1 . $Cambridge: exim/doc/doc-src/spec.src,v 1.8 2005/02/17 11:58:25 ph10 Exp $
4 .set previousversion "4.40"
5 .set versionmonth "February"
6 .set versionyear "2005"
9 . The last of those is to make ACL index entries easier to type. It is put
10 . up here so that it gets picked up by the HTML converter, which otherwise
11 . skips to the first chapter. A longer version is set below for use in the
20 .linelength ~~sys.linelength + 0.2in
21 .set newlinelength ~~sys.linelength
22 .emphasis ~~sys.linelength + 0.1in
23 .pagedepth ~~sys.pagedepth - 0.2in
24 .bindfont 51 "atl/Times-Bold" 9
25 .bindfont 52 "atl/Times-Roman" 9
26 .bindfont 53 "atl/Times-Roman" 7
27 .bindfont 54 "atl/Courier" 9
28 .bindfont 55 "atl/Courier-Bold" ~~maintypesize
29 .bindfont 56 "atl/Times-Italic" 7
30 .bindfont 57 "atl/Times-Bold" 7
31 .bindfont 58 "atl/Symbol" 7
35 . Used for the "small print" incorporated code stuff. Only rm, it, bf, sp are
36 . actually used at present.
37 . rm it sl bf bi ss tt sp sc
38 .fontgroup 9 = 53 56 0 57 0 0 0 58 0
43 .fontgroup 9 = 0 0 0 0 0 0 0 0 0
49 .flag $smc{ "$push$g0$f54"
50 .flag $sm{ "$push$g0$f53"
51 .flag $smi{ "$push$g0$f56"
52 .flag $as{ "$push$g0$f52"
53 .flag $ab{ "$push$g0$f51"
54 .flag $cb{ "$push$g0$f55"
63 .macro isunderscore "string"
65 .set length length "~~1"
69 .macro undrec "offset"
73 .set sub "~~string"(1,~~1)
83 .macro testunderscore "string"
112 .macro option "option" ""
114 .index \-~~1-\ option
131 .macro item "item" "6"
133 .if ~~sys.leftonpage < ~~2ld
142 .set confsection "~~1"
159 .macro conf "option" "type" "default" "6"
161 .if ~~sys.leftonpage < ~~4ld
164 .testunderscore "~~1"
170 .if "~~confsection" == ""
173 .set inssect "$rm{Use:} $it{~~confsection}###"
176 \**~~1**\ $c ~~inssect$rm{Type:} $it{~~2} $e $rm{Default:} $it{~~3}
182 .set displayindent 2em
184 .index @$1, @$2, etc. $it{see numerical variables}
185 .index address||rewriting $it{see rewriting}
186 .index CR character $it{see carriage return}
187 .index CRL $it{see certificate revocation list}
188 .index delivery||failure report $it{see bounce message}
189 .index dialup $it{see intermittently connected hosts}
190 .index exiscan $it{see content scanning}
191 .index failover $it{see fallback}
192 .index fallover $it{see fallback}
193 .index filter||Sieve $it{see Sieve filter}
194 .index ident $it{see RFC 1413}
195 .index LF character $it{see linefeed}
196 .index maximum $it{see limit}
197 .index NUL $it{see binary zero}
198 .index passwd file $it{see \(/etc/passwd)\}
199 .index process id $it{see pid}
200 .index RBL $it{see DNS list}
201 .index redirection $it{see address redirection}
202 .index return path||$it{see also envelope sender}
203 .index scanning $it{see content scanning}
204 .index SSL $it{see TLS}
205 .index string||expansion $it{see expansion}
206 .index top bit $it{see 8-bit characters}
207 .index variables $it{see expansion, variables}
208 .index zero, binary $it{see binary zero}
210 . This is used for the printed index. See setting above for
211 . the HTML index value.
213 .set ACL "access control lists (ACLs)"
215 . ======================================================
222 $chead{University of Cambridge Computing Service}
224 $chead{Specification of the Exim Mail Transfer Agent}
229 .space ~~sys.leftonpage - 15*~~sys.linedepth
231 University Computing Service
238 $it{phone:} $t +44 1223 334600
239 $it{fax:} $t +44 1223 334679
240 $it{email:} $t ph10 $it{at} cus.cam.ac.uk
242 Edition for Exim ~~version, ~~versionmonth ~~versionyear
247 $c$rm{Copyright (c) University of Cambridge ~~versionyear}
258 . Blank verso for title page
263 . Set up for actual text pages
265 . The first one to prevent a warning from sgfr
266 . set runningfoot "~~chapter"
272 .if "~~runningfoot" == ""
275 .set rhs "~~runningfoot (~~chapter)"
277 .set lhs "Exim ~~version"
278 .linelength ~~newlinelength
279 $it{~~lhs}$c[~~sys.pagenumber]$e$it{~~rhs}
290 . ============================================================================
291 .chapter Introduction
292 .set runningfoot "introduction"
295 $c$bi{If I have seen further it is by standing on the shoulders of giants.}##(Isaac Newton)
297 $c"If I have seen further it is by standing on the shoulders of giants."
301 \*If I have seen further it is by standing on the shoulders of giants.*\
306 Exim is a mail transfer agent (MTA) for hosts that are running Unix or
307 Unix-like operating systems. It was designed on the assumption that it would be
308 run on hosts that are permanently connected to the Internet. However, it can be
309 used on intermittently connected hosts with suitable configuration adjustments.
311 Configuration files currently exist for the following operating systems: AIX,
312 BSD/OS (aka BSDI), Darwin (Mac OS X), DGUX, FreeBSD, GNU/Hurd, GNU/Linux,
313 HI-OSF (Hitachi), HP-UX, IRIX, MIPS RISCOS, NetBSD, OpenBSD, QNX, SCO, SCO
314 SVR4.2 (aka UNIX-SV), Solaris (aka SunOS5), SunOS4, Tru64-Unix (formerly
315 Digital UNIX, formerly DEC-OSF1), Ultrix, and Unixware. Some of these operating
316 systems are no longer current and cannot easily be tested, so the configuration
317 files may no longer work in practice.
319 There are also configuration files for compiling Exim in the Cygwin environment
320 that can be installed on systems running Windows. However, this document does
321 not contain any information about running Exim in the Cygwin environment.
323 The terms and conditions for the use and distribution of Exim are contained in
324 the file \(NOTICE)\. Exim is distributed under the terms of the GNU General
325 Public Licence, a copy of which may be found in the file \(LICENCE)\.
327 The use, supply or promotion of Exim for the purpose of sending bulk,
328 unsolicited electronic mail is incompatible with the basic aims of the program,
329 which revolve around the free provision of a service that enhances the quality
330 of personal communications. The author of Exim regards indiscriminate
331 mass-mailing as an antisocial, irresponsible abuse of the Internet.
333 Exim owes a great deal to Smail 3 and its author, Ron Karr. Without the
334 experience of running and working on the Smail 3 code, I could never have
335 contemplated starting to write a new MTA. Many of the ideas and user interfaces
336 were originally taken from Smail 3, though the actual code of Exim is entirely
337 new, and has developed far beyond the initial concept.
339 Many people, both in Cambridge and around the world, have contributed to the
340 development and the testing of Exim, and to porting it to various operating
341 systems. I am grateful to them all. The distribution now contains a file called
342 \(ACKNOWLEDGMENTS)\, in which I have started recording the names of
346 .section Exim documentation
349 This edition of the Exim specification applies to version ~~version of Exim.
350 Substantive changes from the ~~previousversion edition are marked by bars in
351 the right-hand margin in the PostScript, PDF, and plain text versions of the
352 document, and by green text in the HTML version, as shown by this paragraph.
353 Changes are not marked in the Texinfo version, because Texinfo doesn't support
354 change bars. Minor corrections and rewordings are not marked.
357 This document is very much a reference manual; it is not a tutorial. The reader
358 is expected to have some familiarity with the SMTP mail transfer protocol and
359 with general Unix system administration. Although there are some discussions
360 and examples in places, the information is mostly organized in a way that makes
361 it easy to look up, rather than in a natural order for sequential reading.
362 Furthermore, the manual aims to cover every aspect of Exim in detail, including
363 a number of rarely-used, special-purpose features that are unlikely to be of
366 .index books about Exim
367 An `easier' discussion of Exim which provides more in-depth explanatory,
368 introductory, and tutorial material can be found in a book entitled
370 [(A HREF="http://www.uit.co.uk/exim-book/")]
371 $it{The Exim SMTP Mail Server},
373 published by UIT Cambridge.
375 $it{The Exim SMTP Mail Server}, published by UIT Cambridge
376 (\?http://www.uit.co.uk/exim-book/?\).
379 This book also contains a chapter that gives a general introduction to SMTP and
380 Internet mail. Inevitably, however, the book is unlikely to be fully up-to-date
381 with the latest release of Exim. (Note that the earlier book about Exim,
382 published by O'Reilly, covers Exim 3, and many things have changed in Exim 4.)
384 .index \(doc/NewStuff)\
385 .index \(doc/ChangeLog)\
387 As the program develops, there may be features in newer versions that have not
388 yet made it into this document, which is updated only when the most significant
389 digit of the fractional part of the version number changes. Specifications of
390 new features that are not yet in this manual are placed in the file
391 \(doc/NewStuff)\ in the Exim distribution.
394 Some features may be classified as `experimental'. These may change
395 incompatibly while they are developing, or even be withdrawn. For this reason,
396 they are not documented in this manual. Information about experimental features
397 can be found in the file \(doc/experimental.txt)\.
400 All changes to the program (whether new features, bug fixes, or other kinds of
401 change) are noted briefly in the file called \(doc/ChangeLog)\.
403 .index \(doc/spec.txt)\
404 This specification itself is available as an ASCII file in \(doc/spec.txt)\ so
405 that it can easily be searched with a text editor. Other files in the \(doc)\
409 \(OptionLists.txt)\ $t $rm{list of all options in alphabetical order}
410 \(dbm.discuss.txt)\ $t $rm{discussion about DBM libraries}
411 \(exim.8)\ $t $rm{a man page of Exim's command line options}
414 \(experimental.txt)\ $t $rm{documentation of experimental features}
417 \(filter.txt)\ $t $rm{specification of the filter language}
418 \(pcrepattern.txt)\ $t $rm{specification of PCRE regular expressions}
419 \(pcretest.txt)\ $t $rm{specification of the PCRE testing program}
420 \(Exim3.upgrade)\ $t $rm{upgrade notes from release 2 to release 3}
421 \(Exim4.upgrade)\ $t $rm{upgrade notes from release 3 to release 4}
423 The main specification and the specification of the filtering language are also
424 available in other formats (HTML, PostScript, PDF, and Texinfo). Section
425 ~~SECTavail below tells you how to get hold of these.
428 .section FTP and web sites
432 The primary distribution site for Exim is currently the University of
433 Cambridge's FTP site, whose contents are described in \*Where to find the Exim
434 distribution*\ below. In addition, there is a
436 [(A HREF="http://www.exim.org/")]
444 [(A HREF="ftp://ftp.exim.org/")]
450 at \exim.org\. These are now also hosted at the University of Cambridge.
451 The \exim.org\ site was previously hosted for a number of years by Energis
452 Squared, formerly Planet Online Ltd, whose support I gratefully acknowledge.
454 As well as Exim distribution tar files, the Exim web site contains a number of
455 differently formatted versions of the documentation, including the
458 [(A HREF="FAQ.html")]
464 in both text and HTML formats. The HTML version comes with a keyword-in-context
465 index. A recent addition to the online information is the
468 [(A HREF="http://www.exim.org/eximwiki/")]
472 Exim wiki (\?http://www.exim.org/eximwiki/?\).
474 We hope that this will make it easier for Exim users to contribute examples,
475 tips, and know-how for the benefit of others.
478 .section Mailing lists
479 .index mailing lists||for Exim users
481 The following are the three main Exim mailing lists:
484 $it{exim-users@@exim.org} $t general discussion list
485 $it{exim-dev@@exim.org} $t discussion of bugs, enhancements, etc.
486 $it{exim-announce@@exim.org} $t moderated, low volume announcements list
489 You can subscribe to these lists, change your existing subscriptions, and view
490 or search the archives via the
492 [(A HREF="http://www.exim.org/maillist.html")]
498 link on the Exim home page. The $it{exim-users} mailing list is also forwarded
499 to \?http://www.egroups.com/list/exim-users?\, an archiving system with
500 searching capabilities.
502 .section Exim training
503 .index training courses
504 From time to time (approximately annually at the time of writing),
505 lecture-based training courses are run by the author of Exim in Cambridge, UK.
506 Details can be found on the web site
508 [(A HREF="http://www-tus.csx.cam.ac.uk/courses/exim/")]
510 \?http://www-tus@.csx@.cam@.ac.uk/courses/exim/?\.
517 .index reporting bugs
518 Reports of obvious bugs should be emailed to \*bugs@@exim.org*\. However, if
519 you are unsure whether some behaviour is a bug or not, the best thing to do is
520 to post a message to the $it{exim-users} mailing list and have it discussed.
524 .section Where to find the Exim distribution
525 .rset SECTavail "~~chapter.~~section"
527 .index distribution||ftp site
528 The master ftp site for the Exim distribution is
533 \?ftp://ftp.csx.cam.ac.uk/pub/software/email/exim?\
540 \?ftp://ftp.exim.org/pub/exim?\
542 The file references that follow are relative to the \(exim)\ directories at
545 There are now quite a number of independent mirror sites around the world.
546 Those that I know about are listed in the file called \(Mirrors)\.
548 Within the \(exim)\ directory there are subdirectories called \(exim3)\ (for
549 previous Exim 3 distributions), \(exim4)\ (for the latest Exim 4
550 distributions), and \(Testing)\ for testing versions. In the \(exim4)\
551 subdirectory, the current release can always be found in files called
553 \(exim-$it{n.nn}.tar.gz)\
554 \(exim-$it{n.nn}.tar.bz2)\
556 where $it{n.nn} is the highest such version number in the directory. The two
557 files contain identical data; the only difference is the type of compression.
558 The \(.bz2)\ file is usually a lot smaller than the \(.gz)\ file.
559 .index distribution||signing details
560 .index distribution||public key
561 .index public key for signed distribution
562 The distributions are currently signed with Philip Hazel's GPG key. The
563 corresponding public key is available from a number of keyservers, and there is
564 also a copy in the file \(Public-Key)\. The signatures for the tar bundles are
567 \(exim-$it{n.nn}.tar.gz.sig)\
568 \(exim-$it{n.nn}.tar.bz2.sig)\
570 For each released version, the log of changes is made separately available in a
571 separate file in the directory \(ChangeLogs)\ so that it is possible to
572 find out what has changed without having to download the entire distribution.
574 .index documentation||available formats
575 The main distribution contains ASCII versions of this specification and other
576 documentation; other formats of the documents are available in separate files
577 inside the \(exim4)\ directory of the FTP site:
579 \(exim-html-$it{n.nn}.tar.gz)\
580 \(exim-pdf-$it{n.nn}.tar.gz)\
581 \(exim-postscript-$it{n.nn}.tar.gz)\
582 \(exim-texinfo-$it{n.nn}.tar.gz)\
584 These tar files contain only the \(doc)\ directory, not the complete
585 distribution, and are also available in \(.bz2)\ as well as \(.gz)\ forms.
588 The FAQ is available for downloading in two different formats in these files:
591 \(exim4/FAQ.html.tar.gz)\
593 The first of these is a single ASCII file that can be searched with a text
594 editor. The second is a directory of HTML files, normally accessed by starting
595 at \(index.html)\. The HTML version of the FAQ (which is also included in the
596 HTML documentation tarbundle) includes a keyword-in-context index, which is
597 often the most convenient way of finding your way around.
601 A wish list is maintained, containing ideas for new features that have been
602 submitted. From time to time the file is exported to the ftp site into the file
603 \(exim4/WishList)\. Items are removed from the list if they get implemented.
606 .section Contributed material
607 .index contributed material
608 At the ftp site, there is a directory called \(Contrib)\ that contains
609 miscellaneous files contributed to the Exim community by Exim users. There is
610 also a collection of contributed configuration examples in
611 \(exim4/config.samples.tar.gz)\. These samples are referenced from the FAQ.
615 .index limitations of Exim
617 Exim is designed for use as an Internet MTA, and therefore handles addresses
618 in RFC 2822 domain format only.
619 .index bang paths||not handled by Exim
620 It cannot handle UUCP `bang paths', though simple two-component bang paths can
621 be converted by a straightforward rewriting configuration. This restriction
622 does not prevent Exim from being interfaced to UUCP as a transport mechanism,
623 provided that domain addresses are used.
625 .index domainless addresses
626 .index address||without domain
627 Exim insists that every address it handles has a domain attached. For incoming
628 local messages, domainless addresses are automatically qualified with a
629 configured domain value. Configuration options specify from which remote
630 systems unqualified addresses are acceptable. These are then qualified on
633 .index transport||external
634 .index external transports
635 The only external transport currently implemented is an SMTP transport over a
636 TCP/IP network (using sockets, including support for IPv6). However, a pipe
637 transport is available, and there are facilities for writing messages to files
638 and pipes, optionally in \*batched SMTP*\ format; these facilities can be used
639 to send messages to some other transport mechanism such as UUCP, provided it
640 can handle domain-style addresses. Batched SMTP input is also catered for.
642 Exim is not designed for storing mail for dial-in hosts. When the volumes of
643 such mail are large, it is better to get the messages `delivered' into files
644 (that is, off Exim's queue) and subsequently passed on to the dial-in hosts by
648 Although Exim does have basic facilities for scanning incoming messages, these
649 are not comprehensive enough to do full virus or spam scanning. Such operations
650 are best carried out using additional specialized software packages. If you
651 compile Exim with the content-scanning extension, straightforward interfaces to
652 a number of common scanners are provided.
658 .section Run time configuration
659 Exim's run time configuration is held in a single text file that is divided
660 into a number of sections. The entries in this file consist of keywords and
661 values, in the style of Smail 3 configuration files. A default configuration
662 file which is suitable for simple online installations is provided in the
663 distribution, and is described in chapter ~~CHAPdefconfil below.
666 .section Calling interface
667 .index Sendmail compatibility||command line interface
668 Like many MTAs, Exim has adopted the Sendmail command line interface so that it
669 can be a straight replacement for \(/usr/lib/sendmail)\ or
670 \(/usr/sbin/sendmail)\ when sending mail, but you do not need to know anything
671 about Sendmail in order to run Exim. For actions other than sending messages,
672 Sendmail-compatible options also exist, but those that produce output (for
673 example, \-bp-\, which lists the messages on the queue) do so in Exim's own
674 format. There are also some additional options that are compatible with Smail
675 3, and some further options that are new to Exim. Chapter ~~CHAPcommandline
676 documents all Exim's command line options. This information is automatically
677 made into the man page that forms part of the Exim distribution.
679 Control of messages on the queue can be done via certain privileged command
680 line options. There is also an optional monitor program called \*eximon*\, which
681 displays current information in an X window, and which contains a menu
682 interface to Exim's command line administration options.
686 .index terminology definitions
687 .index body of message||definition of
688 The \*body*\ of a message is the actual data that the sender wants to transmit.
689 It is the last part of a message, and is separated from the \*header*\ (see
690 below) by a blank line.
692 .index bounce message||definition of
693 When a message cannot be delivered, it is normally returned to the sender in a
694 delivery failure message or a `non-delivery report' (NDR). The term \*bounce*\
695 is commonly used for this action, and the error reports are often called
696 \*bounce messages*\. This is a convenient shorthand for `delivery failure error
697 report'. Such messages have an empty sender address in the message's
698 \*envelope*\ (see below) to ensure that they cannot themselves give rise to
699 further bounce messages.
701 The term \*default*\ appears frequently in this manual. It is used to qualify a
702 value which is used in the absence of any setting in the configuration. It may
703 also qualify an action which is taken unless a configuration setting specifies
706 The term \*defer*\ is used when the delivery of a message to a specific
707 destination cannot immediately take place for some reason (a remote host may be
708 down, or a user's local mailbox may be full). Such deliveries are \*deferred*\
711 The word \*domain*\ is sometimes used to mean all but the first component of a
712 host's name. It is $it{not} used in that sense here, where it normally
713 refers to the part of an email address following the @@ sign.
715 .index envelope, definition of
716 .index sender||definition of
717 A message in transit has an associated \*envelope*\, as well as a header and a
718 body. The envelope contains a sender address (to which bounce messages should
719 be delivered), and any number of recipient addresses. References to the
720 sender or the recipients of a message usually mean the addresses in the
721 envelope. An MTA uses these addresses for delivery, and for returning bounce
722 messages, not the addresses that appear in the header lines.
