003-04-25 11:17:07 +0100 Start queue run: pid=12762
-
-
-
-
-
-[[SECTwhelogwri]]
-Where the logs are written
-~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[log,destination]
-cindex:[log,to file]
-cindex:[log,to syslog]
-cindex:[syslog]
-The logs may be written to local files, or to syslog, or both. However, it
-should be noted that many syslog implementations use UDP as a transport, and
-are therefore unreliable in the sense that messages are not guaranteed to
-arrive at the loghost, nor is the ordering of messages necessarily maintained.
-It has also been reported that on large log files (tens of megabytes) you may
-need to tweak syslog to prevent it syncing the file with each write -- on Linux
-this has been seen to make syslog take 90% plus of CPU time.
-
-The destination for Exim's logs is configured by setting LOG_FILE_PATH in
-_Local/Makefile_ or by setting %log_file_path% in the run time
-configuration. This latter string is expanded, so it can contain, for example,
-references to the host name:
-
- log_file_path = /var/log/$primary_hostname/exim_%slog
-
-It is generally advisable, however, to set the string in _Local/Makefile_
-rather than at run time, because then the setting is available right from the
-start of Exim's execution. Otherwise, if there's something it wants to log
-before it has read the configuration file (for example, an error in the
-configuration file) it will not use the path you want, and may not be able to
-log at all.
-
-The value of LOG_FILE_PATH or %log_file_path% is a colon-separated
-list, currently limited to at most two items. This is one option where the
-facility for changing a list separator may not be used. The list must always be
-colon-separated. If an item in the list is ``syslog'' then syslog is used;
-otherwise the item must either be an absolute path, containing `%s` at the
-point where ``main'', ``reject'', or ``panic'' is to be inserted, or be empty,
-implying the use of a default path.
-
-When Exim encounters an empty item in the list, it searches the list defined by
-LOG_FILE_PATH, and uses the first item it finds that is neither empty nor
-``syslog''. This means that an empty item in %log_file_path% can be used to
-mean ``use the path specified at build time''. It no such item exists, log files
-are written in the _log_ subdirectory of the spool directory. This is
-equivalent to the setting:
-
- log_file_path = $spool_directory/log/%slog
-
-If you do not specify anything at build time or run time, that is where the
-logs are written.
-
-A log file path may also contain `%D` if datestamped log file names are in
-use -- see section <<SECTdatlogfil>> below.
-
-Here are some examples of possible settings:
-
-&&&
-`LOG_FILE_PATH=syslog ` syslog only
-`LOG_FILE_PATH=:syslog ` syslog and default path
-`LOG_FILE_PATH=syslog : /usr/log/exim_%s ` syslog and specified path
-`LOG_FILE_PATH=/usr/log/exim_%s ` specified path only
-&&&
-
-If there are more than two paths in the list, the first is used and a panic
-error is logged.
-
-
-
-Logging to local files that are periodically ``cycled''
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[log,cycling local files]
-cindex:[cycling logs]
-cindex:['exicyclog']
-cindex:[log,local files; writing to]
-Some operating systems provide centralized and standardised methods for cycling
-log files. For those that do not, a utility script called 'exicyclog' is
-provided (see section <<SECTcyclogfil>>). This renames and compresses the main
-and reject logs each time it is called. The maximum number of old logs to keep
-can be set. It is suggested this script is run as a daily 'cron' job.
-
-An Exim delivery process opens the main log when it first needs to write to it,
-and it keeps the file open in case subsequent entries are required -- for
-example, if a number of different deliveries are being done for the same
-message. However, remote SMTP deliveries can take a long time, and this means
-that the file may be kept open long after it is renamed if 'exicyclog' or
-something similar is being used to rename log files on a regular basis. To
-ensure that a switch of log files is noticed as soon as possible, Exim calls
-'stat()' on the main log's name before reusing an open file, and if the file
-does not exist, or its inode has changed, the old file is closed and Exim
-tries to open the main log from scratch. Thus, an old log file may remain open
-for quite some time, but no Exim processes should write to it once it has been
-renamed.
-
-
-
-[[SECTdatlogfil]]
-Datestamped log files
-~~~~~~~~~~~~~~~~~~~~~
-cindex:[log,datestamped files]
-Instead of cycling the main and reject log files by renaming them
-periodically, some sites like to use files whose names contain a datestamp,
-for example, _mainlog-20031225_. The datestamp is in the form _yyyymmdd_.
-Exim has support for this way of working. It is enabled by setting the
-%log_file_path% option to a path that includes `%D` at the point where the
-datestamp is required. For example:
-
- log_file_path = /var/spool/exim/log/%slog-%D
- log_file_path = /var/log/exim-%s-%D.log
- log_file_path = /var/spool/exim/log/%D-%slog
-
-As before, `%s` is replaced by ``main'' or ``reject''; the following are examples
-of names generated by the above examples:
-
- /var/spool/exim/log/mainlog-20021225
- /var/log/exim-reject-20021225.log
- /var/spool/exim/log/20021225-mainlog
-
-When this form of log file is specified, Exim automatically switches to new
-files at midnight. It does not make any attempt to compress old logs; you
-will need to write your own script if you require this. You should not
-run 'exicyclog' with this form of logging.
-
-The location of the panic log is also determined by %log_file_path%, but it
-is not datestamped, because rotation of the panic log does not make sense.
-When generating the name of the panic log, `%D` is removed from the string.
-In addition, if it immediately follows a slash, a following non-alphanumeric
-character is removed; otherwise a preceding non-alphanumeric character is
-removed. Thus, the three examples above would give these panic log names:
-
- /var/spool/exim/log/paniclog
- /var/log/exim-panic.log
- /var/spool/exim/log/paniclog
-
-
-
-
-Logging to syslog
-~~~~~~~~~~~~~~~~~
-cindex:[log,syslog; writing to]
-The use of syslog does not change what Exim logs or the format of its messages,
-except in one respect. If %syslog_timestamp% is set false, the timestamps on
-Exim's log lines are omitted when these lines are sent to syslog. Apart from
-that, the same strings are written to syslog as to log files. The syslog
-``facility'' is set to LOG_MAIL, and the program name to ``exim''
-by default, but you can change these by setting the %syslog_facility% and
-%syslog_processname% options, respectively. If Exim was compiled with
-SYSLOG_LOG_PID set in _Local/Makefile_ (this is the default in
-_src/EDITME_), then, on systems that permit it (all except ULTRIX), the
-LOG_PID flag is set so that the 'syslog()' call adds the pid as well as
-the time and host name to each line.
-The three log streams are mapped onto syslog priorities as follows:
-
-- 'mainlog' is mapped to LOG_INFO
-
-- 'rejectlog' is mapped to LOG_NOTICE
-
-- 'paniclog' is mapped to LOG_ALERT
-
-Many log lines are written to both 'mainlog' and 'rejectlog', and some are
-written to both 'mainlog' and 'paniclog', so there will be duplicates if
-these are routed by syslog to the same place. You can suppress this duplication
-by setting %syslog_duplication% false.
-
-Exim's log lines can sometimes be very long, and some of its 'rejectlog'
-entries contain multiple lines when headers are included. To cope with both
-these cases, entries written to syslog are split into separate 'syslog()'
-calls at each internal newline, and also after a maximum of
-870 data characters. (This allows for a total syslog line length of 1024, when
-additions such as timestamps are added.) If you are running a syslog
-replacement that can handle lines longer than the 1024 characters allowed by
-RFC 3164, you should set
-
- SYSLOG_LONG_LINES=yes
-
-in _Local/Makefile_ before building Exim. That stops Exim from splitting long
-lines, but it still splits at internal newlines in 'reject' log entries.
-
-To make it easy to re-assemble split lines later, each component of a split
-entry starts with a string of the form ``[<''n'>/<'m'>]' or ``[<''n'>\<'m'>]'
-where <'n'> is the component number and <'m'> is the total number of components
-in the entry. The / delimiter is used when the line was split because it was
-too long; if it was split because of an internal newline, the \ delimiter is
-used. For example, supposing the length limit to be 70 instead of 1000, the
-following would be the result of a typical rejection message to 'mainlog'
-(LOG_INFO), each line in addition being preceded by the time, host name, and
-pid as added by syslog:
-
- $smc\{[1/3] 2002-09-16 16:09:43 16RdAL-0006pc-00 rejected from [127.0.0.1] (ph10):
- [2/3] syntax error in 'From' header when scanning for sender: missing or ma
- [3/3] lformed local part in "<>" (envelope sender is <ph10@cam.example>)\}
-
-The same error might cause the following lines to be written to ``rejectlog''
-(LOG_NOTICE):
-
- $smc\{[1/14] 2002-09-16 16:09:43 16RdAL-0006pc-00 rejected from [127.0.0.1] (ph10):
- [2/14] syntax error in 'From' header when scanning for sender: missing or ma
- [3\14] lformed local part in "<>" (envelope sender is <ph10@cam.example>)
- [4\14] Recipients: ph10@some.domain.cam.example
- [5\14] P Received: from [127.0.0.1] (ident=ph10)
- [6\14] by xxxxx.cam.example with smtp (Exim 4.00)
- [7\14] id 16RdAL-0006pc-00
- [8\14] for ph10@cam.example; Mon, 16 Sep 2002 16:09:43 +0100
- [9\14] F From: <>
- [10\14] Subject: this is a test header
- [11\14] X-something: this is another header
- [12\14] I Message-Id: <E16RdAL-0006pc-00@xxxxx.cam.example>
- [13\14] B Bcc:
- [14/14] Date: Mon, 16 Sep 2002 16:09:43 +0100\}
-
-Log lines that are neither too long nor contain newlines are written to syslog
-without modification.
-
-If only syslog is being used, the Exim monitor is unable to provide a log tail
-display, unless syslog is routing 'mainlog' to a file on the local host and
-the environment variable EXIMON_LOG_FILE_PATH is set to tell the monitor
-where it is.
-
-
-
-Log line flags
-~~~~~~~~~~~~~~
-One line is written to the main log for each message received, and for each
-successful, unsuccessful, and delayed delivery. These lines can readily be
-picked out by the distinctive two-character flags that immediately follow the
-timestamp. The flags are:
-
-&&&
-`<=` message arrival
-`=>` normal message delivery
-`->` additional address in same delivery
-`\*>` delivery suppressed by %-N%
-`\*\*` delivery failed; address bounced
-`==` delivery deferred; temporary problem
-&&&
-
-
-
-Logging message reception
-~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[log,reception line]
-The format of the single-line entry in the main log that is written for every
-message received is shown in the basic example below, which is split over
-several lines in order to fit it on the page:
-
- 2002-10-31 08:57:53 16ZCW1-0005MB-00 <= kryten@dwarf.fict.example
- H=mailer.fict.example [192.168.123.123] U=exim
- P=smtp S=5678 id=<incoming message id>
-
-The address immediately following ``<='' is the envelope sender address. A bounce
-message is shown with the sender address ``<>'', and if it is locally generated,
-this is followed by an item of the form
-
- R=<message id>
-
-which is a reference to the message that caused the bounce to be sent.
-
-cindex:[HELO]
-cindex:[EHLO]
-For messages from other hosts, the H and U fields identify the remote host and
-record the RFC 1413 identity of the user that sent the message, if one was
-received. The number given in square brackets is the IP address of the sending
-host. If there is a single, unparenthesized host name in the H field, as
-above, it has been verified to correspond to the IP address (see the
-%host_lookup% option). If the name is in parentheses, it was the name quoted
-by the remote host in the SMTP HELO or EHLO command, and has not been
-verified. If verification yields a different name to that given for HELO or
-EHLO, the verified name appears first, followed by the HELO or EHLO
-name in parentheses.
-
-Misconfigured hosts (and mail forgers) sometimes put an IP address, with or
-without brackets, in the HELO or EHLO command, leading to entries in
-the log containing text like these examples:
-
- H=(10.21.32.43) [192.168.8.34]
- H=([10.21.32.43]) [192.168.8.34]
-
-This can be confusing. Only the final address in square brackets can be relied
-on.
-
-For locally generated messages (that is, messages not received over TCP/IP),
-the H field is omitted, and the U field contains the login name of the caller
-of Exim.
-
-[revisionflag="changed"]
-cindex:[authentication,logging]
-cindex:[AUTH,logging]
-For all messages, the P field specifies the protocol used to receive the
-message. This is the value that is stored in $received_protocol$. In the case
-of incoming SMTP messages, the value indicates whether or not any SMTP
-extensions (ESMTP), encryption, or authentication were used. If the SMTP
-session was encrypted, there is an additional X field that records the cipher
-suite that was used.
-
-[revisionflag="changed"]
-The protocol is set to ``esmptsa'' or ``esmtpa'' for messages received from
-hosts that have authenticated themselves using the SMTP AUTH command. The first
-value is used when the SMTP connection was encrypted (``secure''). In this case
-there is an additional item A= followed by the name of the authenticator that
-was used. If an authenticated identification was set up by the authenticator's
-%server_set_id% option, this is logged too, separated by a colon from the
-authenticator name.
-
-
-cindex:[size,of message]
-The id field records the existing message id, if present. The size of the
-received message is given by the S field. When the message is delivered,
-headers may be removed or added, so that the size of delivered copies of the
-message may not correspond with this value (and indeed may be different to each
-other).
-
-The %log_selector% option can be used to request the logging of additional
-data when a message is received. See section <<SECTlogselector>> below.
