Some tidies to the new edition.
[exim.git] / doc / doc-src / spec.src
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8408f763 1. $Cambridge: exim/doc/doc-src/spec.src,v 1.7 2005/02/16 16:09:00 ph10 Exp $
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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}
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189.index dialup $it{see intermittently connected hosts}
4964e932 190.index exiscan $it{see content scanning}
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199.index process id $it{see pid}
200.index RBL $it{see DNS list}
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214
215. ======================================================
216
217.push
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219.justify centre
220.nofoot
221.space 8ld
222$chead{University of Cambridge Computing Service}
223.space 2ld
224$chead{Specification of the Exim Mail Transfer Agent}
225.space 3ld
226by
227.space 1ld
228Philip Hazel
229.space ~~sys.leftonpage - 15*~~sys.linedepth
230.justify left
231University Computing Service
232New Museums Site
233Pembroke Street
234Cambridge CB2 3QH
235United Kingdom
236.blank
237.tabs 6
238$it{phone:} $t +44 1223 334600
239$it{fax:} $t +44 1223 334679
240$it{email:} $t ph10 $it{at} cus.cam.ac.uk
241.blank
242Edition for Exim ~~version, ~~versionmonth ~~versionyear
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282
283
284
285
286.
287.
288.
289.
290. ============================================================================
291.chapter Introduction
292.set runningfoot "introduction"
293
294.if ~~sys.fancy
295$c$bi{If I have seen further it is by standing on the shoulders of giants.}##(Isaac Newton)
296.elif !~~html
297$c"If I have seen further it is by standing on the shoulders of giants."
298.newline
299$e (Isaac Newton)
300.else
301\*If I have seen further it is by standing on the shoulders of giants.*\
302(Isaac Newton).
303.fi
304.blank 4
305
306Exim is a mail transfer agent (MTA) for hosts that are running Unix or
307Unix-like operating systems. It was designed on the assumption that it would be
308run on hosts that are permanently connected to the Internet. However, it can be
309used on intermittently connected hosts with suitable configuration adjustments.
310
311Configuration files currently exist for the following operating systems: AIX,
312BSD/OS (aka BSDI), Darwin (Mac OS X), DGUX, FreeBSD, GNU/Hurd, GNU/Linux,
313HI-OSF (Hitachi), HP-UX, IRIX, MIPS RISCOS, NetBSD, OpenBSD, QNX, SCO, SCO
314SVR4.2 (aka UNIX-SV), Solaris (aka SunOS5), SunOS4, Tru64-Unix (formerly
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315Digital UNIX, formerly DEC-OSF1), Ultrix, and Unixware. Some of these operating
316systems are no longer current and cannot easily be tested, so the configuration
317files may no longer work in practice.
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318
319There are also configuration files for compiling Exim in the Cygwin environment
320that can be installed on systems running Windows. However, this document does
321not contain any information about running Exim in the Cygwin environment.
322
323The terms and conditions for the use and distribution of Exim are contained in
324the file \(NOTICE)\. Exim is distributed under the terms of the GNU General
325Public Licence, a copy of which may be found in the file \(LICENCE)\.
326
327The use, supply or promotion of Exim for the purpose of sending bulk,
328unsolicited electronic mail is incompatible with the basic aims of the program,
329which revolve around the free provision of a service that enhances the quality
330of personal communications. The author of Exim regards indiscriminate
331mass-mailing as an antisocial, irresponsible abuse of the Internet.
332
333Exim owes a great deal to Smail 3 and its author, Ron Karr. Without the
334experience of running and working on the Smail 3 code, I could never have
335contemplated starting to write a new MTA. Many of the ideas and user interfaces
336were originally taken from Smail 3, though the actual code of Exim is entirely
337new, and has developed far beyond the initial concept.
338
339Many people, both in Cambridge and around the world, have contributed to the
340development and the testing of Exim, and to porting it to various operating
341systems. I am grateful to them all. The distribution now contains a file called
342\(ACKNOWLEDGMENTS)\, in which I have started recording the names of
343contributors.
344
d43194df 345
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346.section Exim documentation
347.index documentation
d43194df 348.em
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349This edition of the Exim specification applies to version ~~version of Exim.
350Substantive changes from the ~~previousversion edition are marked by bars in
351the right-hand margin in the PostScript, PDF, and plain text versions of the
352document, and by green text in the HTML version, as shown by this paragraph.
353Changes are not marked in the Texinfo version, because Texinfo doesn't support
354change bars. Minor corrections and rewordings are not marked.
d43194df 355.nem
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356
357This document is very much a reference manual; it is not a tutorial. The reader
358is expected to have some familiarity with the SMTP mail transfer protocol and
359with general Unix system administration. Although there are some discussions
360and examples in places, the information is mostly organized in a way that makes
361it easy to look up, rather than in a natural order for sequential reading.
362Furthermore, the manual aims to cover every aspect of Exim in detail, including
363a number of rarely-used, special-purpose features that are unlikely to be of
364very wide interest.
365
366.index books about Exim
367An `easier' discussion of Exim which provides more in-depth explanatory,
368introductory, and tutorial material can be found in a book entitled
369.if ~~html
370[(A HREF="http://www.uit.co.uk/exim-book/")]
371$it{The Exim SMTP Mail Server},
372[(/A)]
4964e932 373published by UIT Cambridge.
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374.else
375$it{The Exim SMTP Mail Server}, published by UIT Cambridge
376(\?http://www.uit.co.uk/exim-book/?\).
377.fi
378
379This book also contains a chapter that gives a general introduction to SMTP and
380Internet mail. Inevitably, however, the book is unlikely to be fully up-to-date
381with the latest release of Exim. (Note that the earlier book about Exim,
382published by O'Reilly, covers Exim 3, and many things have changed in Exim 4.)
383
384.index \(doc/NewStuff)\
385.index \(doc/ChangeLog)\
386.index change log
387As the program develops, there may be features in newer versions that have not
388yet made it into this document, which is updated only when the most significant
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389digit of the fractional part of the version number changes. Specifications of
390new features that are not yet in this manual are placed in the file
391\(doc/NewStuff)\ in the Exim distribution.
392
393.em
394Some features may be classified as `experimental'. These may change
395incompatibly while they are developing, or even be withdrawn. For this reason,
396they are not documented in this manual. Information about experimental features
397can be found in the file \(doc/experimental.txt)\.
398.nem
399
400All changes to the program (whether new features, bug fixes, or other kinds of
401change) are noted briefly in the file called \(doc/ChangeLog)\.
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402
403.index \(doc/spec.txt)\
404This specification itself is available as an ASCII file in \(doc/spec.txt)\ so
405that it can easily be searched with a text editor. Other files in the \(doc)\
406directory are:
407.display rm
408.tabs 18
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}
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412.newline
413.em
414\(experimental.txt)\ $t $rm{documentation of experimental features}
415.nem
416.newline
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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\(Exim4.upgrade)\ $t $rm{upgrade notes from release 3 to release 4}
422.endd
423The main specification and the specification of the filtering language are also
424available in other formats (HTML, PostScript, PDF, and Texinfo). Section
425~~SECTavail below tells you how to get hold of these.
426
427
d43194df 428.section FTP and web sites
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429.index web site
430.index FTP site
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431.em
432The primary distribution site for Exim is currently the University of
433Cambridge's FTP site, whose contents are described in \*Where to find the Exim
434distribution*\ below. In addition, there is a
435.if ~~html
436[(A HREF="http://www.exim.org/")]
437.fi
438web site
439.if ~~html
440[(/A)]
441.fi
442and an
443.if ~~html
444[(A HREF="ftp://ftp.exim.org/")]
445.fi
446FTP site
447.if ~~html
448[(/A)]
449.fi
450at \exim.org\. These are now also hosted at the University of Cambridge.
451The \exim.org\ site was previously hosted for a number of years by Energis
452Squared, formerly Planet Online Ltd, whose support I gratefully acknowledge.
453
454As well as Exim distribution tar files, the Exim web site contains a number of
455differently formatted versions of the documentation, including the
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456.index FAQ
457.if ~~html
458[(A HREF="FAQ.html")]
459.fi
460FAQ
461.if ~~html
462[(/A)]
463.fi
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464in both text and HTML formats. The HTML version comes with a keyword-in-context
465index. A recent addition to the online information is the
466.index wiki
467.if ~~html
468[(A HREF="http://www.exim.org/eximwiki/")]
469Exim wiki.
470[(/A)]
471.else
472Exim wiki (\?http://www.exim.org/eximwiki/?\).
473.fi
474We hope that this will make it easier for Exim users to contribute examples,
475tips, and know-how for the benefit of others.
476.nem
495ae4b0 477
d43194df 478.section Mailing lists
495ae4b0 479.index mailing lists||for Exim users
d43194df 480The following are the two main Exim mailing lists:
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481.display rm
482.tabs 28
483$it{exim-users@@exim.org} $t general discussion list
484$it{exim-announce@@exim.org} $t moderated, low volume announcements list
485.endd
486You can subscribe to these lists, change your existing subscriptions, and view
487or search the archives via the
488.if ~~html
489[(A HREF="http://www.exim.org/maillist.html")]
490.fi
491mailing lists
492.if ~~html
493[(/A)]
494.fi
495link on the Exim home page. The $it{exim-users} mailing list is also forwarded
496to \?http://www.egroups.com/list/exim-users?\, an archiving system with
497searching capabilities.
498
499.section Exim training
500.index training courses
501From time to time (approximately annually at the time of writing),
502lecture-based training courses are run by the author of Exim in Cambridge, UK.
503Details can be found on the web site
504.if ~~html
505[(A HREF="http://www-tus.csx.cam.ac.uk/courses/exim/")]
506.fi
507\?http://www-tus@.csx@.cam@.ac.uk/courses/exim/?\.
508.if ~~html
509[(/A)]
510.fi
511
512.section Bug reports
513.index bug reports
514.index reporting bugs
515Reports of obvious bugs should be emailed to \*bugs@@exim.org*\. However, if
516you are unsure whether some behaviour is a bug or not, the best thing to do is
517to post a message to the $it{exim-users} mailing list and have it discussed.
518
519
d43194df 520.em
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521.section Where to find the Exim distribution
522.rset SECTavail "~~chapter.~~section"
523.index FTP site
524.index distribution||ftp site
525The master ftp site for the Exim distribution is
526.display rm
527.if ! ~~sys.fancy
528.indent 0
529.fi
530\?ftp://ftp.csx.cam.ac.uk/pub/software/email/exim?\
531.endd
d43194df 532This is mirrored by
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533.display rm
534.if ! ~~sys.fancy
535.indent 0
536.fi
d43194df 537\?ftp://ftp.exim.org/pub/exim?\
495ae4b0 538.endd
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539The file references that follow are relative to the \(exim)\ directories at
540these sites.
541
542There are now quite a number of independent mirror sites around the world.
543Those that I know about are listed in the file called \(Mirrors)\.
544
545Within the \(exim)\ directory there are subdirectories called \(exim3)\ (for
546previous Exim 3 distributions), \(exim4)\ (for the latest Exim 4
547distributions), and \(Testing)\ for testing versions. In the \(exim4)\
548subdirectory, the current release can always be found in files called
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549.display rm
550\(exim-$it{n.nn}.tar.gz)\
551\(exim-$it{n.nn}.tar.bz2)\
552.endd
553where $it{n.nn} is the highest such version number in the directory. The two
554files contain identical data; the only difference is the type of compression.
555The \(.bz2)\ file is usually a lot smaller than the \(.gz)\ file.
556.index distribution||signing details
557.index distribution||public key
558.index public key for signed distribution
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559The distributions are currently signed with Philip Hazel's GPG key. The
560corresponding public key is available from a number of keyservers, and there is
561also a copy in the file \(Public-Key)\. The signatures for the tar bundles are
562in:
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563.display rm
564\(exim-$it{n.nn}.tar.gz.sig)\
565\(exim-$it{n.nn}.tar.bz2.sig)\
566.endd
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567For each released version, the log of changes is made separately available in a
568separate file in the directory \(ChangeLogs)\ so that it is possible to
569find out what has changed without having to download the entire distribution.
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570
571.index documentation||available formats
572The main distribution contains ASCII versions of this specification and other
573documentation; other formats of the documents are available in separate files
574inside the \(exim4)\ directory of the FTP site:
575.display rm
576\(exim-html-$it{n.nn}.tar.gz)\
577\(exim-pdf-$it{n.nn}.tar.gz)\
578\(exim-postscript-$it{n.nn}.tar.gz)\
579\(exim-texinfo-$it{n.nn}.tar.gz)\
580.endd
581These tar files contain only the \(doc)\ directory, not the complete
582distribution, and are also available in \(.bz2)\ as well as \(.gz)\ forms.
583
584.index FAQ
d43194df 585The FAQ is available for downloading in two different formats in these files:
495ae4b0 586.display rm
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587\(exim4/FAQ.txt.gz)\
588\(exim4/FAQ.html.tar.gz)\
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589.endd
590The first of these is a single ASCII file that can be searched with a text
591editor. The second is a directory of HTML files, normally accessed by starting
592at \(index.html)\. The HTML version of the FAQ (which is also included in the
593HTML documentation tarbundle) includes a keyword-in-context index, which is
594often the most convenient way of finding your way around.
595
596.section Wish list
597.index wish list
598A wish list is maintained, containing ideas for new features that have been
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599submitted. From time to time the file is exported to the ftp site into the file
600\(exim4/WishList)\. Items are removed from the list if they get implemented.
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601
602
603.section Contributed material
604.index contributed material
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605At the ftp site, there is a directory called \(Contrib)\ that contains
606miscellaneous files contributed to the Exim community by Exim users. There is
607also a collection of contributed configuration examples in
608\(exim4/config.samples.tar.gz)\. These samples are referenced from the FAQ.
609.nem
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610
611.section Limitations
612.index limitations of Exim
613.numberpars $.
614Exim is designed for use as an Internet MTA, and therefore handles addresses
615in RFC 2822 domain format only.
616.index bang paths||not handled by Exim
617It cannot handle UUCP `bang paths', though simple two-component bang paths can
618be converted by a straightforward rewriting configuration. This restriction
619does not prevent Exim from being interfaced to UUCP as a transport mechanism,
620provided that domain addresses are used.
621.nextp
622.index domainless addresses
623.index address||without domain
624Exim insists that every address it handles has a domain attached. For incoming
625local messages, domainless addresses are automatically qualified with a
626configured domain value. Configuration options specify from which remote
627systems unqualified addresses are acceptable. These are then qualified on
628arrival.
629.nextp
630.index transport||external
631.index external transports
632The only external transport currently implemented is an SMTP transport over a
633TCP/IP network (using sockets, including support for IPv6). However, a pipe
634transport is available, and there are facilities for writing messages to files
635and pipes, optionally in \*batched SMTP*\ format; these facilities can be used
636to send messages to some other transport mechanism such as UUCP, provided it
637can handle domain-style addresses. Batched SMTP input is also catered for.
638.nextp
639Exim is not designed for storing mail for dial-in hosts. When the volumes of
640such mail are large, it is better to get the messages `delivered' into files
641(that is, off Exim's queue) and subsequently passed on to the dial-in hosts by
642other means.
643.nextp
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644.em
645Although Exim does have basic facilities for scanning incoming messages, these
4964e932 646are not comprehensive enough to do full virus or spam scanning. Such operations
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647are best carried out using additional specialized software packages. If you
648compile Exim with the content-scanning extension, straightforward interfaces to
649a number of common scanners are provided.
650.nem
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651.endp
652
653
654
655.section Run time configuration
656Exim's run time configuration is held in a single text file that is divided
657into a number of sections. The entries in this file consist of keywords and
658values, in the style of Smail 3 configuration files. A default configuration
659file which is suitable for simple online installations is provided in the
660distribution, and is described in chapter ~~CHAPdefconfil below.
661
662
663.section Calling interface
664.index Sendmail compatibility||command line interface
665Like many MTAs, Exim has adopted the Sendmail command line interface so that it
666can be a straight replacement for \(/usr/lib/sendmail)\ or
667\(/usr/sbin/sendmail)\ when sending mail, but you do not need to know anything
668about Sendmail in order to run Exim. For actions other than sending messages,
669Sendmail-compatible options also exist, but those that produce output (for
670example, \-bp-\, which lists the messages on the queue) do so in Exim's own
671format. There are also some additional options that are compatible with Smail
6723, and some further options that are new to Exim. Chapter ~~CHAPcommandline
673documents all Exim's command line options. This information is automatically
674made into the man page that forms part of the Exim distribution.
675
676Control of messages on the queue can be done via certain privileged command
677line options. There is also an optional monitor program called \*eximon*\, which
678displays current information in an X window, and which contains a menu
679interface to Exim's command line administration options.
680
681
682.section Terminology
683.index terminology definitions
684.index body of message||definition of
685The \*body*\ of a message is the actual data that the sender wants to transmit.
686It is the last part of a message, and is separated from the \*header*\ (see
687below) by a blank line.
688
689.index bounce message||definition of
690When a message cannot be delivered, it is normally returned to the sender in a
d43194df
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691delivery failure message or a `non-delivery report' (NDR). The term \*bounce*\
692is commonly used for this action, and the error reports are often called
693\*bounce messages*\. This is a convenient shorthand for `delivery failure error
694report'. Such messages have an empty sender address in the message's
695\*envelope*\ (see below) to ensure that they cannot themselves give rise to
696further bounce messages.
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697
698The term \*default*\ appears frequently in this manual. It is used to qualify a
699value which is used in the absence of any setting in the configuration. It may
700also qualify an action which is taken unless a configuration setting specifies
701otherwise.
702
703The term \*defer*\ is used when the delivery of a message to a specific
704destination cannot immediately take place for some reason (a remote host may be
705down, or a user's local mailbox may be full). Such deliveries are \*deferred*\
706until a later time.
707
708The word \*domain*\ is sometimes used to mean all but the first component of a
709host's name. It is $it{not} used in that sense here, where it normally
710refers to the part of an email address following the @@ sign.
711
712.index envelope, definition of
713.index sender||definition of
714A message in transit has an associated \*envelope*\, as well as a header and a
715body. The envelope contains a sender address (to which bounce messages should
716be delivered), and any number of recipient addresses. References to the
717sender or the recipients of a message usually mean the addresses in the
718envelope. An MTA uses these addresses for delivery, and for returning bounce
719messages, not the addresses that appear in the header lines.
720
721.index message||header, definition of
722.index header section||definition of
723The \*header*\ of a message is the first part of a message's text, consisting
724of a number of lines, each of which has a name such as ::From::, ::To::,
725::Subject::, etc. Long header lines can be split over several text lines by
726indenting the continuations. The header is separated from the body by a blank
727line.
728
729.index local part||definition of
730.index domain||definition of
731The term \*local part*\, which is taken from RFC 2822, is used to refer to that
732part of an email address that precedes the @@ sign. The part that follows the
733@@ sign is called the \*domain*\ or \*mail domain*\.
734
735.index local delivery||definition of
736.index remote delivery, definition of
737The terms \*local delivery*\ and \*remote delivery*\ are used to distinguish
738delivery to a file or a pipe on the local host from delivery by SMTP over
739TCP/IP to a remote host.
740
741.index return path||definition of
742\*Return path*\ is another name that is used for the sender address in a
743message's envelope.
