. ///////////////////////////////////////////////////////////////////////////// . This is the primary source of the Exim Manual. It is an xfpt document that is . converted into DocBook XML for subsequent conversion into printable and online . formats. The markup used herein is "standard" xfpt markup, with some extras. . The markup is summarized in a file called Markup.txt. . . WARNING: When you use the .new macro, make sure it appears *before* any . adjacent index items; otherwise you get an empty "paragraph" which causes . unwanted vertical space. . ///////////////////////////////////////////////////////////////////////////// .include stdflags .include stdmacs . ///////////////////////////////////////////////////////////////////////////// . This outputs the standard DocBook boilerplate. . ///////////////////////////////////////////////////////////////////////////// .docbook . ///////////////////////////////////////////////////////////////////////////// . These lines are processing instructions for the Simple DocBook Processor that . Philip Hazel has developed as a less cumbersome way of making PostScript and . PDFs than using xmlto and fop. They will be ignored by all other XML . processors. . ///////////////////////////////////////////////////////////////////////////// .literal xml .literal off . ///////////////////////////////////////////////////////////////////////////// . This generates the outermost element that wraps the entire document. . ///////////////////////////////////////////////////////////////////////////// .book . ///////////////////////////////////////////////////////////////////////////// . These definitions set some parameters and save some typing. . Update the Copyright year (only) when changing content. . ///////////////////////////////////////////////////////////////////////////// .set previousversion "4.98" .include ./local_params .set ACL "access control lists (ACLs)" .set I "    " .set drivernamemax "64" .macro copyyear 2024 .endmacro . ///////////////////////////////////////////////////////////////////////////// . Additional xfpt markup used by this document, over and above the default . provided in the xfpt library. . ///////////////////////////////////////////////////////////////////////////// . --- Override the &$ flag to automatically insert a $ with the variable name. .flag &$ $& "$" "" . --- Short flags for daggers in option headings. They will always be inside . --- an italic string, but we want the daggers to be in Roman. .flag &!! "†" .flag &!? "‡" . --- A macro for an Exim option definition heading, generating a one-line . --- table with four columns. For cases when the option name is given with . --- a space, so that it can be split, a fifth argument is used for the . --- index entry. . --- Also one for multiple option def headings be grouped in a single . --- table (but without the split capability). .macro otable .itable all 0 0 4 8* left 6* center 6* center 6* right .endmacro .macro orow .row "&%$1%&" "Use: &'$2'&" "Type: &'$3'&" "Default: &'$4'&" .endmacro .macro option .arg 5 .oindex "&%$5%&" .endarg .arg -5 .oindex "&%$1%&" .endarg .otable .orow "$1" "$2" "$3" "$4" .endtable .endmacro .macro options .eacharg .oindex "&%$+1%&" .endeach 4 .otable .eacharg .orow "$+1" "$+2" "$+3" "$+4" .endeach 4 .endtable .endmacro . --- A macro for the common 2-column tables. The width of the first column . --- is suitable for the many tables at the start of the main options chapter; . --- a small number of other 2-column tables override it. .macro table2 196pt 254pt .itable none 0 0 2 $1 left $2 left .endmacro . --- A macro for a plain variable, including the .vitem and .vindex .macro var .vitem $1 .vindex $1 .endmacro . --- A macro for a "tainted" marker, done as a one-element table .macro tmark .itable none 0 0 1 10pt left .row &'Tainted'& .endtable .endmacro . --- A macro for a tainted variable, adding a taint-marker .macro tvar .var $1 .tmark .endmacro . --- A macro for a cmdline option, including a .oindex . --- 1st arg is the option name, undecorated (we do that here). . --- 2nd arg, optional, text (decorated as needed) to be appended to the name .macro cmdopt .vitem &%$1%&$=2+&~$2+ .oindex &%$1%& .endmacro . --- A macro that generates .row, but puts &I; at the start of the first . --- argument, thus indenting it. Assume a minimum of two arguments, and . --- allow up to four arguments, which is as many as we'll ever need. .macro irow .arg 4 .row "&I;$1" "$2" "$3" "$4" .endarg .arg -4 .arg 3 .row "&I;$1" "$2" "$3" .endarg .arg -3 .row "&I;$1" "$2" .endarg .endarg .endmacro . --- Macros for option, variable, and concept index entries. For a "range" . --- style of entry, use .scindex for the start and .ecindex for the end. The . --- first argument of .scindex and the only argument of .ecindex must be the . --- ID that ties them together. . --- The index entry points to the most-recent chapter head, section or subsection . --- head, or list-item. .macro cindex && &&$1&& .arg 2 &&$2&& .endarg && .endmacro .macro scindex && &&$2&& .arg 3 &&$3&& .endarg && .endmacro .macro ecindex && .endmacro .macro oindex && &&$1&& .arg 2 &&$2&& .endarg && .endmacro . --- The index entry points to the most-recent chapter head, section or subsection . --- head, or varlist item. .macro vindex && &&$1&& .arg 2 &&$2&& .endarg && .endmacro .macro index .echo "** Don't use .index; use .cindex or .oindex or .vindex" .endmacro . use this for a concept-index entry for a header line .macro chindex .cindex "&'$1'& header line" .cindex "header lines" $1 .endmacro . //////////////////////////////////////////////////////////////////////////// . //////////////////////////////////////////////////////////////////////////// . The element is removed from the XML before processing for ASCII . output formats. . //////////////////////////////////////////////////////////////////////////// .literal xml Specification of the Exim Mail Transfer Agent The Exim MTA .fulldate EximMaintainers EM .versiondatexml EM .copyyear The Exim Maintainers .literal off . ///////////////////////////////////////////////////////////////////////////// . These implement index entries of the form "x, see y" and "x, see also y". . However, the DocBook DTD doesn't allow entries . at the top level, so we have to put the .chapter directive first. . ///////////////////////////////////////////////////////////////////////////// .chapter "Introduction" "CHID1" .macro seeother .literal xml $3 .arg 5 $5 .endarg <$1>$4 .literal off .endmacro . NB: for the 4-arg variant the ordering is awkward .macro see .seeother see "$1" "$2" "$3" "$4" .endmacro .macro seealso .seeother seealso "$1" "$2" "$3" "$4" .endmacro .see variable "$1, $2, etc." "numerical variables" .see concept address rewriting rewriting .see concept "Bounce Address Tag Validation" BATV .see concept "Client SMTP Authorization" CSA .see concept "CR character" "carriage return" .see concept CRL "certificate revocation list" .seealso concept de-tainting "tainted data" .see concept delivery "bounce message" "failure report" .see concept dialup "intermittently connected hosts" .see concept exiscan "content scanning" .see concept fallover fallback .see concept filter "Sieve filter" Sieve .see concept headers "header lines" .see concept ident "RFC 1413" .see concept "LF character" "linefeed" .seealso concept maximum limit .see concept monitor "Exim monitor" .see concept "no_xxx" "entry for xxx" .see concept NUL "binary zero" .see concept "passwd file" "/etc/passwd" .see concept "process id" pid .see concept RBL "DNS list" .see concept redirection "address redirection" .see concept "return path" "envelope sender" .see concept scanning "content scanning" .see concept SSL TLS .see concept string expansion expansion .see concept "top bit" "8-bit characters" .see concept variables "expansion, variables" .see concept "zero, binary" "binary zero" . ///////////////////////////////////////////////////////////////////////////// . This is the real start of the first chapter. See the comment above as to why . we can't have the .chapter line here. . chapter "Introduction" . ///////////////////////////////////////////////////////////////////////////// Exim is a mail transfer agent (MTA) for hosts that are running Unix or Unix-like operating systems. It was designed on the assumption that it would be run on hosts that are permanently connected to the Internet. However, it can be used on intermittently connected hosts with suitable configuration adjustments. Configuration files currently exist for the following operating systems: AIX, BSD/OS (aka BSDI), Darwin (Mac OS X), DGUX, Dragonfly, FreeBSD, GNU/Hurd, GNU/Linux, HI-OSF (Hitachi), HI-UX, HP-UX, IRIX, MIPS RISCOS, NetBSD, OpenBSD, OpenUNIX, QNX, SCO, SCO SVR4.2 (aka UNIX-SV), Solaris (aka SunOS5), SunOS4, Tru64-Unix (formerly Digital UNIX, formerly DEC-OSF1), Ultrix, and UnixWare. Some of these operating systems are no longer current and cannot easily be tested, so the configuration files may no longer work in practice. There are also configuration files for compiling Exim in the Cygwin environment that can be installed on systems running Windows. However, this document does not contain any information about running Exim in the Cygwin environment. The terms and conditions for the use and distribution of Exim are contained in the file &_NOTICE_&. Exim is distributed under the terms of the GNU General Public Licence, a copy of which may be found in the file &_LICENCE_&. The use, supply, or promotion of Exim for the purpose of sending bulk, unsolicited electronic mail is incompatible with the basic aims of Exim, which revolve around the free provision of a service that enhances the quality of personal communications. The author of Exim regards indiscriminate mass-mailing as an antisocial, irresponsible abuse of the Internet. Exim owes a great deal to Smail 3 and its author, Ron Karr. Without the experience of running and working on the Smail 3 code, I could never have contemplated starting to write a new MTA. Many of the ideas and user interfaces were originally taken from Smail 3, though the actual code of Exim is entirely new, and has developed far beyond the initial concept. Many people, both in Cambridge and around the world, have contributed to the development and the testing of Exim, and to porting it to various operating systems. I am grateful to them all. The distribution now contains a file called &_ACKNOWLEDGMENTS_&, in which I have started recording the names of contributors. .section "Exim documentation" "SECID1" . Keep this example change bar when updating the documentation! .new .cindex "documentation" This edition of the Exim specification applies to version &version() of Exim. Substantive changes from the &previousversion; edition are marked in some renditions of this document; this paragraph is so marked if the rendition is capable of showing a change indicator. .wen This document is very much a reference manual; it is not a tutorial. The reader is expected to have some familiarity with the SMTP mail transfer protocol and with general Unix system administration. Although there are some discussions and examples in places, the information is mostly organized in a way that makes it easy to look up, rather than in a natural order for sequential reading. Furthermore, this manual aims to cover every aspect of Exim in detail, including a number of rarely-used, special-purpose features that are unlikely to be of very wide interest. .cindex "books about Exim" An &"easier"& discussion of Exim which provides more in-depth explanatory, introductory, and tutorial material can be found in a book entitled &'The Exim SMTP Mail Server'& (second edition, 2007), published by UIT Cambridge (&url(https://www.uit.co.uk/exim-book/)). The book also contains a chapter that gives a general introduction to SMTP and Internet mail. Inevitably, however, the book is unlikely to be fully up-to-date with the latest release of Exim. (Note that the earlier book about Exim, published by O'Reilly, covers Exim 3, and many things have changed in Exim 4.) .cindex "Debian" "information sources" If you are using a Debian distribution of Exim, you will find information about Debian-specific features in the file &_/usr/share/doc/exim4-base/README.Debian_&. The command &(man update-exim.conf)& is another source of Debian-specific information. .cindex "&_doc/NewStuff_&" .cindex "&_doc/ChangeLog_&" .cindex "change log" As Exim develops, there may be features in newer versions that have not yet made it into this document, which is updated only when the most significant digit of the fractional part of the version number changes. Specifications of new features that are not yet in this manual are placed in the file &_doc/NewStuff_& in the Exim distribution. Some features may be classified as &"experimental"&. These may change incompatibly while they are developing, or even be withdrawn. For this reason, they are not documented in this manual. Information about experimental features can be found in the file &_doc/experimental.txt_&. All changes to Exim (whether new features, bug fixes, or other kinds of change) are noted briefly in the file called &_doc/ChangeLog_&. .cindex "&_doc/spec.txt_&" This specification itself is available as an ASCII