-
-
-
-Logging deliveries
-~~~~~~~~~~~~~~~~~~
-cindex:[log,delivery line]
-The format of the single-line entry in the main log that is written for every
-delivery is shown in one of the examples below, for local and remote deliveries,
-respectively. Each example has been split into two lines in order to fit
-it on the page:
-
- 2002-10-31 08:59:13 16ZCW1-0005MB-00 => marv <marv@hitch.fict.example>
- R=localuser T=local_delivery
- 2002-10-31 09:00:10 16ZCW1-0005MB-00 => monk@holistic.fict.example
- R=dnslookup T=remote_smtp H=holistic.fict.example [192.168.234.234]
-
-For ordinary local deliveries, the original address is given in angle brackets
-after the final delivery address, which might be a pipe or a file. If
-intermediate address(es) exist between the original and the final address, the
-last of these is given in parentheses after the final address. The R and T
-fields record the router and transport that were used to process the address.
-
-If a shadow transport was run after a successful local delivery, the log line
-for the successful delivery has an item added on the end, of the form
-
- ST=<shadow transport name>
-
-If the shadow transport did not succeed, the error message is put in
-parentheses afterwards.
-
-cindex:[asterisk,after IP address]
-When more than one address is included in a single delivery (for example, two
-SMTP RCPT commands in one transaction) the second and subsequent addresses are
-flagged with `->` instead of `=>`. When two or more messages are delivered down
-a single SMTP connection, an asterisk follows the IP address in the log lines
-for the second and subsequent messages.
-
-The generation of a reply message by a filter file gets logged as a ``delivery''
-to the addressee, preceded by ``>''.
-
-The %log_selector% option can be used to request the logging of additional
-data when a message is delivered. See section <<SECTlogselector>> below.
-
-
-Discarded deliveries
-~~~~~~~~~~~~~~~~~~~~
-cindex:[discarded messages]
-cindex:[message,discarded]
-cindex:[delivery,discarded; logging]
-When a message is discarded as a result of the command ``seen finish'' being
-obeyed in a filter file which generates no deliveries, a log entry of the form
-
- 2002-12-10 00:50:49 16auJc-0001UB-00 => discarded
- <low.club@bridge.example> R=userforward
-
-is written, to record why no deliveries are logged. When a message is discarded
-because it is aliased to ``:blackhole:'' the log line is like this:
-
- 1999-03-02 09:44:33 10HmaX-0005vi-00 => :blackhole:
- <hole@nowhere.example> R=blackhole_router
-
-
-
-
-Deferred deliveries
-~~~~~~~~~~~~~~~~~~~
-When a delivery is deferred, a line of the following form is logged:
-
- 2002-12-19 16:20:23 16aiQz-0002Q5-00 == marvin@endrest.example
- R=dnslookup T=smtp defer (146): Connection refused
-
-In the case of remote deliveries, the error is the one that was given for the
-last IP address that was tried. Details of individual SMTP failures are also
-written to the log, so the above line would be preceded by something like
-
- 2002-12-19 16:20:23 16aiQz-0002Q5-00 Failed to connect to
- mail1.endrest.example [192.168.239.239]: Connection refused
-
-When a deferred address is skipped because its retry time has not been reached,
-a message is written to the log, but this can be suppressed by setting an
-appropriate value in %log_selector%.
-
-
-
-Delivery failures
-~~~~~~~~~~~~~~~~~
-cindex:[delivery,failure; logging]
-If a delivery fails because an address cannot be routed, a line of the
-following form is logged:
-
- 1995-12-19 16:20:23 0tRiQz-0002Q5-00 ** jim@trek99.example
- <jim@trek99.example>: unknown mail domain
-
-If a delivery fails at transport time, the router and transport are shown, and
-the response from the remote host is included, as in this example:
-
- 2002-07-11 07:14:17 17SXDU-000189-00 ** ace400@pb.example R=dnslookup
- T=remote_smtp: SMTP error from remote mailer after pipelined
- RCPT TO:<ace400@pb.example>: host pbmail3.py.example
- [192.168.63.111]: 553 5.3.0 <ace400@pb.example>...
- Addressee unknown
-
-The word ``pipelined'' indicates that the SMTP PIPELINING extension was being
-used. See %hosts_avoid_esmtp% in the ^smtp^ transport for a way of
-disabling PIPELINING.
-
-The log lines for all forms of delivery failure are flagged with `\*\*`.
-
-
-
-Fake deliveries
-~~~~~~~~~~~~~~~
-cindex:[delivery,fake; logging]
-If a delivery does not actually take place because the %-N% option has been
-used to suppress it, a normal delivery line is written to the log, except that
-``=>'' is replaced by ``\*>''.
-
-
-
-Completion
-~~~~~~~~~~
-A line of the form
-
- 2002-10-31 09:00:11 16ZCW1-0005MB-00 Completed
-
-is written to the main log when a message is about to be removed from the spool
-at the end of its processing.
-
-
-
-
-Summary of Fields in Log Lines
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[log,summary of fields]
-A summary of the field identifiers that are used in log lines is shown in
-the following table:
-
-&&&
-`A ` authenticator name (and optional id)
-`C ` SMTP confirmation on delivery
-`CV ` certificate verification status
-`DN ` distinguished name from peer certificate
-`DT ` on `=>` lines: time taken for a delivery
-`F ` sender address (on delivery lines)
-`H ` host name and IP address
-`I ` local interface used
-`id ` message id for incoming message
-`P ` on `<=` lines: protocol used
-` ` on `=>` and `\*\*` lines: return path
-`QT ` on `=>` lines: time spent on queue so far
-` ` on ``Completed'' lines: time spent on queue
-`R ` on `<=` lines: reference for local bounce
-` ` on `=>` `\*\*` and `==` lines: router name
-`S ` size of message
-`ST ` shadow transport name
-`T ` on `<=` lines: message subject (topic)
-` ` on `=>` `\*\*` and `==` lines: transport name
-`U ` local user or RFC 1413 identity
-`X ` TLS cipher suite
-&&&
-
-
-
-Other log entries
-~~~~~~~~~~~~~~~~~
-Various other types of log entry are written from time to time. Most should be
-self-explanatory. Among the more common are:
-
-- cindex:[retry,time not reached]
-'retry time not reached'~~An address previously suffered a temporary error
-during routing or local delivery, and the time to retry has not yet arrived.
-This message is not written to an individual message log file unless it happens
-during the first delivery attempt.
-
-- 'retry time not reached for any host'~~An address previously suffered
-temporary errors during remote delivery, and the retry time has not yet arrived
-for any of the hosts to which it is routed.
-
-- cindex:[spool directory,file locked]
-'spool file locked'~~An attempt to deliver a message cannot proceed because
-some other Exim process is already working on the message. This can be quite
-common if queue running processes are started at frequent intervals. The
-'exiwhat' utility script can be used to find out what Exim processes are
-doing.
-
-- cindex:[error,ignored]
-'error ignored'~~There are several circumstances that give rise to this
-message:
-
-. Exim failed to deliver a bounce message whose age was greater than
-%ignore_bounce_errors_after%. The bounce was discarded.
-
-. A filter file set up a delivery using the ``noerror'' option, and the delivery
-failed. The delivery was discarded.
-
-. A delivery set up by a router configured with
-+
- errors_to = <>
-+
-failed. The delivery was discarded.
-
-
-
-
-
-[[SECTlogselector]]
-Reducing or increasing what is logged
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[log,selectors]
-By setting the %log_selector% global option, you can disable some of Exim's
-default logging, or you can request additional logging. The value of
-%log_selector% is made up of names preceded by plus or minus characters. For
-example:
-
- log_selector = +arguments -retry_defer
-
-The list of optional log items is in the following table, with the default
-selection marked by asterisks:
-
-&&&
-`\*acl_warn_skipped ` skipped %warn% statement in ACL
-` address_rewrite ` address rewriting
-` all_parents ` all parents in => lines
-` arguments ` command line arguments
-`\*connection_reject ` connection rejections
-`\*delay_delivery ` immediate delivery delayed
-` deliver_time ` time taken to perform delivery
-` delivery_size ` add S=nnn to => lines
-`\*dnslist_defer ` defers of DNS list (aka RBL) lookups
-`\*etrn ` ETRN commands
-`\*host_lookup_failed ` as it says
-` ident_timeout ` timeout for ident connection
-` incoming_interface ` incoming interface on <= lines
-` incoming_port ` incoming port on <= lines
-`\*lost_incoming_connection ` as it says (includes timeouts)
-` outgoing_port ` add remote port to => lines
-`\*queue_run ` start and end queue runs
-` queue_time ` time on queue for one recipient
-` queue_time_overall ` time on queue for whole message
-` received_recipients ` recipients on <= lines
-` received_sender ` sender on <= lines
-`\*rejected_header ` header contents on reject log
-`\*retry_defer ` ``retry time not reached''
-` return_path_on_delivery ` put return path on => and \*\ lines
-` sender_on_delivery ` add sender to => lines
-`\*size_reject ` rejection because too big
-`\*skip_delivery ` delivery skipped in a queue run
-` smtp_confirmation ` SMTP confirmation on => lines
-` smtp_connection ` SMTP connections
-` smtp_incomplete_transaction` incomplete SMTP transactions
-` smtp_protocol_error ` SMTP protocol errors
-` smtp_syntax_error ` SMTP syntax errors
-` subject ` contents of 'Subject:' on <= lines
-` tls_certificate_verified ` certificate verification status
-`\*tls_cipher ` TLS cipher suite on <= and => lines
-` tls_peerdn ` TLS peer DN on <= and => lines
-` unknown_in_list ` DNS lookup failed in list match
-
-` all ` all of the above
-&&&
-
-More details on each of these items follows:
-
-[revisionflag="changed"]
-- cindex:[%warn% statement,log when skipping]
-%acl_warn_skipped%: When an ACL %warn% statement is skipped because one of its
-conditions cannot be evaluated, a log line to this effect is written if this
-log selector is set.
-
-- cindex:[log,rewriting]
-cindex:[rewriting,logging]
-%address_rewrite%: This applies both to global rewrites and per-transport
-rewrites, but not to rewrites in filters run as an unprivileged user (because
-such users cannot access the log).
-
-- cindex:[log,full parentage]
-%all_parents%: Normally only the original and final addresses are logged on
-delivery lines; with this selector, intermediate parents are given in
-parentheses between them.
-
-- cindex:[log,Exim arguments]
-cindex:[Exim arguments, logging]
-%arguments%: This causes Exim to write the arguments with which it was called
-to the main log, preceded by the current working directory. This is a debugging
-feature, added to make it easier to find out how certain MUAs call
-_/usr/sbin/sendmail_. The logging does not happen if Exim has given up root
-privilege because it was called with the %-C% or %-D% options. Arguments that
-are empty or that contain white space are quoted. Non-printing characters are
-shown as escape sequences. This facility cannot log unrecognized arguments,
-because the arguments are checked before the configuration file is read. The
-only way to log such cases is to interpose a script such as _util/logargs.sh_
-between the caller and Exim.
-
-- cindex:[log,connection rejections]
-%connection_reject%: A log entry is written whenever an incoming SMTP
-connection is rejected, for whatever reason.
-
-- cindex:[log,delayed delivery]
-cindex:[delayed delivery, logging]
-%delay_delivery%: A log entry is written whenever a delivery process is not
-started for an incoming message because the load is too high or too many
-messages were received on one connection. Logging does not occur if no delivery
-process is started because %queue_only% is set or %-odq% was used.
-
-- cindex:[log,delivery duration]
-%deliver_time%: For each delivery, the amount of real time it has taken to
-perform the actual delivery is logged as DT=<'time'>, for example, `DT=1s`.
-
-- cindex:[log,message size on delivery]
-cindex:[size,of message]
-%delivery_size%: For each delivery, the size of message delivered is added to
-the ``=>'' line, tagged with S=.
-
-- cindex:[log,dnslist defer]
-cindex:[DNS list,logging defer]
-cindex:[black list (DNS)]
-%dnslist_defer%: A log entry is written if an attempt to look up a host in a
-DNS black list suffers a temporary error.
-
-- cindex:[log,ETRN commands]
-cindex:[ETRN,logging]
-%etrn%: Every legal ETRN command that is received is logged, before the ACL is
-run to determine whether or not it is actually accepted. An invalid ETRN
-command, or one received within a message transaction is not logged by this
-selector (see %smtp_syntax_error% and %smtp_protocol_error%).
-
-- cindex:[log,host lookup failure]
-%host_lookup_failed%: When a lookup of a host's IP addresses fails to find
-any addresses, or when a lookup of an IP address fails to find a host name, a
-log line is written. This logging does not apply to direct DNS lookups when
-routing email addresses, but it does apply to ``byname'' lookups.
-
-- cindex:[log,ident timeout]
-cindex:[RFC 1413,logging timeout]
-%ident_timeout%: A log line is written whenever an attempt to connect to a
-client's ident port times out.
-
-- cindex:[log,incoming interface]
-cindex:[interface,logging]
-%incoming_interface%: The interface on which a message was received is added to
-the ``<='' line as an IP address in square brackets, tagged by I= and followed
-by a colon and the port number. The local interface and port are also added to
-other SMTP log lines, for example ``SMTP connection from'', and to rejection
-lines.