724 .index message||header, definition of
725 .index header section||definition of
726 The \*header*\ of a message is the first part of a message's text, consisting
727 of a number of lines, each of which has a name such as ::From::, ::To::,
728 ::Subject::, etc. Long header lines can be split over several text lines by
729 indenting the continuations. The header is separated from the body by a blank
732 .index local part||definition of
733 .index domain||definition of
734 The term \*local part*\, which is taken from RFC 2822, is used to refer to that
735 part of an email address that precedes the @@ sign. The part that follows the
736 @@ sign is called the \*domain*\ or \*mail domain*\.
738 .index local delivery||definition of
739 .index remote delivery, definition of
740 The terms \*local delivery*\ and \*remote delivery*\ are used to distinguish
741 delivery to a file or a pipe on the local host from delivery by SMTP over
742 TCP/IP to a remote host.
744 .index return path||definition of
745 \*Return path*\ is another name that is used for the sender address in a
748 .index queue||definition of
749 The term \*queue*\ is used to refer to the set of messages awaiting delivery,
750 because this term is in widespread use in the context of MTAs. However, in
751 Exim's case the reality is more like a pool than a queue, because there is
752 normally no ordering of waiting messages.
754 .index queue runner||definition of
755 The term \*queue runner*\ is used to describe a process that scans the queue
756 and attempts to deliver those messages whose retry times have come. This term
757 is used by other MTAs, and also relates to the command \runq\, but in Exim
758 the waiting messages are normally processed in an unpredictable order.
760 .index spool directory||definition of
761 The term \*spool directory*\ is used for a directory in which Exim keeps the
762 messages on its queue -- that is, those that it is in the process of
763 delivering. This should not be confused with the directory in which local
764 mailboxes are stored, which is called a `spool directory' by some people. In
765 the Exim documentation, `spool' is always used in the first sense.
773 . ============================================================================
774 .chapter Incorporated code
775 .set runningfoot "incorporated code"
776 .index incorporated code
777 .index regular expressions||library
779 A number of pieces of external code are included in the Exim distribution.
781 Regular expressions are supported in the main Exim program and in the Exim
782 monitor using the freely-distributable PCRE library, copyright (c) University
783 of Cambridge. The source is distributed in the directory \(src/pcre)\. However,
784 this is a cut-down version of PCRE. If you want to use the PCRE library in
785 other programs, you should obtain and install the full version from
786 \?ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre?\.
790 .index cdb||acknowledgement
791 Support for the cdb (Constant DataBase) lookup method is provided by code
792 contributed by Nigel Metheringham of (at the time he contributed it) Planet
793 Online Ltd. which contains the following statements:
800 Copyright (c) 1998 Nigel Metheringham, Planet Online Ltd
802 This program is free software; you can redistribute it and/or modify it under
803 the terms of the GNU General Public License as published by the Free Software
804 Foundation; either version 2 of the License, or (at your option) any later
807 This code implements Dan Bernstein's Constant DataBase (cdb) spec. Information,
808 the spec and sample code for cdb can be obtained from
809 \?http://www.pobox.com/@~djb/cdb.html?\. This implementation borrows some code
810 from Dan Bernstein's implementation (which has no license restrictions applied
815 The implementation is completely contained within the code of Exim.
816 It does not link against an external cdb library.
819 .index SPA authentication
821 .index Microsoft Secure Password Authentication
822 Client support for Microsoft's \*Secure Password Authentication*\ is provided
823 by code contributed by Marc Prud'hommeaux. Server support was contributed by
824 Tom Kistner. This includes code taken from the Samba project, which is released
830 .index \*pwcheck*\ daemon
831 .index \*pwauthd*\ daemon
832 Support for calling the Cyrus \*pwcheck*\ and \*saslauthd*\ daemons is provided
833 by code taken from the Cyrus-SASL library and adapted by Alexander S.
834 Sabourenkov. The permission notice appears below, in accordance with the
835 conditions expressed therein.
843 Copyright (c) 2001 Carnegie Mellon University. All rights reserved.
845 Redistribution and use in source and binary forms, with or without
846 modification, are permitted provided that the following conditions
850 .cancelflag $npbracket
851 .flag $npbracket "" "."
854 Redistributions of source code must retain the above copyright
855 notice, this list of conditions and the following disclaimer.
857 Redistributions in binary form must reproduce the above copyright
858 notice, this list of conditions and the following disclaimer in
859 the documentation and/or other materials provided with the
862 The name `Carnegie Mellon University' must not be used to
863 endorse or promote products derived from this software without
864 prior written permission. For permission or any other legal
865 details, please contact
867 Office of Technology Transfer
868 Carnegie Mellon University
870 Pittsburgh, PA 15213-3890
871 (412) 268-4387, fax: (412) 268-7395
872 tech-transfer@@andrew.cmu.edu
875 Redistributions of any form whatsoever must retain the following
879 .indent ~~sys.indent + 3em
881 $it{This product includes software developed by Computing Services
882 at Carnegie Mellon University (\?http://www.cmu.edu/computing/?\).}
887 .cancelflag $npbracket
888 .flag $npbracket "(" ")"
891 CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO
892 THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
893 AND FITNESS, IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE
894 FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
895 WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
896 AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
897 OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
907 The Exim Monitor program, which is an X-Window application, includes
908 modified versions of the Athena StripChart and TextPop widgets.
909 This code is copyright by DEC and MIT, and their permission notice appears
910 below, in accordance with the conditions expressed therein.
918 Copyright 1987, 1988 by Digital Equipment Corporation, Maynard, Massachusetts,
919 and the Massachusetts Institute of Technology, Cambridge, Massachusetts.
921 $c All Rights Reserved
923 Permission to use, copy, modify, and distribute this software and its
924 documentation for any purpose and without fee is hereby granted,
925 provided that the above copyright notice appear in all copies and that
926 both that copyright notice and this permission notice appear in
927 supporting documentation, and that the names of Digital or MIT not be
928 used in advertising or publicity pertaining to distribution of the
929 software without specific, written prior permission.
931 DIGITAL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
932 ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
933 DIGITAL BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
934 ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
935 WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
936 ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
944 Many people have contributed code fragments, some large, some small, that were
945 not covered by any specific licence requirements. It is assumed that the
946 contributors are happy to see their code incoporated into Exim under the GPL.
956 . ============================================================================
957 .chapter How Exim receives and delivers mail
958 .set runningfoot "receiving & delivering mail"
960 .section Overall philosophy
961 .index design philosophy
962 Exim is designed to work efficiently on systems that are permanently connected
963 to the Internet and are handling a general mix of mail. In such circumstances,
964 most messages can be delivered immediately. Consequently, Exim does not
965 maintain independent queues of messages for specific domains or hosts, though
966 it does try to send several messages in a single SMTP connection after a host
967 has been down, and it also maintains per-host retry information.
970 .section Policy control
971 .index policy control||overview
972 Policy controls are now an important feature of MTAs that are connected to the
973 Internet. Perhaps their most important job is to stop MTAs being abused as
974 `open relays' by misguided individuals who send out vast amounts of unsolicited
975 junk, and want to disguise its source. Exim provides flexible facilities for
976 specifying policy controls on incoming mail:
978 .index ~~ACL||introduction
979 Exim 4 (unlike previous versions of Exim) implements policy controls on
980 incoming mail by means of \*Access Control Lists*\ (ACLs). Each list is a
981 series of statements that may either grant or deny access. ACLs can be used at
982 several places in the SMTP dialogue while receiving a message from a remote
983 host. However, the most common places are after each \\RCPT\\ command, and at
984 the very end of the message. The sysadmin can specify conditions for accepting
985 or rejecting individual recipients or the entire message, respectively, at
986 these two points (see chapter ~~CHAPACL). Denial of access results in an SMTP
989 An ACL is also available for locally generated, non-SMTP messages. In this
990 case, the only available actions are to accept or deny the entire message.
993 When Exim is compiled with the content-scanning extension, facilities are
994 provided in the ACL mechanism for passing the message to external virus and/or
995 spam scanning software. The result of such a scan is passed back to the ACL,
996 which can then use it to decide what to do with the message.
999 When a message has been received, either from a remote host or from the local
1000 host, but before the final acknowledgement has been sent, a locally supplied C
1001 function called \*local@_scan()*\ can be run to inspect the message and decide
1002 whether to accept it or not (see chapter ~~CHAPlocalscan). If the message is
1003 accepted, the list of recipients can be modified by the function.
1006 Using the \*local@_scan()*\ mechanism is another way of calling external
1007 scanner software. The \SA-Exim\ add-on package works this way. It does not
1008 require Exim to be compiled with the content-scanning extension.
1011 After a message has been accepted, a further checking mechanism is available in
1012 the form of the $it{system filter} (see chapter ~~CHAPsystemfilter). This runs
1013 at the start of every delivery process.
1016 .section User filters
1017 .index filter||introduction
1019 In a conventional Exim configuration, users are able to run private filters by
1020 setting up appropriate \(.forward)\ files in their home directories. See
1021 chapter ~~CHAPredirect (about the \%redirect%\ router) for the configuration
1022 needed to support this, and the separate document entitled
1024 [(A HREF="filter_toc.html")]
1026 \*Exim's interfaces to mail filtering*\
1030 for user details. Two different kinds of filtering are available:
1032 Sieve filters are written in the standard filtering language that is defined by
1035 Exim filters are written in a syntax that is unique to Exim, but which is more
1036 powerful than Sieve, which it pre-dates.
1038 User filters are run as part of the routing process, described below.
1041 .section Message identification
1042 .rset SECTmessiden "~~chapter.~~section"
1043 .index message||ids, details of format
1044 .index format||of message id
1045 .index id of message
1050 Every message handled by Exim is given a \*message id*\ which is sixteen
1051 characters long. It is divided into three parts, separated by hyphens, for
1052 example \"16VDhn-0001bo-D3"\. Each part is a sequence of letters and digits,
1053 normally encoding numbers in base 62. However, in the Darwin operating
1054 system (Mac OS X) and when Exim is compiled to run under Cygwin, base 36
1055 (avoiding the use of lower case letters) is used instead, because the message
1056 id is used to construct file names, and the names of files in those systems are
1059 .index pid (process id)||re-use of
1060 The detail of the contents of the message id have changed as Exim has evolved.
1061 Earlier versions relied on the operating system not re-using a process id (pid)
1062 within one second. On modern operating systems, this assumption can no longer
1063 be made, so the algorithm had to be changed. To retain backward compatibility,
1064 the format of the message id was retained, which is why the following rules are
1067 The first six characters of the message id are the time at which the message
1068 started to be received, to a granularity of one second. That is, this field
1069 contains the number of seconds since the start of the epoch (the normal Unix
1070 way of representing the date and time of day).
1072 After the first hyphen, the next six characters are the id of the process that
1073 received the message.
1075 There are two different possibilities for the final two characters:
1077 .index \localhost@_number\
1078 If \localhost@_number\ is not set, this value is the fractional part of the
1079 time of reception, normally in units of 1/2000 of a second, but for systems
1080 that must use base 36 instead of base 62 (because of case-insensitive file
1081 systems), the units are 1/1000 of a second.
1083 If \localhost@_number\ is set, it is multiplied by 200 (100) and added to
1084 the fractional part of the time, which in this case is in units of 1/200
1085 (1/100) of a second.
1088 After a message has been received, Exim waits for the clock to tick at the
1089 appropriate resolution before proceeding, so that if another message is
1090 received by the same process, or by another process with the same (re-used)
1091 pid, it is guaranteed that the time will be different. In most cases, the clock
1092 will already have ticked while the message was being received.
1094 .section Receiving mail
1095 .index receiving mail
1096 .index message||reception
1097 The only way Exim can receive mail from a remote host is using SMTP over
1098 TCP/IP, in which case the sender and recipient addresses are tranferred using
1099 SMTP commands. However, from a locally running process (such as a user's MUA),
1100 there are several possibilities:
1102 If the process runs Exim with the \-bm-\ option, the message is read
1103 non-interactively (usually via a pipe), with the recipients taken from the
1104 command line, or from the body of the message if \-t-\ is also used.
1106 If the process runs Exim with the \-bS-\ option, the message is also read
1107 non-interactively, but in this case the recipients are listed at the start of
1108 the message in a series of SMTP \\RCPT\\ commands, terminated by a \\DATA\\
1109 command. This is so-called `batch SMTP' format,
1110 but it isn't really SMTP. The SMTP commands are just another way of passing
1111 envelope addresses in a non-interactive submission.
1113 If the process runs Exim with the \-bs-\ option, the message is read
1114 interactively, using the SMTP protocol. A two-way pipe is normally used for
1115 passing data between the local process and the Exim process.
1116 This is `real' SMTP and is handled in the same way as SMTP over TCP/IP. For
1117 example, the ACLs for SMTP commands are used for this form of submission.
1119 A local process may also make a TCP/IP call to the host's loopback address
1120 (127.0.0.1) or any other of its IP addresses. When receiving messages, Exim
1121 does not treat the loopback address specially. It treats all such connections
1122 in the same way as connections from other hosts.
1125 .index message||sender, constructed by Exim
1126 .index sender||constructed by Exim
1127 In the three cases that do not involve TCP/IP, the sender address is
1128 constructed from the login name of the user that called Exim and a default
1129 qualification domain (which can be set by the \qualify@_domain\ configuration
1130 option). For local or batch SMTP, a sender address that is passed using the
1131 SMTP \\MAIL\\ command is ignored. However, the system administrator may allow
1132 certain users (`trusted users') to specify a different sender address
1133 unconditionally, or all users to specify certain forms of different sender
1134 address. The \-f-\ option or the SMTP \\MAIL\\ command is used to specify these
1135 different addresses. See section ~~SECTtrustedadmin for details of trusted
1136 users, and the \untrusted@_set@_sender\ option for a way of allowing untrusted
1137 users to change sender addresses.
1139 Messages received by either of the non-interactive mechanisms are subject to
1140 checking by the non-SMTP ACL, if one is defined. Messages received using SMTP
1141 (either over TCP/IP, or interacting with a local process) can be checked by a
1142 number of ACLs that operate at different times during the SMTP session. Either
1143 individual recipients, or the entire message, can be rejected if local policy
1144 requirements are not met. The \*local@_scan()*\ function (see chapter
1145 ~~CHAPlocalscan) is run for all incoming messages.
1147 Exim can be configured not to start a delivery process when a message is
1148 received; this can be unconditional, or depend on the number of incoming SMTP
1149 connections or the system load. In these situations, new messages wait on the
1150 queue until a queue runner process picks them up. However, in standard
1151 configurations under normal conditions, delivery is started as soon as a
1152 message is received.
1157 .section Handling an incoming message
1158 .index spool directory||files that hold a message
1159 .index file||how a message is held
1160 When Exim accepts a message, it writes two files in its spool directory. The
1161 first contains the envelope information, the current status of the message,
1162 and the header lines, and the second contains the body of the message. The
1163 names of the two spool files consist of the message id, followed by $tt{-H} for
1164 the file containing the envelope and header, and $tt{-D} for the data file.
1166 .index spool directory||\(input)\ sub-directory
1167 By default all these message files are held in a single directory called
1168 \(input)\ inside the general Exim spool directory. Some operating systems do
1169 not perform very well if the number of files in a directory gets very large; to
1170 improve performance in such cases, the \split@_spool@_directory\ option can be
1171 used. This causes Exim to split up the input files into 62 sub-directories
1172 whose names are single letters or digits.
1174 The envelope information consists of the address of the message's sender and
1175 the addresses of the recipients. This information is entirely separate from
1176 any addresses contained in the header lines. The status of the message includes
1177 a list of recipients who have already received the message. The format of the
1178 first spool file is described in chapter ~~CHAPspool.
1180 .index rewriting||addresses
1181 Address rewriting that is specified in the rewrite section of the configuration
1182 (see chapter ~~CHAPrewrite) is done once and for all on incoming addresses,
1183 both in the header lines and the envelope, at the time the message is accepted.
1184 If during the course of delivery additional addresses are generated (for
1185 example, via aliasing), these new addresses are rewritten as soon as they are
1186 generated. At the time a message is actually delivered (transported) further
1187 rewriting can take place; because this is a transport option, it can be
1188 different for different forms of delivery. It is also possible to specify the
1189 addition or removal of certain header lines at the time the message is
1190 delivered (see chapters ~~CHAProutergeneric and ~~CHAPtransportgeneric).
1193 .section Life of a message
1194 .index message||life of
1195 .index message||frozen
1196 A message remains in the spool directory until it is completely delivered to
1197 its recipients or to an error address, or until it is deleted by an
1198 administrator or by the user who originally created it. In cases when delivery
1199 cannot proceed -- for example, when a message can neither be delivered to its
1200 recipients nor returned to its sender, the message is marked `frozen' on the
1201 spool, and no more deliveries are attempted.
1203 .index frozen messages||thawing
1204 .index message||thawing frozen
1205 An administrator can `thaw' such messages when the problem has been corrected,
1206 and can also freeze individual messages by hand if necessary. In addition, an
1207 administrator can force a delivery error, causing a bounce message to be sent.
1210 There is an option called \auto@_thaw\, which can be used to cause Exim to
1211 retry frozen messages after a certain time. When this is set, no message will
1212 remain on the queue for ever, because the delivery timeout will eventually be
1213 reached. Delivery failure reports (bounce messages) that reach this timeout are
1215 .index \timeout@_frozen@_after\
1216 There is also an option called \timeout@_frozen@_after\, which discards frozen
1217 messages after a certain time.
1219 .index message||log file for
1220 .index log||file for each message
1221 While Exim is working on a message, it writes information about each delivery
1222 attempt to the main log file. This includes successful, unsuccessful, and
1223 delayed deliveries for each recipient (see chapter ~~CHAPlog). The log lines
1224 are also written to a separate $it{message log} file for each message. These
1225 logs are solely for the benefit of the administrator, and are normally deleted
1226 along with the spool files when processing of a message is complete.
1227 The use of individual message logs can be disabled by setting
1228 \no@_message@_logs\; this might give an improvement in performance on very
1232 .index file||journal
1233 All the information Exim itself needs to set up a delivery is kept in the first
1234 spool file, along with the header lines. When a successful delivery occurs, the
1235 address is immediately written at the end of a journal file, whose name is the
1236 message id followed by $tt{-J}. At the end of a delivery run, if there are some
1237 addresses left to be tried again later, the first spool file (the $tt{-H} file)
1238 is updated to indicate which these are, and the journal file is then deleted.
1239 Updating the spool file is done by writing a new file and renaming it, to
1240 minimize the possibility of data loss.
1242 Should the system or the program crash after a successful delivery but before
1243 the spool file has been updated, the journal is left lying around. The next
1244 time Exim attempts to deliver the message, it reads the journal file and
1245 updates the spool file before proceeding. This minimizes the chances of double
1246 deliveries caused by crashes.
1249 .section Processing an address for delivery
1250 .rset SECTprocaddress "~~chapter.~~section"
1251 .index drivers||definition of
1252 .index router||definition of
1253 .index transport||definition of
1254 The main delivery processing elements of Exim are called $it{routers} and
1255 $it{transports}, and collectively these are known as $it{drivers}. Code for a
1256 number of them is provided in the source distribution, and compile-time options
1257 specify which ones are included in the binary. Run time options specify which
1258 ones are actually used for delivering messages.
1260 .index drivers||instance definition
1261 Each driver that is specified in the run time configuration is an \*instance*\
1262 of that particular driver type. Multiple instances are allowed; for example,
1263 you can set up several different \%smtp%\ transports, each with different
1264 option values that might specify different ports or different timeouts. Each
1265 instance has its own identifying name. In what follows we will normally use the
1266 instance name when discussing one particular instance (that is, one specific
1267 configuration of the driver), and the generic driver name when discussing
1268 the driver's features in general.
1270 A $it{router} is a driver that operates on an address, either determining how
1271 its delivery should happen, by routing it to a specific transport, or
1272 converting the address into one or more new addresses (for example, via an
1273 alias file). A router may also explicitly choose to fail an address, causing it
1276 A $it{transport} is a driver that transmits a copy of the message from Exim's
1277 spool to some destination. There are two kinds of transport: for a $it{local}
1278 transport, the destination is a file or a pipe on the local host, whereas for a
1279 $it{remote} transport the destination is some other host. A message is passed
1280 to a specific transport as a result of successful routing. If a message has
1281 several recipients, it may be passed to a number of different transports.