file in &_doc/spec.txt_& so that it can easily be searched with a text editor. Other files in the &_doc_& directory are: .table2 100pt .row &_OptionLists.txt_& "list of all options in alphabetical order" .row &_dbm.discuss.txt_& "discussion about DBM libraries" .row &_exim.8_& "a man page of Exim's command line options" .row &_experimental.txt_& "documentation of experimental features" .row &_filter.txt_& "specification of the filter language" .row &_Exim3.upgrade_& "upgrade notes from release 2 to release 3" .row &_Exim4.upgrade_& "upgrade notes from release 3 to release 4" .row &_openssl.txt_& "installing a current OpenSSL release" .endtable The main specification and the specification of the filtering language are also available in other formats (HTML, PostScript, PDF, and Texinfo). Section &<>& below tells you how to get hold of these. .section "FTP site and websites" "SECID2" .cindex "website" .cindex "FTP site" The primary site for Exim source distributions is the &%exim.org%& FTP site, available over HTTPS, HTTP and FTP. These services, and the &%exim.org%& website, are hosted at the University of Cambridge. .cindex "wiki" .cindex "FAQ" As well as Exim distribution tar files, the Exim website contains a number of differently formatted versions of the documentation. A recent addition to the online information is &url(https://wiki.exim.org,the Exim wiki), which contains what used to be a separate FAQ, as well as various other examples, tips, and know-how that have been contributed by Exim users. The wiki site should always redirect to the correct place, which is currently provided by GitHub, and is open to editing by anyone with a GitHub account. .cindex Bugzilla An Exim Bugzilla exists at &url(https://bugs.exim.org). You can use this to report bugs, and also to add items to the wish list. Please search first to check that you are not duplicating a previous entry. Please do not ask for configuration help in the bug-tracker. .section "Mailing lists" "SECID3" .cindex "mailing lists" "for Exim users" The following Exim mailing lists exist: .table2 140pt .row &'exim-announce@lists.exim.org'& "Moderated, low volume announcements list" .row &'exim-users@lists.exim.org'& "General discussion list" .row &'exim-users-de@lists.exim.org'& "General discussion list in German language" .row &'exim-dev@lists.exim.org'& "Discussion of bugs, enhancements, etc." .row &'exim-cvs@lists.exim.org'& "Automated commit messages from the VCS" .endtable You can subscribe to these lists, change your existing subscriptions, and view or search the archives via the mailing lists link on the Exim home page. .cindex "Debian" "mailing list for" If you are using a Debian distribution of Exim, you may wish to subscribe to the Debian-specific mailing list &'pkg-exim4-users@lists.alioth.debian.org'& via this web page: .display &url(https://alioth-lists.debian.net/cgi-bin/mailman/listinfo/pkg-exim4-users) .endd Please ask Debian-specific questions on that list and not on the general Exim lists. .section "Bug reports" "SECID5" .cindex "bug reports" .cindex "reporting bugs" Reports of obvious bugs can be emailed to &'bugs@exim.org'& or reported via &url(https://bugs.exim.org,the Bugzilla). However, if you are unsure whether some behaviour is a bug or not, the best thing to do is to post a message to the &'exim-dev'& mailing list and have it discussed. .section "Where to find the Exim distribution" "SECTavail" .cindex "FTP site" .cindex "HTTPS download site" .cindex "distribution" "FTP site" .cindex "distribution" "https site" The master distribution site for the Exim distribution is .display &url(https://downloads.exim.org/) .endd The service is available over HTTPS, HTTP and FTP. We encourage people to migrate to HTTPS. The content served at &url(https://downloads.exim.org/) is identical to the content served at &url(https://ftp.exim.org/pub/exim) and &url(ftp://ftp.exim.org/pub/exim). If accessing via a hostname containing &'ftp'&, then the file references that follow are relative to the &_exim_& directories at these sites. If accessing via the hostname &'downloads'& then the subdirectories described here are top-level directories. There are now quite a number of independent mirror sites around the world. Those that I know about are listed in the file called &_Mirrors_&. Within the top exim directory there are subdirectories called &_exim3_& (for previous Exim 3 distributions), &_exim4_& (for the latest Exim 4 distributions), and &_Testing_& for testing versions. In the &_exim4_& subdirectory, the current release can always be found in files called .display &_exim-n.nn.tar.xz_& &_exim-n.nn.tar.gz_& &_exim-n.nn.tar.bz2_& .endd where &'n.nn'& is the highest such version number in the directory. The three files contain identical data; the only difference is the type of compression. The &_.xz_& file is usually the smallest, while the &_.gz_& file is the most portable to old systems. .cindex "distribution" "signing details" .cindex "distribution" "public key" .cindex "public key for signed distribution" The distributions will be PGP signed by an individual key of the Release Coordinator. This key will have a uid containing an email address in the &'exim.org'& domain and will have signatures from other people, including other Exim maintainers. We expect that the key will be in the "strong set" of PGP keys. There should be a trust path to that key from the Exim Maintainer's PGP keys, a version of which can be found in the release directory in the file &_Exim-Maintainers-Keyring.asc_&. All keys used will be available in public keyserver pools, such as &'pool.sks-keyservers.net'&. At the time of the last update, releases were being made by Jeremy Harris and signed with key &'0xBCE58C8CE41F32DF'&. Other recent keys used for signing are those of Heiko Schlittermann, &'0x26101B62F69376CE'&, and of Phil Pennock, &'0x4D1E900E14C1CC04'&. The signatures for the tar bundles are in: .display &_exim-n.nn.tar.xz.asc_& &_exim-n.nn.tar.gz.asc_& &_exim-n.nn.tar.bz2.asc_& .endd For each released version, the log of changes is made available in a separate file in the directory &_ChangeLogs_& so that it is possible to find out what has changed without having to download the entire distribution. .cindex "documentation" "available formats" The main distribution contains ASCII versions of this specification and other documentation; other formats of the documents are available in separate files inside the &_exim4_& directory of the FTP site: .display &_exim-html-n.nn.tar.gz_& &_exim-pdf-n.nn.tar.gz_& &_exim-postscript-n.nn.tar.gz_& &_exim-texinfo-n.nn.tar.gz_& .endd These tar files contain