744
745.index queue||definition of
746The term \*queue*\ is used to refer to the set of messages awaiting delivery,
747because this term is in widespread use in the context of MTAs. However, in
748Exim's case the reality is more like a pool than a queue, because there is
749normally no ordering of waiting messages.
750
751.index queue runner||definition of
752The term \*queue runner*\ is used to describe a process that scans the queue
753and attempts to deliver those messages whose retry times have come. This term
754is used by other MTAs, and also relates to the command \runq\, but in Exim
755the waiting messages are normally processed in an unpredictable order.
756
757.index spool directory||definition of
758The term \*spool directory*\ is used for a directory in which Exim keeps the
759messages on its queue -- that is, those that it is in the process of
760delivering. This should not be confused with the directory in which local
761mailboxes are stored, which is called a `spool directory' by some people. In
762the Exim documentation, `spool' is always used in the first sense.
763
764
765
766.
767.
768.
769.
770. ============================================================================
771.chapter Incorporated code
772.set runningfoot "incorporated code"
773.index incorporated code
774.index regular expressions||library
775.index PCRE
776A number of pieces of external code are included in the Exim distribution.
777.numberpars $.
778Regular expressions are supported in the main Exim program and in the Exim
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779monitor using the freely-distributable PCRE library, copyright (c) University
780of Cambridge. The source is distributed in the directory \(src/pcre)\. However,
781this is a cut-down version of PCRE. If you want to use the PCRE library in
782other programs, you should obtain and install the full version from
783\?ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre?\.
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784
785.space 1ld
786.nextp
787.index cdb||acknowledgement
788Support for the cdb (Constant DataBase) lookup method is provided by code
d43194df
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789contributed by Nigel Metheringham of (at the time he contributed it) Planet
790Online Ltd. which contains the following statements:
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791.rule
792.push
793.if ~~sgcal
794.fontgroup 9
795.font 0
796.fi
797Copyright (c) 1998 Nigel Metheringham, Planet Online Ltd
798
799This program is free software; you can redistribute it and/or modify it under
800the terms of the GNU General Public License as published by the Free Software
801Foundation; either version 2 of the License, or (at your option) any later
802version.
803
804This code implements Dan Bernstein's Constant DataBase (cdb) spec. Information,
805the spec and sample code for cdb can be obtained from
806\?http://www.pobox.com/@~djb/cdb.html?\. This implementation borrows some code
807from Dan Bernstein's implementation (which has no license restrictions applied
808to it).
809.newline
810.pop
811.rule
812The implementation is completely contained within the code of Exim.
813It does not link against an external cdb library.
814.space 1ld
815.nextp
816.index SPA authentication
817.index Samba project
818.index Microsoft Secure Password Authentication
819Client support for Microsoft's \*Secure Password Authentication*\ is provided
4964e932 820by code contributed by Marc Prud'hommeaux. Server support was contributed by
495ae4b0
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821Tom Kistner. This includes code taken from the Samba project, which is released
822under the Gnu GPL.
823
824.space 1ld
825.nextp
826.index Cyrus
827.index \*pwcheck*\ daemon
828.index \*pwauthd*\ daemon
829Support for calling the Cyrus \*pwcheck*\ and \*saslauthd*\ daemons is provided
830by code taken from the Cyrus-SASL library and adapted by Alexander S.
831Sabourenkov. The permission notice appears below, in accordance with the
832conditions expressed therein.
833
834.rule
835.push
836.if ~~sgcal
837.fontgroup 9
838.font 0
839.fi
840Copyright (c) 2001 Carnegie Mellon University. All rights reserved.
841
842Redistribution and use in source and binary forms, with or without
843modification, are permitted provided that the following conditions
844are met:
845
846.if ~~sgcal
847.cancelflag $npbracket
848.flag $npbracket "" "."
849.fi
850.numberpars
851Redistributions of source code must retain the above copyright
852notice, this list of conditions and the following disclaimer.
853.nextp
854Redistributions in binary form must reproduce the above copyright
855notice, this list of conditions and the following disclaimer in
856the documentation and/or other materials provided with the
857distribution.
858.nextp
859The name `Carnegie Mellon University' must not be used to
860endorse or promote products derived from this software without
861prior written permission. For permission or any other legal
862details, please contact
863.display rm
864Office of Technology Transfer
865Carnegie Mellon University
8665000 Forbes Avenue
867Pittsburgh, PA 15213-3890
868(412) 268-4387, fax: (412) 268-7395
869tech-transfer@@andrew.cmu.edu
870.endd
871.nextp
872Redistributions of any form whatsoever must retain the following
873acknowledgment:
874.newline
875.push
876.indent ~~sys.indent + 3em
877.justify left
878$it{This product includes software developed by Computing Services
879at Carnegie Mellon University (\?http://www.cmu.edu/computing/?\).}
880.newline
881.pop
4964e932 882.endp
495ae4b0
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883.if ~~sgcal
884.cancelflag $npbracket
885.flag $npbracket "(" ")"
886.fi
887
888CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO
889THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
890AND FITNESS, IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE
891FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
892WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
893AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
894OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
895.newline
896.pop
897.rule
898
899.space 1ld
900.nextp
901.index monitor
902.index X-windows
903.index Athena
904The Exim Monitor program, which is an X-Window application, includes
905modified versions of the Athena StripChart and TextPop widgets.
906This code is copyright by DEC and MIT, and their permission notice appears
907below, in accordance with the conditions expressed therein.
908
909.rule
910.push
911.if ~~sgcal
912.fontgroup 9
913.font 0
914.fi
915Copyright 1987, 1988 by Digital Equipment Corporation, Maynard, Massachusetts,
916and the Massachusetts Institute of Technology, Cambridge, Massachusetts.
917.blank
918$c All Rights Reserved
919.blank
920Permission to use, copy, modify, and distribute this software and its
921documentation for any purpose and without fee is hereby granted,
922provided that the above copyright notice appear in all copies and that
923both that copyright notice and this permission notice appear in
924supporting documentation, and that the names of Digital or MIT not be
925used in advertising or publicity pertaining to distribution of the
926software without specific, written prior permission.
927
928DIGITAL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
929ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
930DIGITAL BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
931ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
932WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
933ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
934SOFTWARE.
935.newline
936.pop
937.rule
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938.space 1ld
939.nextp
940.em
941Many people have contributed code fragments, some large, some small, that were
942not covered by any specific licence requirements. It is assumed that the
943contributors are happy to see their code incoporated into Exim under the GPL.
944.nem
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945.endp
946
947
948
949.
950.
951.
952.
953. ============================================================================
954.chapter How Exim receives and delivers mail
955.set runningfoot "receiving & delivering mail"
956
957.section Overall philosophy
958.index design philosophy
959Exim is designed to work efficiently on systems that are permanently connected
960to the Internet and are handling a general mix of mail. In such circumstances,
961most messages can be delivered immediately. Consequently, Exim does not
962maintain independent queues of messages for specific domains or hosts, though
963it does try to send several messages in a single SMTP connection after a host
964has been down, and it also maintains per-host retry information.
965
966
967.section Policy control
968.index policy control||overview
969Policy controls are now an important feature of MTAs that are connected to the
970Internet. Perhaps their most important job is to stop MTAs being abused as
971`open relays' by misguided individuals who send out vast amounts of unsolicited
972junk, and want to disguise its source. Exim provides flexible facilities for
973specifying policy controls on incoming mail:
974.numberpars $.
975.index ~~ACL||introduction
976Exim 4 (unlike previous versions of Exim) implements policy controls on
d43194df 977incoming mail by means of \*Access Control Lists*\ (ACLs). Each list is a
495ae4b0 978series of statements that may either grant or deny access. ACLs can be used at
d43194df
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979several places in the SMTP dialogue while receiving a message from a remote
980host. However, the most common places are after each \\RCPT\\ command, and at
981the very end of the message. The sysadmin can specify conditions for accepting
982or rejecting individual recipients or the entire message, respectively, at
983these two points (see chapter ~~CHAPACL). Denial of access results in an SMTP
984error code.
495ae4b0 985.nextp
4964e932 986An ACL is also available for locally generated, non-SMTP messages. In this
495ae4b0
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987case, the only available actions are to accept or deny the entire message.
988.nextp
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989.em
990When Exim is compiled with the content-scanning extension, facilities are
991provided in the ACL mechanism for passing the message to external virus and/or
992spam scanning software. The result of such a scan is passed back to the ACL,
993which can then use it to decide what to do with the message.
994.nem
995.nextp
495ae4b0
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996When a message has been received, either from a remote host or from the local
997host, but before the final acknowledgement has been sent, a locally supplied C
998function called \*local@_scan()*\ can be run to inspect the message and decide
999whether to accept it or not (see chapter ~~CHAPlocalscan). If the message is
1000accepted, the list of recipients can be modified by the function.
1001.nextp
d43194df
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1002.em
1003Using the \*local@_scan()*\ mechanism is another way of calling external
1004scanner software. The \SA-Exim\ add-on package works this way. It does not
1005require Exim to be compiled with the content-scanning extension.
1006.nem
1007.nextp
495ae4b0
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1008After a message has been accepted, a further checking mechanism is available in
1009the form of the $it{system filter} (see chapter ~~CHAPsystemfilter). This runs
1010at the start of every delivery process.
1011.endp
1012
1013.section User filters
1014.index filter||introduction
1015.index Sieve filter
4964e932
PH
1016In a conventional Exim configuration, users are able to run private filters by
1017setting up appropriate \(.forward)\ files in their home directories. See
1018chapter ~~CHAPredirect (about the \%redirect%\ router) for the configuration
1019needed to support this, and the separate document entitled
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1020.if ~~html
1021[(A HREF="filter_toc.html")]
1022.fi
1023\*Exim's interfaces to mail filtering*\
1024.if ~~html
1025[(/A)]
1026.fi
1027for user details. Two different kinds of filtering are available:
1028.numberpars $.
4964e932 1029Sieve filters are written in the standard filtering language that is defined by
495ae4b0
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1030RFC 3028.
1031.nextp
4964e932 1032Exim filters are written in a syntax that is unique to Exim, but which is more
495ae4b0
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1033powerful than Sieve, which it pre-dates.
1034.endp
1035User filters are run as part of the routing process, described below.
1036
1037
1038.section Message identification
1039.rset SECTmessiden "~~chapter.~~section"
1040.index message||ids, details of format
1041.index format||of message id
1042.index id of message
1043.index base62
1044.index base36
1045.index Darwin
1046.index Cygwin
1047Every message handled by Exim is given a \*message id*\ which is sixteen
1048characters long. It is divided into three parts, separated by hyphens, for
1049example \"16VDhn-0001bo-D3"\. Each part is a sequence of letters and digits,
1050normally encoding numbers in base 62. However, in the Darwin operating
4964e932
PH
1051system (Mac OS X) and when Exim is compiled to run under Cygwin, base 36
1052(avoiding the use of lower case letters) is used instead, because the message
495ae4b0
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1053id is used to construct file names, and the names of files in those systems are
1054not case-sensitive.
1055
1056.index pid (process id)||re-use of
1057The detail of the contents of the message id have changed as Exim has evolved.
1058Earlier versions relied on the operating system not re-using a process id (pid)
1059within one second. On modern operating systems, this assumption can no longer
4964e932
PH
1060be made, so the algorithm had to be changed. To retain backward compatibility,
1061the format of the message id was retained, which is why the following rules are
495ae4b0
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1062somewhat eccentric:
1063.numberpars $.
1064The first six characters of the message id are the time at which the message
1065started to be received, to a granularity of one second. That is, this field
1066contains the number of seconds since the start of the epoch (the normal Unix
1067way of representing the date and time of day).
1068.nextp
1069After the first hyphen, the next six characters are the id of the process that
1070received the message.
1071.nextp
1072There are two different possibilities for the final two characters:
1073.numberpars alpha
1074.index \localhost@_number\
1075If \localhost@_number\ is not set, this value is the fractional part of the
1076time of reception, normally in units of 1/2000 of a second, but for systems
1077that must use base 36 instead of base 62 (because of case-insensitive file
1078systems), the units are 1/1000 of a second.
1079.nextp
1080If \localhost@_number\ is set, it is multiplied by 200 (100) and added to
1081the fractional part of the time, which in this case is in units of 1/200
1082(1/100) of a second.
1083.endp
1084.endp
1085After a message has been received, Exim waits for the clock to tick at the
1086appropriate resolution before proceeding, so that if another message is
1087received by the same process, or by another process with the same (re-used)
1088pid, it is guaranteed that the time will be different. In most cases, the clock
1089will already have ticked while the message was being received.
1090
1091.section Receiving mail
1092.index receiving mail
1093.index message||reception
1094The only way Exim can receive mail from a remote host is using SMTP over
1095TCP/IP, in which case the sender and recipient addresses are tranferred using
1096SMTP commands. However, from a locally running process (such as a user's MUA),
1097there are several possibilities:
1098.numberpars $.
1099If the process runs Exim with the \-bm-\ option, the message is read
1100non-interactively (usually via a pipe), with the recipients taken from the
1101command line, or from the body of the message if \-t-\ is also used.
1102.nextp
1103If the process runs Exim with the \-bS-\ option, the message is also read
1104non-interactively, but in this case the recipients are listed at the start of
1105the message in a series of SMTP \\RCPT\\ commands, terminated by a \\DATA\\
1106command. This is so-called `batch SMTP' format,
1107but it isn't really SMTP. The SMTP commands are just another way of passing
1108envelope addresses in a non-interactive submission.
1109.nextp
1110If the process runs Exim with the \-bs-\ option, the message is read
1111interactively, using the SMTP protocol. A two-way pipe is normally used for
1112passing data between the local process and the Exim process.
1113This is `real' SMTP and is handled in the same way as SMTP over TCP/IP. For
1114example, the ACLs for SMTP commands are used for this form of submission.
1115.nextp
1116A local process may also make a TCP/IP call to the host's loopback address
1117(127.0.0.1) or any other of its IP addresses. When receiving messages, Exim
1118does not treat the loopback address specially. It treats all such connections
1119in the same way as connections from other hosts.
1120.endp
1121
1122.index message||sender, constructed by Exim
1123.index sender||constructed by Exim
1124In the three cases that do not involve TCP/IP, the sender address is
1125constructed from the login name of the user that called Exim and a default
1126qualification domain (which can be set by the \qualify@_domain\ configuration
1127option). For local or batch SMTP, a sender address that is passed using the
1128SMTP \\MAIL\\ command is ignored. However, the system administrator may allow
1129certain users (`trusted users') to specify a different sender address
1130unconditionally, or all users to specify certain forms of different sender
1131address. The \-f-\ option or the SMTP \\MAIL\\ command is used to specify these
1132different addresses. See section ~~SECTtrustedadmin for details of trusted
1133users, and the \untrusted@_set@_sender\ option for a way of allowing untrusted
1134users to change sender addresses.
1135
4964e932
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1136Messages received by either of the non-interactive mechanisms are subject to
1137checking by the non-SMTP ACL, if one is defined. Messages received using SMTP
1138(either over TCP/IP, or interacting with a local process) can be checked by a
1139number of ACLs that operate at different times during the SMTP session. Either
1140individual recipients, or the entire message, can be rejected if local policy
495ae4b0
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1141requirements are not met. The \*local@_scan()*\ function (see chapter
1142~~CHAPlocalscan) is run for all incoming messages.
1143
1144Exim can be configured not to start a delivery process when a message is
1145received; this can be unconditional, or depend on the number of incoming SMTP
1146connections or the system load. In these situations, new messages wait on the
1147queue until a queue runner process picks them up. However, in standard
1148configurations under normal conditions, delivery is started as soon as a
1149message is received.
1150
1151
1152
1153
1154.section Handling an incoming message
1155.index spool directory||files that hold a message
1156.index file||how a message is held
1157When Exim accepts a message, it writes two files in its spool directory. The
1158first contains the envelope information, the current status of the message,
1159and the header lines, and the second contains the body of the message. The
1160names of the two spool files consist of the message id, followed by $tt{-H} for
1161the file containing the envelope and header, and $tt{-D} for the data file.
1162
1163.index spool directory||\(input)\ sub-directory
1164By default all these message files are held in a single directory called
1165\(input)\ inside the general Exim spool directory. Some operating systems do
1166not perform very well if the number of files in a directory gets very large; to
1167improve performance in such cases, the \split@_spool@_directory\ option can be
1168used. This causes Exim to split up the input files into 62 sub-directories
1169whose names are single letters or digits.
1170
1171The envelope information consists of the address of the message's sender and
1172the addresses of the recipients. This information is entirely separate from
1173any addresses contained in the header lines. The status of the message includes
1174a list of recipients who have already received the message. The format of the
1175first spool file is described in chapter ~~CHAPspool.
1176
1177.index rewriting||addresses
1178Address rewriting that is specified in the rewrite section of the configuration
1179(see chapter ~~CHAPrewrite) is done once and for all on incoming addresses,
1180both in the header lines and the envelope, at the time the message is accepted.
1181If during the course of delivery additional addresses are generated (for
1182example, via aliasing), these new addresses are rewritten as soon as they are
1183generated. At the time a message is actually delivered (transported) further
1184rewriting can take place; because this is a transport option, it can be
1185different for different forms of delivery. It is also possible to specify the
1186addition or removal of certain header lines at the time the message is
1187delivered (see chapters ~~CHAProutergeneric and ~~CHAPtransportgeneric).
1188
1189
1190.section Life of a message
1191.index message||life of
1192.index message||frozen
1193A message remains in the spool directory until it is completely delivered to
1194its recipients or to an error address, or until it is deleted by an
1195administrator or by the user who originally created it. In cases when delivery
1196cannot proceed -- for example, when a message can neither be delivered to its
1197recipients nor returned to its sender, the message is marked `frozen' on the
1198spool, and no more deliveries are attempted.
1199
1200.index frozen messages||thawing
1201.index message||thawing frozen
1202An administrator can `thaw' such messages when the problem has been corrected,
1203and can also freeze individual messages by hand if necessary. In addition, an
1204administrator can force a delivery error, causing a bounce message to be sent.
1205
1206.index \auto@_thaw\
1207There is an option called \auto@_thaw\, which can be used to cause Exim to
1208retry frozen messages after a certain time. When this is set, no message will
1209remain on the queue for ever, because the delivery timeout will eventually be
1210reached. Delivery failure reports (bounce messages) that reach this timeout are
1211discarded.
1212.index \timeout@_frozen@_after\
1213There is also an option called \timeout@_frozen@_after\, which discards frozen
1214messages after a certain time.
1215
1216.index message||log file for
1217.index log||file for each message
1218While Exim is working on a message, it writes information about each delivery
1219attempt to the main log file. This includes successful, unsuccessful, and
1220delayed deliveries for each recipient (see chapter ~~CHAPlog). The log lines
1221are also written to a separate $it{message log} file for each message. These
1222logs are solely for the benefit of the administrator, and are normally deleted
1223along with the spool files when processing of a message is complete.
4964e932 1224The use of individual message logs can be disabled by setting
495ae4b0
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1225\no@_message@_logs\; this might give an improvement in performance on very
1226busy systems.
1227
1228.index journal file
1229.index file||journal
1230All the information Exim itself needs to set up a delivery is kept in the first
1231spool file, along with the header lines. When a successful delivery occurs, the
1232address is immediately written at the end of a journal file, whose name is the
1233message id followed by $tt{-J}. At the end of a delivery run, if there are some
1234addresses left to be tried again later, the first spool file (the $tt{-H} file)
1235is updated to indicate which these are, and the journal file is then deleted.