-
-- cindex:[log,incoming remote port]
-cindex:[port,logging remote]
-cindex:[TCP/IP,logging incoming remote port]
-cindex:[$sender_fullhost$]
-cindex:[$sender_rcvhost$]
-%incoming_port%: The remote port number from which a message was received is
-added to log entries and 'Received:' header lines, following the IP address in
-square brackets, and separated from it by a colon. This is implemented by
-changing the value that is put in the $sender_fullhost$ and
-$sender_rcvhost$ variables. Recording the remote port number has become more
-important with the widening use of NAT (see RFC 2505).
-
-- cindex:[log,dropped connection]
-%lost_incoming_connection%: A log line is written when an incoming SMTP
-connection is unexpectedly dropped.
-
-- cindex:[log,outgoing remote port]
-cindex:[port,logging outgoint remote]
-cindex:[TCP/IP,logging ougtoing remote port]
-%outgoing_port%: The remote port number is added to delivery log lines (those
-containing => tags) following the IP address. This option is not included in
-the default setting, because for most ordinary configurations, the remote port
-number is always 25 (the SMTP port).
-
-- cindex:[log,queue run]
-cindex:[queue runner,logging]
-%queue_run%: The start and end of every queue run are logged.
-
-- cindex:[log,queue time]
-%queue_time%: The amount of time the message has been in the queue on the local
-host is logged as QT=<'time'> on delivery (`=>`) lines, for example,
-`QT=3m45s`. The clock starts when Exim starts to receive the message, so it
-includes reception time as well as the delivery time for the current address.
-This means that it may be longer than the difference between the arrival and
-delivery log line times, because the arrival log line is not written until the
-message has been successfully received.
-
-- %queue_time_overall%: The amount of time the message has been in the queue on
-the local host is logged as QT=<'time'> on ``Completed'' lines, for
-example, `QT=3m45s`. The clock starts when Exim starts to receive the
-message, so it includes reception time as well as the total delivery time.
-
-- cindex:[log,recipients]
-%received_recipients%: The recipients of a message are listed in the main log
-as soon as the message is received. The list appears at the end of the log line
-that is written when a message is received, preceded by the word ``for''. The
-addresses are listed after they have been qualified, but before any rewriting
-has taken place.
-Recipients that were discarded by an ACL for MAIL or RCPT do not appear
-in the list.
-
-- cindex:[log,sender reception]
-%received_sender%: The unrewritten original sender of a message is added to
-the end of the log line that records the message's arrival, after the word
-``from'' (before the recipients if %received_recipients% is also set).
-
-- cindex:[log,header lines for rejection]
-%rejected_header%: If a message's header has been received at the time a
-rejection is written to the reject log, the complete header is added to the
-log. Header logging can be turned off individually for messages that are
-rejected by the 'local_scan()' function (see section <<SECTapiforloc>>).
-
-- cindex:[log,retry defer]
-%retry_defer%: A log line is written if a delivery is deferred because a retry
-time has not yet been reached. However, this ``retry time not reached'' message
-is always omitted from individual message logs after the first delivery
-attempt.
-
-- cindex:[log,return path]
-%return_path_on_delivery%: The return path that is being transmitted with
-the message is included in delivery and bounce lines, using the tag P=.
-This is omitted if no delivery actually happens, for example, if routing fails,
-or if delivery is to _/dev/null_ or to `:blackhole:`.
-
-- cindex:[log,sender on delivery]
-%sender_on_delivery%: The message's sender address is added to every delivery
-and bounce line, tagged by F= (for ``from'').
-This is the original sender that was received with the message; it is not
-necessarily the same as the outgoing return path.
-
-- cindex:[log,size rejection]
-%size_reject%: A log line is written whenever a message is rejected because it
-is too big.
-
-- cindex:[log,frozen messages; skipped]
-cindex:[frozen messages,logging skipping]
-%skip_delivery%: A log line is written whenever a message is skipped during a
-queue run because it is frozen or because another process is already delivering
-it.
-cindex:[``spool file is locked'']
-The message that is written is ``spool file is locked''.
-
-- cindex:[log,smtp confirmation]
-cindex:[SMTP,logging confirmation]
-%smtp_confirmation%: The response to the final ``.'' in the SMTP dialogue for
-outgoing messages is added to delivery log lines in the form ``C="<''text'>"'. A
-number of MTAs (including Exim) return an identifying string in this response.
-
-- cindex:[log,SMTP connections]
-cindex:[SMTP,logging connections]
-%smtp_connection%: A log line is written whenever an SMTP connection is
-established or closed, unless the connection is from a host that matches
-%hosts_connection_nolog%. (In contrast, %lost_incoming_connection% applies only
-when the closure is unexpected.) This applies to connections from local
-processes that use %-bs% as well as to TCP/IP connections. If a connection is
-dropped in the middle of a message, a log line is always written, whether or
-not this selector is set, but otherwise nothing is written at the start and end
-of connections unless this selector is enabled.
-+
-For TCP/IP connections to an Exim daemon, the current number of connections is
-included in the log message for each new connection, but note that the count is
-reset if the daemon is restarted.
-Also, because connections are closed (and the closure is logged) in
-subprocesses, the count may not include connections that have been closed but
-whose termination the daemon has not yet noticed. Thus, while it is possible to
-match up the opening and closing of connections in the log, the value of the
-logged counts may not be entirely accurate.
-
-- cindex:[log,SMTP transaction; incomplete]
-cindex:[SMTP,logging incomplete transactions]
-%smtp_incomplete_transaction%: When a mail transaction is aborted by
-RSET, QUIT, loss of connection, or otherwise, the incident is logged,
-and the message sender plus any accepted recipients are included in the log
-line. This can provide evidence of dictionary attacks.
-
-- cindex:[log,SMTP protocol error]
-cindex:[SMTP,logging protocol error]
-%smtp_protocol_error%: A log line is written for every SMTP protocol error
-encountered. Exim does not have perfect detection of all protocol errors
-because of transmission delays and the use of pipelining. If PIPELINING has
-been advertised to a client, an Exim server assumes that the client will use
-it, and therefore it does not count ``expected'' errors (for example, RCPT
-received after rejecting MAIL) as protocol errors.
-
-- cindex:[SMTP,logging syntax errors]
-cindex:[SMTP,syntax errors; logging]
-cindex:[SMTP,unknown command; logging]
-cindex:[log,unknown SMTP command]
-cindex:[log,SMTP syntax error]
-%smtp_syntax_error%: A log line is written for every SMTP syntax error
-encountered. An unrecognized command is treated as a syntax error. For an
-external connection, the host identity is given; for an internal connection
-using %-bs% the sender identification (normally the calling user) is given.
-
-- cindex:[log,subject]
-cindex:[subject, logging]
-%subject%: The subject of the message is added to the arrival log line,
-preceded by ``T='' (T for ``topic'', since S is already used for ``size'').
-Any MIME ``words'' in the subject are decoded. The %print_topbitchars% option
-specifies whether characters with values greater than 127 should be logged
-unchanged, or whether they should be rendered as escape sequences.
-
-- cindex:[log,certificate verification]
-%tls_certificate_verified%: An extra item is added to <= and => log lines
-when TLS is in use. The item is `CV=yes` if the peer's certificate was
-verified, and `CV=no` if not.
-
-- cindex:[log,TLS cipher]
-cindex:[TLS,logging cipher]
-%tls_cipher%: When a message is sent or received over an encrypted connection,
-the cipher suite used is added to the log line, preceded by X=.
-
-- cindex:[log,TLS peer DN]
-cindex:[TLS,logging peer DN]
-%tls_peerdn%: When a message is sent or received over an encrypted connection,
-and a certificate is supplied by the remote host, the peer DN is added to the
-log line, preceded by DN=.
-
-[revisionflag="changed"]
-- cindex:[log,DNS failure in list]
-%unknown_in_list%: This setting causes a log entry to be written when the
-result of a list match is failure because a DNS lookup failed.
-
-
-Message log
-~~~~~~~~~~~
-cindex:[message,log file for]
-cindex:[log,message log; description of]
-In addition to the general log files, Exim writes a log file for each message
-that it handles. The names of these per-message logs are the message ids, and
-
-cindex:[_msglog_ directory]
-they are kept in the _msglog_ sub-directory of the spool directory. Each
-message log contains copies of the log lines that apply to the message. This
-makes it easier to inspect the status of an individual message without having
-to search the main log. A message log is deleted when processing of the message
-is complete,
-
-cindex:[%preserve_message_logs%]
-unless %preserve_message_logs% is set, but this should be used only with
-great care because they can fill up your disk very quickly.
-
-On a heavily loaded system, it may be desirable to disable the use of
-per-message logs, in order to reduce disk I/O. This can be done by setting the
-%message_logs% option false.
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPutils]]
-Exim utilities
---------------
-cindex:[utilities]
-A number of utility scripts and programs are supplied with Exim and are
-described in this chapter. There is also the Exim Monitor, which is covered in
-the next chapter. The utilities described here are:
-
-[frame="none"]
-`2`8`30`40~
-,<<SECTfinoutwha>> , 'exiwhat' , list what Exim processes are doing
-,<<SECTgreptheque>> , 'exiqgrep' , grep the queue
-,<<SECTsumtheque>> , 'exiqsumm' , summarize the queue
-,<<SECTextspeinf>> , 'exigrep' , search the main log
-,<<SECTexipick>> , 'exipick' , select messages on various criteria
-,<<SECTcyclogfil>> , 'exicyclog' , cycle (rotate) log files
-,<<SECTmailstat>> , 'eximstats' , extract statistics from the log
-,<<SECTcheckaccess>> , 'exim_checkaccess', check address acceptance from given IP
-,<<SECTdbmbuild>> , 'exim_dbmbuild' , build a DBM file
-,<<SECTfinindret>> , 'exinext' , extract retry information
-,<<SECThindatmai>> , 'exim_dumpdb' , dump a hints database
-,<<SECThindatmai>> , 'exim_tidydb' , clean up a hints database
-,<<SECThindatmai>> , 'exim_fixdb' , patch a hints database
-,<<SECTmailboxmaint>>, 'exim_lock' , lock a mailbox file
-~~~~~
-
-[revisionflag="changed"]
-Another utility that might be of use to sites with many MTAs is Tom Kistner's
-'exilog'. It provides log visualizations across multiple Exim servers. See
-(*http://duncanthrax.net/exilog/[]*) for details.
-
-
-
-
-
-[[SECTfinoutwha]]
-Finding out what Exim processes are doing (exiwhat)
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:['exiwhat']
-cindex:[process, querying]
-cindex:[SIGUSR1]
-On operating systems that can restart a system call after receiving a signal
-(most modern OS), an Exim process responds to the SIGUSR1 signal by writing
-a line describing what it is doing to the file _exim-process.info_ in the
-Exim spool directory. The 'exiwhat' script sends the signal to all Exim
-processes it can find, having first emptied the file. It then waits for one
-second to allow the Exim processes to react before displaying the results. In
-order to run 'exiwhat' successfully you have to have sufficient privilege to
-send the signal to the Exim processes, so it is normally run as root.
-
-*Warning*: This is not an efficient process. It is intended for occasional
-use by system administrators. It is not sensible, for example, to set up a
-script that sends SIGUSR1 signals to Exim processes at short intervals.
-
-
-Unfortunately, the 'ps' command that 'exiwhat' uses to find Exim processes
-varies in different operating systems. Not only are different options used,
-but the format of the output is different. For this reason, there are some
-system configuration options that configure exactly how 'exiwhat' works. If it
-doesn't seem to be working for you, check the following compile-time options:
-
-&&&
-`EXIWHAT_PS_CMD ` the command for running 'ps'
-`EXIWHAT_PS_ARG ` the argument for 'ps'
-`EXIWHAT_EGREP_ARG ` the argument for 'egrep' to select from 'ps' output
-`EXIWHAT_KILL_ARG ` the argument for the 'kill' command
-&&&
-
-An example of typical output from 'exiwhat' is
-
- 164 daemon: -q1h, listening on port 25
- 10483 running queue: waiting for 0tAycK-0002ij-00 (10492)
- 10492 delivering 0tAycK-0002ij-00 to mail.ref.example [10.19.42.42]
- (editor@ref.example)
- 10592 handling incoming call from [192.168.243.242]
- 10628 accepting a local non-SMTP message
-
-The first number in the output line is the process number. The third line has
-been split here, in order to fit it on the page.
-
-
-
-[[SECTgreptheque]]
-Selective queue listing (exiqgrep)
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:['exiqgrep']
-cindex:[queue,grepping]
-This utility is a Perl script contributed by Matt Hubbard. It runs
-
- exim -bpu
-
-to obtain a queue listing with undelivered recipients only, and then greps the
-output to select messages that match given criteria. The following selection
-options are available:
-
-*-f*~<'regex'>::
-Match the sender address. The field that is tested is enclosed in angle
-brackets, so you can test for bounce messages with
-
- exiqgrep -f '^<>$'
-
-*-r*~<'regex'>::
-Match a recipient address. The field that is tested is not enclosed in angle
-brackets.
-
-*-s*~<'regex'>::
-Match against the size field.
-
-*-y*~<'seconds'>::
-Match messages that are younger than the given time.
-
-*-o*~<'seconds'>::
-Match messages that are older than the given time.
-
-*-z*::
-Match only frozen messages.
-
-*-x*::
-Match only non-frozen messages.
-
-///
-End of list
-///
-
-The following options control the format of the output:
-
-*-c*::
-Display only the count of matching messages.