only the &_doc_& directory, not the complete distribution, and are also available in &_.bz2_& and &_.xz_& forms. .section "Limitations" "SECID6" .ilist .cindex "limitations of Exim" .cindex "bang paths" "not handled by Exim" Exim is designed for use as an Internet MTA, and therefore handles addresses in &url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822) domain format only. It cannot handle UUCP &"bang paths"&, though simple two-component bang paths can be converted by a straightforward rewriting configuration. This restriction does not prevent Exim from being interfaced to UUCP as a transport mechanism, provided that domain addresses are used. .next .cindex "domainless addresses" .cindex "address" "without domain" Exim insists that every address it handles has a domain attached. For incoming local messages, domainless addresses are automatically qualified with a configured domain value. Configuration options specify from which remote systems unqualified addresses are acceptable. These are then qualified on arrival. .next .cindex "transport" "external" .cindex "external transports" The only external transport mechanisms that are currently implemented are SMTP and LMTP over a TCP/IP network (including support for IPv6). However, a pipe transport is available, and there are facilities for writing messages to files and pipes, optionally in &'batched SMTP'& format; these facilities can be used to send messages to other transport mechanisms such as UUCP, provided they can handle domain-style addresses. Batched SMTP input is also catered for. .next Exim is not designed for storing mail for dial-in hosts. When the volumes of such mail are large, it is better to get the messages &"delivered"& into files (that is, off Exim's queue) and subsequently passed on to the dial-in hosts by other means. .next Although Exim does have basic facilities for scanning incoming messages, these are not comprehensive enough to do full virus or spam scanning. Such operations are best carried out using additional specialized software packages. If you compile Exim with the content-scanning extension, straightforward interfaces to a number of common scanners are provided. .endlist .section "Runtime configuration" "SECID7" Exim's runtime configuration is held in a single text file that is divided into a number of sections. The entries in this file consist of keywords and values, in the style of Smail 3 configuration files. A default configuration file which is suitable for simple online installations is provided in the distribution, and is described in chapter &<>& below. .section "Calling interface" "SECID8" .cindex "Sendmail compatibility" "command line interface" Like many MTAs, Exim has adopted the Sendmail command line interface so that it can be a straight replacement for &_/usr/lib/sendmail_& or &_/usr/sbin/sendmail_& when sending mail, but you do not need to know anything about Sendmail in order to run Exim. For actions other than sending messages, Sendmail-compatible options also exist, but those that produce output (for example, &%-bp%&, which lists the messages in the queue) do so in Exim's own format. There are also some additional options that are compatible with Smail 3, and some further options that are new to Exim. Chapter &<>& documents all Exim's command line options. This information is automatically made into the man page that forms part of the Exim distribution. Control of messages in the queue can be done via certain privileged command line options. There is also an optional monitor program called &'eximon'&, which displays current information in an X window, and which contains a menu interface to Exim's command line administration options. .section "Terminology" "SECID9" .cindex "terminology definitions" .cindex "body of message" "definition of" The &'body'& of a message is the actual data that the sender wants to transmit. It is the last part of a message and is separated from the &'header'& (see below) by a blank line. .cindex "bounce message" "definition of" When a message cannot be delivered, it is normally returned to the sender in a delivery failure message or a &"non-delivery report"& (NDR). The term &'bounce'& is commonly used for this action, and the error reports are often called &'bounce messages'&. This is a convenient shorthand for &"delivery failure error report"&. Such messages have an empty sender address in the message's &'envelope'& (see below) to ensure that they cannot themselves give rise to further bounce messages. The term &'default'& appears frequently in this manual. It is used to qualify a value which is used in the absence of any setting in the configuration. It may also qualify an action which is taken unless a configuration setting specifies otherwise. The term &'defer'& is used when the delivery of a message to a specific destination cannot immediately take place for some reason (a remote host may be down, or a user's local mailbox may be full). Such deliveries are &'deferred'& until a later time. The word &'domain'& is sometimes used to mean all but the first component of a host's name. It is &'not'& used in that sense here, where it normally refers to the part of an email address following the @ sign. .cindex "envelope, definition of" .cindex "sender" "definition of" A message in transit has an associated &'envelope'&, as well as a header and a body. The envelope contains a sender address (to which bounce messages should be delivered), and any number of recipient addresses. References to the sender or the recipients of a message usually mean the addresses in the envelope. An MTA uses these addresses for delivery, and for returning bounce messages, not the addresses that appear in the header lines. .cindex "message" "header, definition of" .cindex "header section" "definition of" The &'header'& of a message is the first part of a message's text, consisting of a number of lines, each of which has a name such as &'From:'&, &'To:'&, &'Subject:'&, etc. Long header lines can be split over several text lines by indenting the continuations. The header is separated from the body by a blank line. .cindex "local part" "definition of" .cindex "domain" "definition of" The term &'local part'&, which is taken from &url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822), is used to refer to the part of an email address that precedes the @ sign. The part that follows the @ sign is called the &'domain'& or &'mail domain'&. .cindex "local delivery" "definition of" .cindex "remote delivery, definition of" The terms &'local delivery'& and &'remote delivery'& are used to distinguish delivery to a file or a pipe