1283 .index preconditions||definition of
1284 An address is processed by passing it to each configured router instance in
1285 turn, subject to certain preconditions, until a router accepts the address or
1286 specifies that it should be bounced. We will describe this process in more
1287 detail shortly. As a simple example, the diagram below illustrates how each
1288 recipient address in a message is processed in a small configuration of three
1289 routers that are configured in various ways.
1292 .figure "Routing an address" rm
1294 .call aspic -sgcal -nv
1295 centre ~~sys.linelength;
1298 ibox depth 14 "address";
1301 A: box width 100 "first router" "conditions ok?";
1303 C: box width 100 "run" "first router";
1305 D: ibox depth 20 "address bounces";
1307 arc clockwise from right of C "accept";
1309 ibox "queue for" "transport";
1311 arrow down from A align bottom of D plus (0,-20) "no"(-6,20)/r;
1312 E: box width 100 "second router" "conditions ok?";
1314 F: box width 100 "run" "second router";
1315 line right 100 "redirect";
1316 line up align middle of B;
1317 arrow left to middle of B "new addresses";
1319 line down 20 from bottom left of F plus (30,0);
1320 arrow left align centre of E "decline";
1322 line down 20 from bottom right of F plus (-30,0);
1324 ibox width 64 "address" "bounces";
1326 arrow down 64 from E "no"(-6,20)/r;
1327 G: box width 100 "third router" "conditions ok?";
1329 H: box width 100 "run" "third router";
1330 arc clockwise from right of H "accept";
1332 ibox "queue for" "transport";
1334 line down 20 from bottom of H;
1335 arrow left align centre of G "decline";
1336 arrow down 64 from G "no"(-6,20)/r;
1338 ibox "no more routers" "address bounces";
1346 |<------------- new addresses -----------------------------
1348 ----------------- ----------------- |
1349 | first router |----- yes ----->| run |--- accept |
1350 | conditions ok?| | first router | | |
1351 ----------------- ----------------- | |
1353 no | fail | queue for |
1358 ----------------- ----------------- |
1359 | second router |----- yes ----->| run |----redirect ----
1360 | conditions ok?| | second router |
1361 ----------------- -----------------
1364 |<-------- decline ----------- --- fail ---> address
1367 ----------------- -----------------
1368 | third router |----- yes ----->| run |--- accept
1369 | conditions ok?| | third router | |
1370 ----------------- ----------------- |
1373 |<-------- decline --------------- transport
1380 [(img src="routing.gif" alt="Routing an address")][(br)]
1382 To make this a more concrete example, we'll describe it in terms of some actual
1383 routers, but remember, this is only an example. You can configure Exim's
1384 routers in many different ways, and there may be any number of routers in a
1387 The first router that is specified in a configuration is often one that handles
1388 addresses in domains that are not recognized specially by the local host. These
1389 are typically addresses for arbitrary domains on the Internet. A precondition
1390 is set up which looks for the special domains known to the host (for example,
1391 its own domain name), and the router is run for addresses that do $it{not}
1392 match. Typically, this is a router that looks up domains in the DNS in order to
1393 find the hosts to which this address routes. If it succeeds, the address is
1394 queued for a suitable SMTP transport; if it does not succeed, the router is
1395 configured to fail the address.
1397 The example pictured could be a configuration of this type. The second and
1398 third routers can only be run for addresses for which the preconditions for
1399 the first router are not met. If one of these preconditions checks the
1400 domain, the second and third routers are run only for domains that are somehow
1401 special to the local host.
1403 The second router does redirection -- also known as aliasing and forwarding.
1404 When it generates one or more new addresses from the original, each of them is
1405 routed independently from the start. Otherwise, the router may cause an address
1406 to fail, or it may simply decline to handle the address, in which case the
1407 address is passed to the next router.
1409 The final router in many configurations is one that checks to see if the
1410 address belongs to a local mailbox. The precondition may involve a check to
1411 see if the local part is the name of a login account, or it may look up the
1412 local part in a file or a database. If its preconditions are not met, or if
1413 the router declines, we have reached the end of the routers. When this happens,
1414 the address is bounced.
1417 .section Processing an address for verification
1418 .index router||for verification
1419 .index verifying||address, overview
1420 As well as being used to decide how to deliver to an address, Exim's routers
1421 are also used for \*address verification*\. Verification can be requested as
1422 one of the checks to be performed in an ACL for incoming messages, on both
1423 sender and recipient addresses, and it can be tested using the \-bv-\ and
1424 \-bvs-\ command line options.
1426 When an address is being verified, the routers are run in `verify mode'. This
1427 does not affect the way the routers work, but it is a state that can be
1428 detected. By this means, a router can be skipped or made to behave differently
1429 when verifying. A common example is a configuration in which the first router
1430 sends all messages to a message-scanning program, unless they have been
1431 previously scanned. Thus, the first router accepts all addresses without any
1432 checking, making it useless for verifying. Normally, the \no@_verify\ option
1433 would be set for such a router, causing it to be skipped in verify mode.
1437 .section Running an individual router
1438 .rset SECTrunindrou "~~chapter.~~section"
1439 .index router||running details
1440 .index preconditions||checking
1441 .index router||result of running
1442 As explained in the example above, a number of preconditions are checked before
1443 running a router. If any are not met, the router is skipped, and the address is
1444 passed to the next router. When all the preconditions on a router $it{are} met,
1445 the router is run. What happens next depends on the outcome, which is one of
1448 \*accept*\: The router accepts the address, and either queues it for a
1449 transport, or generates one or more `child' addresses. Processing the original
1451 .index \unseen\ option
1452 unless the \unseen\ option is set on the router. This option
1453 can be used to set up multiple deliveries with different routing (for example,
1454 for keeping archive copies of messages). When \unseen\ is set, the address is
1455 passed to the next router. Normally, however, an \*accept*\ return marks the
1458 .index case of local parts
1459 .index address||duplicate, discarding
1460 If child addresses are generated, Exim checks to see whether they are
1461 duplicates of any existing recipient addresses. During this check, local parts
1462 are treated as case-sensitive. Duplicate addresses are discarded. Each of the
1463 remaining child addresses is then processed independently, starting with the
1464 first router by default. It is possible to change this by setting the
1465 \redirect@_router\ option to specify which router to start at for child
1466 addresses. Unlike \pass@_router\ (see below) the router specified by
1467 \redirect@_router\ may be anywhere in the router configuration.
1469 \*pass*\: The router recognizes the address, but cannot handle it itself. It
1470 requests that the address be passed to another router. By default the address
1471 is passed to the next router, but this can be changed by setting the
1472 \pass@_router\ option. However, (unlike \redirect@_router\) the named router
1473 must be below the current router (to avoid loops).
1475 \*decline*\: The router declines to accept the address because it does not
1476 recognize it at all. By default, the address is passed to the next router, but
1477 this can be prevented by setting the \no@_more\ option. When \no@_more\ is set,
1478 all the remaining routers are skipped.
1480 \*fail*\: The router determines that the address should fail, and queues it for
1481 the generation of a bounce message. There is no further processing of the
1482 original address unless \unseen\ is set on the router.
1484 \*defer*\: The router cannot handle the address at the present time. (A database
1485 may be offline, or a DNS lookup may have timed out.) No further processing of
1486 the address happens in this delivery attempt. It is tried again next time the
1487 message is considered for delivery.
1489 \*error*\: There is some error in the router (for example, a syntax error in
1490 its configuration). The action is as for defer.
1492 If an address reaches the end of the routers without having been accepted by
1493 any of them, it is bounced as unrouteable.
1494 The default error message in this situation is `unrouteable address', but you
1495 can set your own message by making use of the \cannot@_route@_message\ option.
1496 This can be set for any router; the value from the last router that `saw'
1497 the address is used.
1499 Sometimes while routing you want to fail a delivery when some conditions are
1500 met but others are not, instead of passing the address on for further routing.
1501 You can do this by having a second router that explicitly fails the delivery
1502 when the relevant conditions are met. The \%redirect%\ router has a `fail'
1503 facility for this purpose.
1507 .section Router preconditions
1508 .rset SECTrouprecon "~~chapter.~~section"
1509 .index router||preconditions, order of processing
1510 .index preconditions||order of processing
1511 The preconditions that are tested for each router are listed below, in the
1512 order in which they are tested. The individual configuration options are
1513 described in more detail in chapter ~~CHAProutergeneric.
1515 The \local@_part@_prefix\ and \local@_part@_suffix\ options can specify that
1516 the local parts handled by the router may or must have certain prefixes and/or
1517 suffixes. If a mandatory affix (prefix or suffix) is not present, the router is
1518 skipped. These conditions are tested first. When an affix is present, it is
1519 removed from the local part before further processing, including the evaluation
1520 of any other conditions.
1522 Routers can be designated for use only when not verifying an address, that is,
1523 only when routing it for delivery (or testing its delivery routing). If the
1524 \verify\ option is set false, the router is skipped when Exim is verifying an
1526 Setting the \verify\ option actually sets two options, \verify@_sender\ and
1527 \verify@_recipient\, which independently control the use of the router for
1528 sender and recipient verification. You can set these options directly if
1529 you want a router to be used for only one type of verification.
1531 If the \address@_test\ option is set false, the router is skipped when Exim is
1532 run with the \-bt-\ option to test an address routing. This can be helpful when
1533 the first router sends all new messages to a scanner of some sort; it makes it
1534 possible to use \-bt-\ to test subsequent delivery routing without having to
1535 simulate the effect of the scanner.
1537 Routers can be designated for use only when verifying an address, as
1538 opposed to routing it for delivery. The \verify@_only\ option controls this.
1540 Certain routers can be explicitly skipped when running the routers to check an
1541 address given in the SMTP \\EXPN\\ command (see the \expn\ option).
1543 If the \domains\ option is set, the domain of the address must be in the set of
1544 domains that it defines.
1546 If the \local@_parts\ option is set, the local part of the address must be in
1547 the set of local parts that it defines. If \local@_part@_prefix\ or
1548 \local@_part@_suffix\ is in use, the prefix or suffix is removed from the local
1549 part before this check. If you want to do precondition tests on local parts
1550 that include affixes, you can do so by using a \condition\ option (see below)
1551 that uses the variables \$local@_part$\, \$local@_part@_prefix$\, and
1552 \$local@_part@_suffix$\ as necessary.
1554 If the \check@_local@_user\ option is set, the local part must be the name of
1555 an account on the local host.
1556 If this check succeeds, the uid and gid of the local user are placed in
1557 \$local@_user@_uid$\ and \$local@_user@_gid$\; these values can be used in the
1558 remaining preconditions.
1560 If the \router@_home@_directory\ option is set, it is expanded at this point,
1561 because it overrides the value of \$home$\. If this expansion were left till
1562 later, the value of \$home$\ as set by \check@_local@_user\ would be used in
1563 subsequent tests. Having two different values of \$home$\ in the same router
1564 could lead to confusion.
1566 If the \senders\ option is set, the envelope sender address must be in the set
1567 of addresses that it defines.
1569 If the \require@_files\ option is set, the existence or non-existence of
1570 specified files is tested.
1572 .index customizing||precondition
1573 If the \condition\ option is set, it is evaluated and tested. This option uses
1574 an expanded string to allow you to set up your own custom preconditions.
1575 Expanded strings are described in chapter ~~CHAPexpand.
1578 Note that \require@_files\ comes near the end of the list, so you cannot use it
1579 to check for the existence of a file in which to lookup up a domain, local
1580 part, or sender. However, as these options are all expanded, you can use the
1581 \exists\ expansion condition to make such tests within each condition. The
1582 \require@_files\ option is intended for checking files that the router may be
1583 going to use internally, or which are needed by a specific transport (for
1584 example, \(.procmailrc)\).
1587 .section Delivery in detail
1588 .index delivery||in detail
1589 When a message is to be delivered, the sequence of events is as follows:
1591 If a system-wide filter file is specified, the message is passed to it. The
1592 filter may add recipients to the message, replace the recipients, discard the
1593 message, cause a new message to be generated, or cause the message delivery to
1594 fail. The format of the system filter file is the same as for Exim user filter
1595 files, described in the separate document entitled
1597 [(A HREF="filter.html")]
1599 \*Exim's interfaces to mail filtering*\.
1603 .index Sieve filter||not available for system filter
1604 (\**Note**\: Sieve cannot be used for system filter files.)
1605 Some additional features are available in system filters -- see chapter
1606 ~~CHAPsystemfilter for details. Note that a message is passed to the system
1607 filter only once per delivery attempt, however many recipients it has. However,
1608 if there are several delivery attempts because one or more addresses could not
1609 be immediately delivered, the system filter is run each time. The filter
1610 condition \first@_delivery\ can be used to detect the first run of the system
1613 Each recipient address is offered to each configured router in turn, subject to
1614 its preconditions, until one is able to handle it. If no router can handle
1615 the address, that is, if they all decline, the address is failed. Because
1616 routers can be targeted at particular domains, several locally handled domains
1617 can be processed entirely independently of each other.
1619 .index routing||loops in
1620 .index loop||while routing
1621 A router that accepts an address may set up a local or a remote transport for
1622 it. However, the transport is not run at this time. Instead, the address is
1623 placed on a list for the particular transport, to be run later. Alternatively,
1624 the router may generate one or more new addresses (typically from alias,
1625 forward, or filter files). New addresses are fed back into this process from
1626 the top, but in order to avoid loops, a router ignores any address which has an
1627 identically-named ancestor that was processed by itself.
1629 When all the routing has been done, addresses that have been successfully
1630 handled are passed to their assigned transports. When local transports are
1631 doing real local deliveries, they handle only one address at a time, but if a
1632 local transport is being used as a pseudo-remote transport (for example, to
1633 collect batched SMTP messages for transmission by some other means) multiple
1634 addresses can be handled. Remote transports can always handle more than one
1635 address at a time, but can be configured not to do so, or to restrict multiple
1636 addresses to the same domain.
1638 Each local delivery to a file or a pipe runs in a separate process under a
1639 non-privileged uid, and these deliveries are run one at a time. Remote
1640 deliveries also run in separate processes, normally under a uid that is private
1641 to Exim (`the Exim user'), but in this case, several remote deliveries can be
1642 run in parallel. The maximum number of simultaneous remote deliveries for any
1643 one message is set by the \remote@_max@_parallel\ option.
1644 The order in which deliveries are done is not defined, except that all local
1645 deliveries happen before any remote deliveries.
1648 When it encounters a local delivery during a queue run, Exim checks its retry
1649 database to see if there has been a previous temporary delivery failure for the
1650 address before running the local transport. If there was a previous failure,
1651 Exim does not attempt a new delivery until the retry time for the address is
1652 reached. However, this happens only for delivery attempts that are part of a
1653 queue run. Local deliveries are always attempted when delivery immediately
1654 follows message reception, even if retry times are set for them. This makes for
1655 better behaviour if one particular message is causing problems (for example,
1656 causing quota overflow, or provoking an error in a filter file).
1658 .index delivery||retry in remote transports
1659 Remote transports do their own retry handling, since an address may be
1660 deliverable to one of a number of hosts, each of which may have a different
1661 retry time. If there have been previous temporary failures and no host has
1662 reached its retry time, no delivery is attempted, whether in a queue run or
1663 not. See chapter ~~CHAPretry for details of retry strategies.
1665 If there were any permanent errors, a bounce message is returned to an
1666 appropriate address (the sender in the common case), with details of the error
1667 for each failing address. Exim can be configured to send copies of bounce
1668 messages to other addresses.
1670 .index delivery||deferral
1671 If one or more addresses suffered a temporary failure, the message is left on
1672 the queue, to be tried again later. Delivery of these addresses is said to be
1675 When all the recipient addresses have either been delivered or bounced,
1676 handling of the message is complete. The spool files and message log are
1677 deleted, though the message log can optionally be preserved if required.
1681 .section Retry mechanism
1682 .index delivery||retry mechanism
1683 .index retry||description of mechanism
1685 Exim's mechanism for retrying messages that fail to get delivered at the first
1686 attempt is the queue runner process. You must either run an Exim daemon that
1687 uses the \-q-\ option with a time interval to start queue runners at regular
1688 intervals, or use some other means (such as \*cron*\) to start them. If you do
1689 not arrange for queue runners to be run, messages that fail temporarily at the
1690 first attempt will remain on your queue for ever. A queue runner process works
1691 it way through the queue, one message at a time, trying each delivery that has
1692 passed its retry time.
1693 You can run several queue runners at once.
1695 Exim uses a set of configured rules to determine when next to retry the failing
1696 address (see chapter ~~CHAPretry). These rules also specify when Exim should
1697 give up trying to deliver to the address, at which point it generates a bounce
1698 message. If no retry rules are set for a particular host, address, and error
1699 combination, no retries are attempted, and temporary errors are treated as
1703 .section Temporary delivery failure
1704 .index delivery||temporary failure
1705 There are many reasons why a message may not be immediately deliverable to a
1706 particular address. Failure to connect to a remote machine (because it, or the
1707 connection to it, is down) is one of the most common. Temporary failures may be
1708 detected during routing as well as during the transport stage of delivery.
1709 Local deliveries may be delayed if NFS files are unavailable, or if a mailbox
1710 is on a file system where the user is over quota. Exim can be configured to
1711 impose its own quotas on local mailboxes; where system quotas are set they will
1714 If a host is unreachable for a period of time, a number of messages may be
1715 waiting for it by the time it recovers, and sending them in a single SMTP
1716 connection is clearly beneficial. Whenever a delivery to a remote host is
1718 .index hints database
1719 Exim makes a note in its hints database, and whenever a successful
1720 SMTP delivery has happened, it looks to see if any other messages are waiting
1721 for the same host. If any are found, they are sent over the same SMTP
1722 connection, subject to a configuration limit as to the maximum number in any
1727 .section Permanent delivery failure
1728 .index delivery||permanent failure
1729 .index bounce message||when generated
1730 When a message cannot be delivered to some or all of its intended recipients, a
1731 bounce message is generated. Temporary delivery failures turn into permanent
1732 errors when their timeout expires. All the addresses that fail in a given
1733 delivery attempt are listed in a single message. If the original message has
1734 many recipients, it is possible for some addresses to fail in one delivery
1735 attempt and others to fail subsequently, giving rise to more than one bounce
1736 message. The wording of bounce messages can be customized by the administrator.
1737 See chapter ~~CHAPemsgcust for details.
1739 .index ::X-Failed-Recipients:: header line
1740 Bounce messages contain an ::X-Failed-Recipients:: header line that lists the
1741 failed addresses, for the benefit of programs that try to analyse such messages
1744 .index bounce message||recipient of
1745 A bounce message is normally sent to the sender of the original message, as
1746 obtained from the message's envelope. For incoming SMTP messages, this is the
1747 address given in the \\MAIL\\ command. However, when an address is
1748 expanded via a forward or alias file, an alternative address can be specified
1749 for delivery failures of the generated addresses. For a mailing list expansion
1750 (see section ~~SECTmailinglists) it is common to direct bounce messages to the
1751 manager of the list.
1755 .section Failures to deliver bounce messages
1756 .index bounce message||failure to deliver
1757 If a bounce message (either locally generated or received from a remote host)
1758 itself suffers a permanent delivery failure, the message is left on the queue,
1759 but it is frozen, awaiting the attention of an administrator. There are options
1760 which can be used to make Exim discard such failed messages, or to keep them
1761 for only a short time (see \timeout@_frozen@_after\ and
1762 \ignore@_bounce@_errors@_after\).
1770 . ============================================================================
1771 .chapter Building and installing Exim
1772 .set runningfoot "building/installing"
1774 .index building Exim
1776 Exim is distributed as a gzipped or bzipped tar file which, when upacked,
1777 creates a directory with the name of the current release (for example,
1778 \(exim-~~version)\) into which the following files are placed:
1780 .if !~~sys.fancy && ~~sgcal
1785 \(ACKNOWLEDGMENTS)\ $t contains some acknowledgments
1787 \(CHANGES)\ $t contains a reference to where changes are documented
1788 \(LICENCE)\ $t the GNU General Public Licence
1789 \(Makefile)\ $t top-level make file
1790 \(NOTICE)\ $t conditions for the use of Exim
1791 \(README)\ $t list of files, directories and simple build instructions
1793 Other files whose names begin with \(README)\ may also be present. The
1794 following subdirectories are created:
1796 .if !~~sys.fancy && ~~sgcal
1801 \(Local)\ $t an empty directory for local configuration files
1802 \(OS)\ $t OS-specific files
1803 \(doc)\ $t documentation files
1804 \(exim@_monitor)\$t source files for the Exim monitor
1805 \(scripts)\ $t scripts used in the build process
1806 \(src)\ $t remaining source files
1807 \(util)\ $t independent utilities
1809 The main utility programs are contained in the \(src)\ directory, and are built
1810 with the Exim binary. The \(util)\ directory contains a few optional scripts
1811 that may be useful to some sites.