1236Updating the spool file is done by writing a new file and renaming it, to
1237minimize the possibility of data loss.
1238
1239Should the system or the program crash after a successful delivery but before
1240the spool file has been updated, the journal is left lying around. The next
1241time Exim attempts to deliver the message, it reads the journal file and
1242updates the spool file before proceeding. This minimizes the chances of double
1243deliveries caused by crashes.
1244
1245
1246.section Processing an address for delivery
1247.rset SECTprocaddress "~~chapter.~~section"
1248.index drivers||definition of
1249.index router||definition of
1250.index transport||definition of
1251The main delivery processing elements of Exim are called $it{routers} and
1252$it{transports}, and collectively these are known as $it{drivers}. Code for a
1253number of them is provided in the source distribution, and compile-time options
1254specify which ones are included in the binary. Run time options specify which
1255ones are actually used for delivering messages.
1256
1257.index drivers||instance definition
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1258Each driver that is specified in the run time configuration is an \*instance*\
1259of that particular driver type. Multiple instances are allowed; for example,
1260you can set up several different \%smtp%\ transports, each with different
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1261option values that might specify different ports or different timeouts. Each
1262instance has its own identifying name. In what follows we will normally use the
4964e932 1263instance name when discussing one particular instance (that is, one specific
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1264configuration of the driver), and the generic driver name when discussing
1265the driver's features in general.
1266
1267A $it{router} is a driver that operates on an address, either determining how
1268its delivery should happen, by routing it to a specific transport, or
1269converting the address into one or more new addresses (for example, via an
1270alias file). A router may also explicitly choose to fail an address, causing it
1271to be bounced.
1272
1273A $it{transport} is a driver that transmits a copy of the message from Exim's
1274spool to some destination. There are two kinds of transport: for a $it{local}
1275transport, the destination is a file or a pipe on the local host, whereas for a
1276$it{remote} transport the destination is some other host. A message is passed
1277to a specific transport as a result of successful routing. If a message has
1278several recipients, it may be passed to a number of different transports.
1279
1280.index preconditions||definition of
1281An address is processed by passing it to each configured router instance in
1282turn, subject to certain preconditions, until a router accepts the address or
1283specifies that it should be bounced. We will describe this process in more
1284detail shortly. As a simple example, the diagram below illustrates how each
1285recipient address in a message is processed in a small configuration of three
1286routers that are configured in various ways.
1287
1288.if ~~sys.fancy
1289.figure "Routing an address" rm
1290.indent 0
4964e932 1291.call aspic -sgcal -nv
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1292centre ~~sys.linelength;
1293magnify 0.8;
1294boundingbox 30;
1295 ibox depth 14 "address";
1296B: arrow down 44;
1297 textdepth 14;
1298A: box width 100 "first router" "conditions ok?";
1299 arrow right "yes";
1300C: box width 100 "run" "first router";
1301 arrow down "fail";
1302D: ibox depth 20 "address bounces";
1303
1304 arc clockwise from right of C "accept";
1305 arrow down 10;
1306 ibox "queue for" "transport";
1307
1308 arrow down from A align bottom of D plus (0,-20) "no"(-6,20)/r;
1309E: box width 100 "second router" "conditions ok?";
1310 arrow right "yes";
1311F: box width 100 "run" "second router";
1312 line right 100 "redirect";
1313 line up align middle of B;
1314 arrow left to middle of B "new addresses";
1315
1316 line down 20 from bottom left of F plus (30,0);
1317 arrow left align centre of E "decline";
1318
1319 line down 20 from bottom right of F plus (-30,0);
1320 arrow right "fail";
1321 ibox width 64 "address" "bounces";
1322
1323 arrow down 64 from E "no"(-6,20)/r;
1324G: box width 100 "third router" "conditions ok?";
1325 arrow right "yes";
1326H: box width 100 "run" "third router";
1327 arc clockwise from right of H "accept";
1328 arrow down 10;
1329 ibox "queue for" "transport";
1330
1331 line down 20 from bottom of H;
1332 arrow left align centre of G "decline";
1333 arrow down 64 from G "no"(-6,20)/r;
1334
1335 ibox "no more routers" "address bounces";
1336.endcall
1337.endfigure
1338.elif !~~html
1339.display asis
1340
1341 address
1342 |
1343 |<------------- new addresses -----------------------------
1344 V |
1345 ----------------- ----------------- |
1346 | first router |----- yes ----->| run |--- accept |
1347 | conditions ok?| | first router | | |
1348 ----------------- ----------------- | |
1349 | | V |
1350 no | fail | queue for |
1351 | V transport |
1352 | address bounces |
1353 | |
1354 V |
1355 ----------------- ----------------- |
1356 | second router |----- yes ----->| run |----redirect ----
1357 | conditions ok?| | second router |
1358 ----------------- -----------------
1359 | | |
1360 no | | |
1361 |<-------- decline ----------- --- fail ---> address
1362 | bounces
1363 V
1364 ----------------- -----------------
1365 | third router |----- yes ----->| run |--- accept
1366 | conditions ok?| | third router | |
1367 ----------------- ----------------- |
1368 | | V
1369 no | | queue for
1370 |<-------- decline --------------- transport
1371 |
1372 V
1373 no more routers
1374 address bounces
1375.endd
1376.else
1377[(img src="routing.gif" alt="Routing an address")][(br)]
1378.fi
1379To make this a more concrete example, we'll describe it in terms of some actual
1380routers, but remember, this is only an example. You can configure Exim's
1381routers in many different ways, and there may be any number of routers in a
1382configuration.
1383
1384The first router that is specified in a configuration is often one that handles
1385addresses in domains that are not recognized specially by the local host. These
1386are typically addresses for arbitrary domains on the Internet. A precondition
1387is set up which looks for the special domains known to the host (for example,
1388its own domain name), and the router is run for addresses that do $it{not}
1389match. Typically, this is a router that looks up domains in the DNS in order to
1390find the hosts to which this address routes. If it succeeds, the address is
1391queued for a suitable SMTP transport; if it does not succeed, the router is
1392configured to fail the address.
1393
1394The example pictured could be a configuration of this type. The second and
1395third routers can only be run for addresses for which the preconditions for
1396the first router are not met. If one of these preconditions checks the
1397domain, the second and third routers are run only for domains that are somehow
1398special to the local host.
1399
1400The second router does redirection -- also known as aliasing and forwarding.
1401When it generates one or more new addresses from the original, each of them is
1402routed independently from the start. Otherwise, the router may cause an address
4964e932 1403to fail, or it may simply decline to handle the address, in which case the
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1404address is passed to the next router.
1405
1406The final router in many configurations is one that checks to see if the
1407address belongs to a local mailbox. The precondition may involve a check to
1408see if the local part is the name of a login account, or it may look up the
1409local part in a file or a database. If its preconditions are not met, or if
1410the router declines, we have reached the end of the routers. When this happens,
1411the address is bounced.
1412
1413
1414.section Processing an address for verification
1415.index router||for verification
1416.index verifying||address, overview
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1417As well as being used to decide how to deliver to an address, Exim's routers
1418are also used for \*address verification*\. Verification can be requested as
1419one of the checks to be performed in an ACL for incoming messages, on both
1420sender and recipient addresses, and it can be tested using the \-bv-\ and
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1421\-bvs-\ command line options.
1422
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1423When an address is being verified, the routers are run in `verify mode'. This
1424does not affect the way the routers work, but it is a state that can be
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1425detected. By this means, a router can be skipped or made to behave differently
1426when verifying. A common example is a configuration in which the first router
1427sends all messages to a message-scanning program, unless they have been
1428previously scanned. Thus, the first router accepts all addresses without any
4964e932 1429checking, making it useless for verifying. Normally, the \no@_verify\ option
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1430would be set for such a router, causing it to be skipped in verify mode.
1431
1432
1433
1434.section Running an individual router
1435.rset SECTrunindrou "~~chapter.~~section"
1436.index router||running details
1437.index preconditions||checking
1438.index router||result of running
1439As explained in the example above, a number of preconditions are checked before
1440running a router. If any are not met, the router is skipped, and the address is
1441passed to the next router. When all the preconditions on a router $it{are} met,
1442the router is run. What happens next depends on the outcome, which is one of
1443the following:
1444.numberpars $.
1445\*accept*\: The router accepts the address, and either queues it for a
1446transport, or generates one or more `child' addresses. Processing the original
4964e932 1447address ceases,
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1448.index \unseen\ option
1449unless the \unseen\ option is set on the router. This option
1450can be used to set up multiple deliveries with different routing (for example,
1451for keeping archive copies of messages). When \unseen\ is set, the address is
1452passed to the next router. Normally, however, an \*accept*\ return marks the
1453end of routing.
1454
1455.index case of local parts
1456.index address||duplicate, discarding
1457If child addresses are generated, Exim checks to see whether they are
1458duplicates of any existing recipient addresses. During this check, local parts
1459are treated as case-sensitive. Duplicate addresses are discarded. Each of the
1460remaining child addresses is then processed independently, starting with the
1461first router by default. It is possible to change this by setting the
1462\redirect@_router\ option to specify which router to start at for child
1463addresses. Unlike \pass@_router\ (see below) the router specified by
1464\redirect@_router\ may be anywhere in the router configuration.
1465.nextp
1466\*pass*\: The router recognizes the address, but cannot handle it itself. It
1467requests that the address be passed to another router. By default the address
1468is passed to the next router, but this can be changed by setting the
1469\pass@_router\ option. However, (unlike \redirect@_router\) the named router
1470must be below the current router (to avoid loops).
1471.nextp
1472\*decline*\: The router declines to accept the address because it does not
1473recognize it at all. By default, the address is passed to the next router, but
1474this can be prevented by setting the \no@_more\ option. When \no@_more\ is set,
1475all the remaining routers are skipped.
1476.nextp
1477\*fail*\: The router determines that the address should fail, and queues it for
1478the generation of a bounce message. There is no further processing of the
1479original address unless \unseen\ is set on the router.
1480.nextp
1481\*defer*\: The router cannot handle the address at the present time. (A database
1482may be offline, or a DNS lookup may have timed out.) No further processing of
1483the address happens in this delivery attempt. It is tried again next time the
1484message is considered for delivery.
1485.nextp
1486\*error*\: There is some error in the router (for example, a syntax error in
1487its configuration). The action is as for defer.
1488.endp
1489If an address reaches the end of the routers without having been accepted by
1490any of them, it is bounced as unrouteable.
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1491The default error message in this situation is `unrouteable address', but you
1492can set your own message by making use of the \cannot@_route@_message\ option.
1493This can be set for any router; the value from the last router that `saw'
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1494the address is used.
1495
1496Sometimes while routing you want to fail a delivery when some conditions are
1497met but others are not, instead of passing the address on for further routing.
1498You can do this by having a second router that explicitly fails the delivery
4964e932 1499when the relevant conditions are met. The \%redirect%\ router has a `fail'
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1500facility for this purpose.
1501
1502
1503
1504.section Router preconditions
1505.rset SECTrouprecon "~~chapter.~~section"
1506.index router||preconditions, order of processing
1507.index preconditions||order of processing
1508The preconditions that are tested for each router are listed below, in the
1509order in which they are tested. The individual configuration options are
1510described in more detail in chapter ~~CHAProutergeneric.
1511.numberpars $.
1512The \local@_part@_prefix\ and \local@_part@_suffix\ options can specify that
1513the local parts handled by the router may or must have certain prefixes and/or
1514suffixes. If a mandatory affix (prefix or suffix) is not present, the router is
1515skipped. These conditions are tested first. When an affix is present, it is
1516removed from the local part before further processing, including the evaluation
1517of any other conditions.
1518.nextp
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1519Routers can be designated for use only when not verifying an address, that is,
1520only when routing it for delivery (or testing its delivery routing). If the
1521\verify\ option is set false, the router is skipped when Exim is verifying an
495ae4b0 1522address.
4964e932
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1523Setting the \verify\ option actually sets two options, \verify@_sender\ and
1524\verify@_recipient\, which independently control the use of the router for
1525sender and recipient verification. You can set these options directly if
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1526you want a router to be used for only one type of verification.
1527.nextp
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1528If the \address@_test\ option is set false, the router is skipped when Exim is
1529run with the \-bt-\ option to test an address routing. This can be helpful when
1530the first router sends all new messages to a scanner of some sort; it makes it
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1531possible to use \-bt-\ to test subsequent delivery routing without having to
1532simulate the effect of the scanner.
1533.nextp
1534Routers can be designated for use only when verifying an address, as
1535opposed to routing it for delivery. The \verify@_only\ option controls this.
1536.nextp
1537Certain routers can be explicitly skipped when running the routers to check an
1538address given in the SMTP \\EXPN\\ command (see the \expn\ option).
1539.nextp
1540If the \domains\ option is set, the domain of the address must be in the set of
1541domains that it defines.
1542.nextp
1543If the \local@_parts\ option is set, the local part of the address must be in
1544the set of local parts that it defines. If \local@_part@_prefix\ or
1545\local@_part@_suffix\ is in use, the prefix or suffix is removed from the local
1546part before this check. If you want to do precondition tests on local parts
1547that include affixes, you can do so by using a \condition\ option (see below)
1548that uses the variables \$local@_part$\, \$local@_part@_prefix$\, and
1549\$local@_part@_suffix$\ as necessary.
1550.nextp
1551If the \check@_local@_user\ option is set, the local part must be the name of
1552an account on the local host.
4964e932 1553If this check succeeds, the uid and gid of the local user are placed in
495ae4b0
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1554\$local@_user@_uid$\ and \$local@_user@_gid$\; these values can be used in the
1555remaining preconditions.
1556.nextp
1557If the \router@_home@_directory\ option is set, it is expanded at this point,
4964e932
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1558because it overrides the value of \$home$\. If this expansion were left till
1559later, the value of \$home$\ as set by \check@_local@_user\ would be used in
1560subsequent tests. Having two different values of \$home$\ in the same router
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1561could lead to confusion.
1562.nextp
1563If the \senders\ option is set, the envelope sender address must be in the set
1564of addresses that it defines.
1565.nextp
1566If the \require@_files\ option is set, the existence or non-existence of
1567specified files is tested.
1568.nextp
1569.index customizing||precondition
1570If the \condition\ option is set, it is evaluated and tested. This option uses
1571an expanded string to allow you to set up your own custom preconditions.
1572Expanded strings are described in chapter ~~CHAPexpand.
1573.endp
1574
1575Note that \require@_files\ comes near the end of the list, so you cannot use it
1576to check for the existence of a file in which to lookup up a domain, local
1577part, or sender. However, as these options are all expanded, you can use the
1578\exists\ expansion condition to make such tests within each condition. The
1579\require@_files\ option is intended for checking files that the router may be
1580going to use internally, or which are needed by a specific transport (for
1581example, \(.procmailrc)\).
1582
1583
1584.section Delivery in detail
1585.index delivery||in detail
1586When a message is to be delivered, the sequence of events is as follows:
1587.numberpars $.
1588If a system-wide filter file is specified, the message is passed to it. The
1589filter may add recipients to the message, replace the recipients, discard the
1590message, cause a new message to be generated, or cause the message delivery to
1591fail. The format of the system filter file is the same as for Exim user filter
1592files, described in the separate document entitled
1593.if ~~html
1594[(A HREF="filter.html")]
1595.fi
1596\*Exim's interfaces to mail filtering*\.
1597.if ~~html
1598[(/A)]
1599.fi
1600.index Sieve filter||not available for system filter
1601(\**Note**\: Sieve cannot be used for system filter files.)
1602Some additional features are available in system filters -- see chapter
1603~~CHAPsystemfilter for details. Note that a message is passed to the system
1604filter only once per delivery attempt, however many recipients it has. However,
1605if there are several delivery attempts because one or more addresses could not
1606be immediately delivered, the system filter is run each time. The filter
1607condition \first@_delivery\ can be used to detect the first run of the system
1608filter.
1609.nextp
1610Each recipient address is offered to each configured router in turn, subject to
1611its preconditions, until one is able to handle it. If no router can handle
1612the address, that is, if they all decline, the address is failed. Because
1613routers can be targeted at particular domains, several locally handled domains
1614can be processed entirely independently of each other.
1615.nextp
1616.index routing||loops in
1617.index loop||while routing
1618A router that accepts an address may set up a local or a remote transport for
1619it. However, the transport is not run at this time. Instead, the address is
1620placed on a list for the particular transport, to be run later. Alternatively,
1621the router may generate one or more new addresses (typically from alias,
1622forward, or filter files). New addresses are fed back into this process from
1623the top, but in order to avoid loops, a router ignores any address which has an
1624identically-named ancestor that was processed by itself.
1625.nextp
1626When all the routing has been done, addresses that have been successfully
1627handled are passed to their assigned transports. When local transports are
1628doing real local deliveries, they handle only one address at a time, but if a
1629local transport is being used as a pseudo-remote transport (for example, to
1630collect batched SMTP messages for transmission by some other means) multiple
1631addresses can be handled. Remote transports can always handle more than one
1632address at a time, but can be configured not to do so, or to restrict multiple
1633addresses to the same domain.
1634.nextp
1635Each local delivery to a file or a pipe runs in a separate process under a
1636non-privileged uid, and these deliveries are run one at a time. Remote
1637deliveries also run in separate processes, normally under a uid that is private
1638to Exim (`the Exim user'), but in this case, several remote deliveries can be
1639run in parallel. The maximum number of simultaneous remote deliveries for any
1640one message is set by the \remote@_max@_parallel\ option.
4964e932 1641The order in which deliveries are done is not defined, except that all local
495ae4b0 1642deliveries happen before any remote deliveries.
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1643.nextp
1644.index queue runner
1645When it encounters a local delivery during a queue run, Exim checks its retry
1646database to see if there has been a previous temporary delivery failure for the
1647address before running the local transport. If there was a previous failure,
1648Exim does not attempt a new delivery until the retry time for the address is
1649reached. However, this happens only for delivery attempts that are part of a
1650queue run. Local deliveries are always attempted when delivery immediately
1651follows message reception, even if retry times are set for them. This makes for
1652better behaviour if one particular message is causing problems (for example,
1653causing quota overflow, or provoking an error in a filter file).
1654.nextp
1655.index delivery||retry in remote transports
1656Remote transports do their own retry handling, since an address may be
1657deliverable to one of a number of hosts, each of which may have a different
1658retry time. If there have been previous temporary failures and no host has
1659reached its retry time, no delivery is attempted, whether in a queue run or
1660not. See chapter ~~CHAPretry for details of retry strategies.
1661.nextp
1662If there were any permanent errors, a bounce message is returned to an
1663appropriate address (the sender in the common case), with details of the error
1664for each failing address. Exim can be configured to send copies of bounce
1665messages to other addresses.
1666.nextp
1667.index delivery||deferral
1668If one or more addresses suffered a temporary failure, the message is left on
1669the queue, to be tried again later. Delivery of these addresses is said to be
1670\*deferred*\.
1671.nextp
1672When all the recipient addresses have either been delivered or bounced,
1673handling of the message is complete. The spool files and message log are
1674deleted, though the message log can optionally be preserved if required.