on the local host from delivery by SMTP over TCP/IP to another host. As far as Exim is concerned, all hosts other than the host it is running on are &'remote'&. .cindex "return path" "definition of" &'Return path'& is another name that is used for the sender address in a message's envelope. .cindex "queue" "definition of" The term &'queue'& is used to refer to the set of messages awaiting delivery because this term is in widespread use in the context of MTAs. However, in Exim's case, the reality is more like a pool than a queue, because there is normally no ordering of waiting messages. .cindex "queue runner" "definition of" The term &'queue runner'& is used to describe a process that scans the queue and attempts to deliver those messages whose retry times have come. This term is used by other MTAs and also relates to the command &%runq%&, but in Exim the waiting messages are normally processed in an unpredictable order. .cindex "spool directory" "definition of" The term &'spool directory'& is used for a directory in which Exim keeps the messages in its queue &-- that is, those that it is in the process of delivering. This should not be confused with the directory in which local mailboxes are stored, which is called a &"spool directory"& by some people. In the Exim documentation, &"spool"& is always used in the first sense. . //////////////////////////////////////////////////////////////////////////// . //////////////////////////////////////////////////////////////////////////// .chapter "Incorporated code" "CHID2" .cindex "incorporated code" .cindex "regular expressions" "library" .cindex "PCRE2" .cindex "OpenDMARC" A number of pieces of external code are included in the Exim distribution. .ilist Regular expressions are supported in the main Exim program and in the Exim monitor using the freely-distributable PCRE2 library, copyright © University of Cambridge. The source to PCRE2 is not longer shipped with Exim, so you will need to use the version of PCRE2 shipped with your system, or obtain and install the full version of the library from &url(https://github.com/PhilipHazel/pcre2/releases). .next .cindex "cdb" "acknowledgment" Support for the cdb (Constant DataBase) lookup method is provided by code contributed by Nigel Metheringham of (at the time he contributed it) Planet Online Ltd. The implementation is completely contained within the code of Exim. It does not link against an external cdb library. The code contains the following statements: .blockquote Copyright © 1998 Nigel Metheringham, Planet Online Ltd This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This code implements Dan Bernstein's Constant DataBase (cdb) spec. Information, the spec and sample code for cdb can be obtained from &url(https://cr.yp.to/cdb.html). This implementation borrows some code from Dan Bernstein's implementation (which has no license restrictions applied to it). .endblockquote .next .cindex "SPA authentication" .cindex "Samba project" .cindex "Microsoft Secure Password Authentication" Client support for Microsoft's &'Secure Password Authentication'& is provided by code contributed by Marc Prud'hommeaux. Server support was contributed by Tom Kistner. This includes code taken from the Samba project, which is released under the Gnu GPL. .next .cindex "Cyrus" .cindex "&'pwcheck'& daemon" .cindex "&'pwauthd'& daemon" Support for calling the Cyrus &'pwcheck'& and &'saslauthd'& daemons is provided by code taken from the Cyrus-SASL library and adapted by Alexander S. Sabourenkov. The permission notice appears below, in accordance with the conditions expressed therein. .blockquote Copyright © 2001 Carnegie Mellon University. All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: .olist Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. .next Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. .next The name &"Carnegie Mellon University"& must not be used to endorse or promote products derived from this software without prior written permission. For permission or any other legal details, please contact .display Office of Technology Transfer Carnegie Mellon University 5000 Forbes Avenue Pittsburgh, PA 15213-3890 (412) 268-4387, fax: (412) 268-7395 tech-transfer@andrew.cmu.edu .endd .next Redistributions of any form whatsoever must retain the following acknowledgment: &"This product includes software developed by Computing Services at Carnegie Mellon University (&url(https://www.cmu.edu/computing/)."& CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. .endlist .endblockquote .next .cindex "Exim monitor" "acknowledgment" .cindex "X-windows" .cindex "Athena" The Exim Monitor program, which is an X-Window application, includes modified versions of the Athena StripChart and TextPop widgets. This code is copyright by DEC and MIT, and their permission notice appears below, in accordance with the conditions expressed therein. .blockquote Copyright 1987, 1988 by Digital Equipment Corporation, Maynard, Massachusetts, and the Massachusetts Institute of Technology, Cambridge, Massachusetts. All Rights Reserved Permission to use, copy, modify, and distribute this software and its documentation for any purpose and without fee is hereby granted, provided that the above copyright notice appear in all copies and that both that copyright notice and this permission notice appear in supporting documentation, and that the names of Digital or MIT not be used in advertising or publicity pertaining to distribution of the software without specific, written prior permission. DIGITAL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL DIGITAL BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. .endblockquote .next .cindex "opendmarc" "acknowledgment" The DMARC implementation uses the OpenDMARC library which is Copyrighted by The Trusted Domain Project. Portions of Exim source which use OpenDMARC derived code are indicated in the respective source files. The full OpenDMARC license is provided in the LICENSE.opendmarc file contained in the distributed source code. .next Many people have contributed code fragments, some large, some small, that were not covered by any specific license requirements. It is assumed that the contributors are happy to see their code incorporated into Exim under the GPL. .endlist . //////////////////////////////////////////////////////////////////////////// . //////////////////////////////////////////////////////////////////////////// .chapter "How Exim receives and delivers mail" "CHID11" &&& "Receiving and delivering mail" .section "Overall philosophy" "SECID10" .cindex "design philosophy" Exim is designed to work efficiently on