-
-*-l*::
-Long format -- display the full message information as output by Exim. This is
-the default.
-
-*-i*::
-Display message ids only.
-
-*-b*::
-Brief format -- one line per message.
-
-*-R*::
-Display messages in reverse order.
-
-///
-End of list
-///
-
-There is one more option, %-h%, which outputs a list of options.
-
-
-
-[[SECTsumtheque]]
-Summarising the queue (exiqsumm)
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:['exiqsumm']
-cindex:[queue,summary]
-The 'exiqsumm' utility is a Perl script which reads the output of 'exim
--bp' and produces a summary of the messages on the queue. Thus, you use it by
-running a command such as
-
- exim -bp | exiqsumm
-
-The output consists of one line for each domain that has messages waiting for
-it, as in the following example:
-
- 3 2322 74m 66m msn.com.example
-
-Each line lists the number of
-pending deliveries for a domain, their total volume, and the length of time
-that the oldest and the newest messages have been waiting. Note that the number
-of pending deliveries is greater than the number of messages when messages
-have more than one recipient.
-
-A summary line is output at the end. By default the output is sorted on the
-domain name, but 'exiqsumm' has the options %-a% and %-c%, which cause the
-output to be sorted by oldest message and by count of messages, respectively.
-
-The output of 'exim -bp' contains the original addresses in the message, so
-this also applies to the output from 'exiqsumm'. No domains from addresses
-generated by aliasing or forwarding are included (unless the %one_time% option
-of the ^redirect^ router has been used to convert them into ``top level''
-addresses).
-
-
-
-
-[[SECTextspeinf]]
-Extracting specific information from the log (exigrep)
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-[revisionflag="changed"]
-cindex:['exigrep']
-cindex:[log,extracts; grepping for]
-The 'exigrep' utility is a Perl script that searches one or more main log
-files for entries that match a given pattern. When it finds a match, it
-extracts all the log entries for the relevant message, not just those that
-match the pattern. Thus, 'exigrep' can extract complete log entries for a
-given message, or all mail for a given user, or for a given host, for example.
-The input files can be in Exim log format or syslog format.
-
-If a matching log line is not associated with a specific message, it is always
-included in 'exigrep''s output. The usage is:
-
- exigrep [-l] [-t<n>] <pattern> [<log file>] ...
-
-The %-t% argument specifies a number of seconds. It adds an additional
-condition for message selection. Messages that are complete are shown only if
-they spent more than <'n'> seconds on the queue.
-
-The %-l% flag means ``literal'', that is, treat all characters in the
-pattern as standing for themselves. Otherwise the pattern must be a Perl
-regular expression. The pattern match is case-insensitive. If no file names are
-given on the command line, the standard input is read.
-
-If the location of a 'zcat' command is known from the definition of
-ZCAT_COMMAND in _Local/Makefile_, 'exigrep' automatically passes any file whose
-name ends in COMPRESS_SUFFIX through 'zcat' as it searches it.
-
-
-[[SECTexipick]]
-Selecting messages by various criteria (exipick)
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:['exipick']
-John Jetmore's 'exipick' utility is included in the Exim distribution. It
-lists messages from the queue according to a variety of criteria. For details,
-run:
-
- exipick --help
-
-
-
-
-[[SECTcyclogfil]]
-Cycling log files (exicyclog)
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[log,cycling local files]
-cindex:[cycling logs]
-cindex:['exicyclog']
-The 'exicyclog' script can be used to cycle (rotate) 'mainlog' and
-'rejectlog' files. This is not necessary if only syslog is being used, or if
-you are using log files with datestamps in their names (see section
-<<SECTdatlogfil>>). Some operating systems have their own standard mechanisms for
-log cycling, and these can be used instead of 'exicyclog' if preferred.
-
-Each time 'exicyclog' is run the file names get ``shuffled down'' by one. If
-the main log file name is _mainlog_ (the default) then when 'exicyclog' is
-run _mainlog_ becomes _mainlog.01_, the previous _mainlog.01_ becomes
-_mainlog.02_ and so on, up to a limit which is set in the script, and which
-defaults to 10. Log files whose numbers exceed the limit are discarded. Reject
-logs are handled similarly.
-
-If the limit is greater than 99, the script uses 3-digit numbers such as
-_mainlog.001_, _mainlog.002_, etc. If you change from a number less than 99
-to one that is greater, or 'vice versa', you will have to fix the names of
-any existing log files.
-
-
-If no _mainlog_ file exists, the script does nothing. Files that ``drop off''
-the end are deleted. All files with numbers greater than 01 are compressed,
-using a compression command which is configured by the COMPRESS_COMMAND
-setting in _Local/Makefile_. It is usual to run 'exicyclog' daily from a
-root %crontab% entry of the form
-
- 1 0 * * * su exim -c /usr/exim/bin/exicyclog
-
-assuming you have used the name ``exim'' for the Exim user. You can run
-'exicyclog' as root if you wish, but there is no need.
-
-
-
-[[SECTmailstat]]
-Mail statistics (eximstats)
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[statistics]
-cindex:['eximstats']
-A Perl script called 'eximstats' is provided for extracting statistical
-information from log files. The output is either plain text, or HTML.
-Exim log files are also suported by the 'Lire' system produced by the
-LogReport Foundation (*http://www.logreport.org[]*).
-
-The 'eximstats' script has been hacked about quite a bit over time. The
-latest version is the result of some extensive revision by Steve Campbell. A
-lot of information is given by default, but there are options for suppressing
-various parts of it. Following any options, the arguments to the script are a
-list of files, which should be main log files. For example:
-
- eximstats -nr /var/spool/exim/log/mainlog.01
-
-By default, 'eximstats' extracts information about the number and volume of
-messages received from or delivered to various hosts. The information is sorted
-both by message count and by volume, and the top fifty hosts in each category
-are listed on the standard output. Similar information, based on email
-addresses or domains instead of hosts can be requested by means of various
-options. For messages delivered and received locally, similar statistics are
-also produced per user.
-
-The output also includes total counts and statistics about delivery errors, and
-histograms showing the number of messages received and deliveries made in each
-hour of the day. A delivery with more than one address in its envelope (for
-example, an SMTP transaction with more than one RCPT command) is counted
-as a single delivery by 'eximstats'.
-
-Though normally more deliveries than receipts are reported (as messages may
-have multiple recipients), it is possible for 'eximstats' to report more
-messages received than delivered, even though the queue is empty at the start
-and end of the period in question. If an incoming message contains no valid
-recipients, no deliveries are recorded for it. A bounce message is handled as
-an entirely separate message.
-
-'eximstats' always outputs a grand total summary giving the volume and number
-of messages received and deliveries made, and the number of hosts involved in
-each case. It also outputs the number of messages that were delayed (that is,
-not completely delivered at the first attempt), and the number that had at
-least one address that failed.
-
-The remainder of the output is in sections that can be independently disabled
-or modified by various options. It consists of a summary of deliveries by
-transport, histograms of messages received and delivered per time interval
-(default per hour), information about the time messages spent on the queue,
-a list of relayed messages, lists of the top fifty sending hosts, local
-senders, destination hosts, and destination local users by count and by volume,
-and a list of delivery errors that occurred.
-
-The relay information lists messages that were actually relayed, that is, they
-came from a remote host and were directly delivered to some other remote host,
-without being processed (for example, for aliasing or forwarding) locally.
-
-There are quite a few options for 'eximstats' to control exactly what it
-outputs. These are documented in the Perl script itself, and can be extracted
-by running the command ^perldoc^ on the script. For example:
-
- perldoc /usr/exim/bin/eximstats
-
-
-
-[[SECTcheckaccess]]
-Checking access policy (exim_checkaccess)
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:['exim_checkaccess']
-cindex:[policy control,checking access]
-cindex:[checking access]
-The %-bh% command line argument allows you to run a fake SMTP session with
-debugging output, in order to check what Exim is doing when it is applying
-policy controls to incoming SMTP mail. However, not everybody is sufficiently
-familiar with the SMTP protocol to be able to make full use of %-bh%, and
-sometimes you just want to answer the question 'Does this address have
-access?' without bothering with any further details.
-
-The 'exim_checkaccess' utility is a ``packaged'' version of %-bh%. It takes
-two arguments, an IP address and an email address:
-
- exim_checkaccess 10.9.8.7 A.User@a.domain.example
-
-The utility runs a call to Exim with the %-bh% option, to test whether the
-given email address would be accepted in a RCPT command in a TCP/IP
-connection from the host with the given IP address. The output of the utility
-is either the word ``accepted'', or the SMTP error response, for example:
-
- Rejected:
- 550 Relay not permitted
-
-When running this test, the utility uses `<>` as the envelope sender address
-for the MAIL command, but you can change this by providing additional
-options. These are passed directly to the Exim command. For example, to specify
-that the test is to be run with the sender address 'himself@there.example'
-you can use:
-
-....
-exim_checkaccess 10.9.8.7 A.User@a.domain.example \
- -f himself@there.example
-....
-
-Note that these additional Exim command line items must be given after the two
-mandatory arguments.
-
-Because the %exim_checkaccess% uses %-bh%, it does not perform callouts while
-running its checks. You can run checks that include callouts by using %-bhc%,
-but this is not yet available in a ``packaged'' form.
-
-
-
-[[SECTdbmbuild]]
-Making DBM files (exim_dbmbuild)
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[DBM,building dbm files]
-cindex:[building DBM files]
-cindex:['exim_dbmbuild']
-cindex:[lower casing]
-cindex:[binary zero,in lookup key]
-The 'exim_dbmbuild' program reads an input file containing keys and data in
-the format used by the ^lsearch^ lookup (see section <<SECTsinglekeylookups>>).
-It writes a DBM file using the lower-cased alias names as keys and the
-remainder of the information as data. The lower-casing can be prevented by
-calling the program with the %-nolc% option.
-
-A terminating zero is included as part of the key string. This is expected by
-the ^dbm^ lookup type. However, if the option %-nozero% is given,
-'exim_dbmbuild' creates files without terminating zeroes in either the key
-strings or the data strings. The ^dbmnz^ lookup type can be used with such
-files.
-
-The program requires two arguments: the name of the input file (which can be a
-single hyphen to indicate the standard input), and the name of the output file.
-It creates the output under a temporary name, and then renames it if all went
-well.
-
-cindex:[USE_DB]
-If the native DB interface is in use (USE_DB is set in a compile-time
-configuration file -- this is common in free versions of Unix) the two file
-names must be different, because in this mode the Berkeley DB functions create
-a single output file using exactly the name given. For example,
-
- exim_dbmbuild /etc/aliases /etc/aliases.db
-
-reads the system alias file and creates a DBM version of it in
-_/etc/aliases.db_.
-
-In systems that use the 'ndbm' routines (mostly proprietary versions of Unix),
-two files are used, with the suffixes _.dir_ and _.pag_. In this
-environment, the suffixes are added to the second argument of
-'exim_dbmbuild', so it can be the same as the first. This is also the case
-when the Berkeley functions are used in compatibility mode (though this is not
-recommended), because in that case it adds a _.db_ suffix to the file name.
-
-If a duplicate key is encountered, the program outputs a warning, and when it
-finishes, its return code is 1 rather than zero, unless the %-noduperr% option
-is used. By default, only the first of a set of duplicates is used -- this
-makes it compatible with ^lsearch^ lookups. There is an option %-lastdup%
-which causes it to use the data for the last duplicate instead. There is also
-an option %-nowarn%, which stops it listing duplicate keys to %stderr%. For
-other errors, where it doesn't actually make a new file, the return code is 2.
-
-
-
-
-[[SECTfinindret]]
-Finding individual retry times (exinext)
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[retry,times]
-cindex:['exinext']
-A utility called 'exinext' (mostly a Perl script) provides the ability to fish
-specific information out of the retry database. Given a mail domain (or a
-complete address), it looks up the hosts for that domain, and outputs any retry
-information for the hosts or for the domain. At present, the retry information
-is obtained by running 'exim_dumpdb' (see below) and post-processing the
-output. For example:
-
- $ exinext piglet@milne.fict.example
- kanga.milne.fict.example:192.168.8.1 error 146: Connection refused
- first failed: 21-Feb-1996 14:57:34
- last tried: 21-Feb-1996 14:57:34
- next try at: 21-Feb-1996 15:02:34
- roo.milne.fict.example:192.168.8.3 error 146: Connection refused
- first failed: 20-Jan-1996 13:12:08
- last tried: 21-Feb-1996 11:42:03
- next try at: 21-Feb-1996 19:42:03
- past final cutoff time
-
-You can also give 'exinext' a local part, without a domain, and it
-will give any retry information for that local part in your default domain.
-A message id can be used to obtain retry information pertaining to a specific
-message. This exists only when an attempt to deliver a message to a remote host
-suffers a message-specific error (see section <<SECToutSMTPerr>>). 'exinext' is
-not particularly efficient, but then it isn't expected to be run very often.
-
-The 'exinext' utility calls Exim to find out information such as the location
-of the spool directory. The utility has %-C% and %-D% options, which are
-passed on to the 'exim' commands. The first specifies an alternate Exim
-configuration file, and the second sets macros for use within the configuration
-file. These features are mainly to help in testing, but might also be useful in
-environments where more than one configuration file is in use.