1675.endp
1676
1677
1678.section Retry mechanism
1679.index delivery||retry mechanism
1680.index retry||description of mechanism
1681.index queue runner
1682Exim's mechanism for retrying messages that fail to get delivered at the first
1683attempt is the queue runner process. You must either run an Exim daemon that
1684uses the \-q-\ option with a time interval to start queue runners at regular
1685intervals, or use some other means (such as \*cron*\) to start them. If you do
1686not arrange for queue runners to be run, messages that fail temporarily at the
1687first attempt will remain on your queue for ever. A queue runner process works
1688it way through the queue, one message at a time, trying each delivery that has
1689passed its retry time.
1690You can run several queue runners at once.
1691
1692Exim uses a set of configured rules to determine when next to retry the failing
1693address (see chapter ~~CHAPretry). These rules also specify when Exim should
1694give up trying to deliver to the address, at which point it generates a bounce
1695message. If no retry rules are set for a particular host, address, and error
1696combination, no retries are attempted, and temporary errors are treated as
1697permanent.
1698
1699
1700.section Temporary delivery failure
1701.index delivery||temporary failure
1702There are many reasons why a message may not be immediately deliverable to a
1703particular address. Failure to connect to a remote machine (because it, or the
1704connection to it, is down) is one of the most common. Temporary failures may be
1705detected during routing as well as during the transport stage of delivery.
1706Local deliveries may be delayed if NFS files are unavailable, or if a mailbox
1707is on a file system where the user is over quota. Exim can be configured to
1708impose its own quotas on local mailboxes; where system quotas are set they will
1709also apply.
1710
1711If a host is unreachable for a period of time, a number of messages may be
1712waiting for it by the time it recovers, and sending them in a single SMTP
1713connection is clearly beneficial. Whenever a delivery to a remote host is
4964e932 1714deferred,
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1715.index hints database
1716Exim makes a note in its hints database, and whenever a successful
1717SMTP delivery has happened, it looks to see if any other messages are waiting
1718for the same host. If any are found, they are sent over the same SMTP
1719connection, subject to a configuration limit as to the maximum number in any
1720one connection.
1721
1722
1723
1724.section Permanent delivery failure
1725.index delivery||permanent failure
1726.index bounce message||when generated
1727When a message cannot be delivered to some or all of its intended recipients, a
1728bounce message is generated. Temporary delivery failures turn into permanent
1729errors when their timeout expires. All the addresses that fail in a given
1730delivery attempt are listed in a single message. If the original message has
1731many recipients, it is possible for some addresses to fail in one delivery
1732attempt and others to fail subsequently, giving rise to more than one bounce
1733message. The wording of bounce messages can be customized by the administrator.
1734See chapter ~~CHAPemsgcust for details.
1735
1736.index ::X-Failed-Recipients:: header line
1737Bounce messages contain an ::X-Failed-Recipients:: header line that lists the
1738failed addresses, for the benefit of programs that try to analyse such messages
1739automatically.
1740
1741.index bounce message||recipient of
1742A bounce message is normally sent to the sender of the original message, as
1743obtained from the message's envelope. For incoming SMTP messages, this is the
1744address given in the \\MAIL\\ command. However, when an address is
1745expanded via a forward or alias file, an alternative address can be specified
1746for delivery failures of the generated addresses. For a mailing list expansion
1747(see section ~~SECTmailinglists) it is common to direct bounce messages to the
1748manager of the list.
1749
1750
1751
1752.section Failures to deliver bounce messages
1753.index bounce message||failure to deliver
1754If a bounce message (either locally generated or received from a remote host)
1755itself suffers a permanent delivery failure, the message is left on the queue,
1756but it is frozen, awaiting the attention of an administrator. There are options
1757which can be used to make Exim discard such failed messages, or to keep them
1758for only a short time (see \timeout@_frozen@_after\ and
1759\ignore@_bounce@_errors@_after\).
1760
1761
1762
1763.
1764.
1765.
1766.
1767. ============================================================================
1768.chapter Building and installing Exim
1769.set runningfoot "building/installing"
1770
1771.index building Exim
1772.section Unpacking
1773Exim is distributed as a gzipped or bzipped tar file which, when upacked,
1774creates a directory with the name of the current release (for example,
1775\(exim-~~version)\) into which the following files are placed:
1776.display rm
1777.if !~~sys.fancy && ~~sgcal
1778.tabs 16
1779.else
4964e932 1780.tabs 22
495ae4b0
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1781.fi
1782\(ACKNOWLEDGMENTS)\ $t contains some acknowledgments
1783.newline
1784\(CHANGES)\ $t contains a reference to where changes are documented
1785\(LICENCE)\ $t the GNU General Public Licence
1786\(Makefile)\ $t top-level make file
1787\(NOTICE)\ $t conditions for the use of Exim
1788\(README)\ $t list of files, directories and simple build instructions
1789.endd
1790Other files whose names begin with \(README)\ may also be present. The
1791following subdirectories are created:
1792.display rm
1793.if !~~sys.fancy && ~~sgcal
1794.tabs 16
1795.else
1796.tabs 22
1797.fi
1798\(Local)\ $t an empty directory for local configuration files
1799\(OS)\ $t OS-specific files
1800\(doc)\ $t documentation files
1801\(exim@_monitor)\$t source files for the Exim monitor
1802\(scripts)\ $t scripts used in the build process
1803\(src)\ $t remaining source files
1804\(util)\ $t independent utilities
1805.endd
1806The main utility programs are contained in the \(src)\ directory, and are built
1807with the Exim binary. The \(util)\ directory contains a few optional scripts
1808that may be useful to some sites.
1809
1810.section Multiple machine architectures and operating systems
1811.index building Exim||multiple OS/architectures
1812The building process for Exim is arranged to make it easy to build binaries for
1813a number of different architectures and operating systems from the same set of
1814source files. Compilation does not take place in the \(src)\ directory. Instead,
1815a \*build directory*\ is created for each architecture and operating system.
1816.index symbolic link||to build directory
1817Symbolic links to the sources are installed in this directory, which is where
1818the actual building takes place.
1819
1820In most cases, Exim can discover the machine architecture and operating system
1821for itself, but the defaults can be overridden if necessary.
1822
1823.section DBM libraries
1824.rset SECTdb "~~chapter.~~section"
1825.index DBM||libraries, discussion of
1826.index hints database||DBM files used for
1827Even if you do not use any DBM files in your configuration, Exim still needs a
1828DBM library in order to operate, because it uses indexed files for its hints
1829databases. Unfortunately, there are a number of DBM libraries in existence, and
1830different operating systems often have different ones installed.
1831
1832.index Solaris||DBM library for
1833.index IRIX, DBM library for
1834.index BSD, DBM library for
1835.index Linux, DBM library for
1836If you are using Solaris, IRIX, one of the modern BSD systems, or a modern
1837Linux distribution, the DBM configuration should happen automatically, and you
1838may be able to ignore this section. Otherwise, you may have to learn more than
1839you would like about DBM libraries from what follows.
1840
1841.index \*ndbm*\ DBM library
1842Licensed versions of Unix normally contain a library of DBM functions operating
1843via the \*ndbm*\ interface, and this is what Exim expects by default. Free
1844versions of Unix seem to vary in what they contain as standard. In particular,
1845some early versions of Linux have no default DBM library, and different
1846distributors have chosen to bundle different libraries with their packaged
1847versions. However, the more recent releases seem to have standardised on the
1848Berkeley DB library.
1849
1850Different DBM libraries have different conventions for naming the files they
1851use. When a program opens a file called \(dbmfile)\, there are four
1852possibilities:
1853.numberpars
1854A traditional \*ndbm*\ implementation, such as that supplied as part of
1855Solaris, operates on two files called \(dbmfile.dir)\ and \(dbmfile.pag)\.
1856.nextp
1857.index \*gdbm*\ DBM library
1858The GNU library, \*gdbm*\, operates on a single file. If used via its \*ndbm*\
1859compatibility interface it makes two different hard links to it with names
1860\(dbmfile.dir)\ and \(dbmfile.pag)\, but if used via its native interface, the
1861file name is used unmodified.
1862.nextp
1863.index Berkeley DB library
1864The Berkeley DB package, if called via its \*ndbm*\ compatibility interface,
1865operates on a single file called \(dbmfile.db)\, but otherwise looks to the
1866programmer exactly the same as the traditional \*ndbm*\ implementation.
1867.nextp
1868If the Berkeley package is used in its native mode, it operates on a single
1869file called \(dbmfile)\; the programmer's interface is somewhat different to
1870the traditional \*ndbm*\ interface.
1871.nextp
1872To complicate things further, there are several very different versions of the
1873Berkeley DB package. Version 1.85 was stable for a very long time, releases
18742.$it{x} and 3.$it{x} were current for a while, but the latest versions are now
1875numbered 4.$it{x}. Maintenance of some of the earlier releases has ceased. All
1876versions of Berkeley DB can be obtained from
1877.display rm
1878\?http://www.sleepycat.com/?\
1879.endd
1880.nextp
1881.index \*tdb*\ DBM library
1882Yet another DBM library, called \*tdb*\, has become available from
1883.display rm
1884\?http://download.sourceforge.net/tdb?\
1885.endd
1886It has its own interface, and also operates on a single file.
1887.endp
1888.index \\USE@_DB\\
1889.index DBM||libraries, configuration for building
1890Exim and its utilities can be compiled to use any of these interfaces. In order
1891to use any version of the Berkeley DB package in native mode, you must set
1892\\USE@_DB\\ in an appropriate configuration file (typically
1893\(Local/Makefile)\). For example:
1894.display asis
1895USE_DB=yes
1896.endd
1897Similarly, for gdbm you set \\USE@_GDBM\\, and for tdb you set \\USE@_TDB\\. An
1898error is diagnosed if you set more than one of these.
1899
1900At the lowest level, the build-time configuration sets none of these options,
1901thereby assuming an interface of type (1). However, some operating system
1902configuration files (for example, those for the BSD operating systems and
1903Linux) assume type (4) by setting \\USE@_DB\\ as their default, and the
1904configuration files for Cygwin set \\USE@_GDBM\\. Anything you set in
1905\(Local/Makefile)\, however, overrides these system defaults.
1906
1907As well as setting \\USE@_DB\\, \\USE@_GDBM\\, or \\USE@_TDB\\, it may also be
1908necessary to set \\DBMLIB\\, to cause inclusion of the appropriate library, as
1909in one of these lines:
1910.display asis
1911DBMLIB = -ldb
1912DBMLIB = -ltdb
1913.endd
4964e932 1914Settings like that will work if the DBM library is installed in the standard
495ae4b0
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1915place. Sometimes it is not, and the library's header file may also not be in
1916the default path. You may need to set \\INCLUDE\\ to specify where the header
4964e932 1917file is, and to specify the path to the library more fully in \\DBMLIB\\, as in
495ae4b0
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1918this example:
1919.display asis
1920INCLUDE=-I/usr/local/include/db-4.1
1921DBMLIB=/usr/local/lib/db-4.1/libdb.a
1922.endd
1923
1924There is further detailed discussion about the various DBM libraries in the
1925file \(doc/dbm.discuss.txt)\ in the Exim distribution.
1926
1927
1928.section Pre-building configuration
1929.index building Exim||pre-building configuration
1930.index configuration for building Exim
1931.index \(Local/Makefile)\
1932.index \(src/EDITME)\
1933Before building Exim, a local configuration file that specifies options
1934independent of any operating system has to be created with the name
1935\(Local/Makefile)\. A template for this file is supplied as the file
1936\(src/EDITME)\, and it contains full descriptions of all the option settings
1937therein. These descriptions are therefore not repeated here. If you are
1938building Exim for the first time, the simplest thing to do is to copy
1939\(src/EDITME)\ to \(Local/Makefile)\, then read it and edit it appropriately.
1940
1941There are three settings that you must supply, because Exim will not build
1942without them. They are the location of the run time configuration file
1943(\\CONFIGURE@_FILE\\), the directory in which Exim binaries will be installed
1944(\\BIN@_DIRECTORY\\), and the identity of the Exim user (\\EXIM@_USER\\ and
1945maybe \\EXIM@_GROUP\\ as well). The value of \\CONFIGURE@_FILE\\ can in fact be
1946a colon-separated list of file names; Exim uses the first of them that exists.
1947
1948There are a few other parameters that can be specified either at build time or
1949at run time, to enable the same binary to be used on a number of different
1950machines. However, if the locations of Exim's spool directory and log file
1951directory (if not within the spool directory) are fixed, it is recommended that
1952you specify them in \(Local/Makefile)\ instead of at run time, so that errors
1953detected early in Exim's execution (such as a malformed configuration file) can
1954be logged.
1955
d43194df
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1956.index content scanning||specifying at build time
1957.em
1958Exim's interfaces for calling virus and spam scanning sofware directly from
1959access control lists are not compiled by default. If you want to include these
1960facilities, you need to set
1961.display asis
1962WITH_CONTENT_SCAN=yes
1963.endd
1964in your \(Local/Makefile)\. For details of the facilities themselves, see
1965chapter ~~CHAPexiscan.
1966.nem
1967
495ae4b0
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1968.index \(Local/eximon.conf)\
1969.index \(exim@_monitor/EDITME)\
1970If you are going to build the Exim monitor, a similar configuration process is
1971required. The file \(exim@_monitor/EDITME)\ must be edited appropriately for
1972your installation and saved under the name \(Local/eximon.conf)\. If you are
1973happy with the default settings described in \(exim@_monitor/EDITME)\,
1974\(Local/eximon.conf)\ can be empty, but it must exist.
1975
1976This is all the configuration that is needed in straightforward cases for known
1977operating systems. However, the building process is set up so that it is easy
1978to override options that are set by default or by operating-system-specific
1979configuration files, for example to change the name of the C compiler, which
1980defaults to \gcc\. See section ~~SECToverride below for details of how to do
1981this.
1982
1983
1984.section Support for iconv()
1985.index \*iconv()*\ support
4964e932
PH
1986The contents of header lines in messages may be encoded according to the rules
1987described RFC 2047. This makes it possible to transmit characters that are not
1988in the ASCII character set, and to label them as being in a particular
1989character set. When Exim is inspecting header lines by means of the \@$h@_\
1990mechanism, it decodes them, and translates them into a specified character set
495ae4b0
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1991(default ISO-8859-1). The translation is possible only if the operating system
1992supports the \*iconv()*\ function.
1993
1994However, some of the operating systems that supply \*iconv()*\ do not support
1995very many conversions. The GNU \libiconv\ library (available from
1996\?http:/@/www.gnu.org/software/libiconv/?\) can be installed on such systems to
1997remedy this deficiency, as well as on systems that do not supply \*iconv()*\ at
4964e932 1998all. After installing \libiconv\, you should add
495ae4b0 1999.display asis
4964e932
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2000HAVE_ICONV=yes
2001.endd
495ae4b0
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2002to your \(Local/Makefile)\ and rebuild Exim.
2003
2004
2005.section Including TLS/SSL encryption support
2006.rset SECTinctlsssl "~~chapter.~~section"
2007.index TLS||including support for TLS
2008.index encryption||including support for
2009.index \\SUPPORT@_TLS\\
2010.index OpenSSL||building Exim with
2011.index GnuTLS||building Exim with
2012Exim can be built to support encrypted SMTP connections, using the \\STARTTLS\\
4964e932
PH
2013command as per RFC 2487. It can also support legacy clients that expect to
2014start a TLS session immediately on connection to a non-standard port (see the
d43194df
PH
2015\tls@_on@_connect@_ports\ runtime option and the \-tls-on-connect-\ command
2016line option).
495ae4b0 2017
4964e932 2018If you want to build Exim with TLS support, you must first install either the
495ae4b0
PH
2019OpenSSL or GnuTLS library. There is no cryptographic code in Exim itself for
2020implementing SSL.
2021
2022If OpenSSL is installed, you should set
2023.display asis
2024SUPPORT_TLS=yes
2025TLS_LIBS=-lssl -lcrypto
2026.endd
2027in \(Local/Makefile)\. You may also need to specify the locations of the
2028OpenSSL library and include files. For example:
2029.display asis
2030SUPPORT_TLS=yes
2031TLS_LIBS=-L/usr/local/openssl/lib -lssl -lcrypto
2032TLS_INCLUDE=-I/usr/local/openssl/include/
2033.endd
2034
2035If GnuTLS is installed, you should set
2036.index \\USE@_GNUTLS\\
2037.display asis
2038SUPPORT_TLS=yes
2039USE_GNUTLS=yes
2040TLS_LIBS=-lgnutls -ltasn1 -lgcrypt
2041.endd
2042in \(Local/Makefile)\, and again you may need to specify the locations of the
2043library and include files. For example:
2044.display asis
2045SUPPORT_TLS=yes
4964e932 2046USE_GNUTLS=yes
495ae4b0
PH
2047TLS_LIBS=-L/usr/gnu/lib -lgnutls -ltasn1 -lgcrypt
2048TLS_INCLUDE=-I/usr/gnu/include
2049.endd
2050You do not need to set \\TLS@_INCLUDE\\ if the relevant directory is already
4964e932 2051specified in \\INCLUDE\\. Details of how to configure Exim to make use of TLS
495ae4b0
PH
2052are given in chapter ~~CHAPTLS.
2053
2054
2055
2056.section Use of tcpwrappers
2057.index tcpwrappers, building Exim to support
2058.index \\USE@_TCP@_WRAPPERS\\
2059Exim can be linked with the \*tcpwrappers*\ library in order to check incoming
2060SMTP calls using the \*tcpwrappers*\ control files. This may be a convenient
2061alternative to Exim's own checking facilities for installations that are
2062already making use of \*tcpwrappers*\ for other purposes. To do this, you should
2063set \\USE@_TCP@_WRAPPERS\\ in \(Local/Makefile)\, arrange for the file
2064\(tcpd.h)\ to be available at compile time, and also ensure that the library
2065\(libwrap.a)\ is available at link time, typically by including \-lwrap-\ in
2066\\EXTRALIBS@_EXIM\\. For example, if \*tcpwrappers*\ is installed in
2067\(/usr/local)\, you might have
2068.display
2069USE@_TCP@_WRAPPERS=yes
2070CFLAGS=-O -I/usr/local/include
2071.newline
2072EXTRALIBS@_EXIM=-L/usr/local/lib -lwrap
2073.endd
2074in \(Local/Makefile)\. The name to use in the \*tcpwrappers*\ control files is
2075`exim'. For example, the line
2076.display
2077exim : LOCAL 192.168.1. .friendly.domain.example
2078.endd
2079in your \(/etc/hosts.allow)\ file allows connections from the local host, from
2080the subnet 192.168.1.0/24, and from all hosts in \*friendly.domain.example*\.
2081All other connections are denied. Consult the \*tcpwrappers*\ documentation for
2082further details.
2083
2084
2085.section Including support for IPv6
2086.index IPv6||including support for
2087Exim contains code for use on systems that have IPv6 support. Setting
2088\\HAVE@_IPV6=YES\\ in \(Local/Makefile)\ causes the IPv6 code to be included;
2089it may also be necessary to set \\IPV6@_INCLUDE\\ and \\IPV6@_LIBS\\ on systems
2090where the IPv6 support is not fully integrated into the normal include and
2091library files.
2092
d43194df
PH
2093.em
2094Two different types of DNS record for handling IPv6 addresses have been
2095defined. AAAA records (analagous to A records for IPv4) are in use, and are
2096currently seen as the mainstream. Another record type called A6 was proposed
2097as better than AAAA because it had more flexibility. However, it was felt to
2098be over-complex, and its status was reduced to `experimental'. It is not known
2099if anyone is actually using A6 records. Exim has support for A6 records, but
2100this is included only if you set \\SUPPORT@_A6=YES\\ in \(Local/Makefile)\. The
2101support has not been tested for some time.