systems that are permanently connected to the Internet and are handling a general mix of mail. In such circumstances, most messages can be delivered immediately. Consequently, Exim does not maintain independent queues of messages for specific domains or hosts, though it does try to send several messages in a single SMTP connection after a host has been down, and it also maintains per-host retry information. .section "Policy control" "SECID11" .cindex "policy control" "overview" Policy controls are now an important feature of MTAs that are connected to the Internet. Perhaps their most important job is to stop MTAs from being abused as &"open relays"& by misguided individuals who send out vast amounts of unsolicited junk and want to disguise its source. Exim provides flexible facilities for specifying policy controls on incoming mail: .ilist .cindex "&ACL;" "introduction" Exim 4 (unlike previous versions of Exim) implements policy controls on incoming mail by means of &'Access Control Lists'& (ACLs). Each list is a series of statements that may either grant or deny access. ACLs can be used at several places in the SMTP dialogue while receiving a message from a remote host. However, the most common places are after each RCPT command, and at the very end of the message. The sysadmin can specify conditions for accepting or rejecting individual recipients or the entire message, respectively, at these two points (see chapter &<>&). Denial of access results in an SMTP error code. .next An ACL is also available for locally generated, non-SMTP messages. In this case, the only available actions are to accept or deny the entire message. .next When Exim is compiled with the content-scanning extension, facilities are provided in the ACL mechanism for passing the message to external virus and/or spam scanning software. The result of such a scan is passed back to the ACL, which can then use it to decide what to do with the message. .next When a message has been received, either from a remote host or from the local host, but before the final acknowledgment has been sent, a locally supplied C function called &[local_scan()]& can be run to inspect the message and decide whether to accept it or not (see chapter &<>&). If the message is accepted, the list of recipients can be modified by the function. .next Using the &[local_scan()]& mechanism is another way of calling external scanner software. The &%SA-Exim%& add-on package works this way. It does not require Exim to be compiled with the content-scanning extension. .next After a message has been accepted, a further checking mechanism is available in the form of the &'system filter'& (see chapter &<>&). This runs at the start of every delivery process. .endlist .section "User filters" "SECID12" .cindex "filter" "introduction" .cindex "Sieve filter" In a conventional Exim configuration, users are able to run private filters by setting up appropriate &_.forward_& files in their home directories. See chapter &<>& (about the &(redirect)& router) for the configuration needed to support this, and the separate document entitled &'Exim's interfaces to mail filtering'& for user details. Two different kinds of filtering are available: .ilist Sieve filters are written in the standard filtering language that is defined by &url(https://www.rfc-editor.org/rfc/rfc3028.html,RFC 3028). .next Exim filters are written in a syntax that is unique to Exim, but which is more powerful than Sieve, which it pre-dates. .endlist User filters are run as part of the routing process, described below. .section "Message identification" "SECTmessiden" .cindex "message ids" "details of format" .cindex "format" "of message id" .cindex "id of message" .cindex "base62" .cindex "base36" .cindex "Darwin" .cindex "Cygwin" .cindex "exim_msgdate" Every message handled by Exim is given a &'message id'& which is 23 characters long. It is divided into three parts, separated by hyphens, for example &`16VDhn-000000001bo-D342`&. Each part is a sequence of letters and digits, normally encoding numbers in base 62. However, in the Darwin operating system (Mac OS X) and when Exim is compiled to run under Cygwin, base 36 (avoiding the use of lower case letters) is used instead, because the message id is used to construct filenames, and the names of files in those systems are not always case-sensitive. .cindex "pid (process id)" "re-use of" The detail of the contents of the message id have changed as Exim has evolved. Earlier versions relied on the operating system not re-using a process id (pid) within one second. On modern operating systems, this assumption can no longer be made, so the algorithm had to be changed. To retain backward compatibility, the format of the message id was retained, which is why the following rules are somewhat eccentric: .ilist The first six characters of the message id are the time at which the message started to be received, to a granularity of one second. That is, this field contains the number of seconds since the start of the epoch (the normal Unix way of representing the date and time of day). .next After the first hyphen, the next eleven characters are the id of the process that received the message. .next There are two different possibilities for the final four characters: .olist .oindex "&%localhost_number%&" If &%localhost_number%& is not set, this value is the fractional part of the time of reception, normally in units of microseconds. but for systems that must use base 36 instead of base 62 (because of case-insensitive file systems), the units are 2 us. .next If &%localhost_number%& is set, it is multiplied by 500000 (250000) and added to the fractional part of the time, which in this case is in units of 2 us (4 us). .endlist .endlist After a message has been received, Exim waits for the clock to tick at the appropriate resolution before proceeding, so that if another message is received by the same process, or by another process with the same (re-used) pid, it is guaranteed that the time will be different. In most cases, the clock will already have ticked while the message was being received. The exim_msgdate utility (see section &<>&) can be used to display the date, and optionally the process id, of an Exim Message ID. .section "Receiving mail" "SECID13" .cindex "receiving mail" .cindex "message" "reception" The only way Exim can receive mail from another host is using SMTP over TCP/IP, in which case the sender and recipient addresses are transferred using SMTP commands. However, from a locally running process (such as a user's MUA), there are several possibilities: .ilist If the process runs Exim with the &%-bm%& option, the message is read non-interactively (usually via a pipe), with the recipients taken from the command line, or from the body of the message if &%-t%& is also used. .next If the process runs Exim with the &%-bS%& option, the message is also read non-interactively, but in this case the recipients are listed at the start of the message in a series of SMTP RCPT commands, terminated by a DATA command. This is called &"batch SMTP"& format, but it isn't really SMTP. The SMTP commands are just another way of passing envelope addresses in a non-interactive submission. .next If the process runs Exim with the &%-bs%& option, the message is read interactively, using the SMTP protocol. A two-way pipe is normally used for passing data between the local process and the Exim process. This is &"real"& SMTP and is handled in the same way as SMTP over TCP/IP. For example, the ACLs for SMTP commands are used for this form of submission. .next A local process may also make a TCP/IP call to the host's loopback address (127.0.0.1) or any other of its IP addresses. When receiving messages, Exim does not treat the loopback address specially. It treats all such connections in the same way as connections from other hosts. .endlist .cindex "message sender, constructed by Exim" .cindex "sender" "constructed by Exim" In the three cases that do not involve TCP/IP, the sender address is constructed from the login name of the user that called Exim and a default qualification domain (which can be set by the &%qualify_domain%& configuration option). For local or batch SMTP, a sender address that is passed using the SMTP MAIL command is ignored. However, the system administrator may allow certain users (&"trusted users"&) to specify a different sender addresses unconditionally, or all users to specify certain forms of different sender address. The &%-f%& option or the SMTP MAIL command is used to specify these different addresses. See section &<>& for details of trusted users, and the &%untrusted_set_sender%& option for a way of allowing untrusted users to change sender addresses. Messages received by either of the non-interactive mechanisms are subject to checking by the non-SMTP ACL if one is defined. Messages received using SMTP (either over TCP/IP or interacting with a local process) can be checked by a number of ACLs that operate at different times during the SMTP session. Either individual recipients or the entire message can be rejected if local policy requirements are not met. The &[local_scan()]& function (see chapter &<>&) is run for all incoming messages. Exim can be configured not to start a delivery process when a message is received; this can be unconditional, or depend on the number of incoming SMTP connections or the system load. In these situations, new messages wait on the queue until a queue runner process picks them up. However, in standard configurations under normal conditions, delivery is started as soon as a message is received. .section "Handling an incoming message" "SECID14" .cindex "spool directory" "files that hold a message" .cindex "file" "how a message is held" When Exim accepts a message, it writes two files in its spool directory. The first contains the envelope information, the current status of the message, and the header lines, and the second contains the body of the message. The names of the two spool files consist of the message id, followed by &`-H`& for the file containing the envelope and header, and &`-D`& for the data file. .cindex "spool directory" "&_input_& sub-directory" By default, all these message files are held in a single directory called &_input_& inside the general Exim spool directory. Some operating systems do not perform very well if the number of files in a directory gets large; to improve performance in such cases, the &%split_spool_directory%& option can be used. This causes Exim to split up the input files into 62 sub-directories whose names are single letters or digits. When this is done, the queue is processed one sub-directory at a time instead of all at once, which can improve overall performance even when there are not enough files in each directory to affect file system performance. The envelope information consists of the address of the message's sender and the addresses of the recipients. This information is entirely separate from any addresses contained in the header lines. The status of the message includes a list of recipients who have already received the message. The format of the first spool file is described in chapter &<>&. .cindex "rewriting" "addresses" Address rewriting that is specified in the rewrite section of the configuration (see chapter &<>&) is done once and for all on incoming addresses, both in the header lines and the envelope, at the time the message is accepted. If during the course of delivery additional addresses are generated (for example, via aliasing), these new addresses are rewritten as soon as they are generated. At the time a message is actually delivered (transported) further rewriting can take place; because this is a transport option, it can be different for different forms of delivery. It is also possible to specify the addition or removal of certain header lines at the time the message is delivered (see chapters &<>& and &<>&). .section "Life of a message" "SECID15" .cindex "message" "life of" .cindex "message" "frozen" A message remains in the spool directory until it is completely delivered to its recipients or to an error address, or until it is deleted by an administrator or by the user who originally created it. In cases when delivery cannot proceed &-- for example when a message can neither be delivered to its recipients nor returned to its sender, the message is marked &"frozen"& on the spool, and no more deliveries are attempted. .cindex "frozen messages" "thawing" .cindex "message" "thawing frozen" An administrator can &"thaw"& such messages when the problem has been corrected, and can also freeze individual messages by hand if necessary. In addition, an administrator can force a delivery error, causing a bounce message to be sent. .oindex "&%timeout_frozen_after%&" .oindex "&%ignore_bounce_errors_after%&" There are options called &%ignore_bounce_errors_after%& and &%timeout_frozen_after%&, which discard frozen messages after a certain time. The first applies only to frozen bounces, the second to all frozen messages. .cindex "message" "log file for" .cindex "log" "file for each message" While Exim is working on a message, it writes information about each delivery attempt to its main log file. This includes successful, unsuccessful, and