-
-
-
-
-[[SECThindatmai]]
-Hints database maintenance (exim_dumpdb, exim_fixdb, exim_tidydb)
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[hints database,maintenance]
-cindex:[maintaining Exim's hints database]
-Three utility programs are provided for maintaining the DBM files that Exim
-uses to contain its delivery hint information. Each program requires two
-arguments. The first specifies the name of Exim's spool directory, and the
-second is the name of the database it is to operate on. These are as follows:
-
-- 'retry': the database of retry information
-
-- 'wait-'<'transport name'>: databases of information about messages waiting
-for remote hosts
-
-- 'callout': the callout cache
-
-[revisionflag="changed"]
-- 'ratelimit': the data for implementing the ratelimit ACL condition
-
-- 'misc': other hints data
-
-The 'misc' database is used for
-
-- Serializing ETRN runs (when %smtp_etrn_serialize% is set)
-
-- Serializing delivery to a specific host (when %serialize_hosts% is set in an
-^smtp^ transport)
-
-
-
-exim_dumpdb
-~~~~~~~~~~~
-cindex:['exim_dumpdb']
-The entire contents of a database are written to the standard output by the
-'exim_dumpdb' program, which has no options or arguments other than the
-spool and database names. For example, to dump the retry database:
-
- exim_dumpdb /var/spool/exim retry
-
-Two lines of output are produced for each entry:
-
- T:mail.ref.example:192.168.242.242 146 77 Connection refused
- 31-Oct-1995 12:00:12 02-Nov-1995 12:21:39 02-Nov-1995 20:21:39 *
-
-The first item on the first line is the key of the record. It starts with one
-of the letters R, or T, depending on whether it refers to a routing or
-transport retry. For a local delivery, the next part is the local address; for
-a remote delivery it is the name of the remote host, followed by its failing IP
-address (unless %no_retry_include_ip_address% is set on the ^smtp^
-transport). If the remote port is not the standard one (port 25), it is added
-to the IP address. Then there follows an error code, an additional error code,
-and a textual description of the error.
-
-The three times on the second line are the time of first failure, the time of
-the last delivery attempt, and the computed time for the next attempt. The line
-ends with an asterisk if the cutoff time for the last retry rule has been
-exceeded.
-
-Each output line from 'exim_dumpdb' for the 'wait-''xxx' databases
-consists of a host name followed by a list of ids for messages that are or were
-waiting to be delivered to that host. If there are a very large number for any
-one host, continuation records, with a sequence number added to the host name,
-may be seen. The data in these records is often out of date, because a message
-may be routed to several alternative hosts, and Exim makes no effort to keep
-cross-references.
-
-
-
-exim_tidydb
-~~~~~~~~~~~
-[revisionflag="changed"]
-cindex:['exim_tidydb']
-The 'exim_tidydb' utility program is used to tidy up the contents of a hints
-database. If run with no options, it removes all records that are more than 30
-days old. The age is calculated from the date and time that the record was last
-updated. Note that, in the case of the retry database, it is 'not' the time
-since the first delivery failure. Information about a host that has been down
-for more than 30 days will remain in the database, provided that the record is
-updated sufficiently often.
-
-The cutoff date can be altered by means of the %-t% option, which must be
-followed by a time. For example, to remove all records older than a week from
-the retry database:
-
- exim_tidydb -t 7d /var/spool/exim retry
-
-Both the 'wait-''xxx' and 'retry' databases contain items that involve
-message ids. In the former these appear as data in records keyed by host --
-they were messages that were waiting for that host -- and in the latter they
-are the keys for retry information for messages that have suffered certain
-types of error. When 'exim_tidydb' is run, a check is made to ensure that
-message ids in database records are those of messages that are still on the
-queue. Message ids for messages that no longer exist are removed from
-'wait-''xxx' records, and if this leaves any records empty, they are
-deleted. For the 'retry' database, records whose keys are non-existent
-message ids are removed. The 'exim_tidydb' utility outputs comments on the
-standard output whenever it removes information from the database.
-
-Certain records are automatically removed by Exim when they are no longer
-needed, but others are not. For example, if all the MX hosts for a domain are
-down, a retry record is created for each one. If the primary MX host comes back
-first, its record is removed when Exim successfully delivers to it, but the
-records for the others remain because Exim has not tried to use those hosts.
-
-It is important, therefore, to run 'exim_tidydb' periodically on all the
-hints databases. You should do this at a quiet time of day, because it requires
-a database to be locked (and therefore inaccessible to Exim) while it does its
-work. Removing records from a DBM file does not normally make the file smaller,
-but all the common DBM libraries are able to re-use the space that is released.
-After an initial phase of increasing in size, the databases normally reach a
-point at which they no longer get any bigger, as long as they are regularly
-tidied.
-
-*Warning*: If you never run 'exim_tidydb', the space used by the hints
-databases is likely to keep on increasing.
-
-
-
-
-exim_fixdb
-~~~~~~~~~~
-cindex:['exim_fixdb']
-The 'exim_fixdb' program is a utility for interactively modifying databases.
-Its main use is for testing Exim, but it might also be occasionally useful for
-getting round problems in a live system. It has no options, and its interface
-is somewhat crude. On entry, it prompts for input with a right angle-bracket. A
-key of a database record can then be entered, and the data for that record is
-displayed.
-
-If ``d'' is typed at the next prompt, the entire record is deleted. For all
-except the 'retry' database, that is the only operation that can be carried
-out. For the 'retry' database, each field is output preceded by a number, and
-data for individual fields can be changed by typing the field number followed
-by new data, for example:
-
- > 4 951102:1000
-
-resets the time of the next delivery attempt. Time values are given as a
-sequence of digit pairs for year, month, day, hour, and minute. Colons can be
-used as optional separators.
-
-
-
-
-[[SECTmailboxmaint]]
-Mailbox maintenance (exim_lock)
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[mailbox,maintenance]
-cindex:['exim_lock']
-cindex:[locking mailboxes]
-The 'exim_lock' utility locks a mailbox file using the same algorithm as
-Exim. For a discussion of locking issues, see section <<SECTopappend>>.
-'Exim_lock' can be used to prevent any modification of a mailbox by Exim or
-a user agent while investigating a problem. The utility requires the name of
-the file as its first argument. If the locking is successful, the second
-argument is run as a command (using C's 'system()' function); if there is no
-second argument, the value of the SHELL environment variable is used; if this
-is unset or empty, _/bin/sh_ is run. When the command finishes, the mailbox
-is unlocked and the utility ends. The following options are available:
-
-*-fcntl*:: Use 'fcntl()' locking on the open mailbox.
-
-*-flock*:: Use 'flock()' locking on the open mailbox, provided the operating
-system supports it.
-
-*-interval*:: This must be followed by a number, which is a number of seconds;
-it sets the interval to sleep between retries (default 3).
-
-*-lockfile*:: Create a lock file before opening the mailbox.
-
-*-mbx*:: Lock the mailbox using MBX rules.
-
-*-q*:: Suppress verification output.
-
-*-retries*:: This must be followed by a number; it sets the number of times to
-try to get the lock (default 10).
-
-*-restore_time*:: This option causes %exim_lock% to restore the modified and
-read times to the locked file before exiting. This allows you to access a
-locked mailbox (for example, to take a backup copy) without disturbing the
-times that the user subsequently sees.
-
-*-timeout*:: This must be followed by a number, which is a number of seconds;
-it sets a timeout to be used with a blocking 'fcntl()' lock. If it is not set
-(the default), a non-blocking call is used.
-
-*-v*:: Generate verbose output.
-
-If none of %-fcntl%, %-flock%, %-lockfile% or %-mbx% are given, the default is
-to create a lock file and also to use 'fcntl()' locking on the mailbox, which
-is the same as Exim's default. The use of %-flock% or %-fcntl% requires that
-the file be writeable; the use of %-lockfile% requires that the directory
-containing the file be writeable. Locking by lock file does not last for ever;
-Exim assumes that a lock file is expired if it is more than 30 minutes old.
-
-The %-mbx% option can be used with either or both of %-fcntl% or %-flock%.
-It assumes %-fcntl% by default.
-MBX locking causes a shared lock to be taken out on the open mailbox, and an
-exclusive lock on the file _/tmp/._'n'.'m' where 'n' and 'm' are
-the device number and inode number of the mailbox file. When the locking is
-released, if an exclusive lock can be obtained for the mailbox, the file in
-_/tmp_ is deleted.
-
-The default output contains verification of the locking that takes place. The
-%-v% option causes some additional information to be given. The %-q% option
-suppresses all output except error messages.
-
-A command such as
-
- exim_lock /var/spool/mail/spqr
-
-runs an interactive shell while the file is locked, whereas
-
- exim_lock -q /var/spool/mail/spqr <<End
- <some commands>
- End
-
-runs a specific non-interactive sequence of commands while the file is locked,
-suppressing all verification output. A single command can be run by a command
-such as
-
-....
-exim_lock -q /var/spool/mail/spqr \
- "cp /var/spool/mail/spqr /some/where"
-....
-
-Note that if a command is supplied, it must be entirely contained within the
-second argument -- hence the quotes.
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPeximon]]
-The Exim monitor
-----------------
-cindex:[Exim monitor,description]
-cindex:[X-windows]
-cindex:['eximon']
-cindex:[Local/eximon.conf]
-cindex:[_exim_monitor/EDITME_]
-The Exim monitor is an application which displays in an X window information
-about the state of Exim's queue and what Exim is doing. An admin user can
-perform certain operations on messages from this GUI interface; however all
-such facilities are also available from the command line, and indeed, the
-monitor itself makes use of the command line to perform any actions requested.
-
-
-
-Running the monitor
-~~~~~~~~~~~~~~~~~~~
-The monitor is started by running the script called 'eximon'. This is a shell
-script that sets up a number of environment variables, and then runs the
-binary called _eximon.bin_. The default appearance of the monitor window can
-be changed by editing the _Local/eximon.conf_ file created by editing
-_exim_monitor/EDITME_. Comments in that file describe what the various
-parameters are for.
-
-The parameters that get built into the 'eximon' script can be overridden for a
-particular invocation by setting up environment variables of the same names,
-preceded by `EXIMON_`. For example, a shell command such as
-
- EXIMON_LOG_DEPTH=400 eximon
-
-(in a Bourne-compatible shell) runs 'eximon' with an overriding setting of the
-LOG_DEPTH parameter. If EXIMON_LOG_FILE_PATH is set in the
-environment, it overrides the Exim log file configuration. This makes it
-possible to have 'eximon' tailing log data that is written to syslog, provided
-that MAIL.INFO syslog messages are routed to a file on the local host.
-
-X resources can be used to change the appearance of the window in the normal
-way. For example, a resource setting of the form
-
- Eximon*background: gray94
-
-changes the colour of the background to light grey rather than white. The
-stripcharts are drawn with both the data lines and the reference lines in
-black. This means that the reference lines are not visible when on top of the
-data. However, their colour can be changed by setting a resource called
-``highlight'' (an odd name, but that's what the Athena stripchart widget uses).
-For example, if your X server is running Unix, you could set up lighter
-reference lines in the stripcharts by obeying
-
- xrdb -merge <<End
- Eximon*highlight: gray
- End
-
-
-cindex:[admin user]
-In order to see the contents of messages on the queue, and to operate on them,
-'eximon' must either be run as root or by an admin user.
-
-The monitor's window is divided into three parts. The first contains one or
-more stripcharts and two action buttons, the second contains a ``tail'' of the
-main log file, and the third is a display of the queue of messages awaiting
-delivery, with two more action buttons. The following sections describe these
-different parts of the display.
-
-
-
-
-The stripcharts
-~~~~~~~~~~~~~~~
-cindex:[stripchart]
-The first stripchart is always a count of messages on the queue. Its name can
-be configured by setting QUEUE_STRIPCHART_NAME in the
-_Local/eximon.conf_ file. The remaining stripcharts are defined in the
-configuration script by regular expression matches on log file entries, making
-it possible to display, for example, counts of messages delivered to certain
-hosts or using certain transports. The supplied defaults display counts of
-received and delivered messages, and of local and SMTP deliveries. The default
-period between stripchart updates is one minute; this can be adjusted by a
-parameter in the _Local/eximon.conf_ file.
-
-The stripchart displays rescale themselves automatically as the value they are
-displaying changes. There are always 10 horizontal lines in each chart; the
-title string indicates the value of each division when it is greater than one.
-For example, ``x2'' means that each division represents a value of 2.
-
-It is also possible to have a stripchart which shows the percentage fullness of
-a particular disk partition, which is useful when local deliveries are confined
-to a single partition.
-
-cindex:[%statvfs% function]
-This relies on the availability of the 'statvfs()' function or equivalent in
-the operating system. Most, but not all versions of Unix that support Exim have
-this. For this particular stripchart, the top of the chart always represents
-100%, and the scale is given as ``x10%''. This chart is configured by setting
-SIZE_STRIPCHART and (optionally) SIZE_STRIPCHART_NAME in the
-_Local/eximon.conf_ file.
-
-
-
-
-Main action buttons
-~~~~~~~~~~~~~~~~~~~
-cindex:[size,of monitor window]
-cindex:[Exim monitor,window size]
-cindex:[window size]
-Below the stripcharts there is an action button for quitting the monitor. Next
-to this is another button marked ``Size''. They are placed here so that shrinking
-the window to its default minimum size leaves just the queue count stripchart
-and these two buttons visible. Pressing the ``Size'' button causes the window to
-expand to its maximum size, unless it is already at the maximum, in which case
-it is reduced to its minimum.