2102.nem
495ae4b0
PH
2103
2104.section The building process
2105.index build directory
2106Once \(Local/Makefile)\ (and \(Local/eximon.conf)\, if required) have been
2107created, run \*make*\ at the top level. It determines the architecture and
2108operating system types, and creates a build directory if one does not exist.
2109For example, on a Sun system running Solaris 8, the directory
2110\(build-SunOS5-5.8-sparc)\ is created.
2111.index symbolic link||to source files
2112Symbolic links to relevant source files are installed in the build directory.
2113
4964e932 2114\**Warning**\: The \-j-\ (parallel) flag must not be used with \*make*\; the
495ae4b0 2115building process fails if it is set.
495ae4b0
PH
2116
2117If this is the first time \*make*\ has been run, it calls a script that builds
2118a make file inside the build directory, using the configuration files from the
2119\(Local)\ directory. The new make file is then passed to another instance of
2120\*make*\. This does the real work, building a number of utility scripts, and
2121then compiling and linking the binaries for the Exim monitor (if configured), a
2122number of utility programs, and finally Exim itself. The command \*make
2123makefile*\ can be used to force a rebuild of the make file in the build
2124directory, should this ever be necessary.
2125
2126If you have problems building Exim, check for any comments there may be in the
2127\(README)\ file concerning your operating system, and also take a look at the
2128.if ~~html
2129[(A HREF="FAQ.html")]
2130.fi
2131FAQ,
2132.if ~~html
2133[(/A)]
2134.fi
2135where some common problems are covered.
2136
2137
2138
2139.section Overriding build-time options for Exim
2140.index build-time options, overriding
2141.rset SECToverride "~~chapter.~~section"
2142The main make file that is created at the beginning of the building process
2143consists of the concatenation of a number of files which set configuration
2144values, followed by a fixed set of \*make*\ instructions. If a value is set
2145more than once, the last setting overrides any previous ones. This provides a
2146convenient way of overriding defaults. The files that are concatenated are, in
2147order:
2148.display rm
2149\(OS/Makefile-Default)\
2150\(OS/Makefile-)\<<ostype>>
2151\(Local/Makefile)\
2152\(Local/Makefile-)\<<ostype>>
2153\(Local/Makefile-)\<<archtype>>
2154\(Local/Makefile-)\<<ostype>>-<<archtype>>
2155\(OS/Makefile-Base)\
2156.endd
2157.index \(Local/Makefile)\
2158where <<ostype>> is the operating system type and <<archtype>> is the
2159.index building Exim||operating system type
2160.index building Exim||architecture type
2161architecture type. \(Local/Makefile)\ is required to exist, and the building
2162process fails if it is absent. The other three \(Local)\ files are optional,
2163and are often not needed.
2164
2165The values used for <<ostype>> and <<archtype>> are obtained from scripts
2166called \(scripts/os-type)\ and \(scripts/arch-type)\ respectively. If either of
2167the environment variables \\EXIM@_OSTYPE\\ or \\EXIM@_ARCHTYPE\\ is set, their
2168values are used, thereby providing a means of forcing particular settings.
2169Otherwise, the scripts try to get values from the \uname\ command. If this
2170fails, the shell variables \\OSTYPE\\ and \\ARCHTYPE\\ are inspected. A number
2171of $it{ad hoc} transformations are then applied, to produce the standard names
2172that Exim expects. You can run these scripts directly from the shell in order
2173to find out what values are being used on your system.
2174
2175
2176\(OS/Makefile-Default)\ contains comments about the variables that are set
2177therein. Some (but not all) are mentioned below. If there is something that
2178needs changing, review the contents of this file and the contents of the make
2179file for your operating system (\(OS/Makefile-<<ostype>>)\) to see what the
2180default values are.
2181
2182
2183.index building Exim||overriding default settings
2184If you need to change any of the values that are set in \(OS/Makefile-Default)\
4964e932 2185or in \(OS/Makefile-<<ostype>>)\, or to add any new definitions, you do not
495ae4b0
PH
2186need to change the original files. Instead, you should make the changes by
2187putting the new values in an appropriate \(Local)\ file. For example,
2188.index Tru64-Unix build-time settings
2189when building Exim in many releases of the Tru64-Unix (formerly Digital UNIX,
2190formerly DEC-OSF1) operating system, it is necessary to specify that the C
4964e932 2191compiler is called \*cc*\ rather than \*gcc*\. Also, the compiler must be
495ae4b0 2192called with the option \-std1-\, to make it recognize some of the features of
4964e932 2193Standard C that Exim uses. (Most other compilers recognize Standard C by
495ae4b0
PH
2194default.) To do this, you should create a file called \(Local/Makefile-OSF1)\
2195containing the lines
2196.display
2197CC=cc
2198CFLAGS=-std1
2199.endd
4964e932 2200If you are compiling for just one operating system, it may be easier to put
495ae4b0
PH
2201these lines directly into \(Local/Makefile)\.
2202
2203Keeping all your local configuration settings separate from the distributed
2204files makes it easy to transfer them to new versions of Exim simply by copying
2205the contents of the \(Local)\ directory.
2206
2207
2208.index NIS lookup type||including support for
2209.index NIS@+ lookup type||including support for
2210.index LDAP||including support for
2211.index lookup||inclusion in binary
2212Exim contains support for doing LDAP, NIS, NIS+, and other kinds of file
2213lookup, but not all systems have these components installed, so the default is
2214not to include the relevant code in the binary. All the different kinds of file
2215and database lookup that Exim supports are implemented as separate code modules
2216which are included only if the relevant compile-time options are set. In the
2217case of LDAP, NIS, and NIS+, the settings for \(Local/Makefile)\ are:
2218.display asis
2219LOOKUP_LDAP=yes
2220LOOKUP_NIS=yes
2221LOOKUP_NISPLUS=yes
2222.endd
2223and similar settings apply to the other lookup types. They are all listed in
2224\(src/EDITME)\. In most cases the relevant include files and interface
2225libraries need to be installed before compiling Exim.
2226.index cdb||including support for
2227However, in the case of cdb, which is included in the binary only if
2228.display asis
2229LOOKUP_CDB=yes
2230.endd
2231is set, the code is entirely contained within Exim, and no external include
2232files or libraries are required. When a lookup type is not included in the
2233binary, attempts to configure Exim to use it cause run time configuration
2234errors.
2235
2236.index Perl||including support for
2237Exim can be linked with an embedded Perl interpreter, allowing Perl
2238subroutines to be called during string expansion. To enable this facility,
2239.display asis
2240EXIM_PERL=perl.o
2241.endd
2242must be defined in \(Local/Makefile)\. Details of this facility are given in
2243chapter ~~CHAPperl.
2244
2245.index X11 libraries, location of
2246The location of the X11 libraries is something that varies a lot between
2247operating systems, and of course there are different versions of X11 to cope
2248with. Exim itself makes no use of X11, but if you are compiling the Exim
2249monitor, the X11 libraries must be available.
2250The following three variables are set in \(OS/Makefile-Default)\:
2251.display asis
2252X11=/usr/X11R6
2253XINCLUDE=-I$(X11)/include
2254XLFLAGS=-L$(X11)/lib
2255.endd
2256These are overridden in some of the operating-system configuration files. For
2257example, in \(OS/Makefile-SunOS5)\ there is
2258.display asis
2259X11=/usr/openwin
2260XINCLUDE=-I$(X11)/include
2261XLFLAGS=-L$(X11)/lib -R$(X11)/lib
2262.endd
2263If you need to override the default setting for your operating system, place a
2264definition of all three of these variables into your
2265\(Local/Makefile-<<ostype>>)\ file.
2266
2267.index \\EXTRALIBS\\
2268If you need to add any extra libraries to the link steps, these can be put in a
2269variable called \\EXTRALIBS\\, which appears in all the link commands, but by
2270default is not defined. In contrast, \\EXTRALIBS@_EXIM\\ is used only on the
2271command for linking the main Exim binary, and not for any associated utilities.
2272.index DBM||libraries, configuration for building
2273There is also \\DBMLIB\\, which appears in the link commands for binaries that
2274use DBM functions (see also section ~~SECTdb). Finally, there is
2275\\EXTRALIBS@_EXIMON\\, which appears only in the link step for the Exim monitor
2276binary, and which can be used, for example, to include additional X11
2277libraries.
2278
2279.index configuration file||editing
2280The make file copes with rebuilding Exim correctly if any of the configuration
2281files are edited. However, if an optional configuration file is deleted, it is
2282necessary to touch the associated non-optional file (that is, \(Local/Makefile)\
2283or \(Local/eximon.conf)\) before rebuilding.
2284
2285.section OS-specific header files
2286.index \(os.h)\
2287.index building Exim||OS-specific C header files
2288The \(OS)\ directory contains a number of files with names of the form
2289\(os.h-<<ostype>>)\. These are system-specific C header files that should not
2290normally need to be changed. There is a list of macro settings that are
2291recognized in the file \(OS/os.configuring)\, which should be consulted if you
2292are porting Exim to a new operating system.
2293
2294
2295.section Overriding build-time options for the monitor
2296.index building Eximon||overriding default options
2297A similar process is used for overriding things when building the Exim monitor,
2298where the files that are involved are
2299.display rm
2300\(OS/eximon.conf-Default)\
2301\(OS/eximon.conf-)\<<ostype>>
2302\(Local/eximon.conf)\
2303\(Local/eximon.conf-)\<<ostype>>
2304\(Local/eximon.conf-)\<<archtype>>
2305\(Local/eximon.conf-)\<<ostype>>-<<archtype>>
2306.endd
2307.index \(Local/eximon.conf)\
2308As with Exim itself, the final three files need not exist, and in this case the
2309\(OS/eximon.conf-<<ostype>>)\ file is also optional. The default values in
2310\(OS/eximon.conf-Default)\ can be overridden dynamically by setting environment
2311variables of the same name, preceded by \\EXIMON@_\\. For example, setting
2312\\EXIMON@_LOG@_DEPTH\\ in the environment overrides the value of
2313\\LOG@_DEPTH\\ at run time.
2314
2315
2316
2317.section Installing Exim binaries and scripts
2318.index installing Exim
2319.index \\BIN@_DIRECTORY\\
2320The command \*make install*\ runs the \*exim@_install*\ script with no
2321arguments. The script copies binaries and utility scripts into the directory
2322whose name is specified by the \\BIN@_DIRECTORY\\ setting in
4964e932 2323\(Local/Makefile)\.
495ae4b0
PH
2324
2325Exim's run time configuration file is named by the \\CONFIGURE@_FILE\\ setting
2326.index \\CONFIGURE@_FILE\\
2327in \(Local/Makefile)\. If this names a single file, and the file does not
2328exist, the default configuration file \(src/configure.default)\ is copied there
2329by the installation script. If a run time configuration file already exists, it
2330is left alone. If \\CONFIGURE@_FILE\\ is a colon-separated list, naming several
2331alternative files, no default is installed.
2332
2333.index system aliases file
2334.index \(/etc/aliases)\
2335One change is made to the default configuration file when it is installed: the
2336default configuration contains a router that references a system aliases file.
2337The path to this file is set to the value specified by
2338\\SYSTEM@_ALIASES@_FILE\\ in \(Local/Makefile)\ (\(/etc/aliases)\ by default).
2339If the system aliases file does not exist, the installation script creates it,
2340and outputs a comment to the user.
2341
2342The created file contains no aliases, but it does contain comments about the
2343aliases a site should normally have. Mail aliases have traditionally been
2344kept in \(/etc/aliases)\. However, some operating systems are now using
2345\(/etc/mail/aliases)\. You should check if yours is one of these, and change
2346Exim's configuration if necessary.
2347
2348The default configuration uses the local host's name as the only local domain,
2349and is set up to do local deliveries into the shared directory \(/var/mail)\,
2350running as the local user. System aliases and \(.forward)\ files in users' home
2351directories are supported, but no NIS or NIS+ support is configured. Domains
2352other than the name of the local host are routed using the DNS, with delivery
2353over SMTP.
2354
2355The install script copies files only if they are newer than the files they are
2356going to replace. The Exim binary is required to be owned by root and have the
2357\*setuid*\ bit set,
2358.index setuid||installing Exim with
2359for normal configurations. Therefore, you must run \*make install*\ as root so
2360that it can set up the Exim binary in this way. However, in some special
2361situations (for example, if a host is doing no local deliveries) it may be
2362possible to run Exim without making the binary setuid root (see chapter
2363~~CHAPsecurity for details).
2364
2365It is possible to install Exim for special purposes (such as building a binary
2366distribution) in a private part of the file system. You can do this by a
2367command such as
2368.display asis
2369make DESTDIR=/some/directory/ install
2370.endd
4964e932
PH
2371This has the effect of pre-pending the specified directory to all the file
2372paths, except the name of the system aliases file that appears in the default
495ae4b0 2373configuration. (If a default alias file is created, its name \*is*\ modified.)
4964e932 2374For backwards compatibility, \\ROOT\\ is used if \\DESTDIR\\ is not set,
495ae4b0
PH
2375but this usage is deprecated.
2376
2377.index installing Exim||what is not installed
2378Running \*make install*\ does not copy the Exim 4 conversion script
2379\*convert4r4*\, or the \*pcretest*\ test program. You will probably run the
2380first of these only once (if you are upgrading from Exim 3), and the second
2381isn't really part of Exim. None of the documentation files in the \(doc)\
2382directory are copied, except for the info files when you have set
2383\\INFO@_DIRECTORY\\, as described in section ~~SECTinsinfdoc below.
2384
2385For the utility programs, old versions are renamed by adding the suffix \(.O)\
2386to their names. The Exim binary itself, however, is handled differently. It is
2387installed under a name that includes the version number and the compile number,
2388for example \(exim-~~version-1)\. The script then arranges for a symbolic link
2389called \(exim)\ to point to the binary. If you are updating a previous version
2390of Exim, the script takes care to ensure that the name \(exim)\ is never absent
2391from the directory (as seen by other processes).
2392
2393.index installing Exim||testing the script
2394If you want to see what the \*make install*\ will do before running it for
2395real, you can pass the \-n-\ option to the installation script by this command:
2396.display asis
2397make INSTALL_ARG=-n install
2398.endd
2399The contents of the variable \\INSTALL@_ARG\\ are passed to the installation
2400script. You do not need to be root to run this test. Alternatively, you can run
2401the installation script directly, but this must be from within the build
2402directory. For example, from the top-level Exim directory you could use this
2403command:
2404.display
2405(cd build-SunOS5-5.5.1-sparc; ../scripts/exim@_install -n)
2406.endd
2407
2408.index installing Exim||install script options
2409There are two other options that can be supplied to the installation script.
2410.numberpars $.
2411\-no@_chown-\ bypasses the call to change the owner of the installed binary
2412to root, and the call to make it a setuid binary.
2413.nextp
2414\-no@_symlink-\ bypasses the setting up of the symbolic link \(exim)\ to the
2415installed binary.
2416.endp
2417\\INSTALL@_ARG\\ can be used to pass these options to the script. For example:
2418.display asis
2419make INSTALL_ARG=-no_symlink install
2420.endd
2421
4964e932
PH
2422The installation script can also be given arguments specifying which files are
2423to be copied. For example, to install just the Exim binary, and nothing else,
495ae4b0
PH
2424without creating the symbolic link, you could use:
2425.display asis
2426make INSTALL_ARG='-no_symlink exim' install
2427.endd
2428
2429
2430.section Installing info documentation
2431.rset SECTinsinfdoc "~~chapter.~~section"
2432.index installing Exim||\*info*\ documentation
2433Not all systems use the GNU \*info*\ system for documentation, and for this
2434reason, the Texinfo source of Exim's documentation is not included in the main
2435distribution. Instead it is available separately from the ftp site (see section
2436~~SECTavail).
2437
2438If you have defined \\INFO@_DIRECTORY\\ in \(Local/Makefile)\ and the Texinfo
2439source of the documentation is found in the source tree, running \*make
2440install*\ automatically builds the info files and installs them.
2441
2442
2443.section Setting up the spool directory
2444.index spool directory||creating
2445When it starts up, Exim tries to create its spool directory if it does not
2446exist. The Exim uid and gid are used for the owner and group of the spool
2447directory. Sub-directories are automatically created in the spool directory as
2448necessary.
2449
2450
2451
2452.section Testing
2453.index testing||installation
2454Having installed Exim, you can check that the run time configuration file is
2455syntactically valid by running the following command, which assumes that the
2456Exim binary directory is within your \\PATH\\ environment variable:
2457.display
2458exim -bV
2459.endd
2460If there are any errors in the configuration file, Exim outputs error messages.
2461Otherwise it outputs the version number and build date,
4964e932 2462the DBM library that is being used, and information about which drivers and
495ae4b0
PH
2463other optional code modules are included in the binary.
2464Some simple routing tests can be done by using the address testing option. For
2465example,
2466.display
2467exim -bt <<local username>>
2468.endd
2469should verify that it recognizes a local mailbox, and
2470.display
2471exim -bt <<remote address>>
2472.endd
2473a remote one. Then try getting it to deliver mail, both locally and remotely.
2474This can be done by passing messages directly to Exim, without going through a
2475user agent. For example:
2476.display
2477exim -v postmaster@@your.domain.example
2478From: user@@your.domain.example
2479To: postmaster@@your.domain.example
2480Subject: Testing Exim
2481
2482This is a test message.
2483^D
2484.endd
2485The \-v-\ option causes Exim to output some verification of what it is doing.
2486In this case you should see copies of three log lines, one for the message's
2487arrival, one for its delivery, and one containing `Completed'.
2488
2489.index delivery||problems with
2490If you encounter problems, look at Exim's log files (\*mainlog*\ and
2491\*paniclog*\) to see if there is any relevant information there. Another source
2492of information is running Exim with debugging turned on, by specifying the
2493\-d-\ option. If a message is stuck on Exim's spool, you can force a delivery
2494with debugging turned on by a command of the form
2495.display
2496exim -d -M <<message-id>>
2497.endd
2498You must be root or an `admin user' in order to do this. The \-d-\ option
2499produces rather a lot of output, but you can cut this down to specific areas.
2500For example, if you use \-d-all+route-\ only the debugging information relevant
2501to routing is included. (See the \-d-\ option in chapter ~~CHAPcommandline for
2502more details.)
2503
2504.index `sticky' bit
2505.index lock files
2506One specific problem that has shown up on some sites is the inability to do
2507local deliveries into a shared mailbox directory, because it does not have the
2508`sticky bit' set on it. By default, Exim tries to create a lock file before
2509writing to a mailbox file, and if it cannot create the lock file, the delivery
2510is deferred. You can get round this either by setting the `sticky bit' on the
2511directory, or by setting a specific group for local deliveries and allowing
2512that group to create files in the directory (see the comments above the
2513\%local@_delivery%\ transport in the default configuration file). Another
2514approach is to configure Exim not to use lock files, but just to rely on
2515\*fcntl()*\ locking instead. However, you should do this only if all user
2516agents also use \*fcntl()*\ locking. For further discussion of locking issues,
2517see chapter ~~CHAPappendfile.