1813 .section Multiple machine architectures and operating systems
1814 .index building Exim||multiple OS/architectures
1815 The building process for Exim is arranged to make it easy to build binaries for
1816 a number of different architectures and operating systems from the same set of
1817 source files. Compilation does not take place in the \(src)\ directory. Instead,
1818 a \*build directory*\ is created for each architecture and operating system.
1819 .index symbolic link||to build directory
1820 Symbolic links to the sources are installed in this directory, which is where
1821 the actual building takes place.
1823 In most cases, Exim can discover the machine architecture and operating system
1824 for itself, but the defaults can be overridden if necessary.
1826 .section DBM libraries
1827 .rset SECTdb "~~chapter.~~section"
1828 .index DBM||libraries, discussion of
1829 .index hints database||DBM files used for
1830 Even if you do not use any DBM files in your configuration, Exim still needs a
1831 DBM library in order to operate, because it uses indexed files for its hints
1832 databases. Unfortunately, there are a number of DBM libraries in existence, and
1833 different operating systems often have different ones installed.
1835 .index Solaris||DBM library for
1836 .index IRIX, DBM library for
1837 .index BSD, DBM library for
1838 .index Linux, DBM library for
1839 If you are using Solaris, IRIX, one of the modern BSD systems, or a modern
1840 Linux distribution, the DBM configuration should happen automatically, and you
1841 may be able to ignore this section. Otherwise, you may have to learn more than
1842 you would like about DBM libraries from what follows.
1844 .index \*ndbm*\ DBM library
1845 Licensed versions of Unix normally contain a library of DBM functions operating
1846 via the \*ndbm*\ interface, and this is what Exim expects by default. Free
1847 versions of Unix seem to vary in what they contain as standard. In particular,
1848 some early versions of Linux have no default DBM library, and different
1849 distributors have chosen to bundle different libraries with their packaged
1850 versions. However, the more recent releases seem to have standardised on the
1851 Berkeley DB library.
1853 Different DBM libraries have different conventions for naming the files they
1854 use. When a program opens a file called \(dbmfile)\, there are four
1857 A traditional \*ndbm*\ implementation, such as that supplied as part of
1858 Solaris, operates on two files called \(dbmfile.dir)\ and \(dbmfile.pag)\.
1860 .index \*gdbm*\ DBM library
1861 The GNU library, \*gdbm*\, operates on a single file. If used via its \*ndbm*\
1862 compatibility interface it makes two different hard links to it with names
1863 \(dbmfile.dir)\ and \(dbmfile.pag)\, but if used via its native interface, the
1864 file name is used unmodified.
1866 .index Berkeley DB library
1867 The Berkeley DB package, if called via its \*ndbm*\ compatibility interface,
1868 operates on a single file called \(dbmfile.db)\, but otherwise looks to the
1869 programmer exactly the same as the traditional \*ndbm*\ implementation.
1871 If the Berkeley package is used in its native mode, it operates on a single
1872 file called \(dbmfile)\; the programmer's interface is somewhat different to
1873 the traditional \*ndbm*\ interface.
1875 To complicate things further, there are several very different versions of the
1876 Berkeley DB package. Version 1.85 was stable for a very long time, releases
1877 2.$it{x} and 3.$it{x} were current for a while, but the latest versions are now
1878 numbered 4.$it{x}. Maintenance of some of the earlier releases has ceased. All
1879 versions of Berkeley DB can be obtained from
1881 \?http://www.sleepycat.com/?\
1884 .index \*tdb*\ DBM library
1885 Yet another DBM library, called \*tdb*\, has become available from
1887 \?http://download.sourceforge.net/tdb?\
1889 It has its own interface, and also operates on a single file.
1892 .index DBM||libraries, configuration for building
1893 Exim and its utilities can be compiled to use any of these interfaces. In order
1894 to use any version of the Berkeley DB package in native mode, you must set
1895 \\USE@_DB\\ in an appropriate configuration file (typically
1896 \(Local/Makefile)\). For example:
1900 Similarly, for gdbm you set \\USE@_GDBM\\, and for tdb you set \\USE@_TDB\\. An
1901 error is diagnosed if you set more than one of these.
1903 At the lowest level, the build-time configuration sets none of these options,
1904 thereby assuming an interface of type (1). However, some operating system
1905 configuration files (for example, those for the BSD operating systems and
1906 Linux) assume type (4) by setting \\USE@_DB\\ as their default, and the
1907 configuration files for Cygwin set \\USE@_GDBM\\. Anything you set in
1908 \(Local/Makefile)\, however, overrides these system defaults.
1910 As well as setting \\USE@_DB\\, \\USE@_GDBM\\, or \\USE@_TDB\\, it may also be
1911 necessary to set \\DBMLIB\\, to cause inclusion of the appropriate library, as
1912 in one of these lines:
1917 Settings like that will work if the DBM library is installed in the standard
1918 place. Sometimes it is not, and the library's header file may also not be in
1919 the default path. You may need to set \\INCLUDE\\ to specify where the header
1920 file is, and to specify the path to the library more fully in \\DBMLIB\\, as in
1923 INCLUDE=-I/usr/local/include/db-4.1
1924 DBMLIB=/usr/local/lib/db-4.1/libdb.a
1927 There is further detailed discussion about the various DBM libraries in the
1928 file \(doc/dbm.discuss.txt)\ in the Exim distribution.
1931 .section Pre-building configuration
1932 .index building Exim||pre-building configuration
1933 .index configuration for building Exim
1934 .index \(Local/Makefile)\
1935 .index \(src/EDITME)\
1936 Before building Exim, a local configuration file that specifies options
1937 independent of any operating system has to be created with the name
1938 \(Local/Makefile)\. A template for this file is supplied as the file
1939 \(src/EDITME)\, and it contains full descriptions of all the option settings
1940 therein. These descriptions are therefore not repeated here. If you are
1941 building Exim for the first time, the simplest thing to do is to copy
1942 \(src/EDITME)\ to \(Local/Makefile)\, then read it and edit it appropriately.
1944 There are three settings that you must supply, because Exim will not build
1945 without them. They are the location of the run time configuration file
1946 (\\CONFIGURE@_FILE\\), the directory in which Exim binaries will be installed
1947 (\\BIN@_DIRECTORY\\), and the identity of the Exim user (\\EXIM@_USER\\ and
1948 maybe \\EXIM@_GROUP\\ as well). The value of \\CONFIGURE@_FILE\\ can in fact be
1949 a colon-separated list of file names; Exim uses the first of them that exists.
1951 There are a few other parameters that can be specified either at build time or
1952 at run time, to enable the same binary to be used on a number of different
1953 machines. However, if the locations of Exim's spool directory and log file
1954 directory (if not within the spool directory) are fixed, it is recommended that
1955 you specify them in \(Local/Makefile)\ instead of at run time, so that errors
1956 detected early in Exim's execution (such as a malformed configuration file) can
1959 .index content scanning||specifying at build time
1961 Exim's interfaces for calling virus and spam scanning sofware directly from
1962 access control lists are not compiled by default. If you want to include these
1963 facilities, you need to set
1965 WITH_CONTENT_SCAN=yes
1967 in your \(Local/Makefile)\. For details of the facilities themselves, see
1968 chapter ~~CHAPexiscan.
1971 .index \(Local/eximon.conf)\
1972 .index \(exim@_monitor/EDITME)\
1973 If you are going to build the Exim monitor, a similar configuration process is
1974 required. The file \(exim@_monitor/EDITME)\ must be edited appropriately for
1975 your installation and saved under the name \(Local/eximon.conf)\. If you are
1976 happy with the default settings described in \(exim@_monitor/EDITME)\,
1977 \(Local/eximon.conf)\ can be empty, but it must exist.
1979 This is all the configuration that is needed in straightforward cases for known
1980 operating systems. However, the building process is set up so that it is easy
1981 to override options that are set by default or by operating-system-specific
1982 configuration files, for example to change the name of the C compiler, which
1983 defaults to \gcc\. See section ~~SECToverride below for details of how to do
1987 .section Support for iconv()
1988 .index \*iconv()*\ support
1989 The contents of header lines in messages may be encoded according to the rules
1990 described RFC 2047. This makes it possible to transmit characters that are not
1991 in the ASCII character set, and to label them as being in a particular
1992 character set. When Exim is inspecting header lines by means of the \@$h@_\
1993 mechanism, it decodes them, and translates them into a specified character set
1994 (default ISO-8859-1). The translation is possible only if the operating system
1995 supports the \*iconv()*\ function.
1997 However, some of the operating systems that supply \*iconv()*\ do not support
1998 very many conversions. The GNU \libiconv\ library (available from
1999 \?http:/@/www.gnu.org/software/libiconv/?\) can be installed on such systems to
2000 remedy this deficiency, as well as on systems that do not supply \*iconv()*\ at
2001 all. After installing \libiconv\, you should add
2005 to your \(Local/Makefile)\ and rebuild Exim.
2008 .section Including TLS/SSL encryption support
2009 .rset SECTinctlsssl "~~chapter.~~section"
2010 .index TLS||including support for TLS
2011 .index encryption||including support for
2012 .index \\SUPPORT@_TLS\\
2013 .index OpenSSL||building Exim with
2014 .index GnuTLS||building Exim with
2015 Exim can be built to support encrypted SMTP connections, using the \\STARTTLS\\
2016 command as per RFC 2487. It can also support legacy clients that expect to
2017 start a TLS session immediately on connection to a non-standard port (see the
2018 \tls@_on@_connect@_ports\ runtime option and the \-tls-on-connect-\ command
2021 If you want to build Exim with TLS support, you must first install either the
2022 OpenSSL or GnuTLS library. There is no cryptographic code in Exim itself for
2025 If OpenSSL is installed, you should set
2028 TLS_LIBS=-lssl -lcrypto
2030 in \(Local/Makefile)\. You may also need to specify the locations of the
2031 OpenSSL library and include files. For example:
2034 TLS_LIBS=-L/usr/local/openssl/lib -lssl -lcrypto
2035 TLS_INCLUDE=-I/usr/local/openssl/include/
2038 If GnuTLS is installed, you should set
2039 .index \\USE@_GNUTLS\\
2043 TLS_LIBS=-lgnutls -ltasn1 -lgcrypt
2045 in \(Local/Makefile)\, and again you may need to specify the locations of the
2046 library and include files. For example:
2050 TLS_LIBS=-L/usr/gnu/lib -lgnutls -ltasn1 -lgcrypt
2051 TLS_INCLUDE=-I/usr/gnu/include
2053 You do not need to set \\TLS@_INCLUDE\\ if the relevant directory is already
2054 specified in \\INCLUDE\\. Details of how to configure Exim to make use of TLS
2055 are given in chapter ~~CHAPTLS.
2059 .section Use of tcpwrappers
2060 .index tcpwrappers, building Exim to support
2061 .index \\USE@_TCP@_WRAPPERS\\
2062 Exim can be linked with the \*tcpwrappers*\ library in order to check incoming
2063 SMTP calls using the \*tcpwrappers*\ control files. This may be a convenient
2064 alternative to Exim's own checking facilities for installations that are
2065 already making use of \*tcpwrappers*\ for other purposes. To do this, you should
2066 set \\USE@_TCP@_WRAPPERS\\ in \(Local/Makefile)\, arrange for the file
2067 \(tcpd.h)\ to be available at compile time, and also ensure that the library
2068 \(libwrap.a)\ is available at link time, typically by including \-lwrap-\ in
2069 \\EXTRALIBS@_EXIM\\. For example, if \*tcpwrappers*\ is installed in
2070 \(/usr/local)\, you might have
2072 USE@_TCP@_WRAPPERS=yes
2073 CFLAGS=-O -I/usr/local/include
2075 EXTRALIBS@_EXIM=-L/usr/local/lib -lwrap
2077 in \(Local/Makefile)\. The name to use in the \*tcpwrappers*\ control files is
2078 `exim'. For example, the line
2080 exim : LOCAL 192.168.1. .friendly.domain.example
2082 in your \(/etc/hosts.allow)\ file allows connections from the local host, from
2083 the subnet 192.168.1.0/24, and from all hosts in \*friendly.domain.example*\.
2084 All other connections are denied. Consult the \*tcpwrappers*\ documentation for
2088 .section Including support for IPv6
2089 .index IPv6||including support for
2090 Exim contains code for use on systems that have IPv6 support. Setting
2091 \\HAVE@_IPV6=YES\\ in \(Local/Makefile)\ causes the IPv6 code to be included;
2092 it may also be necessary to set \\IPV6@_INCLUDE\\ and \\IPV6@_LIBS\\ on systems
2093 where the IPv6 support is not fully integrated into the normal include and
2097 Two different types of DNS record for handling IPv6 addresses have been
2098 defined. AAAA records (analagous to A records for IPv4) are in use, and are
2099 currently seen as the mainstream. Another record type called A6 was proposed
2100 as better than AAAA because it had more flexibility. However, it was felt to
2101 be over-complex, and its status was reduced to `experimental'. It is not known
2102 if anyone is actually using A6 records. Exim has support for A6 records, but
2103 this is included only if you set \\SUPPORT@_A6=YES\\ in \(Local/Makefile)\. The
2104 support has not been tested for some time.
2107 .section The building process
2108 .index build directory
2109 Once \(Local/Makefile)\ (and \(Local/eximon.conf)\, if required) have been
2110 created, run \*make*\ at the top level. It determines the architecture and
2111 operating system types, and creates a build directory if one does not exist.
2112 For example, on a Sun system running Solaris 8, the directory
2113 \(build-SunOS5-5.8-sparc)\ is created.
2114 .index symbolic link||to source files
2115 Symbolic links to relevant source files are installed in the build directory.
2117 \**Warning**\: The \-j-\ (parallel) flag must not be used with \*make*\; the
2118 building process fails if it is set.
2120 If this is the first time \*make*\ has been run, it calls a script that builds
2121 a make file inside the build directory, using the configuration files from the
2122 \(Local)\ directory. The new make file is then passed to another instance of
2123 \*make*\. This does the real work, building a number of utility scripts, and
2124 then compiling and linking the binaries for the Exim monitor (if configured), a
2125 number of utility programs, and finally Exim itself. The command \*make
2126 makefile*\ can be used to force a rebuild of the make file in the build
2127 directory, should this ever be necessary.
2129 If you have problems building Exim, check for any comments there may be in the
2130 \(README)\ file concerning your operating system, and also take a look at the
2132 [(A HREF="FAQ.html")]
2138 where some common problems are covered.
2142 .section Overriding build-time options for Exim
2143 .index build-time options, overriding
2144 .rset SECToverride "~~chapter.~~section"
2145 The main make file that is created at the beginning of the building process
2146 consists of the concatenation of a number of files which set configuration
2147 values, followed by a fixed set of \*make*\ instructions. If a value is set
2148 more than once, the last setting overrides any previous ones. This provides a
2149 convenient way of overriding defaults. The files that are concatenated are, in
2152 \(OS/Makefile-Default)\
2153 \(OS/Makefile-)\<<ostype>>
2155 \(Local/Makefile-)\<<ostype>>
2156 \(Local/Makefile-)\<<archtype>>
2157 \(Local/Makefile-)\<<ostype>>-<<archtype>>
2158 \(OS/Makefile-Base)\
2160 .index \(Local/Makefile)\
2161 where <<ostype>> is the operating system type and <<archtype>> is the
2162 .index building Exim||operating system type
2163 .index building Exim||architecture type
2164 architecture type. \(Local/Makefile)\ is required to exist, and the building
2165 process fails if it is absent. The other three \(Local)\ files are optional,
2166 and are often not needed.
2168 The values used for <<ostype>> and <<archtype>> are obtained from scripts
2169 called \(scripts/os-type)\ and \(scripts/arch-type)\ respectively. If either of
2170 the environment variables \\EXIM@_OSTYPE\\ or \\EXIM@_ARCHTYPE\\ is set, their
2171 values are used, thereby providing a means of forcing particular settings.
2172 Otherwise, the scripts try to get values from the \uname\ command. If this
2173 fails, the shell variables \\OSTYPE\\ and \\ARCHTYPE\\ are inspected. A number
2174 of $it{ad hoc} transformations are then applied, to produce the standard names
2175 that Exim expects. You can run these scripts directly from the shell in order
2176 to find out what values are being used on your system.
2179 \(OS/Makefile-Default)\ contains comments about the variables that are set
2180 therein. Some (but not all) are mentioned below. If there is something that
2181 needs changing, review the contents of this file and the contents of the make
2182 file for your operating system (\(OS/Makefile-<<ostype>>)\) to see what the
2186 .index building Exim||overriding default settings
2187 If you need to change any of the values that are set in \(OS/Makefile-Default)\
2188 or in \(OS/Makefile-<<ostype>>)\, or to add any new definitions, you do not
2189 need to change the original files. Instead, you should make the changes by
2190 putting the new values in an appropriate \(Local)\ file. For example,
2191 .index Tru64-Unix build-time settings
2192 when building Exim in many releases of the Tru64-Unix (formerly Digital UNIX,
2193 formerly DEC-OSF1) operating system, it is necessary to specify that the C
2194 compiler is called \*cc*\ rather than \*gcc*\. Also, the compiler must be
2195 called with the option \-std1-\, to make it recognize some of the features of
2196 Standard C that Exim uses. (Most other compilers recognize Standard C by
2197 default.) To do this, you should create a file called \(Local/Makefile-OSF1)\
2198 containing the lines
2203 If you are compiling for just one operating system, it may be easier to put
2204 these lines directly into \(Local/Makefile)\.
2206 Keeping all your local configuration settings separate from the distributed
2207 files makes it easy to transfer them to new versions of Exim simply by copying
2208 the contents of the \(Local)\ directory.
2211 .index NIS lookup type||including support for
2212 .index NIS@+ lookup type||including support for
2213 .index LDAP||including support for
2214 .index lookup||inclusion in binary
2215 Exim contains support for doing LDAP, NIS, NIS+, and other kinds of file
2216 lookup, but not all systems have these components installed, so the default is
2217 not to include the relevant code in the binary. All the different kinds of file
2218 and database lookup that Exim supports are implemented as separate code modules
2219 which are included only if the relevant compile-time options are set. In the
2220 case of LDAP, NIS, and NIS+, the settings for \(Local/Makefile)\ are:
2226 and similar settings apply to the other lookup types. They are all listed in
2227 \(src/EDITME)\. In most cases the relevant include files and interface
2228 libraries need to be installed before compiling Exim.
2229 .index cdb||including support for
2230 However, in the case of cdb, which is included in the binary only if
2234 is set, the code is entirely contained within Exim, and no external include
2235 files or libraries are required. When a lookup type is not included in the
2236 binary, attempts to configure Exim to use it cause run time configuration
2239 .index Perl||including support for
2240 Exim can be linked with an embedded Perl interpreter, allowing Perl
2241 subroutines to be called during string expansion. To enable this facility,
2245 must be defined in \(Local/Makefile)\. Details of this facility are given in
2248 .index X11 libraries, location of
2249 The location of the X11 libraries is something that varies a lot between
2250 operating systems, and of course there are different versions of X11 to cope
2251 with. Exim itself makes no use of X11, but if you are compiling the Exim
2252 monitor, the X11 libraries must be available.
2253 The following three variables are set in \(OS/Makefile-Default)\:
2256 XINCLUDE=-I$(X11)/include
2257 XLFLAGS=-L$(X11)/lib
2259 These are overridden in some of the operating-system configuration files. For
2260 example, in \(OS/Makefile-SunOS5)\ there is
2263 XINCLUDE=-I$(X11)/include
2264 XLFLAGS=-L$(X11)/lib -R$(X11)/lib
2266 If you need to override the default setting for your operating system, place a
2267 definition of all three of these variables into your
2268 \(Local/Makefile-<<ostype>>)\ file.
2270 .index \\EXTRALIBS\\
2271 If you need to add any extra libraries to the link steps, these can be put in a
2272 variable called \\EXTRALIBS\\, which appears in all the link commands, but by
2273 default is not defined. In contrast, \\EXTRALIBS@_EXIM\\ is used only on the
2274 command for linking the main Exim binary, and not for any associated utilities.