-
-When expanding to the maximum, if the window cannot be fully seen where it
-currently is, it is moved back to where it was the last time it was at full
-size. When it is expanding from its minimum size, the old position is
-remembered, and next time it is reduced to the minimum it is moved back there.
-
-The idea is that you can keep a reduced window just showing one or two
-stripcharts at a convenient place on your screen, easily expand it to show
-the full window when required, and just as easily put it back to what it was.
-The idea is copied from what the 'twm' window manager does for its
-'f.fullzoom' action. The minimum size of the window can be changed by setting
-the MIN_HEIGHT and MIN_WIDTH values in _Local/eximon.conf_.
-
-Normally, the monitor starts up with the window at its full size, but it can be
-built so that it starts up with the window at its smallest size, by setting
-START_SMALL=yes in _Local/eximon.conf_.
-
-
-
-The log display
-~~~~~~~~~~~~~~~
-cindex:[log,tail of; in monitor]
-The second section of the window is an area in which a display of the tail of
-the main log is maintained.
-To save space on the screen, the timestamp on each log line is shortened by
-removing the date and, if %log_timezone% is set, the timezone.
-The log tail is not available when the only destination for logging data is
-syslog, unless the syslog lines are routed to a local file whose name is passed
-to 'eximon' via the EXIMON_LOG_FILE_PATH environment variable.
-
-The log sub-window has a scroll bar at its lefthand side which can be used to
-move back to look at earlier text, and the up and down arrow keys also have a
-scrolling effect. The amount of log that is kept depends on the setting of
-LOG_BUFFER in _Local/eximon.conf_, which specifies the amount of memory
-to use. When this is full, the earlier 50% of data is discarded -- this is much
-more efficient than throwing it away line by line. The sub-window also has a
-horizontal scroll bar for accessing the ends of long log lines. This is the
-only means of horizontal scrolling; the right and left arrow keys are not
-available. Text can be cut from this part of the window using the mouse in the
-normal way. The size of this subwindow is controlled by parameters in the
-configuration file _Local/eximon.conf_.
-
-Searches of the text in the log window can be carried out by means of the ^R
-and ^S keystrokes, which default to a reverse and a forward search,
-respectively. The search covers only the text that is displayed in the window.
-It cannot go further back up the log.
-
-The point from which the search starts is indicated by a caret marker. This is
-normally at the end of the text in the window, but can be positioned explicitly
-by pointing and clicking with the left mouse button, and is moved automatically
-by a successful search. If new text arrives in the window when it is scrolled
-back, the caret remains where it is, but if the window is not scrolled back,
-the caret is moved to the end of the new text.
-
-Pressing ^R or ^S pops up a window into which the search text can be typed.
-There are buttons for selecting forward or reverse searching, for carrying out
-the search, and for cancelling. If the ``Search'' button is pressed, the search
-happens and the window remains so that further searches can be done. If the
-``Return'' key is pressed, a single search is done and the window is closed. If
-^C is typed the search is cancelled.
-
-The searching facility is implemented using the facilities of the Athena text
-widget. By default this pops up a window containing both ``search'' and ``replace''
-options. In order to suppress the unwanted ``replace'' portion for eximon, a
-modified version of the %TextPop% widget is distributed with Exim. However, the
-linkers in BSDI and HP-UX seem unable to handle an externally provided version
-of %TextPop% when the remaining parts of the text widget come from the standard
-libraries. The compile-time option EXIMON_TEXTPOP can be unset to cut out
-the modified %TextPop%, making it possible to build Eximon on these systems, at
-the expense of having unwanted items in the search popup window.
-
-
-
-The queue display
-~~~~~~~~~~~~~~~~~
-cindex:[queue,display in monitor]
-The bottom section of the monitor window contains a list of all messages that
-are on the queue, which includes those currently being received or delivered,
-as well as those awaiting delivery. The size of this subwindow is controlled by
-parameters in the configuration file _Local/eximon.conf_, and the frequency
-at which it is updated is controlled by another parameter in the same file --
-the default is 5 minutes, since queue scans can be quite expensive. However,
-there is an ``Update'' action button just above the display which can be used to
-force an update of the queue display at any time.
-
-When a host is down for some time, a lot of pending mail can build up for it,
-and this can make it hard to deal with other messages on the queue. To help
-with this situation there is a button next to ``Update'' called ``Hide''. If
-pressed, a dialogue box called ``Hide addresses ending with'' is put up. If you
-type anything in here and press ``Return'', the text is added to a chain of such
-texts, and if every undelivered address in a message matches at least one
-of the texts, the message is not displayed.
-
-If there is an address that does not match any of the texts, all the addresses
-are displayed as normal. The matching happens on the ends of addresses so, for
-example, 'cam.ac.uk' specifies all addresses in Cambridge, while
-'xxx@foo.com.example' specifies just one specific address. When any hiding
-has been set up, a button called ``Unhide'' is displayed. If pressed, it cancels
-all hiding. Also, to ensure that hidden messages do not get forgotten, a hide
-request is automatically cancelled after one hour.
-
-While the dialogue box is displayed, you can't press any buttons or do anything
-else to the monitor window. For this reason, if you want to cut text from the
-queue display to use in the dialogue box, you have to do the cutting before
-pressing the ``Hide'' button.
-
-The queue display contains, for each unhidden queued message, the length of
-time it has been on the queue, the size of the message, the message id, the
-message sender, and the first undelivered recipient, all on one line. If it is
-a bounce message, the sender is shown as ``<>''. If there is more than one
-recipient to which the message has not yet been delivered, subsequent ones are
-listed on additional lines, up to a maximum configured number, following which
-an ellipsis is displayed. Recipients that have already received the message are
-not shown.
-
-cindex:[frozen messages,display]
-If a message is frozen, an asterisk is displayed at the left-hand side.
-
-The queue display has a vertical scroll bar, and can also be scrolled by means
-of the arrow keys. Text can be cut from it using the mouse in the normal way.
-The text searching facilities, as described above for the log window, are also
-available, but the caret is always moved to the end of the text when the queue
-display is updated.
-
-
-
-The queue menu
-~~~~~~~~~~~~~~
-cindex:[queue,menu in monitor]
-If the %shift% key is held down and the left button is clicked when the mouse
-pointer is over the text for any message, an action menu pops up, and the first
-line of the queue display for the message is highlighted. This does not affect
-any selected text.
-
-If you want to use some other event for popping up the menu, you can set the
-MENU_EVENT parameter in _Local/eximon.conf_ to change the default, or
-set EXIMON_MENU_EVENT in the environment before starting the monitor. The
-value set in this parameter is a standard X event description. For example, to
-run eximon using %ctrl% rather than %shift% you could use
-
- EXIMON_MENU_EVENT='Ctrl<Btn1Down>' eximon
-
-The title of the menu is the message id, and it contains entries which act as
-follows:
-
-- 'message log': The contents of the message log for the message are displayed in
-a new text window.
-
-- 'headers': Information from the spool file that contains the envelope
-information and headers is displayed in a new text window. See chapter
-<<CHAPspool>> for a description of the format of spool files.
-
-- 'body': The contents of the spool file containing the body of the message are
-displayed in a new text window. There is a default limit of 20,000 bytes to the
-amount of data displayed. This can be changed by setting the BODY_MAX
-option at compile time, or the EXIMON_BODY_MAX option at run time.
-
-- 'deliver message': A call to Exim is made using the %-M% option to request
-delivery of the message. This causes an automatic thaw if the message is
-frozen. The %-v% option is also set, and the output from Exim is displayed in
-a new text window. The delivery is run in a separate process, to avoid holding
-up the monitor while the delivery proceeds.
-
-- 'freeze message': A call to Exim is made using the %-Mf% option to request
-that the message be frozen.
-
-- cindex:[thawing messages]
-cindex:[unfreezing messages]
-cindex:[frozen messages,thawing]
-'thaw message': A call to Exim is made using the %-Mt% option to request that
-the message be thawed.
-
-- cindex:[delivery,forcing failure]
-'give up on msg': A call to Exim is made using the %-Mg% option to request
-that Exim gives up trying to deliver the message. A bounce message is generated
-for any remaining undelivered addresses.
-
-- 'remove message': A call to Exim is made using the %-Mrm% option to request
-that the message be deleted from the system without generating a bounce
-message.
-
-- 'add recipient': A dialog box is displayed into which a recipient address can
-be typed. If the address is not qualified and the QUALIFY_DOMAIN parameter
-is set in _Local/eximon.conf_, the address is qualified with that domain.
-Otherwise it must be entered as a fully qualified address. Pressing RETURN
-causes a call to Exim to be made using the %-Mar% option to request that an
-additional recipient be added to the message, unless the entry box is empty, in
-which case no action is taken.
-
-- 'mark delivered': A dialog box is displayed into which a recipient address can
-be typed. If the address is not qualified and the QUALIFY_DOMAIN parameter
-is set in _Local/eximon.conf_, the address is qualified with that domain.
-Otherwise it must be entered as a fully qualified address. Pressing RETURN
-causes a call to Exim to be made using the %-Mmd% option to mark the given
-recipient address as already delivered, unless the entry box is empty, in which
-case no action is taken.
-
-- 'mark all delivered': A call to Exim is made using the %-Mmad% option to mark
-all recipient addresses as already delivered.
-
-- 'edit sender': A dialog box is displayed initialized with the current sender's
-address. Pressing RETURN causes a call to Exim to be made using the %-Mes%
-option to replace the sender address, unless the entry box is empty, in which
-case no action is taken. If you want to set an empty sender (as in bounce
-messages), you must specify it as ``<>''. Otherwise, if the address is not
-qualified and the QUALIFY_DOMAIN parameter is set in
-_Local/eximon.conf_, the address is qualified with that domain.
-
-When a delivery is forced, a window showing the %-v% output is displayed. In
-other cases when a call to Exim is made, if there is any output from Exim (in
-particular, if the command fails) a window containing the command and the
-output is displayed. Otherwise, the results of the action are normally apparent
-from the log and queue displays. However, if you set ACTION_OUTPUT=yes in
-_Local/eximon.conf_, a window showing the Exim command is always opened, even
-if no output is generated.
-
-The queue display is automatically updated for actions such as freezing and
-thawing, unless ACTION_QUEUE_UPDATE=no has been set in
-_Local/eximon.conf_. In this case the ``Update'' button has to be used to force
-an update of the display after one of these actions.
-
-In any text window that is displayed as result of a menu action, the normal
-cut-and-paste facility is available, and searching can be carried out using ^R
-and ^S, as described above for the log tail window.
-
-
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPsecurity]]
-Security considerations
------------------------
-cindex:[security]
-This chapter discusses a number of issues concerned with security, some of
-which are also covered in other parts of this manual.
-
-For reasons that this author does not understand, some people have promoted
-Exim as a ``particularly secure'' mailer. Perhaps it is because of the existence
-of this chapter in the documentation. However, the intent of the chapter is
-simply to describe the way Exim works in relation to certain security concerns,
-not to make any specific claims about the effectiveness of its security as
-compared with other MTAs.
-
-What follows is a description of the way Exim is supposed to be. Best efforts
-have been made to try to ensure that the code agrees with the theory, but an
-absence of bugs can never be guaranteed. Any that are reported will get fixed
-as soon as possible.
-
-
-Building a more ``hardened'' Exim
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[security,build-time features]
-There are a number of build-time options that can be set in _Local/Makefile_
-to create Exim binaries that are ``harder'' to attack, in particular by a rogue
-Exim administrator who does not have the root password, or by someone who has
-penetrated the Exim (but not the root) account. These options are as follows:
-
-- ALT_CONFIG_PREFIX can be set to a string that is required to match the
-start of any file names used with the %-C% option. When it is set, these file
-names are also not allowed to contain the sequence ``/../''. (However, if the
-value of the %-C% option is identical to the value of CONFIGURE_FILE in
-_Local/Makefile_, Exim ignores %-C% and proceeds as usual.) There is no
-default setting for %ALT_CONFIG_PREFIX%.
-+
-If the permitted configuration files are confined to a directory to
-which only root has access, this guards against someone who has broken
-into the Exim account from running a privileged Exim with an arbitrary
-configuration file, and using it to break into other accounts.
-
-- If ALT_CONFIG_ROOT_ONLY is defined, root privilege is retained for %-C%
-and %-D% only if the caller of Exim is root. Without it, the Exim user may
-also use %-C% and %-D% and retain privilege. Setting this option locks out
-the possibility of testing a configuration using %-C% right through message
-reception and delivery, even if the caller is root. The reception works, but by
-that time, Exim is running as the Exim user, so when it re-execs to regain
-privilege for the delivery, the use of %-C% causes privilege to be lost.
-However, root can test reception and delivery using two separate commands.
-ALT_CONFIG_ROOT_ONLY is not set by default.
-
-- If DISABLE_D_OPTION is defined, the use of the %-D% command line option
-is disabled.
-
-- FIXED_NEVER_USERS can be set to a colon-separated list of users that are
-never to be used for any deliveries. This is like the %never_users% runtime
-option, but it cannot be overridden; the runtime option adds additional users
-to the list. The default setting is ``root''; this prevents a non-root user who
-is permitted to modify the runtime file from using Exim as a way to get root.