2518
2519One thing that cannot be tested on a system that is already running an MTA is
2520the receipt of incoming SMTP mail on the standard SMTP port. However, the
2521\-oX-\ option can be used to run an Exim daemon that listens on some other
2522port, or \*inetd*\ can be used to do this. The \-bh-\ option and the
2523\*exim@_checkaccess*\ utility can be used to check out policy controls on
2524incoming SMTP mail.
2525
2526Testing a new version on a system that is already running Exim can most easily
2527be done by building a binary with a different \\CONFIGURE@_FILE\\ setting. From
2528within the run time configuration, all other file and directory names
2529that Exim uses can be altered, in order to keep it entirely clear of the
2530production version.
2531
2532.section Replacing another MTA with Exim
2533.index replacing another MTA
2534Building and installing Exim for the first time does not of itself put it in
2535general use. The name by which the system's MTA is called by mail user agents
2536is either \(/usr/sbin/sendmail)\, or \(/usr/lib/sendmail)\ (depending on the
2537operating system), and it is necessary to make this name point to the \*exim*\
2538binary in order to get the user agents to pass messages to Exim. This is
2539normally done by renaming any existing file and making \(/usr/sbin/sendmail)\
2540or \(/usr/lib/sendmail)\
2541.index symbolic link||to \*exim*\ binary
2542a symbolic link to the \*exim*\ binary. It is a good idea to remove any setuid
2543privilege and executable status from the old MTA. It is then necessary to stop
2544and restart the mailer daemon, if one is running.
2545
2546.index FreeBSD, MTA indirection
2547.index \(/etc/mail/mailer.conf)\
2548Some operating systems have introduced alternative ways of switching MTAs. For
2549example, if you are running FreeBSD, you need to edit the file
2550\(/etc/mail/mailer.conf)\ instead of setting up a symbolic link as just
2551described. A typical example of the contents of this file for running Exim is
2552as follows:
2553.display asis
2554sendmail /usr/exim/bin/exim
2555send-mail /usr/exim/bin/exim
2556mailq /usr/exim/bin/exim -bp
2557newaliases /usr/bin/true
2558.endd
2559
2560Once you have set up the symbolic link, or edited \(/etc/mail/mailer.conf)\,
2561your Exim installation is `live'. Check it by sending a message from your
2562favourite user agent.
2563
2564You should consider what to tell your users about the change of MTA. Exim may
2565have different capabilities to what was previously running, and there are
2566various operational differences such as the text of messages produced by
2567command line options and in bounce messages. If you allow your users to make
2568use of Exim's filtering capabilities, you should make the document entitled
2569.if ~~html
2570[(A HREF="filter.html")]
2571.fi
2572\*Exim's interface to mail filtering*\
2573.if ~~html
2574[(/A)]
2575.fi
2576available to them.
2577
2578
2579.section Upgrading Exim
2580.index upgrading Exim
2581If you are already running Exim on your host, building and installing a new
2582version automatically makes it available to MUAs, or any other programs that
2583call the MTA directly. However, if you are running an Exim daemon, you do need
2584to send it a HUP signal, to make it re-exec itself, and thereby pick up the new
2585binary. You do not need to stop processing mail in order to install a new
2586version of Exim.
2587
2588
2589.section Stopping the Exim daemon on Solaris
2590.index Solaris||stopping Exim on
2591The standard command for stopping the mailer daemon on Solaris is
2592.display
2593/etc/init.d/sendmail stop
2594.endd
2595If \(/usr/lib/sendmail)\ has been turned into a symbolic link, this script
2596fails to stop Exim because it uses the command \*ps -e*\ and greps the output
2597for the text `sendmail'; this is not present because the actual program name
2598(that is, `exim') is given by the \*ps*\ command with these options. A solution
2599is to replace the line that finds the process id with something like
2600.display asis
2601pid=`cat /var/spool/exim/exim-daemon.pid`
2602.endd
2603to obtain the daemon's pid directly from the file that Exim saves it in.
2604
4964e932
PH
2605Note, however, that stopping the daemon does not `stop Exim'. Messages can
2606still be received from local processes, and if automatic delivery is configured
495ae4b0
PH
2607(the normal case), deliveries will still occur.
2608
2609
2610.
2611.
2612.
2613.
2614. ============================================================================
2615.chapter The Exim command line
2616.set runningfoot "command line"
2617.rset CHAPcommandline ~~chapter
2618.index command line||options
2619.index options||command line
2620
2621Exim's command line takes the standard Unix form of a sequence of options,
2622each starting with a hyphen character, followed by a number of arguments. The
2623options are compatible with the main options of Sendmail, and there are also
2624some additional options, some of which are compatible with Smail 3. Certain
2625combinations of options do not make sense, and provoke an error if used.
2626The form of the arguments depends on which options are set.
2627
2628.section Setting options by program name
2629.index \*mailq*\
2630If Exim is called under the name \*mailq*\, it behaves as if the option \-bp-\
4964e932
PH
2631were present before any other options.
2632The \-bp-\ option requests a listing of the contents of the mail queue on the
495ae4b0
PH
2633standard output.
2634This feature is for compatibility with some systems that contain a command of
2635that name in one of the standard libraries, symbolically linked to
2636\(/usr/sbin/sendmail)\ or \(/usr/lib/sendmail)\.
2637
2638.index \*rsmtp*\
2639If Exim is called under the name \*rsmtp*\ it behaves as if the option \-bS-\
2640were present before any other options, for compatibility with Smail. The \-bS-\
2641option is used for reading in a number of messages in batched SMTP format.
2642
2643.index \*rmail*\
2644If Exim is called under the name \*rmail*\ it behaves as if the \-i-\ and
2645\-oee-\ options were present before any other options, for compatibility with
2646Smail. The name \*rmail*\ is used as an interface by some UUCP systems.
2647
2648.index \*runq*\
2649.index queue runner
2650If Exim is called under the name \*runq*\ it behaves as if the option \-q-\ were
2651present before any other options, for compatibility with Smail. The \-q-\
2652option causes a single queue runner process to be started.
2653
2654.index \*newaliases*\
2655.index alias file||building
2656.index Sendmail compatibility||calling Exim as \*newaliases*\
2657If Exim is called under the name \*newaliases*\ it behaves as if the option
2658\-bi-\ were present before any other options, for compatibility with Sendmail.
2659This option is used for rebuilding Sendmail's alias file. Exim does not have
2660the concept of a single alias file, but can be configured to run a given
2661command if called with the \-bi-\ option.
2662
2663.section Trusted and admin users
2664.rset SECTtrustedadmin "~~chapter.~~section"
2665Some Exim options are available only to \*trusted users*\ and others are
2666available only to \*admin users*\. In the description below, the phrases `Exim
2667user' and `Exim group' mean the user and group defined by \\EXIM@_USER\\ and
2668\\EXIM@_GROUP\\ in \(Local/Makefile)\ or set by the \exim@_user\ and
2669\exim@_group\ options. These do not necessarily have to use the name `exim'.
2670
2671.numberpars $.
2672.index trusted user||definition of
2673.index user||trusted, definition of
2674The trusted users are root, the Exim user, any user listed in the
2675\trusted@_users\ configuration option, and any user whose current group or any
2676supplementary group is one of those listed in the \trusted@_groups\
2677configuration option. Note that the Exim group is not automatically trusted.
2678
2679.index `From' line
2680.index envelope sender
2681Trusted users are always permitted to use the \-f-\ option or a leading `From '
2682line to specify the envelope sender of a message that is passed to Exim through
2683the local interface (see the \-bm-\ and \-f-\ options below). See the
2684\untrusted@_set@_sender\ option for a way of permitting non-trusted users to
2685set envelope senders.
2686.index ::From:: header line
2687.index ::Sender:: header line
2688For a trusted user, there is never any check on the contents of the ::From::
2689header line, and a ::Sender:: line is never added. Furthermore, any existing
2690::Sender:: line in incoming local (non-TCP/IP) messages is not removed.
2691
2692Trusted users may also specify a host name, host address, interface address,
2693protocol name, ident value, and authentication data when submitting a message
2694locally. Thus, they are able to insert messages into Exim's queue locally that
2695have the characteristics of messages received from a remote host. Untrusted
2696users may in some circumstances use \-f-\, but can never set the other values
2697that are available to trusted users.
2698.nextp
2699.index user||admin, definition of
2700.index admin user||definition of
2701The admin users are root, the Exim user, and any user that is a member of the
2702Exim group or of any group listed in the \admin@_groups\ configuration option.
2703The current group does not have to be one of these groups.
2704
2705Admin users are permitted to list the queue, and to carry out certain
2706operations on messages, for example, to force delivery failures. It is also
2707necessary to be an admin user in order to see the full information provided by
2708the Exim monitor, and full debugging output.
2709
2710By default, the use of the \-M-\, \-q-\, \-R-\, and \-S-\ options to cause Exim
2711to attempt delivery of messages on its queue is restricted to admin users.
2712However, this restriction can be relaxed by setting the \prod@_requires@_admin\
2713option false (that is, specifying \no@_prod@_requires@_admin\).
2714
2715Similarly, the use of the \-bp-\ option to list all the messages in the queue
2716is restricted to admin users unless \queue@_list@_requires@_admin\ is set
2717false.
2718.endp
2719
4964e932
PH
2720\**Warning**\: If you configure your system so that admin users are able to
2721edit Exim's configuration file, you are giving those users an easy way of
2722getting root. There is further discussion of this issue at the start of chapter
495ae4b0
PH
2723~~CHAPconf.
2724
2725
2726
2727.section Command line options
2728The command options are described in alphabetical order below.
2729
2730.startoptions
2731
2732.option @-
2733.index options||command line, terminating
2734This is a pseudo-option whose only purpose is to terminate the options and
2735therefore to cause subsequent command line items to be treated as arguments
2736rather than options, even if they begin with hyphens.
2737
2738.option -help
2739This option causes Exim to output a few sentences stating what it is.
4964e932 2740The same output is generated if the Exim binary is called with no options and
495ae4b0
PH
2741no arguments.
2742
2743.option B <<type>>
2744.index 8-bit characters
2745.index Sendmail compatibility||8-bit characters
2746This is a Sendmail option for selecting 7 or 8 bit processing. Exim is 8-bit
2747clean; it ignores this option.
2748
2749.option bd
2750.index daemon
2751.index SMTP listener
2752.index queue runner
2753This option runs Exim as a daemon, awaiting incoming SMTP connections. Usually
2754the \-bd-\ option is combined with the \-q-\<<time>> option, to specify that
2755the daemon should also initiate periodic queue runs.
2756
2757The \-bd-\ option can be used only by an admin user. If either of the \-d-\
2758(debugging) or \-v-\ (verifying) options are set, the daemon does not
2759disconnect from the controlling terminal. When running this way, it can be
2760stopped by pressing ctrl-C.
2761
2762By default, Exim listens for incoming connections to the standard SMTP port on
2763all the host's running interfaces. However, it is possible to listen on other
2764ports, on multiple ports, and only on specific interfaces. Chapter
2765~~CHAPinterfaces contains a description of the options that control this.
2766
2767.index daemon||process id (pid)
2768.index pid (process id)||of daemon
2769When a listening daemon is started without the use of \-oX-\ (that is, without
2770overriding the normal configuration), it writes its process id to a file called
2771\(exim-daemon.pid)\ in Exim's spool directory. This location can be overridden
2772by setting \\PID@_FILE@_PATH\\ in \(Local/Makefile)\. The file is written while
2773Exim is still running as root.
2774
2775When \-oX-\ is used on the command line to start a listening daemon, the
2776process id is not written to the normal pid file path. However, \-oP-\ can be
2777used to specify a path on the command line if a pid file is required.
2778
2779.index \\SIGHUP\\
2780The \\SIGHUP\\ signal can be used to cause the daemon to re-exec itself. This
2781should be done whenever Exim's configuration file, or any file that is
4964e932 2782incorporated into it by means of the \.include\ facility, is changed, and also
495ae4b0
PH
2783whenever a new version of Exim is installed. It is not necessary to do this
2784when other files that are referenced from the configuration (for example, alias
2785files) are changed, because these are reread each time they are used.
2786
2787.option bdf
2788This option has the same effect as \-bd-\ except that it never disconnects from
2789the controlling terminal, even when no debugging is specified.
2790
2791.option be
2792.index testing||string expansion
2793.index expansion||testing
2794Run Exim in expansion testing mode. Exim discards its root privilege, to
2795prevent ordinary users from using this mode to read otherwise inaccessible
2796files. If no arguments are given, Exim runs interactively, prompting for lines
d43194df
PH
2797of data.
2798.em
2799If Exim was built with \\USE@_READLINE\\=yes in \(Local/Makefile)\, it tries
2800to load the \libreadline\ library dynamically whenever the \-be-\ option is
2801used without command line arguments. If successful, it uses the \*readline()*\
2802function, which provides extensive line-editing facilities, for reading the
2803test data. A line history is supported.
2804.nem
495ae4b0 2805
d43194df
PH
2806Long expansion expressions can be split over several lines by using backslash
2807continuations. As in Exim's run time configuration, whitespace at the start of
2808continuation lines is ignored. Each argument or data line is passed through the
2809string expansion mechanism, and the result is output. Variable values from the
2810configuration file (for example, \$qualify@_domain$\) are available, but no
2811message-specific values (such as \$domain$\) are set, because no message is
2812being processed.
495ae4b0
PH
2813
2814.option bF #<<filename>>
2815.index system filter||testing
2816.index testing||system filter
2817This option is the same as \-bf-\ except that it assumes that the filter being
2818tested is a system filter. The additional commands that are available only in
2819system filters are recognized.
2820
2821.option bf #<<filename>>
2822.index filter||testing
2823.index testing||filter file
2824.index forward file||testing
2825.index testing||forward file
2826.index Sieve filter||testing
d43194df
PH
2827This option runs Exim in user filter testing mode; the file is the filter file
2828to be tested, and a test message must be supplied on the standard input. If
2829there are no message-dependent tests in the filter, an empty file can be
2830supplied.
2831.em
2832If you want to test a system filter file, use \-bF-\ instead of \-bf-\. You can
2833use both \-bF-\ and \-bf-\ on the same command, in order to
2834test a system filter and a user filter in the same run. For example:
2835.display asis
2836exim -bF /system/filter -bf /user/filter </test/message
2837.endd
2838This is helpful when the system filter adds header lines or sets filter
2839variables that are used by the user filter.
2840.nem
2841
2842If the test filter file does not begin with one of the special lines
495ae4b0
PH
2843.display asis
2844# Exim filter
2845# Sieve filter
2846.endd
2847it is taken to be a normal \(.forward)\ file, and is tested for validity under
4964e932 2848that interpretation. See sections ~~SECTitenonfilred to ~~SECTspecitredli for a
495ae4b0
PH
2849description of the possible contents of non-filter redirection lists.
2850
2851The result of an Exim command that uses \-bf-\, provided no errors are
2852detected, is a list of the actions that Exim would try to take if presented
2853with the message for real. More details of filter testing are given in the
2854separate document entitled \*Exim's interfaces to mail filtering*\.
2855
2856.index `From' line
2857.index envelope sender
2858.index \-f-\ option||for filter testing
2859When testing a filter file, the envelope sender can be set by the \-f-\ option,
2860or by a `From ' line at the start of the test message. Various parameters that
2861would normally be taken from the envelope recipient address of the message can
d43194df
PH
2862be set by means of additional command line options (see the next four options).
2863
2864.em
2865.option bfd #<<domain>>
2866This sets the domain of the recipient address when a filter file is being
2867tested by means of the \-bf-\ option. The default is the value of
2868\$qualify@_domain$\.
2869
2870.option bfl #<<local part>>
2871This sets the local part of the recipient address when a filter file is being
2872tested by means of the \-bf-\ option. The default is the username of the
2873process that calls Exim. A local part should be specified with any prefix or
495ae4b0
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2874suffix stripped, because that is how it appears to the filter when a message is
2875actually being delivered.
2876
d43194df
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2877.option bfp #<<prefix>>
2878This sets the prefix of the local part of the recipient address when a filter
2879file is being tested by means of the \-bf-\ option. The default is an empty
2880prefix.
2881
2882.option bfp #<<suffix>>
2883This sets the suffix of the local part of the recipient address when a filter
2884file is being tested by means of the \-bf-\ option. The default is an empty
2885suffix.
2886.em
2887
2888
495ae4b0
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2889.option bh #<<IP address>>
2890.index testing||incoming SMTP
2891.index SMTP||testing incoming
2892.index testing||relay control
2893.index relaying||testing configuration
2894.index policy control||testing
2895.index debugging||\-bh-\ option
2896This option runs a fake SMTP session as if from the given IP address, using the
2897standard input and output. The IP address may include a port number at the end,
2898after a full stop. For example:
2899.display asis
2900exim -bh 10.9.8.7.1234
2901exim -bh fe80::a00:20ff:fe86:a061.5678
2902.endd
d43194df
PH
2903.em
2904When an IPv6 address is given, it is converted into canonical form. In the case
2905of the second example above, the value of \$sender@_host@_address$\ after
2906conversion to the canonical form is \"fe80:0000:0000:0a00:20ff:fe86:a061.5678"\.
2907.nem
2908
495ae4b0
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2909Comments as to what is going on are written to the standard error file. These
2910include lines beginning with `LOG' for anything that would have been logged.
4964e932
PH
2911This facility is provided for testing configuration options for incoming
2912messages, to make sure they implement the required policy. For example, you can
495ae4b0
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2913test your relay controls using \-bh-\.
2914
2915.index RFC 1413
2916\**Warning 1**\: You cannot test features of the configuration that rely on
2917ident (RFC 1413) callouts. These cannot be done when testing using
2918\-bh-\ because there is no incoming SMTP connection.
2919
2920\**Warning 2**\: Address verification callouts (see section ~~SECTcallver) are
4964e932 2921also skipped when testing using \-bh-\. If you want these callouts to occur,
495ae4b0
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2922use \-bhc-\ instead.
2923
2924Messages supplied during the testing session are discarded, and nothing is
2925written to any of the real log files. There may be pauses when DNS (and other)
2926lookups are taking place, and of course these may time out. The \-oMi-\ option
2927can be used to specify a specific IP interface and port if this is important.
2928
2929The \*exim@_checkaccess*\ utility is a `packaged' version of \-bh-\ whose
2930output just states whether a given recipient address from a given host is
2931acceptable or not. See section ~~SECTcheckaccess.
2932
2933.option bhc #<<IP address>>
4964e932
PH
2934This option operates in the same way as \-bh-\, except that address
2935verification callouts are performed if required. This includes consulting and
2936updating the callout cache database.
495ae4b0
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2937
2938.option bi
2939.index alias file||building
2940.index building alias file
2941.index Sendmail compatibility||\-bi-\ option
2942Sendmail interprets the \-bi-\ option as a request to rebuild its alias file.
2943Exim does not have the concept of a single alias file, and so it cannot mimic
2944this behaviour. However, calls to \(/usr/lib/sendmail)\ with the \-bi-\ option
2945tend to appear in various scripts such as NIS make files, so the option must be
2946recognized.
2947
2948If \-bi-\ is encountered, the command specified by the \bi@_command\
2949configuration option is run, under the uid and gid of the caller of Exim. If
2950the \-oA-\ option is used, its value is passed to the command as an argument.