2275 .index DBM||libraries, configuration for building
2276 There is also \\DBMLIB\\, which appears in the link commands for binaries that
2277 use DBM functions (see also section ~~SECTdb). Finally, there is
2278 \\EXTRALIBS@_EXIMON\\, which appears only in the link step for the Exim monitor
2279 binary, and which can be used, for example, to include additional X11
2282 .index configuration file||editing
2283 The make file copes with rebuilding Exim correctly if any of the configuration
2284 files are edited. However, if an optional configuration file is deleted, it is
2285 necessary to touch the associated non-optional file (that is, \(Local/Makefile)\
2286 or \(Local/eximon.conf)\) before rebuilding.
2288 .section OS-specific header files
2290 .index building Exim||OS-specific C header files
2291 The \(OS)\ directory contains a number of files with names of the form
2292 \(os.h-<<ostype>>)\. These are system-specific C header files that should not
2293 normally need to be changed. There is a list of macro settings that are
2294 recognized in the file \(OS/os.configuring)\, which should be consulted if you
2295 are porting Exim to a new operating system.
2298 .section Overriding build-time options for the monitor
2299 .index building Eximon||overriding default options
2300 A similar process is used for overriding things when building the Exim monitor,
2301 where the files that are involved are
2303 \(OS/eximon.conf-Default)\
2304 \(OS/eximon.conf-)\<<ostype>>
2305 \(Local/eximon.conf)\
2306 \(Local/eximon.conf-)\<<ostype>>
2307 \(Local/eximon.conf-)\<<archtype>>
2308 \(Local/eximon.conf-)\<<ostype>>-<<archtype>>
2310 .index \(Local/eximon.conf)\
2311 As with Exim itself, the final three files need not exist, and in this case the
2312 \(OS/eximon.conf-<<ostype>>)\ file is also optional. The default values in
2313 \(OS/eximon.conf-Default)\ can be overridden dynamically by setting environment
2314 variables of the same name, preceded by \\EXIMON@_\\. For example, setting
2315 \\EXIMON@_LOG@_DEPTH\\ in the environment overrides the value of
2316 \\LOG@_DEPTH\\ at run time.
2320 .section Installing Exim binaries and scripts
2321 .index installing Exim
2322 .index \\BIN@_DIRECTORY\\
2323 The command \*make install*\ runs the \*exim@_install*\ script with no
2324 arguments. The script copies binaries and utility scripts into the directory
2325 whose name is specified by the \\BIN@_DIRECTORY\\ setting in
2328 Exim's run time configuration file is named by the \\CONFIGURE@_FILE\\ setting
2329 .index \\CONFIGURE@_FILE\\
2330 in \(Local/Makefile)\. If this names a single file, and the file does not
2331 exist, the default configuration file \(src/configure.default)\ is copied there
2332 by the installation script. If a run time configuration file already exists, it
2333 is left alone. If \\CONFIGURE@_FILE\\ is a colon-separated list, naming several
2334 alternative files, no default is installed.
2336 .index system aliases file
2337 .index \(/etc/aliases)\
2338 One change is made to the default configuration file when it is installed: the
2339 default configuration contains a router that references a system aliases file.
2340 The path to this file is set to the value specified by
2341 \\SYSTEM@_ALIASES@_FILE\\ in \(Local/Makefile)\ (\(/etc/aliases)\ by default).
2342 If the system aliases file does not exist, the installation script creates it,
2343 and outputs a comment to the user.
2345 The created file contains no aliases, but it does contain comments about the
2346 aliases a site should normally have. Mail aliases have traditionally been
2347 kept in \(/etc/aliases)\. However, some operating systems are now using
2348 \(/etc/mail/aliases)\. You should check if yours is one of these, and change
2349 Exim's configuration if necessary.
2351 The default configuration uses the local host's name as the only local domain,
2352 and is set up to do local deliveries into the shared directory \(/var/mail)\,
2353 running as the local user. System aliases and \(.forward)\ files in users' home
2354 directories are supported, but no NIS or NIS+ support is configured. Domains
2355 other than the name of the local host are routed using the DNS, with delivery
2358 The install script copies files only if they are newer than the files they are
2359 going to replace. The Exim binary is required to be owned by root and have the
2361 .index setuid||installing Exim with
2362 for normal configurations. Therefore, you must run \*make install*\ as root so
2363 that it can set up the Exim binary in this way. However, in some special
2364 situations (for example, if a host is doing no local deliveries) it may be
2365 possible to run Exim without making the binary setuid root (see chapter
2366 ~~CHAPsecurity for details).
2368 It is possible to install Exim for special purposes (such as building a binary
2369 distribution) in a private part of the file system. You can do this by a
2372 make DESTDIR=/some/directory/ install
2374 This has the effect of pre-pending the specified directory to all the file
2375 paths, except the name of the system aliases file that appears in the default
2376 configuration. (If a default alias file is created, its name \*is*\ modified.)
2377 For backwards compatibility, \\ROOT\\ is used if \\DESTDIR\\ is not set,
2378 but this usage is deprecated.
2380 .index installing Exim||what is not installed
2381 Running \*make install*\ does not copy the Exim 4 conversion script
2382 \*convert4r4*\, or the \*pcretest*\ test program. You will probably run the
2383 first of these only once (if you are upgrading from Exim 3), and the second
2384 isn't really part of Exim. None of the documentation files in the \(doc)\
2385 directory are copied, except for the info files when you have set
2386 \\INFO@_DIRECTORY\\, as described in section ~~SECTinsinfdoc below.
2388 For the utility programs, old versions are renamed by adding the suffix \(.O)\
2389 to their names. The Exim binary itself, however, is handled differently. It is
2390 installed under a name that includes the version number and the compile number,
2391 for example \(exim-~~version-1)\. The script then arranges for a symbolic link
2392 called \(exim)\ to point to the binary. If you are updating a previous version
2393 of Exim, the script takes care to ensure that the name \(exim)\ is never absent
2394 from the directory (as seen by other processes).
2396 .index installing Exim||testing the script
2397 If you want to see what the \*make install*\ will do before running it for
2398 real, you can pass the \-n-\ option to the installation script by this command:
2400 make INSTALL_ARG=-n install
2402 The contents of the variable \\INSTALL@_ARG\\ are passed to the installation
2403 script. You do not need to be root to run this test. Alternatively, you can run
2404 the installation script directly, but this must be from within the build
2405 directory. For example, from the top-level Exim directory you could use this
2408 (cd build-SunOS5-5.5.1-sparc; ../scripts/exim@_install -n)
2411 .index installing Exim||install script options
2412 There are two other options that can be supplied to the installation script.
2414 \-no@_chown-\ bypasses the call to change the owner of the installed binary
2415 to root, and the call to make it a setuid binary.
2417 \-no@_symlink-\ bypasses the setting up of the symbolic link \(exim)\ to the
2420 \\INSTALL@_ARG\\ can be used to pass these options to the script. For example:
2422 make INSTALL_ARG=-no_symlink install
2425 The installation script can also be given arguments specifying which files are
2426 to be copied. For example, to install just the Exim binary, and nothing else,
2427 without creating the symbolic link, you could use:
2429 make INSTALL_ARG='-no_symlink exim' install
2433 .section Installing info documentation
2434 .rset SECTinsinfdoc "~~chapter.~~section"
2435 .index installing Exim||\*info*\ documentation
2436 Not all systems use the GNU \*info*\ system for documentation, and for this
2437 reason, the Texinfo source of Exim's documentation is not included in the main
2438 distribution. Instead it is available separately from the ftp site (see section
2441 If you have defined \\INFO@_DIRECTORY\\ in \(Local/Makefile)\ and the Texinfo
2442 source of the documentation is found in the source tree, running \*make
2443 install*\ automatically builds the info files and installs them.
2446 .section Setting up the spool directory
2447 .index spool directory||creating
2448 When it starts up, Exim tries to create its spool directory if it does not
2449 exist. The Exim uid and gid are used for the owner and group of the spool
2450 directory. Sub-directories are automatically created in the spool directory as
2456 .index testing||installation
2457 Having installed Exim, you can check that the run time configuration file is
2458 syntactically valid by running the following command, which assumes that the
2459 Exim binary directory is within your \\PATH\\ environment variable:
2463 If there are any errors in the configuration file, Exim outputs error messages.
2464 Otherwise it outputs the version number and build date,
2465 the DBM library that is being used, and information about which drivers and
2466 other optional code modules are included in the binary.
2467 Some simple routing tests can be done by using the address testing option. For
2470 exim -bt <<local username>>
2472 should verify that it recognizes a local mailbox, and
2474 exim -bt <<remote address>>
2476 a remote one. Then try getting it to deliver mail, both locally and remotely.
2477 This can be done by passing messages directly to Exim, without going through a
2478 user agent. For example:
2480 exim -v postmaster@@your.domain.example
2481 From: user@@your.domain.example
2482 To: postmaster@@your.domain.example
2483 Subject: Testing Exim
2485 This is a test message.
2488 The \-v-\ option causes Exim to output some verification of what it is doing.
2489 In this case you should see copies of three log lines, one for the message's
2490 arrival, one for its delivery, and one containing `Completed'.
2492 .index delivery||problems with
2493 If you encounter problems, look at Exim's log files (\*mainlog*\ and
2494 \*paniclog*\) to see if there is any relevant information there. Another source
2495 of information is running Exim with debugging turned on, by specifying the
2496 \-d-\ option. If a message is stuck on Exim's spool, you can force a delivery
2497 with debugging turned on by a command of the form
2499 exim -d -M <<message-id>>
2501 You must be root or an `admin user' in order to do this. The \-d-\ option
2502 produces rather a lot of output, but you can cut this down to specific areas.
2503 For example, if you use \-d-all+route-\ only the debugging information relevant
2504 to routing is included. (See the \-d-\ option in chapter ~~CHAPcommandline for
2509 One specific problem that has shown up on some sites is the inability to do
2510 local deliveries into a shared mailbox directory, because it does not have the
2511 `sticky bit' set on it. By default, Exim tries to create a lock file before
2512 writing to a mailbox file, and if it cannot create the lock file, the delivery
2513 is deferred. You can get round this either by setting the `sticky bit' on the
2514 directory, or by setting a specific group for local deliveries and allowing
2515 that group to create files in the directory (see the comments above the
2516 \%local@_delivery%\ transport in the default configuration file). Another
2517 approach is to configure Exim not to use lock files, but just to rely on
2518 \*fcntl()*\ locking instead. However, you should do this only if all user
2519 agents also use \*fcntl()*\ locking. For further discussion of locking issues,
2520 see chapter ~~CHAPappendfile.
2522 One thing that cannot be tested on a system that is already running an MTA is
2523 the receipt of incoming SMTP mail on the standard SMTP port. However, the
2524 \-oX-\ option can be used to run an Exim daemon that listens on some other
2525 port, or \*inetd*\ can be used to do this. The \-bh-\ option and the
2526 \*exim@_checkaccess*\ utility can be used to check out policy controls on
2529 Testing a new version on a system that is already running Exim can most easily
2530 be done by building a binary with a different \\CONFIGURE@_FILE\\ setting. From
2531 within the run time configuration, all other file and directory names
2532 that Exim uses can be altered, in order to keep it entirely clear of the
2535 .section Replacing another MTA with Exim
2536 .index replacing another MTA
2537 Building and installing Exim for the first time does not of itself put it in
2538 general use. The name by which the system's MTA is called by mail user agents
2539 is either \(/usr/sbin/sendmail)\, or \(/usr/lib/sendmail)\ (depending on the
2540 operating system), and it is necessary to make this name point to the \*exim*\
2541 binary in order to get the user agents to pass messages to Exim. This is
2542 normally done by renaming any existing file and making \(/usr/sbin/sendmail)\
2543 or \(/usr/lib/sendmail)\
2544 .index symbolic link||to \*exim*\ binary
2545 a symbolic link to the \*exim*\ binary. It is a good idea to remove any setuid
2546 privilege and executable status from the old MTA. It is then necessary to stop
2547 and restart the mailer daemon, if one is running.
2549 .index FreeBSD, MTA indirection
2550 .index \(/etc/mail/mailer.conf)\
2551 Some operating systems have introduced alternative ways of switching MTAs. For
2552 example, if you are running FreeBSD, you need to edit the file
2553 \(/etc/mail/mailer.conf)\ instead of setting up a symbolic link as just
2554 described. A typical example of the contents of this file for running Exim is
2557 sendmail /usr/exim/bin/exim
2558 send-mail /usr/exim/bin/exim
2559 mailq /usr/exim/bin/exim -bp
2560 newaliases /usr/bin/true
2563 Once you have set up the symbolic link, or edited \(/etc/mail/mailer.conf)\,
2564 your Exim installation is `live'. Check it by sending a message from your
2565 favourite user agent.
2567 You should consider what to tell your users about the change of MTA. Exim may
2568 have different capabilities to what was previously running, and there are
2569 various operational differences such as the text of messages produced by
2570 command line options and in bounce messages. If you allow your users to make
2571 use of Exim's filtering capabilities, you should make the document entitled
2573 [(A HREF="filter.html")]
2575 \*Exim's interface to mail filtering*\
2582 .section Upgrading Exim
2583 .index upgrading Exim
2584 If you are already running Exim on your host, building and installing a new
2585 version automatically makes it available to MUAs, or any other programs that
2586 call the MTA directly. However, if you are running an Exim daemon, you do need
2587 to send it a HUP signal, to make it re-exec itself, and thereby pick up the new
2588 binary. You do not need to stop processing mail in order to install a new
2592 .section Stopping the Exim daemon on Solaris
2593 .index Solaris||stopping Exim on
2594 The standard command for stopping the mailer daemon on Solaris is
2596 /etc/init.d/sendmail stop
2598 If \(/usr/lib/sendmail)\ has been turned into a symbolic link, this script
2599 fails to stop Exim because it uses the command \*ps -e*\ and greps the output
2600 for the text `sendmail'; this is not present because the actual program name
2601 (that is, `exim') is given by the \*ps*\ command with these options. A solution
2602 is to replace the line that finds the process id with something like
2604 pid=`cat /var/spool/exim/exim-daemon.pid`
2606 to obtain the daemon's pid directly from the file that Exim saves it in.
2608 Note, however, that stopping the daemon does not `stop Exim'. Messages can
2609 still be received from local processes, and if automatic delivery is configured
2610 (the normal case), deliveries will still occur.
2617 . ============================================================================
2618 .chapter The Exim command line
2619 .set runningfoot "command line"
2620 .rset CHAPcommandline ~~chapter
2621 .index command line||options
2622 .index options||command line
2624 Exim's command line takes the standard Unix form of a sequence of options,
2625 each starting with a hyphen character, followed by a number of arguments. The
2626 options are compatible with the main options of Sendmail, and there are also
2627 some additional options, some of which are compatible with Smail 3. Certain
2628 combinations of options do not make sense, and provoke an error if used.
2629 The form of the arguments depends on which options are set.
2631 .section Setting options by program name
2633 If Exim is called under the name \*mailq*\, it behaves as if the option \-bp-\
2634 were present before any other options.
2635 The \-bp-\ option requests a listing of the contents of the mail queue on the
2637 This feature is for compatibility with some systems that contain a command of
2638 that name in one of the standard libraries, symbolically linked to
2639 \(/usr/sbin/sendmail)\ or \(/usr/lib/sendmail)\.
2642 If Exim is called under the name \*rsmtp*\ it behaves as if the option \-bS-\
2643 were present before any other options, for compatibility with Smail. The \-bS-\
2644 option is used for reading in a number of messages in batched SMTP format.
2647 If Exim is called under the name \*rmail*\ it behaves as if the \-i-\ and
2648 \-oee-\ options were present before any other options, for compatibility with
2649 Smail. The name \*rmail*\ is used as an interface by some UUCP systems.
2653 If Exim is called under the name \*runq*\ it behaves as if the option \-q-\ were
2654 present before any other options, for compatibility with Smail. The \-q-\
2655 option causes a single queue runner process to be started.
2657 .index \*newaliases*\
2658 .index alias file||building
2659 .index Sendmail compatibility||calling Exim as \*newaliases*\
2660 If Exim is called under the name \*newaliases*\ it behaves as if the option
2661 \-bi-\ were present before any other options, for compatibility with Sendmail.
2662 This option is used for rebuilding Sendmail's alias file. Exim does not have
2663 the concept of a single alias file, but can be configured to run a given
2664 command if called with the \-bi-\ option.
2666 .section Trusted and admin users
2667 .rset SECTtrustedadmin "~~chapter.~~section"
2668 Some Exim options are available only to \*trusted users*\ and others are
2669 available only to \*admin users*\. In the description below, the phrases `Exim
2670 user' and `Exim group' mean the user and group defined by \\EXIM@_USER\\ and
2671 \\EXIM@_GROUP\\ in \(Local/Makefile)\ or set by the \exim@_user\ and
2672 \exim@_group\ options. These do not necessarily have to use the name `exim'.
2675 .index trusted user||definition of
2676 .index user||trusted, definition of
2677 The trusted users are root, the Exim user, any user listed in the
2678 \trusted@_users\ configuration option, and any user whose current group or any
2679 supplementary group is one of those listed in the \trusted@_groups\
2680 configuration option. Note that the Exim group is not automatically trusted.
2683 .index envelope sender
2684 Trusted users are always permitted to use the \-f-\ option or a leading `From '
2685 line to specify the envelope sender of a message that is passed to Exim through
2686 the local interface (see the \-bm-\ and \-f-\ options below). See the
2687 \untrusted@_set@_sender\ option for a way of permitting non-trusted users to
2688 set envelope senders.
2689 .index ::From:: header line
2690 .index ::Sender:: header line
2691 For a trusted user, there is never any check on the contents of the ::From::
2692 header line, and a ::Sender:: line is never added. Furthermore, any existing
2693 ::Sender:: line in incoming local (non-TCP/IP) messages is not removed.
2695 Trusted users may also specify a host name, host address, interface address,
2696 protocol name, ident value, and authentication data when submitting a message
2697 locally. Thus, they are able to insert messages into Exim's queue locally that
2698 have the characteristics of messages received from a remote host. Untrusted
2699 users may in some circumstances use \-f-\, but can never set the other values
2700 that are available to trusted users.
2702 .index user||admin, definition of
2703 .index admin user||definition of
2704 The admin users are root, the Exim user, and any user that is a member of the
2705 Exim group or of any group listed in the \admin@_groups\ configuration option.
2706 The current group does not have to be one of these groups.
2708 Admin users are permitted to list the queue, and to carry out certain
2709 operations on messages, for example, to force delivery failures. It is also
2710 necessary to be an admin user in order to see the full information provided by
2711 the Exim monitor, and full debugging output.
2713 By default, the use of the \-M-\, \-q-\, \-R-\, and \-S-\ options to cause Exim
2714 to attempt delivery of messages on its queue is restricted to admin users.
2715 However, this restriction can be relaxed by setting the \prod@_requires@_admin\
2716 option false (that is, specifying \no@_prod@_requires@_admin\).
2718 Similarly, the use of the \-bp-\ option to list all the messages in the queue
2719 is restricted to admin users unless \queue@_list@_requires@_admin\ is set
2723 \**Warning**\: If you configure your system so that admin users are able to
2724 edit Exim's configuration file, you are giving those users an easy way of
2725 getting root. There is further discussion of this issue at the start of chapter
2730 .section Command line options
2731 The command options are described in alphabetical order below.
2736 .index options||command line, terminating
2737 This is a pseudo-option whose only purpose is to terminate the options and
2738 therefore to cause subsequent command line items to be treated as arguments
2739 rather than options, even if they begin with hyphens.
2742 This option causes Exim to output a few sentences stating what it is.
2743 The same output is generated if the Exim binary is called with no options and
2747 .index 8-bit characters
2748 .index Sendmail compatibility||8-bit characters
2749 This is a Sendmail option for selecting 7 or 8 bit processing. Exim is 8-bit
2750 clean; it ignores this option.
2754 .index SMTP listener
2756 This option runs Exim as a daemon, awaiting incoming SMTP connections. Usually
2757 the \-bd-\ option is combined with the \-q-\<<time>> option, to specify that
2758 the daemon should also initiate periodic queue runs.
2760 The \-bd-\ option can be used only by an admin user. If either of the \-d-\
2761 (debugging) or \-v-\ (verifying) options are set, the daemon does not
2762 disconnect from the controlling terminal. When running this way, it can be
2763 stopped by pressing ctrl-C.