-
-
-
-
-Root privilege
-~~~~~~~~~~~~~~
-cindex:[setuid]
-cindex:[root privilege]
-The Exim binary is normally setuid to root, which means that it gains root
-privilege (runs as root) when it starts execution. In some special cases (for
-example, when the daemon is not in use and there are no local deliveries), it
-may be possible to run Exim setuid to some user other than root. This is
-discussed in the next section. However, in most installations, root privilege
-is required for two things:
-
-- To set up a socket connected to the standard SMTP port (25) when initialising
-the listening daemon. If Exim is run from 'inetd', this privileged action is
-not required.
-
-- To be able to change uid and gid in order to read users' _.forward_ files and
-perform local deliveries as the receiving user or as specified in the
-configuration.
-
-It is not necessary to be root to do any of the other things Exim does, such as
-receiving messages and delivering them externally over SMTP, and it is
-obviously more secure if Exim does not run as root except when necessary.
-For this reason, a user and group for Exim to use must be defined in
-_Local/Makefile_. These are known as ``the Exim user'' and ``the Exim group''.
-Their values can be changed by the run time configuration, though this is not
-recommended. Often a user called 'exim' is used, but some sites use 'mail'
-or another user name altogether.
-
-Exim uses 'setuid()' whenever it gives up root privilege. This is a permanent
-abdication; the process cannot regain root afterwards. Prior to release 4.00,
-'seteuid()' was used in some circumstances, but this is no longer the case.
-
-After a new Exim process has interpreted its command line options, it changes
-uid and gid in the following cases:
-
-- cindex:[%-C% option]
-cindex:[%-D% option]
-If the %-C% option is used to specify an alternate configuration file, or if
-the %-D% option is used to define macro values for the configuration, and the
-calling process is not running as root or the Exim user, the uid and gid are
-changed to those of the calling process.
-However, if ALT_CONFIG_ROOT_ONLY is defined in _Local/Makefile_, only
-root callers may use %-C% and %-D% without losing privilege, and if
-DISABLE_D_OPTION is set, the %-D% option may not be used at all.
-
-- cindex:[%-be% option]
-cindex:[%-bf% option]
-cindex:[%-bF% option]
-If the expansion test option (%-be%) or one of the filter testing options
-(%-bf% or %-bF%) are used, the uid and gid are changed to those of the
-calling process.
-
-- If the process is not a daemon process or a queue runner process or a delivery
-process or a process for testing address routing (started with %-bt%), the uid
-and gid are changed to the Exim user and group. This means that Exim always
-runs under its own uid and gid when receiving messages. This also applies when
-testing address verification
-cindex:[%-bv% option]
-cindex:[%-bh% option]
-(the %-bv% option) and testing incoming message policy controls (the %-bh%
-option).
-
-- For a daemon, queue runner, delivery, or address testing process, the uid
-remains as root at this stage, but the gid is changed to the Exim group.
-
-///
-End of list
-///
-
-The processes that initially retain root privilege behave as follows:
-
-- A daemon process changes the gid to the Exim group and the uid to the Exim
-user after setting up one or more listening sockets. The 'initgroups()'
-function is called, so that if the Exim user is in any additional groups, they
-will be used during message reception.
-
-- A queue runner process retains root privilege throughout its execution. Its
-job is to fork a controlled sequence of delivery processes.
-
-- A delivery process retains root privilege throughout most of its execution,
-but any actual deliveries (that is, the transports themselves) are run in
-subprocesses which always change to a non-root uid and gid. For local
-deliveries this is typically the uid and gid of the owner of the mailbox; for
-remote deliveries, the Exim uid and gid are used. Once all the delivery
-subprocesses have been run, a delivery process changes to the Exim uid and gid
-while doing post-delivery tidying up such as updating the retry database and
-generating bounce and warning messages.
-+
-While the recipient addresses in a message are being routed, the delivery
-process runs as root. However, if a user's filter file has to be processed,
-this is done in a subprocess that runs under the individual user's uid and
-gid. A system filter is run as root unless %system_filter_user% is set.
-
-- A process that is testing addresses (the %-bt% option) runs as root so that
-the routing is done in the same environment as a message delivery.
-
-
-
-
-[[SECTrunexiwitpri]]
-Running Exim without privilege
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-cindex:[privilege, running without]
-cindex:[unprivileged running]
-cindex:[root privilege,running without]
-Some installations like to run Exim in an unprivileged state for more of its
-operation, for added security. Support for this mode of operation is provided
-by the global option %deliver_drop_privilege%. When this is set, the uid and
-gid are changed to the Exim user and group at the start of a delivery process
-(and also queue runner and address testing processes). This means that address
-routing is no longer run as root, and the deliveries themselves cannot change
-to any other uid.
-
-Leaving the binary setuid to root, but setting %deliver_drop_privilege% means
-that the daemon can still be started in the usual way, and it can respond
-correctly to SIGHUP because the re-invocation regains root privilege.
-
-An alternative approach is to make Exim setuid to the Exim user and also setgid
-to the Exim group.
-If you do this, the daemon must be started from a root process. (Calling
-Exim from a root process makes it behave in the way it does when it is setuid
-root.) However, the daemon cannot restart itself after a SIGHUP signal because
-it cannot regain privilege.
-
-It is still useful to set %deliver_drop_privilege% in this case, because it
-stops Exim from trying to re-invoke itself to do a delivery after a message has
-been received. Such a re-invocation is a waste of resources because it has no
-effect.
-
-If restarting the daemon is not an issue (for example, if %mua_wrapper% is set,
-or 'inetd' is being used instead of a daemon), having the binary setuid to the
-Exim user seems a clean approach, but there is one complication:
-
-In this style of operation, Exim is running with the real uid and gid set to
-those of the calling process, and the effective uid/gid set to Exim's values.
-Ideally, any association with the calling process' uid/gid should be dropped,
-that is, the real uid/gid should be reset to the effective values so as to
-discard any privileges that the caller may have. While some operating systems
-have a function that permits this action for a non-root effective uid, quite a
-number of them do not. Because of this lack of standardization, Exim does not
-address this problem at this time.
-
-For this reason, the recommended approach for ``mostly unprivileged'' running is
-to keep the Exim binary setuid to root, and to set %deliver_drop_privilege%.
-This also has the advantage of allowing a daemon to be used in the most
-straightforward way.
-
-If you configure Exim not to run delivery processes as root, there are a
-number of restrictions on what you can do:
-
-- You can deliver only as the Exim user/group. You should explicitly use the
-%user% and %group% options to override routers or local transports that
-normally deliver as the recipient. This makes sure that configurations that
-work in this mode function the same way in normal mode. Any implicit or
-explicit specification of another user causes an error.
-
-- Use of _.forward_ files is severely restricted, such that it is usually
-not worthwhile to include them in the configuration.
-
-- Users who wish to use _.forward_ would have to make their home directory and
-the file itself accessible to the Exim user. Pipe and append-to-file entries,
-and their equivalents in Exim filters, cannot be used. While they could be
-enabled in the Exim user's name, that would be insecure and not very useful.
-
-- Unless the local user mailboxes are all owned by the Exim user (possible in
-some POP3 or IMAP-only environments):
-
-* They must be owned by the Exim group and be writable by that group. This
-implies you must set %mode% in the appendfile configuration, as well as the
-mode of the mailbox files themselves.
-
-* You must set %no_check_owner%, since most or all of the files will not be
-owned by the Exim user.
-
-* You must set %file_must_exist%, because Exim cannot set the owner correctly
-on a newly created mailbox when unprivileged. This also implies that new
-mailboxes need to be created manually.
-
-These restrictions severely restrict what can be done in local deliveries.
-However, there are no restrictions on remote deliveries. If you are running a
-gateway host that does no local deliveries, setting %deliver_drop_privilege%
-gives more security at essentially no cost.
-
-If you are using the %mua_wrapper% facility (see chapter <<CHAPnonqueueing>>),
-%deliver_drop_privilege% is forced to be true.
-
-
-
-
-Delivering to local files
-~~~~~~~~~~~~~~~~~~~~~~~~~
-Full details of the checks applied by ^appendfile^ before it writes to a file
-are given in chapter <<CHAPappendfile>>.
-
-
-
-IPv4 source routing
-~~~~~~~~~~~~~~~~~~~
-cindex:[source routing,in IP packets]
-cindex:[IP source routing]
-Many operating systems suppress IP source-routed packets in the kernel, but
-some cannot be made to do this, so Exim does its own check. It logs incoming
-IPv4 source-routed TCP calls, and then drops them. Things are all different in
-IPv6. No special checking is currently done.
-
-
-
-The VRFY, EXPN, and ETRN commands in SMTP
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Support for these SMTP commands is disabled by default. If required, they can
-be enabled by defining suitable ACLs.
-
-
-
-
-Privileged users
-~~~~~~~~~~~~~~~~
-cindex:[trusted user]
-cindex:[admin user]
-cindex:[privileged user]
-cindex:[user,trusted]
-cindex:[user,admin]
-Exim recognises two sets of users with special privileges. Trusted users are
-able to submit new messages to Exim locally, but supply their own sender
-addresses and information about a sending host. For other users submitting
-local messages, Exim sets up the sender address from the uid, and doesn't
-permit a remote host to be specified.
-
-cindex:[%-f% option]
-However, an untrusted user is permitted to use the %-f% command line option in
-the special form %-f <>% to indicate that a delivery failure for the message
-should not cause an error report. This affects the message's envelope, but it
-does not affect the 'Sender:' header. Untrusted users may also be permitted to
-use specific forms of address with the %-f% option by setting the
-%untrusted_set_sender% option.
-
-Trusted users are used to run processes that receive mail messages from some
-other mail domain and pass them on to Exim for delivery either locally, or over
-the Internet. Exim trusts a caller that is running as root, as the Exim user,
-as any user listed in the %trusted_users% configuration option, or under any
-group listed in the %trusted_groups% option.
-
-Admin users are permitted to do things to the messages on Exim's queue. They
-can freeze or thaw messages, cause them to be returned to their senders, remove
-them entirely, or modify them in various ways. In addition, admin users can run
-the Exim monitor and see all the information it is capable of providing, which
-includes the contents of files on the spool.
-
-cindex:[%-M% option]
-cindex:[%-q% option]
-By default, the use of the %-M% and %-q% options to cause Exim to attempt
-delivery of messages on its queue is restricted to admin users. This
-restriction can be relaxed by setting the %no_prod_requires_admin% option.
-Similarly, the use of %-bp% (and its variants) to list the contents of the
-queue is also restricted to admin users. This restriction can be relaxed by
-setting %no_queue_list_requires_admin%.
-
-Exim recognises an admin user if the calling process is running as root or as
-the Exim user or if any of the groups associated with the calling process is
-the Exim group. It is not necessary actually to be running under the Exim
-group. However, if admin users who are not root or the Exim user are to access
-the contents of files on the spool via the Exim monitor (which runs
-unprivileged), Exim must be built to allow group read access to its spool
-files.
-
-
-
-Spool files
-~~~~~~~~~~~
-cindex:[spool directory,files]
-Exim's spool directory and everything it contains is owned by the Exim user and
-set to the Exim group. The mode for spool files is defined in the
-_Local/Makefile_ configuration file, and defaults to 0640. This means that
-any user who is a member of the Exim group can access these files.
-
-
-
-Use of argv[0]
-~~~~~~~~~~~~~~
-Exim examines the last component of %argv[0]%, and if it matches one of a set
-of specific strings, Exim assumes certain options. For example, calling Exim
-with the last component of %argv[0]% set to ``rsmtp'' is exactly equivalent to
-calling it with the option %-bS%. There are no security implications in this.
-
-
-
-Use of %f formatting
-~~~~~~~~~~~~~~~~~~~~
-The only use made of ``%f'' by Exim is in formatting load average values. These
-are actually stored in integer variables as 1000 times the load average.
-Consequently, their range is limited and so therefore is the length of the
-converted output.
-
-
-
-Embedded Exim path
-~~~~~~~~~~~~~~~~~~
-Exim uses its own path name, which is embedded in the code, only when it needs
-to re-exec in order to regain root privilege. Therefore, it is not root when it
-does so. If some bug allowed the path to get overwritten, it would lead to an
-arbitrary program's being run as exim, not as root.
-
-
-
-Use of sprintf()
-~~~~~~~~~~~~~~~~
-cindex:['sprintf()']
-A large number of occurrences of ``sprintf'' in the code are actually calls to
-'string_sprintf()', a function that returns the result in malloc'd store.
-The intermediate formatting is done into a large fixed buffer by a function
-that runs through the format string itself, and checks the length of each
-conversion before performing it, thus preventing buffer overruns.
-
-The remaining uses of 'sprintf()' happen in controlled circumstances where
-the output buffer is known to be sufficiently long to contain the converted
-string.
-
-
-
-Use of debug_printf() and log_write()
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Arbitrary strings are passed to both these functions, but they do their
-formatting by calling the function 'string_vformat()', which runs through
-the format string itself, and checks the length of each conversion.
-
-
-
-Use of strcat() and strcpy()
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-These are used only in cases where the output buffer is known to be large
-enough to hold the result.
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[[CHAPspool]]
-Format of spool files
----------------------
-cindex:[format,spool files]
-cindex:[spool directory,format of files]
-cindex:[spool files, format of]
-cindex:[spool files, editing]
-A message on Exim's queue consists of two files, whose names are the message id
-followed by -D and -H, respectively. The data portion of the message is kept in
-the -D file on its own. The message's envelope, status, and headers are all
-kept in the -H file, whose format is described in this chapter. Each of these
-two files contains the final component of its own name as its first line. This
-is insurance against disk crashes where the directory is lost but the files
-themselves are recoverable.