2951The command set by \bi@_command\ may not contain arguments. The command can use
2952the \*exim@_dbmbuild*\ utility, or some other means, to rebuild alias files if
2953this is required. If the \bi@_command\ option is not set, calling Exim with
2954\-bi-\ is a no-op.
2955
2956.option bm
2957.index local message reception
2958This option runs an Exim receiving process that accepts an incoming,
2959locally-generated message on the current input. The recipients are given as the
2960command arguments (except when \-t-\ is also present -- see below). Each
2961argument can be a comma-separated list of RFC 2822 addresses. This is the
2962default option for selecting the overall action of an Exim call; it is assumed
2963if no other conflicting option is present.
2964
2965If any addresses in the message are unqualified (have no domain), they are
2966qualified by the values of the \qualify@_domain\ or \qualify@_recipient\
2967options, as appropriate. The \-bnq-\ option (see below) provides a way of
2968suppressing this for special cases.
2969
4964e932 2970Policy checks on the contents of local messages can be enforced by means of the
495ae4b0
PH
2971non-SMTP ACL. See chapter ~~CHAPACL for details.
2972.index return code||for \-bm-\
2973The return code is zero if the message is successfully accepted. Otherwise, the
2974action is controlled by the \-oe$it{x}-\ option setting -- see below.
2975
2976.index message||format
2977.index format||message
2978.index `From' line
2979.index UUCP||`From' line
2980.index Sendmail compatibility||`From' line
2981The format of the message must be as defined in RFC 2822, except that, for
2982compatibility with Sendmail and Smail, a line in one of the forms
2983.display
2984From sender Fri Jan 5 12:55 GMT 1997
2985From sender Fri, 5 Jan 97 12:55:01
2986.endd
2987(with the weekday optional, and possibly with additional text after the date)
2988is permitted to appear at the start of the message. There appears to be no
2989authoritative specification of the format of this line. Exim recognizes it by
2990matching against the regular expression defined by the \uucp@_from@_pattern\
4964e932 2991option, which can be changed if necessary.
495ae4b0
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2992.index \-f-\ option||overriding `From' line
2993The specified sender is treated as if it were given as the argument to the
2994\-f-\ option, but if a \-f-\ option is also present, its argument is used in
2995preference to the address taken from the message. The caller of Exim must be a
2996trusted user for the sender of a message to be set in this way.
2997
2998.option bnq
2999.index address||qualification, suppressing
3000By default, Exim automatically qualifies unqualified addresses (those
3001without domains) that appear in messages that are submitted locally (that
3002is, not over TCP/IP). This qualification applies both to addresses in
4964e932
PH
3003envelopes, and addresses in header lines. Sender addresses are qualified using
3004\qualify@_domain\, and recipient addresses using \qualify@_recipient\ (which
495ae4b0
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3005defaults to the value of \qualify@_domain\).
3006
3007Sometimes, qualification is not wanted. For example, if \-bS-\ (batch SMTP) is
3008being used to re-submit messages that originally came from remote hosts after
3009content scanning, you probably do not want to qualify unqualified addresses in
3010header lines. (Such lines will be present only if you have not enabled a header
3011syntax check in the appropriate ACL.)
3012
3013The \-bnq-\ option suppresses all qualification of unqualified addresses in
3014messages that originate on the local host. When this is used, unqualified
3015addresses in the envelope provoke errors (causing message rejection) and
3016unqualified addresses in header lines are left alone.
3017
3018
3019.option bP
3020.index configuration options, extracting
3021.index options||configuration, extracting
3022If this option is given with no arguments, it causes the values of all Exim's
3023main configuration options to be written to the standard output. The values
3024of one or more specific options can be requested by giving their names as
3025arguments, for example:
3026.display
3027exim -bP qualify@_domain hold@_domains
3028.endd
3029However, any option setting that is preceded by the word `hide' in the
3030configuration file is not shown in full, except to an admin user. For other
3031users, the output is as in this example:
3032.display asis
3033mysql_servers = <value not displayable>
3034.endd
3035If \configure@_file\ is given as an argument, the name of the run time
3036configuration file is output.
4964e932 3037If a list of configuration files was supplied, the value that is output here
495ae4b0
PH
3038is the name of the file that was actually used.
3039
3040.index daemon||process id (pid)
3041.index pid (process id)||of daemon
3042If \log__file__path\ or \pid@_file@_path\ are given, the names of the
3043directories where log files and daemon pid files are written are output,
3044respectively. If these values are unset, log files are written in a
3045sub-directory of the spool directory called \log\, and the pid file is written
3046directly into the spool directory.
3047
3048If \-bP-\ is followed by a name preceded by \"+"\, for example,
3049.display asis
3050exim -bP +local_domains
3051.endd
3052it searches for a matching named list of any type (domain, host, address, or
3053local part) and outputs what it finds.
3054
3055.index options||router, extracting
3056.index options||transport, extracting
3057If one of the words \router\, \transport\, or \authenticator\ is given,
3058followed by the name of an appropriate driver instance, the option settings for
3059that driver are output. For example:
3060.display
3061exim -bP transport local@_delivery
3062.endd
3063The generic driver options are output first, followed by the driver's private
3064options. A list of the names of drivers of a particular type can be obtained by
3065using one of the words \router@_list\, \transport@_list\, or
3066\authenticator@_list\, and a complete list of all drivers with their option
3067settings can be obtained by using \routers\, \transports\, or \authenticators\.
3068
3069
3070.option bp
3071.index queue||listing messages on
3072.index listing||messages on the queue
3073This option requests a listing of the contents of the mail queue on the
3074standard output. If the \-bp-\ option is followed by a list of message ids,
3075just those messages are listed. By default, this option can be used only by an
3076admin user. However, the \queue__list__requires__admin\ option can be set false
3077to allow any user to see the queue.
3078
3079Each message on the queue is displayed as in the following example:
3080.display
308125m 2.9K 0t5C6f-0000c8-00 <alice@@wonderland.fict.example>
3082 red.king@@looking-glass.fict.example
3083 <<other addresses>>
3084.endd
3085.index message||size in queue listing
3086.index size||of message
3087The first line contains the length of time the message has been on the queue
3088(in this case 25 minutes), the size of the message (2.9K), the unique local
3089identifier for the message, and the message sender, as contained in the
3090envelope. For bounce messages, the sender address is empty, and appears as
3091`<>'. If the message was submitted locally by an untrusted user who overrode
3092the default sender address, the user's login name is shown in parentheses
3093before the sender address.
3094.index frozen messages||in queue listing
3095If the message is frozen (attempts to deliver it are suspended) then the text
3096`$*$$*$$*$ frozen $*$$*$$*$' is displayed at the end of this line.
3097
3098The recipients of the message (taken from the envelope, not the headers) are
3099displayed on subsequent lines. Those addresses to which the message has already
3100been delivered are marked with the letter D. If an original address gets
3101expanded into several addresses via an alias or forward file, the original is
3102displayed with a D only when deliveries for all of its child addresses are
3103complete.
3104
3105
3106.option bpa
3107This option operates like \-bp-\, but in addition it shows delivered addresses
3108that were generated from the original top level address(es) in each message by
3109alias or forwarding operations. These addresses are flagged with `+D' instead
3110of just `D'.
3111
3112
3113.option bpc
3114.index queue||count of messages on
3115This option counts the number of messages on the queue, and writes the total
3116to the standard output. It is restricted to admin users, unless
3117\queue__list__requires__admin\ is set false.
3118
3119
3120.option bpr
3121This option operates like \-bp-\, but the output is not sorted into
3122chronological order of message arrival. This can speed it up when there are
3123lots of messages on the queue, and is particularly useful if the output is
3124going to be post-processed in a way that doesn't need the sorting.
3125
3126.option bpra
3127This option is a combination of \-bpr-\ and \-bpa-\.
3128
3129.option bpru
3130This option is a combination of \-bpr-\ and \-bpu-\.
3131
3132
3133.option bpu
3134This option operates like \-bp-\ but shows only undelivered top-level addresses
3135for each message displayed. Addresses generated by aliasing or forwarding are
3136not shown, unless the message was deferred after processing by a router with
3137the \one@_time\ option set.
3138
3139
3140.option brt
3141.index testing||retry configuration
3142.index retry||configuration testing
3143This option is for testing retry rules, and it must be followed by up to three
3144arguments. It causes Exim to look for a retry rule that matches the values
3145and to write it to the standard output. For example:
3146.display asis
3147exim -brt bach.comp.mus.example
3148Retry rule: *.comp.mus.example F,2h,15m; F,4d,30m;
3149.endd
3150See chapter ~~CHAPretry for a description of Exim's retry rules. The first
3151argument, which is required, can be a complete address in the form
3152\*local@_part@@domain*\, or it can be just a domain name. The second argument is
3153an optional second domain name; if no retry rule is found for the first
3154argument, the second is tried. This ties in with Exim's behaviour when looking
3155for retry rules for remote hosts -- if no rule is found that matches the host,
3156one that matches the mail domain is sought. The final argument is the name of a
3157specific delivery error, as used in setting up retry rules, for example
3158`quota@_3d'.
3159
3160.option brw
3161.index testing||rewriting
3162.index rewriting||testing
3163This option is for testing address rewriting rules, and it must be followed by
3164a single argument, consisting of either a local part without a domain, or a
3165complete address with a fully qualified domain. Exim outputs how this address
3166would be rewritten for each possible place it might appear. See chapter
3167~~CHAPrewrite for further details.
3168
3169.option bS
3170.index SMTP||batched incoming
3171.index batched SMTP input
3172This option is used for batched SMTP input, which is an alternative interface
3173for non-interactive local message submission. A number of messages can be
3174submitted in a single run. However, despite its name, this is not really SMTP
3175input. Exim reads each message's envelope from SMTP commands on the standard
3176input, but generates no responses. If the caller is trusted, or
3177\untrusted@_set@_sender\ is set, the senders in the SMTP \\MAIL\\ commands are
3178believed; otherwise the sender is always the caller of Exim.
3179
3180The message itself is read from the standard input, in SMTP format (leading
3181dots doubled), terminated by a line containing just a single dot. An error is
3182provoked if the terminating dot is missing. A further message may then follow.
3183
3184As for other local message submissions, the contents of incoming batch SMTP
3185messages can be checked using the non-SMTP ACL (see chapter ~~CHAPACL).
3186Unqualified addresses are automatically qualified using \qualify@_domain\ and
3187\qualify@_recipient\, as appropriate, unless the \-bnq-\ option is used.
3188
3189Some other SMTP commands are recognized in the input. \\HELO\\ and \\EHLO\\ act
3190as \\RSET\\; \\VRFY\\, \\EXPN\\, \\ETRN\\, and \\HELP\\ act as \\NOOP\\;
3191\\QUIT\\ quits, ignoring the rest of the standard input.
3192
3193If any error is encountered, reports are written to the standard output and
3194error streams, and Exim gives up immediately.
3195.index return code||for \-bS-\
3196The return code is 0 if no error was detected; it is 1 if one or more messages
3197were accepted before the error was detected; otherwise it is 2.
3198
3199More details of input using batched SMTP are given in section
3200~~SECTincomingbatchedSMTP.
3201
3202.option bs
3203.index SMTP||local input
3204.index local SMTP input
3205This option causes Exim to accept one or more messages by reading SMTP commands
3206on the standard input, and producing SMTP replies on the standard output. SMTP
4964e932 3207policy controls, as defined in ACLs (see chapter ~~CHAPACL) are applied.
495ae4b0
PH
3208
3209Some user agents use this interface as a way of passing locally-generated
3210messages to the MTA.
3211.index sender||source of
3212In this usage, if the caller of Exim is trusted, or \untrusted@_set@_sender\ is
3213set, the senders of messages are taken from the SMTP \\MAIL\\ commands.
3214Otherwise the content of these commands is ignored and the sender is set up as
3215the calling user. Unqualified addresses are automatically qualified using
3216\qualify@_domain\ and \qualify@_recipient\, as appropriate, unless the \-bnq-\
3217option is used.
3218
3219.index inetd
3220The \-bs-\ option is also used to run Exim from \*inetd*\, as an alternative to
3221using a listening daemon. Exim can distinguish the two cases by checking
4964e932
PH
3222whether the standard input is a TCP/IP socket. When Exim is called from
3223\*inetd*\, the source of the mail is assumed to be remote, and the comments
3224above concerning senders and qualification do not apply. In this situation,
3225Exim behaves in exactly the same way as it does when receiving a message via
495ae4b0
PH
3226the listening daemon.
3227
3228.option bt
3229.index testing||addresses
3230.index address||testing
3231This option runs Exim in address testing mode, in which each argument is taken
3232as an address to be tested for deliverability. The results are written to the
d43194df
PH
3233standard output. If a test fails, and the caller is not an admin user, no
3234details of the failure are output, because these might contain sensitive
3235information such as usernames and passwords for database lookups.
495ae4b0
PH
3236
3237If no arguments are given, Exim runs in an interactive manner, prompting with a
d43194df
PH
3238right angle bracket for addresses to be tested.
3239.em
3240Unlike the \-be-\ test option, you cannot arrange for Exim to use the
3241\*readline()*\ function, because it is running as \*root*\ and there are
3242security issues.
3243.nem
3244
3245Each address is handled as if it were the recipient address of a message
3246(compare the \-bv-\ option). It is passed to the routers and the result is
3247written to the standard output. However, any router that has
3248\no@_address@_test\ set is bypassed. This can make \-bt-\ easier to use for
3249genuine routing tests if your first router passes everything to a scanner
3250program.
495ae4b0
PH
3251
3252.index return code||for \-bt-\
3253The return code is 2 if any address failed outright; it is 1 if no address
3254failed outright but at least one could not be resolved for some reason. Return
3255code 0 is given only when all addresses succeed.
3256
3257\**Warning**\: \-bt-\ can only do relatively simple testing. If any of the
3258routers in the configuration makes any tests on the sender address of a
4964e932 3259message,
495ae4b0
PH
3260.index \-f-\ option||for address testing
3261you can use the \-f-\ option to set an appropriate sender when running
3262\-bt-\ tests. Without it, the sender is assumed to be the calling user at the
3263default qualifying domain. However, if you have set up (for example) routers
3264whose behaviour depends on the contents of an incoming message, you cannot test
3265those conditions using \-bt-\. The \-N-\ option provides a possible way of
3266doing such tests.
3267
3268.option bV
3269.index version number of Exim, verifying
3270This option causes Exim to write the current version number, compilation
3271number, and compilation date of the \*exim*\ binary to the standard output.
3272It also lists the DBM library this is being used, the optional modules (such as
3273specific lookup types), the drivers that are included in the binary, and the
3274name of the run time configuration file that is in use.
3275
d43194df
PH
3276.em
3277As part of its operation, \-bV-\ causes Exim to read and syntax check its
3278configuration file. However, this is a static check only. It cannot check
8408f763
PH
3279values that are to be expanded. For example, although a misspelt ACL verb is
3280detected, an error in the verb's arguments is not. You cannot rely on \-bV-\
3281alone to discover (for example) all the typos in the configuration; some
3282realistic testing is needed. The \-bh-\ and \-N-\ options provide more dynamic
3283testing facilities.
d43194df
PH
3284.nem
3285
3286
495ae4b0
PH
3287.option bv
3288.index verifying||address, using \-bv-\
3289.index address||verification
3290This option runs Exim in address verification mode, in which each argument is
3291taken as an address to be verified. During normal operation, verification
3292happens mostly as a consequence processing a \verify\ condition in an ACL (see
3293chapter ~~CHAPACL). If you want to test an entire ACL, see the \-bh-\ option.
3294
3295If verification fails, and the caller is not an admin user, no details of the
3296failure are output, because these might contain sensitive information such as
3297usernames and passwords for database lookups.
3298
3299If no arguments are given, Exim runs in an interactive manner, prompting with a
d43194df
PH
3300right angle bracket for addresses to be verified.
3301.em
3302Unlike the \-be-\ test option, you cannot arrange for Exim to use the
3303\*readline()*\ function, because it is running as \*exim*\ and there are
3304security issues.
3305.nem
3306
3307Verification differs from address testing (the \-bt-\ option) in that routers
3308that have \no@_verify\ set are skipped, and if the address is accepted by a
3309router that has \fail@_verify\ set, verification fails. The address is verified
3310as a recipient if \-bv-\ is used; to test verification for a sender address,
3311\-bvs-\ should be used.
495ae4b0
PH
3312
3313If the \-v-\ option is not set, the output consists of a single line for each
3314address, stating whether it was verified or not, and giving a reason in the
3315latter case. Otherwise, more details are given of how the address has been
3316handled, and in the case of address redirection, all the generated addresses
3317are also considered. Without \-v-\, generating more than one address by
3318redirection causes verification to end sucessfully.
3319
3320.index return code||for \-bv-\
3321The return code is 2 if any address failed outright; it is 1 if no address
3322failed outright but at least one could not be resolved for some reason. Return
3323code 0 is given only when all addresses succeed.
3324
3325If any of the routers in the configuration makes any tests on the sender
3326address of a message, you should use the \-f-\ option to set an appropriate
3327sender when running \-bv-\ tests. Without it, the sender is assumed to be the
3328calling user at the default qualifying domain.
3329
3330.option bvs
3331This option acts like \-bv-\, but verifies the address as a sender rather
3332than a recipient address. This affects any rewriting and qualification that
3333might happen.
3334
3335.option C #<<filelist>>
3336.index configuration file||alternate
3337.index \\CONFIGURE@_FILE\\
3338.index alternate configuration file
3339This option causes Exim to find the run time configuration file from the given
3340list instead of from the list specified by the \\CONFIGURE@_FILE\\
3341compile-time setting. Usually, the list will consist of just a single file
3342name, but it can be a colon-separated list of names. In this case, the first
3343file that exists is used. Failure to open an existing file stops Exim from
3344proceeding any further along the list, and an error is generated.
3345
d43194df
PH
3346When this option is used by a caller other than root or the Exim user, and the
3347list is different from the compiled-in list, Exim gives up its root privilege
3348immediately, and runs with the real and effective uid and gid set to those of
3349the caller. However, if \\ALT@_CONFIG@_ROOT@_ONLY\\ is defined in
3350\(Local/Makefile)\, root privilege is retained for \-C-\ only if the caller of
3351Exim is root.
3352.em
3353That is, the Exim user is no longer privileged in this regard. This build-time
3354option is not set by default in the Exim source distribution tarbundle.
3355However, if you are using a `packaged' version of Exim (source or binary), the
3356packagers might have enabled it.
3357.nem
495ae4b0
PH
3358
3359Setting \\ALT@_CONFIG@_ROOT@_ONLY\\ locks out the possibility of testing a
3360configuration using \-C-\ right through message reception and delivery, even if
3361the caller is root. The reception works, but by that time, Exim is running as
3362the Exim user, so when it re-execs to regain privilege for the delivery, the
3363use of \-C-\ causes privilege to be lost. However, root can test reception and
4964e932 3364delivery using two separate commands (one to put a message on the queue, using
495ae4b0
PH
3365\-odq-\, and another to do the delivery, using \-M-\).
3366
3367If \\ALT@_CONFIG@_PREFIX\\ is defined \(in Local/Makefile)\, it specifies a
3368prefix string with which any file named in a \-C-\ command line option
3369must start. In addition, the file name must not contain the sequence \"/../"\.