2765 By default, Exim listens for incoming connections to the standard SMTP port on
2766 all the host's running interfaces. However, it is possible to listen on other
2767 ports, on multiple ports, and only on specific interfaces. Chapter
2768 ~~CHAPinterfaces contains a description of the options that control this.
2770 .index daemon||process id (pid)
2771 .index pid (process id)||of daemon
2772 When a listening daemon is started without the use of \-oX-\ (that is, without
2773 overriding the normal configuration), it writes its process id to a file called
2774 \(exim-daemon.pid)\ in Exim's spool directory. This location can be overridden
2775 by setting \\PID@_FILE@_PATH\\ in \(Local/Makefile)\. The file is written while
2776 Exim is still running as root.
2778 When \-oX-\ is used on the command line to start a listening daemon, the
2779 process id is not written to the normal pid file path. However, \-oP-\ can be
2780 used to specify a path on the command line if a pid file is required.
2783 The \\SIGHUP\\ signal can be used to cause the daemon to re-exec itself. This
2784 should be done whenever Exim's configuration file, or any file that is
2785 incorporated into it by means of the \.include\ facility, is changed, and also
2786 whenever a new version of Exim is installed. It is not necessary to do this
2787 when other files that are referenced from the configuration (for example, alias
2788 files) are changed, because these are reread each time they are used.
2791 This option has the same effect as \-bd-\ except that it never disconnects from
2792 the controlling terminal, even when no debugging is specified.
2795 .index testing||string expansion
2796 .index expansion||testing
2797 Run Exim in expansion testing mode. Exim discards its root privilege, to
2798 prevent ordinary users from using this mode to read otherwise inaccessible
2799 files. If no arguments are given, Exim runs interactively, prompting for lines
2802 If Exim was built with \\USE@_READLINE\\=yes in \(Local/Makefile)\, it tries
2803 to load the \libreadline\ library dynamically whenever the \-be-\ option is
2804 used without command line arguments. If successful, it uses the \*readline()*\
2805 function, which provides extensive line-editing facilities, for reading the
2806 test data. A line history is supported.
2809 Long expansion expressions can be split over several lines by using backslash
2810 continuations. As in Exim's run time configuration, whitespace at the start of
2811 continuation lines is ignored. Each argument or data line is passed through the
2812 string expansion mechanism, and the result is output. Variable values from the
2813 configuration file (for example, \$qualify@_domain$\) are available, but no
2814 message-specific values (such as \$domain$\) are set, because no message is
2817 .option bF #<<filename>>
2818 .index system filter||testing
2819 .index testing||system filter
2820 This option is the same as \-bf-\ except that it assumes that the filter being
2821 tested is a system filter. The additional commands that are available only in
2822 system filters are recognized.
2824 .option bf #<<filename>>
2825 .index filter||testing
2826 .index testing||filter file
2827 .index forward file||testing
2828 .index testing||forward file
2829 .index Sieve filter||testing
2830 This option runs Exim in user filter testing mode; the file is the filter file
2831 to be tested, and a test message must be supplied on the standard input. If
2832 there are no message-dependent tests in the filter, an empty file can be
2835 If you want to test a system filter file, use \-bF-\ instead of \-bf-\. You can
2836 use both \-bF-\ and \-bf-\ on the same command, in order to
2837 test a system filter and a user filter in the same run. For example:
2839 exim -bF /system/filter -bf /user/filter </test/message
2841 This is helpful when the system filter adds header lines or sets filter
2842 variables that are used by the user filter.
2845 If the test filter file does not begin with one of the special lines
2850 it is taken to be a normal \(.forward)\ file, and is tested for validity under
2851 that interpretation. See sections ~~SECTitenonfilred to ~~SECTspecitredli for a
2852 description of the possible contents of non-filter redirection lists.
2854 The result of an Exim command that uses \-bf-\, provided no errors are
2855 detected, is a list of the actions that Exim would try to take if presented
2856 with the message for real. More details of filter testing are given in the
2857 separate document entitled \*Exim's interfaces to mail filtering*\.
2860 .index envelope sender
2861 .index \-f-\ option||for filter testing
2862 When testing a filter file, the envelope sender can be set by the \-f-\ option,
2863 or by a `From ' line at the start of the test message. Various parameters that
2864 would normally be taken from the envelope recipient address of the message can
2865 be set by means of additional command line options (see the next four options).
2868 .option bfd #<<domain>>
2869 This sets the domain of the recipient address when a filter file is being
2870 tested by means of the \-bf-\ option. The default is the value of
2871 \$qualify@_domain$\.
2873 .option bfl #<<local part>>
2874 This sets the local part of the recipient address when a filter file is being
2875 tested by means of the \-bf-\ option. The default is the username of the
2876 process that calls Exim. A local part should be specified with any prefix or
2877 suffix stripped, because that is how it appears to the filter when a message is
2878 actually being delivered.
2880 .option bfp #<<prefix>>
2881 This sets the prefix of the local part of the recipient address when a filter
2882 file is being tested by means of the \-bf-\ option. The default is an empty
2885 .option bfp #<<suffix>>
2886 This sets the suffix of the local part of the recipient address when a filter
2887 file is being tested by means of the \-bf-\ option. The default is an empty
2892 .option bh #<<IP address>>
2893 .index testing||incoming SMTP
2894 .index SMTP||testing incoming
2895 .index testing||relay control
2896 .index relaying||testing configuration
2897 .index policy control||testing
2898 .index debugging||\-bh-\ option
2899 This option runs a fake SMTP session as if from the given IP address, using the
2900 standard input and output. The IP address may include a port number at the end,
2901 after a full stop. For example:
2903 exim -bh 10.9.8.7.1234
2904 exim -bh fe80::a00:20ff:fe86:a061.5678
2907 When an IPv6 address is given, it is converted into canonical form. In the case
2908 of the second example above, the value of \$sender@_host@_address$\ after
2909 conversion to the canonical form is \"fe80:0000:0000:0a00:20ff:fe86:a061.5678"\.
2912 Comments as to what is going on are written to the standard error file. These
2913 include lines beginning with `LOG' for anything that would have been logged.
2914 This facility is provided for testing configuration options for incoming
2915 messages, to make sure they implement the required policy. For example, you can
2916 test your relay controls using \-bh-\.
2919 \**Warning 1**\: You cannot test features of the configuration that rely on
2920 ident (RFC 1413) callouts. These cannot be done when testing using
2921 \-bh-\ because there is no incoming SMTP connection.
2923 \**Warning 2**\: Address verification callouts (see section ~~SECTcallver) are
2924 also skipped when testing using \-bh-\. If you want these callouts to occur,
2925 use \-bhc-\ instead.
2927 Messages supplied during the testing session are discarded, and nothing is
2928 written to any of the real log files. There may be pauses when DNS (and other)
2929 lookups are taking place, and of course these may time out. The \-oMi-\ option
2930 can be used to specify a specific IP interface and port if this is important.
2932 The \*exim@_checkaccess*\ utility is a `packaged' version of \-bh-\ whose
2933 output just states whether a given recipient address from a given host is
2934 acceptable or not. See section ~~SECTcheckaccess.
2936 .option bhc #<<IP address>>
2937 This option operates in the same way as \-bh-\, except that address
2938 verification callouts are performed if required. This includes consulting and
2939 updating the callout cache database.
2942 .index alias file||building
2943 .index building alias file
2944 .index Sendmail compatibility||\-bi-\ option
2945 Sendmail interprets the \-bi-\ option as a request to rebuild its alias file.
2946 Exim does not have the concept of a single alias file, and so it cannot mimic
2947 this behaviour. However, calls to \(/usr/lib/sendmail)\ with the \-bi-\ option
2948 tend to appear in various scripts such as NIS make files, so the option must be
2951 If \-bi-\ is encountered, the command specified by the \bi@_command\
2952 configuration option is run, under the uid and gid of the caller of Exim. If
2953 the \-oA-\ option is used, its value is passed to the command as an argument.
2954 The command set by \bi@_command\ may not contain arguments. The command can use
2955 the \*exim@_dbmbuild*\ utility, or some other means, to rebuild alias files if
2956 this is required. If the \bi@_command\ option is not set, calling Exim with
2960 .index local message reception
2961 This option runs an Exim receiving process that accepts an incoming,
2962 locally-generated message on the current input. The recipients are given as the
2963 command arguments (except when \-t-\ is also present -- see below). Each
2964 argument can be a comma-separated list of RFC 2822 addresses. This is the
2965 default option for selecting the overall action of an Exim call; it is assumed
2966 if no other conflicting option is present.
2968 If any addresses in the message are unqualified (have no domain), they are
2969 qualified by the values of the \qualify@_domain\ or \qualify@_recipient\
2970 options, as appropriate. The \-bnq-\ option (see below) provides a way of
2971 suppressing this for special cases.
2973 Policy checks on the contents of local messages can be enforced by means of the
2974 non-SMTP ACL. See chapter ~~CHAPACL for details.
2975 .index return code||for \-bm-\
2976 The return code is zero if the message is successfully accepted. Otherwise, the
2977 action is controlled by the \-oe$it{x}-\ option setting -- see below.
2979 .index message||format
2980 .index format||message
2982 .index UUCP||`From' line
2983 .index Sendmail compatibility||`From' line
2984 The format of the message must be as defined in RFC 2822, except that, for
2985 compatibility with Sendmail and Smail, a line in one of the forms
2987 From sender Fri Jan 5 12:55 GMT 1997
2988 From sender Fri, 5 Jan 97 12:55:01
2990 (with the weekday optional, and possibly with additional text after the date)
2991 is permitted to appear at the start of the message. There appears to be no
2992 authoritative specification of the format of this line. Exim recognizes it by
2993 matching against the regular expression defined by the \uucp@_from@_pattern\
2994 option, which can be changed if necessary.
2995 .index \-f-\ option||overriding `From' line
2996 The specified sender is treated as if it were given as the argument to the
2997 \-f-\ option, but if a \-f-\ option is also present, its argument is used in
2998 preference to the address taken from the message. The caller of Exim must be a
2999 trusted user for the sender of a message to be set in this way.
3002 .index address||qualification, suppressing
3003 By default, Exim automatically qualifies unqualified addresses (those
3004 without domains) that appear in messages that are submitted locally (that
3005 is, not over TCP/IP). This qualification applies both to addresses in
3006 envelopes, and addresses in header lines. Sender addresses are qualified using
3007 \qualify@_domain\, and recipient addresses using \qualify@_recipient\ (which
3008 defaults to the value of \qualify@_domain\).
3010 Sometimes, qualification is not wanted. For example, if \-bS-\ (batch SMTP) is
3011 being used to re-submit messages that originally came from remote hosts after
3012 content scanning, you probably do not want to qualify unqualified addresses in
3013 header lines. (Such lines will be present only if you have not enabled a header
3014 syntax check in the appropriate ACL.)
3016 The \-bnq-\ option suppresses all qualification of unqualified addresses in
3017 messages that originate on the local host. When this is used, unqualified
3018 addresses in the envelope provoke errors (causing message rejection) and
3019 unqualified addresses in header lines are left alone.
3023 .index configuration options, extracting
3024 .index options||configuration, extracting
3025 If this option is given with no arguments, it causes the values of all Exim's
3026 main configuration options to be written to the standard output. The values
3027 of one or more specific options can be requested by giving their names as
3028 arguments, for example:
3030 exim -bP qualify@_domain hold@_domains
3032 However, any option setting that is preceded by the word `hide' in the
3033 configuration file is not shown in full, except to an admin user. For other
3034 users, the output is as in this example:
3036 mysql_servers = <value not displayable>
3038 If \configure@_file\ is given as an argument, the name of the run time
3039 configuration file is output.
3040 If a list of configuration files was supplied, the value that is output here
3041 is the name of the file that was actually used.
3043 .index daemon||process id (pid)
3044 .index pid (process id)||of daemon
3045 If \log__file__path\ or \pid@_file@_path\ are given, the names of the
3046 directories where log files and daemon pid files are written are output,
3047 respectively. If these values are unset, log files are written in a
3048 sub-directory of the spool directory called \log\, and the pid file is written
3049 directly into the spool directory.
3051 If \-bP-\ is followed by a name preceded by \"+"\, for example,
3053 exim -bP +local_domains
3055 it searches for a matching named list of any type (domain, host, address, or
3056 local part) and outputs what it finds.
3058 .index options||router, extracting
3059 .index options||transport, extracting
3060 If one of the words \router\, \transport\, or \authenticator\ is given,
3061 followed by the name of an appropriate driver instance, the option settings for
3062 that driver are output. For example:
3064 exim -bP transport local@_delivery
3066 The generic driver options are output first, followed by the driver's private
3067 options. A list of the names of drivers of a particular type can be obtained by
3068 using one of the words \router@_list\, \transport@_list\, or
3069 \authenticator@_list\, and a complete list of all drivers with their option
3070 settings can be obtained by using \routers\, \transports\, or \authenticators\.
3074 .index queue||listing messages on
3075 .index listing||messages on the queue
3076 This option requests a listing of the contents of the mail queue on the
3077 standard output. If the \-bp-\ option is followed by a list of message ids,
3078 just those messages are listed. By default, this option can be used only by an
3079 admin user. However, the \queue__list__requires__admin\ option can be set false
3080 to allow any user to see the queue.
3082 Each message on the queue is displayed as in the following example:
3084 25m 2.9K 0t5C6f-0000c8-00 <alice@@wonderland.fict.example>
3085 red.king@@looking-glass.fict.example
3088 .index message||size in queue listing
3089 .index size||of message
3090 The first line contains the length of time the message has been on the queue
3091 (in this case 25 minutes), the size of the message (2.9K), the unique local
3092 identifier for the message, and the message sender, as contained in the
3093 envelope. For bounce messages, the sender address is empty, and appears as
3094 `<>'. If the message was submitted locally by an untrusted user who overrode
3095 the default sender address, the user's login name is shown in parentheses
3096 before the sender address.
3097 .index frozen messages||in queue listing
3098 If the message is frozen (attempts to deliver it are suspended) then the text
3099 `$*$$*$$*$ frozen $*$$*$$*$' is displayed at the end of this line.
3101 The recipients of the message (taken from the envelope, not the headers) are
3102 displayed on subsequent lines. Those addresses to which the message has already
3103 been delivered are marked with the letter D. If an original address gets
3104 expanded into several addresses via an alias or forward file, the original is
3105 displayed with a D only when deliveries for all of its child addresses are
3110 This option operates like \-bp-\, but in addition it shows delivered addresses
3111 that were generated from the original top level address(es) in each message by
3112 alias or forwarding operations. These addresses are flagged with `+D' instead
3117 .index queue||count of messages on
3118 This option counts the number of messages on the queue, and writes the total
3119 to the standard output. It is restricted to admin users, unless
3120 \queue__list__requires__admin\ is set false.
3124 This option operates like \-bp-\, but the output is not sorted into
3125 chronological order of message arrival. This can speed it up when there are
3126 lots of messages on the queue, and is particularly useful if the output is
3127 going to be post-processed in a way that doesn't need the sorting.
3130 This option is a combination of \-bpr-\ and \-bpa-\.
3133 This option is a combination of \-bpr-\ and \-bpu-\.
3137 This option operates like \-bp-\ but shows only undelivered top-level addresses
3138 for each message displayed. Addresses generated by aliasing or forwarding are
3139 not shown, unless the message was deferred after processing by a router with
3140 the \one@_time\ option set.
3144 .index testing||retry configuration
3145 .index retry||configuration testing
3146 This option is for testing retry rules, and it must be followed by up to three
3147 arguments. It causes Exim to look for a retry rule that matches the values
3148 and to write it to the standard output. For example:
3150 exim -brt bach.comp.mus.example
3151 Retry rule: *.comp.mus.example F,2h,15m; F,4d,30m;
3153 See chapter ~~CHAPretry for a description of Exim's retry rules. The first
3154 argument, which is required, can be a complete address in the form
3155 \*local@_part@@domain*\, or it can be just a domain name. The second argument is
3156 an optional second domain name; if no retry rule is found for the first
3157 argument, the second is tried. This ties in with Exim's behaviour when looking
3158 for retry rules for remote hosts -- if no rule is found that matches the host,
3159 one that matches the mail domain is sought. The final argument is the name of a
3160 specific delivery error, as used in setting up retry rules, for example
3164 .index testing||rewriting
3165 .index rewriting||testing
3166 This option is for testing address rewriting rules, and it must be followed by
3167 a single argument, consisting of either a local part without a domain, or a
3168 complete address with a fully qualified domain. Exim outputs how this address
3169 would be rewritten for each possible place it might appear. See chapter
3170 ~~CHAPrewrite for further details.
3173 .index SMTP||batched incoming
3174 .index batched SMTP input
3175 This option is used for batched SMTP input, which is an alternative interface
3176 for non-interactive local message submission. A number of messages can be
3177 submitted in a single run. However, despite its name, this is not really SMTP
3178 input. Exim reads each message's envelope from SMTP commands on the standard
3179 input, but generates no responses. If the caller is trusted, or
3180 \untrusted@_set@_sender\ is set, the senders in the SMTP \\MAIL\\ commands are
3181 believed; otherwise the sender is always the caller of Exim.
3183 The message itself is read from the standard input, in SMTP format (leading
3184 dots doubled), terminated by a line containing just a single dot. An error is
3185 provoked if the terminating dot is missing. A further message may then follow.
3187 As for other local message submissions, the contents of incoming batch SMTP
3188 messages can be checked using the non-SMTP ACL (see chapter ~~CHAPACL).
3189 Unqualified addresses are automatically qualified using \qualify@_domain\ and
3190 \qualify@_recipient\, as appropriate, unless the \-bnq-\ option is used.
3192 Some other SMTP commands are recognized in the input. \\HELO\\ and \\EHLO\\ act
3193 as \\RSET\\; \\VRFY\\, \\EXPN\\, \\ETRN\\, and \\HELP\\ act as \\NOOP\\;
3194 \\QUIT\\ quits, ignoring the rest of the standard input.
3196 If any error is encountered, reports are written to the standard output and
3197 error streams, and Exim gives up immediately.
3198 .index return code||for \-bS-\
3199 The return code is 0 if no error was detected; it is 1 if one or more messages
3200 were accepted before the error was detected; otherwise it is 2.
3202 More details of input using batched SMTP are given in section
3203 ~~SECTincomingbatchedSMTP.
3206 .index SMTP||local input
3207 .index local SMTP input
3208 This option causes Exim to accept one or more messages by reading SMTP commands
3209 on the standard input, and producing SMTP replies on the standard output. SMTP
3210 policy controls, as defined in ACLs (see chapter ~~CHAPACL) are applied.
3212 Some user agents use this interface as a way of passing locally-generated
3213 messages to the MTA.
3214 .index sender||source of
3215 In this usage, if the caller of Exim is trusted, or \untrusted@_set@_sender\ is
3216 set, the senders of messages are taken from the SMTP \\MAIL\\ commands.
3217 Otherwise the content of these commands is ignored and the sender is set up as
3218 the calling user. Unqualified addresses are automatically qualified using
3219 \qualify@_domain\ and \qualify@_recipient\, as appropriate, unless the \-bnq-\
3223 The \-bs-\ option is also used to run Exim from \*inetd*\, as an alternative to
3224 using a listening daemon. Exim can distinguish the two cases by checking
3225 whether the standard input is a TCP/IP socket. When Exim is called from
3226 \*inetd*\, the source of the mail is assumed to be remote, and the comments
3227 above concerning senders and qualification do not apply. In this situation,
3228 Exim behaves in exactly the same way as it does when receiving a message via
3229 the listening daemon.
3232 .index testing||addresses
3233 .index address||testing
3234 This option runs Exim in address testing mode, in which each argument is taken
3235 as an address to be tested for deliverability. The results are written to the
3236 standard output. If a test fails, and the caller is not an admin user, no
3237 details of the failure are output, because these might contain sensitive
3238 information such as usernames and passwords for database lookups.
3240 If no arguments are given, Exim runs in an interactive manner, prompting with a
3241 right angle bracket for addresses to be tested.
3243 Unlike the \-be-\ test option, you cannot arrange for Exim to use the
3244 \*readline()*\ function, because it is running as \*root*\ and there are
3248 Each address is handled as if it were the recipient address of a message
3249 (compare the \-bv-\ option). It is passed to the routers and the result is
3250 written to the standard output. However, any router that has
3251 \no@_address@_test\ set is bypassed. This can make \-bt-\ easier to use for
3252 genuine routing tests if your first router passes everything to a scanner
3255 .index return code||for \-bt-\
3256 The return code is 2 if any address failed outright; it is 1 if no address
3257 failed outright but at least one could not be resolved for some reason. Return
3258 code 0 is given only when all addresses succeed.