-
-Some people are tempted into editing -D files in order to modify messages. You
-need to be extremely careful if you do this; it is not recommended and you are
-on your own if you do it. Here are some of the pitfalls:
-
-[revisionflag="changed"]
-- You must ensure that Exim does not try to deliver the message while you are
-fiddling with it. The safest way is to take out a write lock on the -D file,
-which is what Exim itself does, using ^^fcntl()^^. If you update the file in
-place, the lock will be retained. If you write a new file and rename it, the
-lock will be lost at the instant of rename.
-
-[revisionflag="changed"]
-- cindex:[$body_linecount$]
-If you change the number of lines in the file, the value of
-$body_linecount$, which is stored in the -H file, will be incorrect. At
-present, this value is not used by Exim, but there is no guarantee that this
-will always be the case.
-
-- If the message is in MIME format, you must take care not to break it.
-
-- If the message is cryptographically signed, any change will invalidate the
-signature.
-
-
-Files whose names end with -J may also be seen in the _input_ directory (or
-its subdirectories when %split_spool_directory% is set). These are journal
-files, used to record addresses to which the message has been delivered during
-the course of a delivery run. At the end of the run, the -H file is updated,
-and the -J file is deleted.
-
-
-Format of the -H file
-~~~~~~~~~~~~~~~~~~~~~
-cindex:[uid (user id),in spool file]
-cindex:[gid (group id),in spool file]
-The second line of the -H file contains the login name for the uid of the
-process that called Exim to read the message, followed by the numerical uid and
-gid. For a locally generated message, this is normally the user who sent the
-message. For a message received over TCP/IP, it is normally the Exim user.
-
-The third line of the file contains the address of the message's sender as
-transmitted in the envelope, contained in angle brackets. The sender address is
-empty for bounce messages. For incoming SMTP mail, the sender address is given
-in the MAIL command. For locally generated mail, the sender address is
-created by Exim from the login name of the current user and the configured
-%qualify_domain%. However, this can be overridden by the %-f% option or a
-leading ``From'' line if the caller is trusted, or if the supplied address is
-``<>'' or an address that matches %untrusted_set_senders%.
-
-The fourth line contains two numbers. The first is the time that the message
-was received, in the conventional Unix form -- the number of seconds since the
-start of the epoch. The second number is a count of the number of messages
-warning of delayed delivery that have been sent to the sender.
-
-There follow a number of lines starting with a hyphen. These can appear in any
-order, and are omitted when not relevant:
-
-%-acl% <'number'> <'length'>::
-A line of this form is present for every ACL variable that is not empty. The
-number identifies the variable; the %acl_c%*x* variables are numbered 0--9 and
-the %acl_m%*x* variables are numbered 10--19. The length is the length of the
-data string for the variable. The string itself starts at the beginning of the
-next line, and is followed by a newline character. It may contain internal
-newlines.
-
-%-active_hostname% <'hostname'>::
-This is present if, when the message was received over SMTP, the value of
-$smtp_active_hostname$ was different to the value of $primary_hostname$.
-
-%-allow_unqualified_recipient%::
-This is present if unqualified recipient addresses are permitted in header
-lines (to stop such addresses from being qualified if rewriting occurs at
-transport time). Local messages that were input using %-bnq% and remote
-messages from hosts that match %recipient_unqualified_hosts% set this flag.
-
-%-allow_unqualified_sender%::
-This is present if unqualified sender addresses are permitted in header lines
-(to stop such addresses from being qualified if rewriting occurs at transport
-time). Local messages that were input using %-bnq% and remote messages from
-hosts that match %sender_unqualified_hosts% set this flag.
-
-%-auth_id% <'text'>::
-The id information for a message received on an authenticated SMTP connection
--- the value of the $authenticated_id$ variable.
-
-%-auth_sender% <'address'>::
-The address of an authenticated sender -- the value of the
-$authenticated_sender$ variable.
-
-%-body_linecount% <'number'>::
-This records the number of lines in the body of the message, and is always
-present.
-
-%-body_zerocount% <'number'>::
-This records the number of binary zero bytes in the body of the message, and is
-present if the number is greater than zero.
-
-%-deliver_firsttime%::
-This is written when a new message is first added to the spool. When the spool
-file is updated after a deferral, it is omitted.
-
-%-frozen% <'time'>::
-cindex:[frozen messages,spool data]
-The message is frozen, and the freezing happened at <'time'>.
-
-%-helo_name% <'text'>::
-This records the host name as specified by a remote host in a HELO or EHLO
-command.
-
-%-host_address% <'address'>.<'port'>::
-This records the IP address of the host from which the message was received and
-the remote port number that was used. It is omitted for locally generated
-messages.
-
-%-host_auth% <'text'>::
-If the message was received on an authenticated SMTP connection, this records
-the name of the authenticator -- the value of the $sender_host_authenticated$
-variable.
-
-%-host_lookup_failed%::
-This is present if an attempt to look up the sending host's name from its IP
-address failed. It corresponds to the $host_lookup_failed$ variable.
-
-%-host_name% <'text'>::
-cindex:[reverse DNS lookup]
-cindex:[DNS,reverse lookup]
-This records the name of the remote host from which the message was received,
-if the host name was looked up from the IP address when the message was being
-received. It is not present if no reverse lookup was done.
-
-%-ident% <'text'>::
-For locally submitted messages, this records the login of the originating user,
-unless it was a trusted user and the %-oMt% option was used to specify an ident
-value. For messages received over TCP/IP, this records the ident string
-supplied by the remote host, if any.
-
-%-interface_address% <'address'>.<'port'>::
-This records the IP address of the local interface and the port number through
-which a message was received from a remote host. It is omitted for locally
-generated messages.
-
-%-local%::
-The message is from a local sender.
-
-%-localerror%::
-The message is a locally-generated bounce message.
-
-%-local_scan% <'string'>::
-This records the data string that was returned by the 'local_scan()' function
-when the message was received -- the value of the $local_scan_data$ variable.
-It is omitted if no data was returned.
-
-%-manual_thaw%::
-The message was frozen but has been thawed manually, that is, by an explicit
-Exim command rather than via the auto-thaw process.
-
-%-N%::
-A testing delivery process was started using the %-N% option to suppress any
-actual deliveries, but delivery was deferred. At any further delivery attempts,
-%-N% is assumed.
-
-%-received_protocol%::
-This records the value of the $received_protocol$ variable, which contains the
-name of the protocol by which the message was received.
-
-%-sender_set_untrusted%::
-The envelope sender of this message was set by an untrusted local caller (used
-to ensure that the caller is displayed in queue listings).
-
-%-spam_score_int% <'number'>::
-If a message was scanned by SpamAssassin, this is present. It records the value
-of $spam_score_int$.
-
-%-tls_certificate_verified%::
-A TLS certificate was received from the client that sent this message, and the
-certificate was verified by the server.
-
-%-tls_cipher% <'cipher name'>::
-When the message was received over an encrypted connection, this records the
-name of the cipher suite that was used.
-
-%-tls_peerdn% <'peer DN'>::
-When the message was received over an encrypted connection, and a certificate
-was received from the client, this records the Distinguished Name from that
-certificate.
-
-///
-End of list
-///
-
-Following the options there is a list of those addresses to which the message
-is not to be delivered. This set of addresses is initialized from the command
-line when the %-t% option is used and %extract_addresses_remove_arguments%
-is set; otherwise it starts out empty. Whenever a successful delivery is made,
-the address is added to this set. The addresses are kept internally as a
-balanced binary tree, and it is a representation of that tree which is written
-to the spool file. If an address is expanded via an alias or forward file, the
-original address is added to the tree when deliveries to all its child
-addresses are complete.
-
-If the tree is empty, there is a single line in the spool file containing just
-the text ``XX''. Otherwise, each line consists of two letters, which are either
-Y or N, followed by an address. The address is the value for the node of the
-tree, and the letters indicate whether the node has a left branch and/or a
-right branch attached to it, respectively. If branches exist, they immediately
-follow. Here is an example of a three-node tree:
-
- YY darcy@austen.fict.example
- NN alice@wonderland.fict.example
- NN editor@thesaurus.ref.example
-
-After the non-recipients tree, there is a list of the message's recipients.
-This is a simple list, preceded by a count. It includes all the original
-recipients of the message, including those to whom the message has already been
-delivered. In the simplest case, the list contains one address per line. For
-example:
-
- 4
- editor@thesaurus.ref.example
- darcy@austen.fict.example
- rdo@foundation
- alice@wonderland.fict.example
-
-However, when a child address has been added to the top-level addresses as a
-result of the use of the %one_time% option on a ^redirect^ router, each line
-is of the following form:
-
-&&&
-<'top-level address'> <'errors_to address'> <'length'>,<'parent number'>#<'flag bits'>
-&&&
-
-The 01 flag bit indicates the presence of the three other fields that follow
-the top-level address. Other bits may be used in future to support additional
-fields. The <'parent number'> is the offset in the recipients list of the
-original parent of the ``one time'' address. The first two fields are the
-envelope sender that is associated with this address and its length. If the
-length is zero, there is no special envelope sender (there are then two space
-characters in the line). A non-empty field can arise from a ^redirect^ router
-that has an %errors_to% setting.
-
-
-A blank line separates the envelope and status information from the headers
-which follow. A header may occupy several lines of the file, and to save effort
-when reading it in, each header is preceded by a number and an identifying
-character. The number is the number of characters in the header, including any
-embedded newlines and the terminating newline. The character is one of the
-following:
-
-[frame="none"]
-`-`--------`----------------------------------------------
- <'blank'>header in which Exim has no special interest
- `B` 'Bcc:' header
- `C` 'Cc:' header
- `F` 'From:' header
- `I` 'Message-id:' header
- `P` 'Received:' header -- P for ``postmark''
- `R` 'Reply-To:' header
- `S` 'Sender:' header
- `T` 'To:' header
- `*` replaced or deleted header
-----------------------------------------------------------
-
-Deleted or replaced (rewritten) headers remain in the spool file for debugging
-purposes. They are not transmitted when the message is delivered. Here is a
-typical set of headers:
-
- 111P Received: by hobbit.fict.example with local (Exim 4.00)
- id 14y9EI-00026G-00; Fri, 11 May 2001 10:28:59 +0100
- 049 Message-Id: <E14y9EI-00026G-00@hobbit.fict.example>
- 038* X-rewrote-sender: bb@hobbit.fict.example
- 042* From: Bilbo Baggins <bb@hobbit.fict.example>
- 049F From: Bilbo Baggins <B.Baggins@hobbit.fict.example>
- 099* To: alice@wonderland.fict.example, rdo@foundation,
- darcy@austen.fict.example, editor@thesaurus.ref.example
- 109T To: alice@wonderland.fict.example, rdo@foundation.fict.example,
- darcy@austen.fict.example, editor@thesaurus.ref.example
- 038 Date: Fri, 11 May 2001 10:28:59 +0100
-
-The asterisked headers indicate that the envelope sender, 'From:' header, and
-'To:' header have been rewritten, the last one because routing expanded the
-unqualified domain 'foundation'.
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[titleabbrev="Adding drivers or lookups"]
-Adding new drivers or lookup types
-----------------------------------
-cindex:[adding drivers]
-cindex:[new drivers, adding]
-cindex:[drivers,adding new]
-The following actions have to be taken in order to add a new router, transport,
-authenticator, or lookup type to Exim:
-
-. Choose a name for the driver or lookup type that does not conflict with any
-existing name; I will use ``newdriver'' in what follows.
-
-. Add to _src/EDITME_ the line
-+
- <type>_NEWDRIVER=yes
-+
-where <'type'> is ROUTER, TRANSPORT, AUTH, or LOOKUP. If the
-code is not to be included in the binary by default, comment this line out. You
-should also add any relevant comments about the driver or lookup type.
-
-. Add to _src/config.h.defaults_ the line
-+
- #define <type>_NEWDRIVER
-
-. Edit _src/drtables.c_, adding conditional code to pull in the private header
-and create a table entry as is done for all the other drivers and lookup types.
-
-. Edit _Makefile_ in the appropriate sub-directory (_src/routers_,
-_src/transports_, _src/auths_, or _src/lookups_); add a line for the new
-driver or lookup type and add it to the definition of OBJ.
-
-. Create _newdriver.h_ and _newdriver.c_ in the appropriate sub-directory of
-_src_.
-
-. Edit _scripts/MakeLinks_ and add commands to link the _.h_ and _.c_ files
-as for other drivers and lookups.
-
-Then all you need to do is write the code! A good way to start is to make a
-proforma by copying an existing module of the same type, globally changing all
-occurrences of the name, and cutting out most of the code. Note that any
-options you create must be listed in alphabetical order, because the tables are
-searched using a binary chop procedure.
-
-There is a _README_ file in each of the sub-directories of _src_ describing
-the interface that is expected.
-
-
-
-
-////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////
-
-[title="Option index",role="option"]
-Index
------
-
-[title="Concept index",role="concept"]
-Index
------
-
-///////////////////////////////////////////////////////////////////////////////
-Nothing needs to be included here except "Index" as pseudo chapter headings.
-///////////////////////////////////////////////////////////////////////////////
projects / exim.git / blobdiff