3370However, if the value of the \-C-\ option is identical to the value of
3371\\CONFIGURE@_FILE\\ in \(Local/Makefile)\, Exim ignores \-C-\ and proceeds as
4964e932 3372usual. There is no default setting for \\ALT@_CONFIG@_PREFIX\\; when it is
495ae4b0
PH
3373unset, any file name can be used with \-C-\.
3374
3375\\ALT@_CONFIG@_PREFIX\\ can be used to confine alternative configuration files
3376to a directory to which only root has access. This prevents someone who has
3377broken into the Exim account from running a privileged Exim with an arbitrary
3378configuration file.
3379
3380The \-C-\ facility is useful for ensuring that configuration files are
3381syntactically correct, but cannot be used for test deliveries, unless the
3382caller is privileged, or unless it is an exotic configuration that does not
3383require privilege. No check is made on the owner or group of the files
3384specified by this option.
3385
3386.option D <<macro>>=<<value>>
3387.index macro||setting on command line
3388This option can be used to override macro definitions in the configuration file
3389(see section ~~SECTmacrodefs). However, like \-C-\, if it is used by an
4964e932 3390unprivileged caller, it causes Exim to give up its root privilege.
495ae4b0
PH
3391If \\DISABLE@_D@_OPTION\\ is defined in \(Local/Makefile)\, the use of \-D-\ is
3392completely disabled, and its use causes an immediate error exit.
3393
3394The entire option (including equals sign if present) must all be within one
4964e932
PH
3395command line item. \-D-\ can be used to set the value of a macro to the empty
3396string, in which case the equals sign is optional. These two commands are
495ae4b0
PH
3397synonymous:
3398.display asis
3399exim -DABC ...
3400exim -DABC= ...
3401.endd
4964e932
PH
3402To include spaces in a macro definition item, quotes must be used. If you use
3403quotes, spaces are permitted around the macro name and the equals sign. For
495ae4b0
PH
3404example:
3405.display asis
3406exim '-D ABC = something' ...
3407.endd
3408\-D-\ may be repeated up to 10 times on a command line.
3409
3410.option d <<debug options>>
3411.index debugging||list of selectors
3412.index debugging||\-d-\ option
3413This option causes debugging information to be written to the standard
3414error stream. It is restricted to admin users because debugging output may show
3415database queries that contain password information. Also, the details of users'
3416filter files should be protected. When \-d-\ is used, \-v-\ is assumed. If
3417\-d-\ is given on its own, a lot of standard debugging data is output. This can
3418be reduced, or increased to include some more rarely needed information, by
3419following \-d-\ with a string made up of names preceded by plus or minus
3420characters. These add or remove sets of debugging data, respectively. For
3421example, \-d+filter-\ adds filter debugging, whereas \-d-all+filter-\ selects
3422only filter debugging. The available debugging categories are:
3423.display flow
3424.tabs 21
3425.
3426. The odd formatting of the lines below is deliberate. It does not affect the
3427. SGCAL output, but by putting in the space it keeps things aligned in the man
3428. page that is automatically generated from this text.
3429.
3430acl $t $rm{ACL interpretation}
3431auth $t $rm{authenticators}
3432deliver $t $rm{general delivery logic}
3433dns $t $rm{DNS lookups (see also resolver)}
3434dnsbl $t $rm{DNS black list (aka RBL) code}
3435exec $t $rm{arguments for \execv@(@)\ calls}
3436expand $t $rm{detailed debugging for string expansions}
3437filter $t $rm{filter handling}
3438hints@_lookup $t $rm{hints data lookups}
3439host@_lookup $t $rm{all types of name-to-IP address handling}
3440ident $t $rm{ident lookup}
3441interface $t $rm{lists of local interfaces}
3442lists $t $rm{matching things in lists}
3443load $t $rm{system load checks}
4964e932 3444local@_scan $t $rm{can be used by \*local@_scan()*\ (see chapter ~~CHAPlocalscan)}
495ae4b0
PH
3445lookup $t $rm{general lookup code and all lookups}
3446memory $t $rm{memory handling}
3447pid $t $rm{add pid to debug output lines}
3448process@_info $t $rm{setting info for the process log}
3449queue@_run $t $rm{queue runs}
3450receive $t $rm{general message reception logic}
3451resolver $t $rm{turn on the DNS resolver's debugging output}
3452retry $t $rm{retry handling}
3453rewrite $t $rm{address rewriting}
3454route $t $rm{address routing}
3455timestamp $t $rm{add timestamp to debug output lines}
3456tls $t $rm{TLS logic}
3457transport $t $rm{transports}
3458uid $t $rm{changes of uid/gid and looking up uid/gid}
3459verify $t $rm{address verification logic}
3460
3461all $t $rm{all of the above, and also \-v-\}
3462.endd
495ae4b0
PH
3463.index resolver, debugging output
3464.index DNS||resolver, debugging output
4964e932 3465The \"resolver"\ option produces output only if the DNS resolver was compiled
495ae4b0
PH
3466with \\DEBUG\\ enabled. This is not the case in some operating systems. Also,
3467unfortunately, debugging output from the DNS resolver is written to stdout
3468rather than stderr.
495ae4b0
PH
3469
3470The default (\-d-\ with no argument) omits \"expand"\, \"filter"\,
3471\"interface"\, \"load"\, \"memory"\, \"pid"\, \"resolver"\, and \"timestamp"\.
3472However, the \"pid"\ selector is forced when debugging is turned on for a
3473daemon, which then passes it on to any re-executed Exims. Exim also
3474automatically adds the pid to debug lines when several remote deliveries are
3475run in parallel.
3476
3477The \"timestamp"\ selector causes the current time to be inserted at the start
3478of all debug output lines. This can be useful when trying to track down delays
3479in processing.
3480
3481If the \debug@_print\ option is set in any driver, it produces output whenever
3482any debugging is selected, or if \-v-\ is used.
3483
d43194df
PH
3484.em
3485.option dd <<debug options>>
3486This option behaves exactly like \-d-\ except when used on a command that
3487starts a daemon process. In that case, debugging is turned off for the
3488subprocesses that the daemon creates. Thus, it is useful for monitoring the
3489behaviour of the daemon without creating as much output as full debugging does.
3490.nem
3491
495ae4b0 3492.option dropcr
4964e932
PH
3493This is an obsolete option that is now a no-op. It used to affect the way Exim
3494handled CR and LF characters in incoming messages. What happens now is
495ae4b0
PH
3495described in section ~~SECTlineendings.
3496
3497
3498.option E
3499.index bounce message||generating
3500This option specifies that an incoming message is a locally-generated delivery
3501failure report. It is used internally by Exim when handling delivery failures
3502and is not intended for external use. Its only effect is to stop Exim
3503generating certain messages to the postmaster, as otherwise message cascades
3504could occur in some situations. As part of the same option, a message id may
3505follow the characters \-E-\. If it does, the log entry for the receipt of the
3506new message contains the id, following `R=', as a cross-reference.
3507
3508.option e$it{x}
3509There are a number of Sendmail options starting with \-oe-\ which seem to be
3510called by various programs without the leading \o\ in the option. For example,
3511the \vacation\ program uses \-eq-\. Exim treats all options of the form
3512\-e$it{x}-\ as synonymous with the corresponding \-oe$it{x}-\ options.
3513
3514.option F #<<string>>
3515.index sender||name
3516.index name||of sender
3517This option sets the sender's full name for use when a locally-generated
3518message is being accepted. In the absence of this option, the user's \*gecos*\
3519entry from the password data is used. As users are generally permitted to alter
3520their \*gecos*\ entries, no security considerations are involved. White space
3521between \-F-\ and the <<string>> is optional.
3522
3523.option f #<<address>>
3524.index sender||address
3525.index address||sender
3526.index trusted user
3527.index envelope sender
3528.index user||trusted
3529This option sets the address of the envelope sender of a locally-generated
3530message (also known as the return path). The option can normally be used only
3531by a trusted user, but \untrusted@_set@_sender\ can be set to allow untrusted
d43194df
PH
3532users to use it.
3533.em
3534Processes running as root or the Exim user are always trusted. Other
3535trusted users are defined by the \trusted@_users\ or \trusted@_groups\ options.
3536
3537In the absence of \-f-\, or if the caller is not trusted, the sender of a local
3538message is set to the caller's login name at the default qualify domain.
495ae4b0 3539
4964e932 3540There is one exception to the restriction on the use of \-f-\: an empty sender
d43194df
PH
3541can be specified by any user, trusted or not,
3542.nem
3543to create a message that can never provoke a bounce. An empty sender can be
3544specified either as an empty string, or as a pair of angle brackets with
3545nothing between them, as in these examples of shell commands:
495ae4b0
PH
3546.display asis
3547exim -f '<>' user@domain
3548exim -f "" user@domain
3549.endd
3550In addition, the use of \-f-\ is not restricted when testing a filter file with
3551\-bf-\ or when testing or verifying addresses using the \-bt-\ or \-bv-\
3552options.
3553
3554Allowing untrusted users to change the sender address does not of itself make
3555it possible to send anonymous mail. Exim still checks that the ::From:: header
3556refers to the local user, and if it does not, it adds a ::Sender:: header,
3557though this can be overridden by setting \no@_local@_from@_check\.
3558
3559.index `From' line
3560White space between \-f-\ and the <<address>> is optional
3561(that is, they can be given as two arguments or one combined argument).
3562The sender of a locally-generated message can also be set (when permitted) by
3563an initial `From ' line in the message -- see the description of \-bm-\ above
3564-- but if \-f-\ is also present, it overrides `From'.
3565
3566.option G
3567.index Sendmail compatibility||\-G-\ option ignored
3568This is a Sendmail option which is ignored by Exim.
3569
3570.option h #<<number>>
3571.index Sendmail compatibility||\-h-\ option ignored
3572This option is accepted for compatibility with Sendmail, but has no effect. (In
3573Sendmail it overrides the `hop count' obtained by counting ::Received::
3574headers.)
3575
3576.option i
3577.index Solaris||\*mail*\ command
3578.index dot||in incoming, non-SMTP message
3579This option, which has the same effect as \-oi-\, specifies that a dot on a
3580line by itself should not terminate an incoming, non-SMTP message. I can find
3581no documentation for this option in Solaris 2.4 Sendmail, but the \*mailx*\
3582command in Solaris 2.4 uses it. See also \-ti-\.
3583
3584.option M #<<message id>>#<<message id>> ...
3585.index forcing delivery
3586.index delivery||forcing attempt
3587.index frozen messages||forcing delivery
3588This option requests Exim to run a delivery attempt on each message in turn. If
3589any of the messages are frozen, they are automatically thawed before the
3590delivery attempt. The settings of \queue@_domains\, \queue@_smtp@_domains\, and
4964e932 3591\hold@_domains\ are ignored.
495ae4b0
PH
3592.index hints database||overriding retry hints
3593Retry hints for any of the addresses are
3594overridden -- Exim tries to deliver even if the normal retry time has not yet
3595been reached. This option requires the caller to be an admin user. However,
3596there is an option called \prod@_requires@_admin\ which can be set false to
3597relax this restriction (and also the same requirement for the \-q-\, \-R-\, and
3598\-S-\ options).
3599
3600
3601.option Mar #<<message id>>#<<address>>#<<address>> ...
3602.index message||adding recipients
3603.index recipient||adding
3604This option requests Exim to add the addresses to the list of recipients of the
3605message (`ar' for `add recipients'). The first argument must be a message id,
3606and the remaining ones must be email addresses. However, if the message is
3607active (in the middle of a delivery attempt), it is not altered. This option
3608can be used only by an admin user.
3609
3610.index SMTP||passed connection
3611.index SMTP||multiple deliveries
3612.index multiple SMTP deliveries
3613.option MC #<<transport>>#<<hostname>>#<<sequence number>>#<<message id>>
3614This option is not intended for use by external callers. It is used internally
3615by Exim to invoke another instance of itself to deliver a waiting message using
3616an existing SMTP connection, which is passed as the standard input. Details are
3617given in chapter ~~CHAPSMTP. This must be the final option, and the caller must
3618be root or the Exim user in order to use it.
3619
3620.option MCA
3621This option is not intended for use by external callers. It is used internally
3622by Exim in conjunction with the \-MC-\ option. It signifies that the connection
3623to the remote host has been authenticated.
3624
3625.option MCP
4964e932
PH
3626This option is not intended for use by external callers. It is used internally
3627by Exim in conjunction with the \-MC-\ option. It signifies that the server to
495ae4b0
PH
3628which Exim is connected supports pipelining.
3629
3630.option MCQ #<<process id>> <<pipe fd>>
3631This option is not intended for use by external callers. It is used internally
3632by Exim in conjunction with the \-MC-\ option when the original delivery was
3633started by a queue runner. It passes on the process id of the queue runner,
3634together with the file descriptor number of an open pipe. Closure of the pipe
3635signals the final completion of the sequence of processes that are passing
3636messages through the same SMTP connection.
3637
3638.option MCS
3639This option is not intended for use by external callers. It is used internally
3640by Exim in conjunction with the \-MC-\ option, and passes on the fact that the
3641SMTP \\SIZE\\ option should be used on messages delivered down the existing
3642connection.
3643
3644.option MCT
3645This option is not intended for use by external callers. It is used internally
3646by Exim in conjunction with the \-MC-\ option, and passes on the fact that the
3647host to which Exim is connected supports TLS encryption.
3648
3649.option Mc #<<message id>>#<<message id>> ...
3650.index hints database||not overridden by \-Mc-\
3651.index delivery||manually started, not forced
3652This option requests Exim to run a delivery attempt on each message in turn,
3653but unlike the \-M-\ option, it does check for retry hints, and respects any
3654that are found. This option is not very useful to external callers. It is
3655provided mainly for internal use by Exim when it needs to re-invoke itself in
3656order to regain root privilege for a delivery (see chapter ~~CHAPsecurity).
3657However, \-Mc-\ can be useful when testing, in order to run a delivery that
3658respects retry times and other options such as \hold@_domains\ that are
3659overridden when \-M-\ is used. Such a delivery does not count as a queue run.
3660If you want to run a specific delivery as if in a queue run, you should use
3661\-q-\ with a message id argument. A distinction between queue run deliveries
3662and other deliveries is made in one or two places.
3663
3664.option Mes #<<message id>>#<<address>>
3665.index message||changing sender
3666.index sender||changing
3667This option requests Exim to change the sender address in the message to the
3668given address, which must be a fully qualified address or `<>' (`es' for `edit
3669sender'). There must be exactly two arguments. The first argument must be a
3670message id, and the second one an email address. However, if the message is
3671active (in the middle of a delivery attempt), its status is not altered. This
3672option can be used only by an admin user.
3673
3674.option Mf #<<message id>>#<<message id>> ...
3675.index freezing messages
3676.index message||manually freezing
3677This option requests Exim to mark each listed message as `frozen'. This
3678prevents any delivery attempts taking place until the message is `thawed',
3679either manually or as a result of the \auto@_thaw\ configuration option.
3680However, if any of the messages are active (in the middle of a delivery
3681attempt), their status is not altered. This option can be used only by an admin
3682user.
3683
3684.option Mg #<<message id>>#<<message id>> ...
3685.index giving up on messages
3686.index message||abandoning delivery attempts
3687.index delivery||abandoning further attempts
3688This option requests Exim to give up trying to deliver the listed messages,
3689including any that are frozen. However, if any of the messages are active,
4964e932 3690their status is not altered.
495ae4b0
PH
3691For non-bounce messages, a delivery error message is sent to the sender,
3692containing the text `cancelled by administrator'. Bounce messages are just
3693discarded.
3694This option can be used only by an admin user.
3695
3696.option Mmad #<<message id>>#<<message id>> ...
3697.index delivery||cancelling all
3698This option requests Exim to mark all the recipient addresses in the messages
3699as already delivered (`mad' for `mark all delivered'). However, if any message
3700is active (in the middle of a delivery attempt), its status is not altered.
3701This option can be used only by an admin user.
3702
3703.option Mmd #<<message id>>#<<address>>#<<address>> ...
3704.index delivery||cancelling by address
3705.index recipient||removing
3706.index removing recipients
3707This option requests Exim to mark the given addresses as already delivered
3708(`md' for `mark delivered'). The first argument must be a message id, and the
3709remaining ones must be email addresses. These are matched to recipient
3710addresses in the message in a case-sensitive manner. If the message is active
3711(in the middle of a delivery attempt), its status is not altered. This option
3712can be used only by an admin user.
3713
3714.option Mrm #<<message id>>#<<message id>> ...
3715.index removing messages
3716.index abandoning mail
3717.index message||manually discarding
3718This option requests Exim to remove the given messages from the queue. No
3719bounce messages are sent; each message is simply forgotten. However, if any of
3720the messages are active, their status is not altered. This option can be used
3721only by an admin user or by the user who originally caused the message to be
3722placed on the queue.
3723
3724.option Mt #<<message id>>#<<message id>> ...
3725.index thawing messages
3726.index unfreezing messages
3727.index frozen messages||thawing
3728.index message||thawing frozen
3729This option requests Exim to `thaw' any of the listed messages that are
3730`frozen', so that delivery attempts can resume. However, if any of the messages
3731are active, their status is not altered. This option can be used only by an
3732admin user.
3733
3734.option Mvb #<<message id>>
3735.index listing||message body
3736.index message||listing body of
3737This option causes the contents of the message body (-D) spool file to be
3738written to the standard output. This option can be used only by an admin user.
3739
3740.option Mvh #<<message id>>
3741.index listing||message headers
3742.index header lines||listing
3743.index message||listing header lines
3744This option causes the contents of the message headers (-H) spool file to be
3745written to the standard output. This option can be used only by an admin user.
3746
3747.option Mvl #<<message id>>
3748.index listing||message log
3749.index message||listing message log
3750This option causes the contents of the message log spool file to be written to
3751the standard output. This option can be used only by an admin user.
3752
3753.option m
3754This is apparently a synonym for \-om-\ that is accepted by Sendmail, so Exim
3755treats it that way too.
3756
3757.option N
3758.index debugging||\-N-\ option
3759.index debugging||suppressing delivery
3760This is a debugging option that inhibits delivery of a message at the transport
3761level. It implies \-v-\. Exim goes through many of the motions of delivery --
3762it just doesn't actually transport the message, but instead behaves as if it
3763had successfully done so. However, it does not make any updates to the retry
3764database, and the log entries for deliveries are flagged with `$*$>' rather
3765than `=>'.
3766
3767Because \-N-\ discards any message to which it applies, only root or the Exim
3768user are allowed to use it with \-bd-\, \-q-\, \-R-\ or \-M-\. In other words,
3769an ordinary user can use it only when supplying an incoming message to which it
3770will apply. Although transportation never fails when \-N-\ is set, an address
3771may be deferred because of a configuration problem on a transport, or a routing
3772problem. Once \-N-\ has been used for a delivery attempt, it sticks to the
3773message, and applies to any subsequent delivery attempts that may happen for
3774that message.
3775
3776.option n
3777.index Sendmail compatibility||\-n-\ option ignored
3778This option is interpreted by Sendmail to mean `no aliasing'. It is ignored by
3779Exim.
3780
3781.option O #<<data>>
4964e932 3782This option is interpreted by Sendmail to mean `set option`. It is ignored by
495ae4b0
PH
3783Exim.
3784
3785.option oA #<<file name>>
3786.index Sendmail compatibility||\-oA-\ option
3787This option is used by Sendmail in conjunction with \-bi-\ to specify an