3260 \**Warning**\: \-bt-\ can only do relatively simple testing. If any of the
3261 routers in the configuration makes any tests on the sender address of a
3263 .index \-f-\ option||for address testing
3264 you can use the \-f-\ option to set an appropriate sender when running
3265 \-bt-\ tests. Without it, the sender is assumed to be the calling user at the
3266 default qualifying domain. However, if you have set up (for example) routers
3267 whose behaviour depends on the contents of an incoming message, you cannot test
3268 those conditions using \-bt-\. The \-N-\ option provides a possible way of
3272 .index version number of Exim, verifying
3273 This option causes Exim to write the current version number, compilation
3274 number, and compilation date of the \*exim*\ binary to the standard output.
3275 It also lists the DBM library this is being used, the optional modules (such as
3276 specific lookup types), the drivers that are included in the binary, and the
3277 name of the run time configuration file that is in use.
3280 As part of its operation, \-bV-\ causes Exim to read and syntax check its
3281 configuration file. However, this is a static check only. It cannot check
3282 values that are to be expanded. For example, although a misspelt ACL verb is
3283 detected, an error in the verb's arguments is not. You cannot rely on \-bV-\
3284 alone to discover (for example) all the typos in the configuration; some
3285 realistic testing is needed. The \-bh-\ and \-N-\ options provide more dynamic
3291 .index verifying||address, using \-bv-\
3292 .index address||verification
3293 This option runs Exim in address verification mode, in which each argument is
3294 taken as an address to be verified. During normal operation, verification
3295 happens mostly as a consequence processing a \verify\ condition in an ACL (see
3296 chapter ~~CHAPACL). If you want to test an entire ACL, see the \-bh-\ option.
3298 If verification fails, and the caller is not an admin user, no details of the
3299 failure are output, because these might contain sensitive information such as
3300 usernames and passwords for database lookups.
3302 If no arguments are given, Exim runs in an interactive manner, prompting with a
3303 right angle bracket for addresses to be verified.
3305 Unlike the \-be-\ test option, you cannot arrange for Exim to use the
3306 \*readline()*\ function, because it is running as \*exim*\ and there are
3310 Verification differs from address testing (the \-bt-\ option) in that routers
3311 that have \no@_verify\ set are skipped, and if the address is accepted by a
3312 router that has \fail@_verify\ set, verification fails. The address is verified
3313 as a recipient if \-bv-\ is used; to test verification for a sender address,
3314 \-bvs-\ should be used.
3316 If the \-v-\ option is not set, the output consists of a single line for each
3317 address, stating whether it was verified or not, and giving a reason in the
3318 latter case. Otherwise, more details are given of how the address has been
3319 handled, and in the case of address redirection, all the generated addresses
3320 are also considered. Without \-v-\, generating more than one address by
3321 redirection causes verification to end sucessfully.
3323 .index return code||for \-bv-\
3324 The return code is 2 if any address failed outright; it is 1 if no address
3325 failed outright but at least one could not be resolved for some reason. Return
3326 code 0 is given only when all addresses succeed.
3328 If any of the routers in the configuration makes any tests on the sender
3329 address of a message, you should use the \-f-\ option to set an appropriate
3330 sender when running \-bv-\ tests. Without it, the sender is assumed to be the
3331 calling user at the default qualifying domain.
3334 This option acts like \-bv-\, but verifies the address as a sender rather
3335 than a recipient address. This affects any rewriting and qualification that
3338 .option C #<<filelist>>
3339 .index configuration file||alternate
3340 .index \\CONFIGURE@_FILE\\
3341 .index alternate configuration file
3342 This option causes Exim to find the run time configuration file from the given
3343 list instead of from the list specified by the \\CONFIGURE@_FILE\\
3344 compile-time setting. Usually, the list will consist of just a single file
3345 name, but it can be a colon-separated list of names. In this case, the first
3346 file that exists is used. Failure to open an existing file stops Exim from
3347 proceeding any further along the list, and an error is generated.
3349 When this option is used by a caller other than root or the Exim user, and the
3350 list is different from the compiled-in list, Exim gives up its root privilege
3351 immediately, and runs with the real and effective uid and gid set to those of
3352 the caller. However, if \\ALT@_CONFIG@_ROOT@_ONLY\\ is defined in
3353 \(Local/Makefile)\, root privilege is retained for \-C-\ only if the caller of
3356 That is, the Exim user is no longer privileged in this regard. This build-time
3357 option is not set by default in the Exim source distribution tarbundle.
3358 However, if you are using a `packaged' version of Exim (source or binary), the
3359 packagers might have enabled it.
3362 Setting \\ALT@_CONFIG@_ROOT@_ONLY\\ locks out the possibility of testing a
3363 configuration using \-C-\ right through message reception and delivery, even if
3364 the caller is root. The reception works, but by that time, Exim is running as
3365 the Exim user, so when it re-execs to regain privilege for the delivery, the
3366 use of \-C-\ causes privilege to be lost. However, root can test reception and
3367 delivery using two separate commands (one to put a message on the queue, using
3368 \-odq-\, and another to do the delivery, using \-M-\).
3370 If \\ALT@_CONFIG@_PREFIX\\ is defined \(in Local/Makefile)\, it specifies a
3371 prefix string with which any file named in a \-C-\ command line option
3372 must start. In addition, the file name must not contain the sequence \"/../"\.
3373 However, if the value of the \-C-\ option is identical to the value of
3374 \\CONFIGURE@_FILE\\ in \(Local/Makefile)\, Exim ignores \-C-\ and proceeds as
3375 usual. There is no default setting for \\ALT@_CONFIG@_PREFIX\\; when it is
3376 unset, any file name can be used with \-C-\.
3378 \\ALT@_CONFIG@_PREFIX\\ can be used to confine alternative configuration files
3379 to a directory to which only root has access. This prevents someone who has
3380 broken into the Exim account from running a privileged Exim with an arbitrary
3383 The \-C-\ facility is useful for ensuring that configuration files are
3384 syntactically correct, but cannot be used for test deliveries, unless the
3385 caller is privileged, or unless it is an exotic configuration that does not
3386 require privilege. No check is made on the owner or group of the files
3387 specified by this option.
3389 .option D <<macro>>=<<value>>
3390 .index macro||setting on command line
3391 This option can be used to override macro definitions in the configuration file
3392 (see section ~~SECTmacrodefs). However, like \-C-\, if it is used by an
3393 unprivileged caller, it causes Exim to give up its root privilege.
3394 If \\DISABLE@_D@_OPTION\\ is defined in \(Local/Makefile)\, the use of \-D-\ is
3395 completely disabled, and its use causes an immediate error exit.
3397 The entire option (including equals sign if present) must all be within one
3398 command line item. \-D-\ can be used to set the value of a macro to the empty
3399 string, in which case the equals sign is optional. These two commands are
3405 To include spaces in a macro definition item, quotes must be used. If you use
3406 quotes, spaces are permitted around the macro name and the equals sign. For
3409 exim '-D ABC = something' ...
3411 \-D-\ may be repeated up to 10 times on a command line.
3413 .option d <<debug options>>
3414 .index debugging||list of selectors
3415 .index debugging||\-d-\ option
3416 This option causes debugging information to be written to the standard
3417 error stream. It is restricted to admin users because debugging output may show
3418 database queries that contain password information. Also, the details of users'
3419 filter files should be protected. When \-d-\ is used, \-v-\ is assumed. If
3420 \-d-\ is given on its own, a lot of standard debugging data is output. This can
3421 be reduced, or increased to include some more rarely needed information, by
3422 following \-d-\ with a string made up of names preceded by plus or minus
3423 characters. These add or remove sets of debugging data, respectively. For
3424 example, \-d+filter-\ adds filter debugging, whereas \-d-all+filter-\ selects
3425 only filter debugging. The available debugging categories are:
3429 . The odd formatting of the lines below is deliberate. It does not affect the
3430 . SGCAL output, but by putting in the space it keeps things aligned in the man
3431 . page that is automatically generated from this text.
3433 acl $t $rm{ACL interpretation}
3434 auth $t $rm{authenticators}
3435 deliver $t $rm{general delivery logic}
3436 dns $t $rm{DNS lookups (see also resolver)}
3437 dnsbl $t $rm{DNS black list (aka RBL) code}
3438 exec $t $rm{arguments for \execv@(@)\ calls}
3439 expand $t $rm{detailed debugging for string expansions}
3440 filter $t $rm{filter handling}
3441 hints@_lookup $t $rm{hints data lookups}
3442 host@_lookup $t $rm{all types of name-to-IP address handling}
3443 ident $t $rm{ident lookup}
3444 interface $t $rm{lists of local interfaces}
3445 lists $t $rm{matching things in lists}
3446 load $t $rm{system load checks}
3447 local@_scan $t $rm{can be used by \*local@_scan()*\ (see chapter ~~CHAPlocalscan)}
3448 lookup $t $rm{general lookup code and all lookups}
3449 memory $t $rm{memory handling}
3450 pid $t $rm{add pid to debug output lines}
3451 process@_info $t $rm{setting info for the process log}
3452 queue@_run $t $rm{queue runs}
3453 receive $t $rm{general message reception logic}
3454 resolver $t $rm{turn on the DNS resolver's debugging output}
3455 retry $t $rm{retry handling}
3456 rewrite $t $rm{address rewriting}
3457 route $t $rm{address routing}
3458 timestamp $t $rm{add timestamp to debug output lines}
3459 tls $t $rm{TLS logic}
3460 transport $t $rm{transports}
3461 uid $t $rm{changes of uid/gid and looking up uid/gid}
3462 verify $t $rm{address verification logic}
3464 all $t $rm{all of the above, and also \-v-\}
3466 .index resolver, debugging output
3467 .index DNS||resolver, debugging output
3468 The \"resolver"\ option produces output only if the DNS resolver was compiled
3469 with \\DEBUG\\ enabled. This is not the case in some operating systems. Also,
3470 unfortunately, debugging output from the DNS resolver is written to stdout
3473 The default (\-d-\ with no argument) omits \"expand"\, \"filter"\,
3474 \"interface"\, \"load"\, \"memory"\, \"pid"\, \"resolver"\, and \"timestamp"\.
3475 However, the \"pid"\ selector is forced when debugging is turned on for a
3476 daemon, which then passes it on to any re-executed Exims. Exim also
3477 automatically adds the pid to debug lines when several remote deliveries are
3480 The \"timestamp"\ selector causes the current time to be inserted at the start
3481 of all debug output lines. This can be useful when trying to track down delays
3484 If the \debug@_print\ option is set in any driver, it produces output whenever
3485 any debugging is selected, or if \-v-\ is used.
3488 .option dd <<debug options>>
3489 This option behaves exactly like \-d-\ except when used on a command that
3490 starts a daemon process. In that case, debugging is turned off for the
3491 subprocesses that the daemon creates. Thus, it is useful for monitoring the
3492 behaviour of the daemon without creating as much output as full debugging does.
3496 This is an obsolete option that is now a no-op. It used to affect the way Exim
3497 handled CR and LF characters in incoming messages. What happens now is
3498 described in section ~~SECTlineendings.
3502 .index bounce message||generating
3503 This option specifies that an incoming message is a locally-generated delivery
3504 failure report. It is used internally by Exim when handling delivery failures
3505 and is not intended for external use. Its only effect is to stop Exim
3506 generating certain messages to the postmaster, as otherwise message cascades
3507 could occur in some situations. As part of the same option, a message id may
3508 follow the characters \-E-\. If it does, the log entry for the receipt of the
3509 new message contains the id, following `R=', as a cross-reference.
3512 There are a number of Sendmail options starting with \-oe-\ which seem to be
3513 called by various programs without the leading \o\ in the option. For example,
3514 the \vacation\ program uses \-eq-\. Exim treats all options of the form
3515 \-e$it{x}-\ as synonymous with the corresponding \-oe$it{x}-\ options.
3517 .option F #<<string>>
3519 .index name||of sender
3520 This option sets the sender's full name for use when a locally-generated
3521 message is being accepted. In the absence of this option, the user's \*gecos*\
3522 entry from the password data is used. As users are generally permitted to alter
3523 their \*gecos*\ entries, no security considerations are involved. White space
3524 between \-F-\ and the <<string>> is optional.
3526 .option f #<<address>>
3527 .index sender||address
3528 .index address||sender
3530 .index envelope sender
3531 .index user||trusted
3532 This option sets the address of the envelope sender of a locally-generated
3533 message (also known as the return path). The option can normally be used only
3534 by a trusted user, but \untrusted@_set@_sender\ can be set to allow untrusted
3537 Processes running as root or the Exim user are always trusted. Other
3538 trusted users are defined by the \trusted@_users\ or \trusted@_groups\ options.
3540 In the absence of \-f-\, or if the caller is not trusted, the sender of a local
3541 message is set to the caller's login name at the default qualify domain.
3543 There is one exception to the restriction on the use of \-f-\: an empty sender
3544 can be specified by any user, trusted or not,
3546 to create a message that can never provoke a bounce. An empty sender can be
3547 specified either as an empty string, or as a pair of angle brackets with
3548 nothing between them, as in these examples of shell commands:
3550 exim -f '<>' user@domain
3551 exim -f "" user@domain
3553 In addition, the use of \-f-\ is not restricted when testing a filter file with
3554 \-bf-\ or when testing or verifying addresses using the \-bt-\ or \-bv-\
3557 Allowing untrusted users to change the sender address does not of itself make
3558 it possible to send anonymous mail. Exim still checks that the ::From:: header
3559 refers to the local user, and if it does not, it adds a ::Sender:: header,
3560 though this can be overridden by setting \no@_local@_from@_check\.
3563 White space between \-f-\ and the <<address>> is optional
3564 (that is, they can be given as two arguments or one combined argument).
3565 The sender of a locally-generated message can also be set (when permitted) by
3566 an initial `From ' line in the message -- see the description of \-bm-\ above
3567 -- but if \-f-\ is also present, it overrides `From'.
3570 .index Sendmail compatibility||\-G-\ option ignored
3571 This is a Sendmail option which is ignored by Exim.
3573 .option h #<<number>>
3574 .index Sendmail compatibility||\-h-\ option ignored
3575 This option is accepted for compatibility with Sendmail, but has no effect. (In
3576 Sendmail it overrides the `hop count' obtained by counting ::Received::
3580 .index Solaris||\*mail*\ command
3581 .index dot||in incoming, non-SMTP message
3582 This option, which has the same effect as \-oi-\, specifies that a dot on a
3583 line by itself should not terminate an incoming, non-SMTP message. I can find
3584 no documentation for this option in Solaris 2.4 Sendmail, but the \*mailx*\
3585 command in Solaris 2.4 uses it. See also \-ti-\.
3587 .option M #<<message id>>#<<message id>> ...
3588 .index forcing delivery
3589 .index delivery||forcing attempt
3590 .index frozen messages||forcing delivery
3591 This option requests Exim to run a delivery attempt on each message in turn. If
3592 any of the messages are frozen, they are automatically thawed before the
3593 delivery attempt. The settings of \queue@_domains\, \queue@_smtp@_domains\, and
3594 \hold@_domains\ are ignored.
3595 .index hints database||overriding retry hints
3596 Retry hints for any of the addresses are
3597 overridden -- Exim tries to deliver even if the normal retry time has not yet
3598 been reached. This option requires the caller to be an admin user. However,
3599 there is an option called \prod@_requires@_admin\ which can be set false to
3600 relax this restriction (and also the same requirement for the \-q-\, \-R-\, and
3604 .option Mar #<<message id>>#<<address>>#<<address>> ...
3605 .index message||adding recipients
3606 .index recipient||adding
3607 This option requests Exim to add the addresses to the list of recipients of the
3608 message (`ar' for `add recipients'). The first argument must be a message id,
3609 and the remaining ones must be email addresses. However, if the message is
3610 active (in the middle of a delivery attempt), it is not altered. This option
3611 can be used only by an admin user.
3613 .index SMTP||passed connection
3614 .index SMTP||multiple deliveries
3615 .index multiple SMTP deliveries
3616 .option MC #<<transport>>#<<hostname>>#<<sequence number>>#<<message id>>
3617 This option is not intended for use by external callers. It is used internally
3618 by Exim to invoke another instance of itself to deliver a waiting message using
3619 an existing SMTP connection, which is passed as the standard input. Details are
3620 given in chapter ~~CHAPSMTP. This must be the final option, and the caller must
3621 be root or the Exim user in order to use it.
3624 This option is not intended for use by external callers. It is used internally
3625 by Exim in conjunction with the \-MC-\ option. It signifies that the connection
3626 to the remote host has been authenticated.
3629 This option is not intended for use by external callers. It is used internally
3630 by Exim in conjunction with the \-MC-\ option. It signifies that the server to
3631 which Exim is connected supports pipelining.
3633 .option MCQ #<<process id>> <<pipe fd>>
3634 This option is not intended for use by external callers. It is used internally
3635 by Exim in conjunction with the \-MC-\ option when the original delivery was
3636 started by a queue runner. It passes on the process id of the queue runner,
3637 together with the file descriptor number of an open pipe. Closure of the pipe
3638 signals the final completion of the sequence of processes that are passing
3639 messages through the same SMTP connection.
3642 This option is not intended for use by external callers. It is used internally
3643 by Exim in conjunction with the \-MC-\ option, and passes on the fact that the
3644 SMTP \\SIZE\\ option should be used on messages delivered down the existing
3648 This option is not intended for use by external callers. It is used internally
3649 by Exim in conjunction with the \-MC-\ option, and passes on the fact that the
3650 host to which Exim is connected supports TLS encryption.
3652 .option Mc #<<message id>>#<<message id>> ...
3653 .index hints database||not overridden by \-Mc-\
3654 .index delivery||manually started, not forced
3655 This option requests Exim to run a delivery attempt on each message in turn,
3656 but unlike the \-M-\ option, it does check for retry hints, and respects any
3657 that are found. This option is not very useful to external callers. It is
3658 provided mainly for internal use by Exim when it needs to re-invoke itself in
3659 order to regain root privilege for a delivery (see chapter ~~CHAPsecurity).
3660 However, \-Mc-\ can be useful when testing, in order to run a delivery that
3661 respects retry times and other options such as \hold@_domains\ that are
3662 overridden when \-M-\ is used. Such a delivery does not count as a queue run.
3663 If you want to run a specific delivery as if in a queue run, you should use
3664 \-q-\ with a message id argument. A distinction between queue run deliveries
3665 and other deliveries is made in one or two places.
3667 .option Mes #<<message id>>#<<address>>
3668 .index message||changing sender
3669 .index sender||changing
3670 This option requests Exim to change the sender address in the message to the
3671 given address, which must be a fully qualified address or `<>' (`es' for `edit
3672 sender'). There must be exactly two arguments. The first argument must be a
3673 message id, and the second one an email address. However, if the message is
3674 active (in the middle of a delivery attempt), its status is not altered. This
3675 option can be used only by an admin user.
3677 .option Mf #<<message id>>#<<message id>> ...
3678 .index freezing messages
3679 .index message||manually freezing
3680 This option requests Exim to mark each listed message as `frozen'. This
3681 prevents any delivery attempts taking place until the message is `thawed',
3682 either manually or as a result of the \auto@_thaw\ configuration option.
3683 However, if any of the messages are active (in the middle of a delivery
3684 attempt), their status is not altered. This option can be used only by an admin
3687 .option Mg #<<message id>>#<<message id>> ...
3688 .index giving up on messages
3689 .index message||abandoning delivery attempts
3690 .index delivery||abandoning further attempts
3691 This option requests Exim to give up trying to deliver the listed messages,
3692 including any that are frozen. However, if any of the messages are active,
3693 their status is not altered.
3694 For non-bounce messages, a delivery error message is sent to the sender,
3695 containing the text `cancelled by administrator'. Bounce messages are just
3697 This option can be used only by an admin user.
3699 .option Mmad #<<message id>>#<<message id>> ...
3700 .index delivery||cancelling all
3701 This option requests Exim to mark all the recipient addresses in the messages
3702 as already delivered (`mad' for `mark all delivered'). However, if any message
3703 is active (in the middle of a delivery attempt), its status is not altered.
3704 This option can be used only by an admin user.
3706 .option Mmd #<<message id>>#<<address>>#<<address>> ...
3707 .index delivery||cancelling by address
3708 .index recipient||removing
3709 .index removing recipients
3710 This option requests Exim to mark the given addresses as already delivered
3711 (`md' for `mark delivered'). The first argument must be a message id, and the
3712 remaining ones must be email addresses. These are matched to recipient
3713 addresses in the message in a case-sensitive manner. If the message is active
3714 (in the middle of a delivery attempt), its status is not altered. This option
3715 can be used only by an admin user.
3717 .option Mrm #<<message id>>#<<message id>> ...
3718 .index removing messages
3719 .index abandoning mail
3720 .index message||manually discarding
3721 This option requests Exim to remove the given messages from the queue. No
3722 bounce messages are sent; each message is simply forgotten. However, if any of
3723 the messages are active, their status is not altered. This option can be used
3724 only by an admin user or by the user who originally caused the message to be
3725 placed on the queue.
3727 .option Mt #<<message id>>#<<message id>> ...
3728 .index thawing messages
3729 .index unfreezing messages
3730 .index frozen messages||thawing
3731 .index message||thawing frozen
3732 This option requests Exim to `thaw' any of the listed messages that are
3733 `frozen', so that delivery attempts can resume. However, if any of the messages
3734 are active, their status is not altered. This option can be used only by an
3737 .option Mvb #<<message id>>
3738 .index listing||message body
3739 .index message||listing body of
3740 This option causes the contents of the message body (-D) spool file to be
3741 written to the standard output. This option can be used only by an admin user.
3743 .option Mvh #<<message id>>
3744 .index listing||message headers
3745 .index header lines||listing
3746 .index message||listing header lines
3747 This option causes the contents of the message headers (-H) spool file to be
3748 written to the standard output. This option can be used only by an admin user.
3750 .option Mvl #<<message id>>
3751 .index listing||message log
3752 .index message||listing message log
3753 This option causes the contents of the message log spool file to be written to
3754 the standard output. This option can be used only by an admin user.
3757 This is apparently a synonym for \-om-\ that is accepted by Sendmail, so Exim
3758 treats it that way too.
3761 .index debugging||\-N-\ option
3762 .index debugging||suppressing delivery
3763 This is a debugging option that inhibits delivery of a message at the transport
3764 level. It implies \-v-\. Exim goes through many of the motions of delivery --
3765 it just doesn't actually transport the message, but instead behaves as if it
3766 had successfully done so. However, it does not make any updates to the retry
3767 database, and the log entries for deliveries are flagged with `$*$>' rather
3770 Because \-N-\ discards any message to which it applies, only root or the Exim
3771 user are allowed to use it with \-bd-\, \-q-\, \-R-\ or \-M-\. In other words,
3772 an ordinary user can use it only when supplying an incoming message to which it
3773 will apply. Although transportation never fails when \-N-\ is set, an address
3774 may be deferred because of a configuration problem on a transport, or a routing
3775 problem. Once \-N-\ has been used for a delivery attempt, it sticks to the
3776 message, and applies to any subsequent delivery attempts that may happen for
3780 .index Sendmail compatibility||\-n-\ option ignored
3781 This option is interpreted by Sendmail to mean `no aliasing'. It is ignored by
3785 This option is interpreted by Sendmail to mean `set option`. It is ignored by
3788 .option oA #<<file name>>
3789 .index Sendmail compatibility||\-oA-\ option
3790 This option is used by Sendmail in conjunction with \-bi-\ to specify an
3791 alternative alias file name. Exim handles \-bi-\ differently; see the
3794 .index SMTP||passed connection
3796 .index SMTP||multiple deliveries
3797 .index multiple SMTP deliveries
3798 This is a debugging option which limits the maximum number of messages that can
3799 be delivered down one SMTP connection, overriding the value set in any \%smtp%\
3800 transport. If <<n>> is omitted, the limit is set to 1.
3803 .index background delivery
3804 .index delivery||in the background
3805 This option applies to all modes in which Exim accepts incoming messages,
3806 including the listening daemon. It requests `background' delivery of such
3807 messages, which means that the accepting process automatically starts a
3808 delivery process for each message received, but does not wait for the delivery
3809 processes to finish.
3811 When all the messages have been received, the reception process exits, leaving
3812 the delivery processes to finish in their own time. The standard output and
3813 error streams are closed at the start of each delivery process.
3815 This is the default action if none of the \-od-\ options are present.
3817 If one of the queueing options in the configuration file
3818 (\queue@_only\ or \queue@_only@_file\, for example) is in effect, \-odb-\
3819 overrides it if \queue@_only@_override\ is set true, which is the default
3820 setting. If \queue@_only@_override\ is set false, \-odb-\ has no effect.
3823 .index foreground delivery
3824 .index delivery||in the foreground
3825 This option requests `foreground' (synchronous) delivery when Exim has accepted
3826 a locally-generated message. (For the daemon it is exactly the same as
3827 \-odb-\.) A delivery process is automatically started to deliver the
3828 message, and Exim waits for it to complete before proceeding.
3830 The original Exim reception process does not finish until the delivery
3831 process for the final message has ended. The standard error stream is left open
3834 However, like \-odb-\, this option has no effect if \queue@_only@_override\ is
3835 false and one of the queueing options in the configuration file is in effect.
3838 If there is a temporary delivery error during foreground delivery, the message
3839 is left on the queue for later delivery, and the original reception process
3840 exists. See chapter ~~CHAPnonqueueing for a way of setting up a restricted
3841 configuration that never queues messages.
3845 This option is synonymous with \-odf-\. It is provided for compatibility with
3849 .index non-immediate delivery
3850 .index delivery||suppressing immediate
3851 .index queueing incoming messages
3852 This option applies to all modes in which Exim accepts incoming messages,
3853 including the listening daemon. It specifies that the accepting process should
3854 not automatically start a delivery process for each message received. Messages
3855 are placed on the queue, and remain there until a subsequent queue runner
3856 process encounters them.
3857 There are several configuration options (such as \queue@_only\) that can be
3858 used to queue incoming messages under certain conditions. This option overrides
3859 all of them and also \-odqs-\. It always forces queueing.
3862 .index SMTP||delaying delivery
3863 This option is a hybrid between \-odb-\/\-odi-\ and \-odq-\.
3864 However, like \-odb-\ and \-odi-\, this option has no effect if
3865 \queue@_only@_override\ is false and one of the queueing options in the
3866 configuration file is in effect.
3868 When \-odqs-\ does operate, a delivery process is started for each incoming
3869 message, in the background by default, but in the foreground if \-odi-\ is also
3871 The recipient addresses are routed, and local deliveries are done in the normal
3872 way. However, if any SMTP deliveries are required, they are not done at this
3873 time, so the message remains on the queue until a subsequent queue runner
3874 process encounters it. Because routing was done, Exim knows which messages are
3875 waiting for which hosts, and so a number of messages for the same host can be
3876 sent in a single SMTP connection. The \queue@_smtp@_domains\ configuration
3877 option has the same effect for specific domains. See also the \-qq-\ option.
3880 .index error||reporting
3881 If an error is detected while a non-SMTP message is being received (for
3882 example, a malformed address), the error is reported to the sender in a mail
3884 .index return code||for \-oee-\
3885 Provided this error message is successfully sent, the Exim receiving process
3886 exits with a return code of zero. If not, the return code is 2 if the problem
3887 is that the original message has no recipients, or 1 any other error. This is
3888 the default \-oe$it{x}-\ option if Exim is called as \*rmail*\.
3891 .index error||reporting
3892 .index return code||for \-oem-\
3893 This is the same as \-oee-\, except that Exim always exits with a non-zero
3894 return code, whether or not the error message was successfully sent.
3895 This is the default \-oe$it{x}-\ option, unless Exim is called as \*rmail*\.
3898 .index error||reporting
3899 If an error is detected while a non-SMTP message is being received, the
3900 error is reported by writing a message to the standard error file (stderr).
3901 .index return code||for \-oep-\
3902 The return code is 1 for all errors.
3905 .index error||reporting
3906 This option is supported for compatibility with Sendmail, but has the same
3910 .index error||reporting
3911 This option is supported for compatibility with Sendmail, but has the same
3915 .index dot||in incoming, non-SMTP message
3916 This option, which has the same effect as \-i-\, specifies that a dot on a line
3917 by itself should not terminate an incoming, non-SMTP message.
3918 Otherwise, a single dot does terminate, though Exim does no special processing
3919 for other lines that start with a dot.
3920 This option is set by default if Exim is called as \*rmail*\. See also \-ti-\.
3923 This option is treated as synonymous with \-oi-\.
3925 .option oMa #<<host address>>
3926 .index sender||host address, specifying for local message
3927 A number of options starting with \-oM-\ can be used to set values associated
3928 with remote hosts on locally-submitted messages (that is, messages not received
3929 over TCP/IP). These options can be used by any caller in conjunction with the
3932 \-bf-\, \-bF-\, \-bt-\, or \-bv-\ testing options. In other circumstances, they
3933 are ignored unless the caller is trusted.
3935 The \-oMa-\ option sets the sender host address. This may include a port number
3936 at the end, after a full stop (period). For example:
3938 exim -bs -oMa 10.9.8.7.1234
3940 An alternative syntax is to enclose the IP address in square brackets, followed
3941 by a colon and the port number:
3943 exim -bs -oMa [10.9.8.7]:1234
3945 The IP address is placed in the \$sender@_host@_address$\ variable, and the
3946 port, if present, in \$sender@_host@_port$\.
3948 .option oMaa #<<name>>
3949 .index authentication||name, specifying for local message
3950 See \-oMa-\ above for general remarks about the \-oM-\ options. The \-oMaa-\
3951 option sets the value of \$sender@_host@_authenticated$\ (the authenticator
3952 name). See chapter ~~CHAPSMTPAUTH for a discussion of SMTP authentication.
3954 .option oMai #<<string>>
3955 .index authentication||id, specifying for local message
3956 See \-oMa-\ above for general remarks about the \-oM-\ options. The \-oMai-\
3958 value of \$authenticated@_id$\ (the id that was authenticated).
3959 This overrides the default value (the caller's login id) for messages from
3960 local sources. See chapter ~~CHAPSMTPAUTH for a discussion of authenticated
3963 .option oMas #<<address>>
3964 .index authentication||sender, specifying for local message
3965 See \-oMa-\ above for general remarks about the \-oM-\ options. The \-oMas-\
3966 option sets the authenticated sender value
3967 in \$authenticated@_sender$\.
3968 It overrides the sender address that is created from the caller's login id for
3969 messages from local sources. See chapter ~~CHAPSMTPAUTH for a discussion of
3970 authenticated senders.
3972 .option oMi #<<interface address>>
3973 .index interface||address, specifying for local message
3974 See \-oMa-\ above for general remarks about the \-oM-\ options. The \-oMi-\
3975 option sets the IP interface address value. A port number may be included,
3976 using the same syntax as for \-oMa-\.
3977 The interface address is placed in \$interface@_address$\ and the port number,
3978 if present, in \$interface@_port$\.
3980 .option oMr #<<protocol name>>
3981 .index protocol||incoming, specifying for local message
3982 See \-oMa-\ above for general remarks about the \-oM-\ options. The \-oMr-\
3983 option sets the received protocol value that is stored in
3984 \$received@_protocol$\. However, this applies only when \-bs-\ is not used. For
3985 interactive SMTP input (\-bs-\), the protocol is always
3987 `local-' followed by one of the standard SMTP protocol names (see the
3988 description of \$received@_protocol$\ in section ~~SECTexpvar).
3990 For \-bS-\ (batch SMTP) however, the protocol can be set by \-oMr-\.
3992 .option oMs #<<host name>>
3993 .index sender||host name, specifying for local message
3994 See \-oMa-\ above for general remarks about the \-oM-\ options. The \-oMs-\
3995 option sets the sender host name
3996 in \$sender@_host@_name$\. When this option is present, Exim does not attempt
3997 to look up a host name from an IP address; it uses the name it is given.
3999 .option oMt #<<ident string>>
4000 .index sender||ident string, specifying for local message
4001 See \-oMa-\ above for general remarks about the \-oM-\ options. The \-oMt-\
4002 option sets the sender ident value
4003 in \$sender@_ident$\.
4004 The default setting for local callers is the login id of the calling process.
4007 .index Sendmail compatibility||\-om-\ option ignored
4008 In Sendmail, this option means `me too', indicating that the sender of a
4009 message should receive a copy of the message if the sender appears in an alias
4010 expansion. Exim always does this, so the option does nothing.
4013 .index Sendmail compatibility||\-oo-\ option ignored
4014 This option is ignored. In Sendmail it specifies `old style headers', whatever
4017 .option oP #<<path>>
4018 .index pid (process id)||of daemon
4019 .index daemon||process id (pid)
4020 This option is useful only in conjunction with \-bd-\ or \-q-\ with a time
4021 value. The option specifies the file to which the process id of the daemon is
4022 written. When \-oX-\ is used with \-bd-\, or when \-q-\ with a time is used
4023 without \-bd-\, this is the only way of causing Exim to write a pid file,
4024 because in those cases, the normal pid file is not used.
4026 .option or #<<time>>
4027 .index timeout||for non-SMTP input
4028 This option sets a timeout value for incoming non-SMTP messages. If it is not
4029 set, Exim will wait forever for the standard input. The value can also be set
4030 by the \receive@_timeout\ option. The format used for specifying times is
4031 described in section ~~SECTtimeformat.
4033 .option os #<<time>>
4034 .index timeout||for SMTP input
4035 .index SMTP||timeout, input
4036 This option sets a timeout value for incoming SMTP messages. The timeout
4037 applies to each SMTP command and block of data. The value can also be set by
4038 the \smtp@_receive@_timeout\ option; it defaults to 5 minutes. The format used
4039 for specifying times is described in section ~~SECTtimeformat.
4042 This option has exactly the same effect as \-v-\.
4044 .option oX #<<number or string>>
4045 .index TCP/IP||setting listening ports
4046 .index TCP/IP||setting listening interfaces
4047 .index port||receiving TCP/IP
4048 This option is relevant only when the \-bd-\ (start listening daemon) option is
4049 also given. It controls which ports and interfaces the daemon uses. Details of
4050 the syntax, and how it interacts with configuration file options, are given in
4051 chapter ~~CHAPinterfaces. When \-oX-\ is used to start a daemon, no pid file is
4052 written unless \-oP-\ is also present to specify a pid file name.
4055 .index Perl||starting the interpreter
4056 This option applies when an embedded Perl interpreter is linked with Exim (see
4057 chapter ~~CHAPperl). It overrides the setting of the \perl@_at@_start\ option,
4058 forcing the starting of the interpreter to be delayed until it is needed.
4061 .index Perl||starting the interpreter
4062 This option applies when an embedded Perl interpreter is linked with Exim (see
4063 chapter ~~CHAPperl). It overrides the setting of the \perl@_at@_start\ option,
4064 forcing the starting of the interpreter to occur as soon as Exim is started.
4066 .option p<<rval>>:<<sval>>
4067 For compatibility with Sendmail, this option
4070 -oMr <<rval>> -oMs <<sval>>
4072 It sets the incoming protocol and host name (for trusted callers). The
4073 host name and its colon can be omitted when only the protocol is to be set.
4074 Note the Exim already has two private options, \-pd-\ and \-ps-\, that refer to
4075 embedded Perl. It is therefore impossible to set a protocol value of \"p"\ or
4076 \"s"\ using this option (but that does not seem a real limitation).
4079 .index queue runner||starting manually
4080 This option is normally restricted to admin users. However, there is a
4081 configuration option called \prod@_requires@_admin\ which can be set false to
4082 relax this restriction (and also the same requirement for the \-M-\, \-R-\, and
4085 .index queue runner||description of operation
4086 The \-q-\ option starts one queue runner process. This scans the queue of
4087 waiting messages, and runs a delivery process for each one in turn. It waits
4088 for each delivery process to finish before starting the next one. A delivery
4089 process may not actually do any deliveries if the retry times for the addresses
4090 have not been reached. Use \-qf-\ (see below) if you want to override this.
4091 .index SMTP||passed connection
4092 .index SMTP||multiple deliveries
4093 .index multiple SMTP deliveries
4094 If the delivery process spawns other processes to deliver other messages down
4095 passed SMTP connections, the queue runner waits for these to finish before
4098 When all the queued messages have been considered, the original queue runner
4099 process terminates. In other words, a single pass is made over the waiting
4100 mail, one message at a time. Use \-q-\ with a time (see below) if you want this
4101 to be repeated periodically.
4103 Exim processes the waiting messages in an unpredictable order. It isn't very
4104 random, but it is likely to be different each time, which is all that matters.
4105 If one particular message screws up a remote MTA, other messages to the same
4106 MTA have a chance of getting through if they get tried first.
4108 It is possible to cause the messages to be processed in lexical message id
4109 order, which is essentially the order in which they arrived, by setting the
4110 \queue@_run@_in@_order\ option, but this is not recommended for normal use.
4112 .option q <<qflags>>
4113 The \-q-\ option may be followed by one or more flag letters that change its
4114 behaviour. They are all optional, but if more than one is present, they must
4115 appear in the correct order. Each flag is described in a separate item below.
4118 .index queue||double scanning
4119 .index queue||routing
4120 .index routing||whole queue before delivery
4121 An option starting with \-qq-\ requests a two-stage queue run. In the first
4122 stage, the queue is scanned as if the \queue@_smtp@_domains\ option matched
4123 every domain. Addresses are routed, local deliveries happen, but no remote
4125 .index hints database||remembering routing
4126 The hints database that remembers which messages are
4127 waiting for specific hosts is updated, as if delivery to those hosts had been
4128 deferred. After this is complete, a second, normal queue scan happens, with
4129 routing and delivery taking place as normal. Messages that are routed to the
4130 same host should mostly be delivered down a single SMTP
4131 .index SMTP||passed connection
4132 .index SMTP||multiple deliveries
4133 .index multiple SMTP deliveries
4134 connection because of the hints that were set up during the first queue scan.
4135 This option may be useful for hosts that are connected to the Internet
4139 .index queue||initial delivery
4140 If the \*i*\ flag is present, the queue runner runs delivery processes only for
4141 those messages that haven't previously been tried. (\*i*\ stands for `initial
4142 delivery'.) This can be helpful if you are putting messages on the queue using
4143 \-odq-\ and want a queue runner just to process the new messages.
4146 .index queue||forcing delivery
4147 .index delivery||forcing in queue run
4148 If one \*f*\ flag is present, a delivery attempt is forced for each non-frozen
4149 message, whereas without \f\ only those non-frozen addresses that have passed
4150 their retry times are tried.
4152 .option q[q][i]ff...
4153 .index frozen messages||forcing delivery
4154 If \*ff*\ is present, a delivery attempt is forced for every message, whether
4157 .option q[q][i][f[f]]l
4158 .index queue||local deliveries only
4159 The \*l*\ (the letter `ell') flag specifies that only local deliveries are to be
4160 done. If a message requires any remote deliveries, it remains on the queue for
4163 .option q <<qflags>>#<<start id>>#<<end id>>
4164 .index queue||delivering specific messages
4165 When scanning the queue, Exim can be made to skip over messages whose ids are
4166 lexically less than a given value by following the \-q-\ option with a starting
4167 message id. For example:
4169 exim -q 0t5C6f-0000c8-00
4171 Messages that arrived earlier than \"0t5C6f-0000c8-00"\ are not inspected. If a
4172 second message id is given, messages whose ids are lexically greater than it
4173 are also skipped. If the same id is given twice, for example,
4175 exim -q 0t5C6f-0000c8-00 0t5C6f-0000c8-00
4177 just one delivery process is started, for that message. This differs from \-M-\
4178 in that retry data is respected, and it also differs from \-Mc-\ in that it
4179 counts as a delivery from a queue run. Note that the selection mechanism does
4180 not affect the order in which the messages are scanned. There are also other
4181 ways of selecting specific sets of messages for delivery in a queue run -- see
4184 .option q <<qflags>><<time>>
4185 .index queue runner||starting periodically
4186 .index periodic queue running
4187 When a time value is present, the \-q-\ option causes Exim to run as a daemon,
4188 starting a queue runner process at intervals specified by the given time value
4189 (whose format is described in section ~~SECTtimeformat). This form of the \-q-\
4190 option is commonly combined with the \-bd-\ option, in which case a single
4191 daemon process handles both functions. A common way of starting up a combined
4192 daemon at system boot time is to use a command such as
4194 /usr/exim/bin/exim -bd -q30m
4196 Such a daemon listens for incoming SMTP calls, and also starts a queue runner
4197 process every 30 minutes.
4199 When a daemon is started by \-q-\ with a time value, but without \-bd-\, no pid
4200 file is written unless one is explicitly requested by the \-oP-\ option.
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