delayed deliveries for each recipient (see chapter &<>&). The log lines are also written to a separate &'message log'& file for each message. These logs are solely for the benefit of the administrator and are normally deleted along with the spool files when processing of a message is complete. The use of individual message logs can be disabled by setting &%no_message_logs%&; this might give an improvement in performance on very busy systems. .cindex "journal file" .cindex "file" "journal" All the information Exim itself needs to set up a delivery is kept in the first spool file, along with the header lines. When a successful delivery occurs, the address is immediately written at the end of a journal file, whose name is the message id followed by &`-J`&. At the end of a delivery run, if there are some addresses left to be tried again later, the first spool file (the &`-H`& file) is updated to indicate which these are, and the journal file is then deleted. Updating the spool file is done by writing a new file and renaming it, to minimize the possibility of data loss. Should the system or Exim crash after a successful delivery but before the spool file has been updated, the journal is left lying around. The next time Exim attempts to deliver the message, it reads the journal file and updates the spool file before proceeding. This minimizes the chances of double deliveries caused by crashes. .section "Processing an address for delivery" "SECTprocaddress" .cindex "drivers" "definition of" .cindex "router" "definition of" .cindex "transport" "definition of" The main delivery processing elements of Exim are called &'routers'& and &'transports'&, and collectively these are known as &'drivers'&. Code for a number of them is provided in the source distribution, and compile-time options specify which ones are included in the binary. Runtime options specify which ones are actually used for delivering messages. .cindex "drivers" "instance definition" Each driver that is specified in the runtime configuration is an &'instance'& of that particular driver type. Multiple instances are allowed; for example, you can set up several different &(smtp)& transports, each with different option values that might specify different ports or different timeouts. Each instance has its own identifying name. In what follows we will normally use the instance name when discussing one particular instance (that is, one specific configuration of the driver), and the generic driver name when discussing the driver's features in general. A &'router'& is a driver that operates on an address, either determining how its delivery should happen, by assigning it to a specific transport, or converting the address into one or more new addresses (for example, via an alias file). A router may also explicitly choose to fail an address, causing it to be bounced. A &'transport'& is a driver that transmits a copy of the message from Exim's spool to some destination. There are two kinds of transport: for a &'local'& transport, the destination is a file or a pipe on the local host, whereas for a &'remote'& transport the destination is some other host. A message is passed to a specific transport as a result of successful routing. If a message has several recipients, it may be passed to a number of different transports. .cindex "preconditions" "definition of" An address is processed by passing it to each configured router instance in turn, subject to certain preconditions, until a router accepts the address or specifies that it should be bounced. We will describe this process in more detail shortly. First, as a simple example, we consider how each recipient address in a message is processed in a small configuration of three routers. To make this a more concrete example, it is described in terms of some actual routers, but remember, this is only an example. You can configure Exim's routers in many different ways, and there may be any number of routers in a configuration. The first router that is specified in a configuration is often one that handles addresses in domains that are not recognized specifically by the local host. Typically these are addresses for arbitrary domains on the Internet. A precondition is set up which looks for the special domains known to the host (for example, its own domain name), and the router is run for addresses that do &'not'& match. Typically, this is a router that looks up domains in the DNS in order to find the hosts to which this address routes. If it succeeds, the address is assigned to a suitable SMTP transport; if it does not succeed, the router is configured to fail the address. The second router is reached only when the domain is recognized as one that &"belongs"& to the local host. This router does redirection &-- also known as aliasing and forwarding. When it generates one or more new addresses from the original, each of them is routed independently from the start. Otherwise, the router may cause an address to fail, or it may simply decline to handle the address, in which case the address is passed to the next router. The final router in many configurations is one that checks to see if the address belongs to a local mailbox. The precondition may involve a check to see if the local part is the name of a login account, or it may look up the local part in a file or a database. If its preconditions are not met, or if the router declines, we have reached the end of the routers. When this happens, the address is bounced. .section "Processing an address for verification" "SECID16" .cindex "router" "for verification" .cindex "verifying address" "overview" As well as being used to decide how to deliver to an address, Exim's routers are also used for &'address verification'&. Verification can be requested as one of the checks to be performed in an ACL for incoming messages, on both sender and recipient addresses, and it can be tested using the &%-bv%& and &%-bvs%& command line options. When an address is being verified, the routers are run in &"verify mode"&. This does not affect the way the routers work, but it is a state that can be detected. By this means, a router can be skipped or made to behave differently when verifying. A common example is a configuration in which the first router sends all messages to a message-scanning program unless they have been previously scanned. Thus, the first router accepts all addresses without any checking, making it useless for verifying. Normally, the &%no_verify%& option would be set for such a router, causing it to be skipped in verify mode. .section "Running an individual router" "SECTrunindrou" .cindex "router" "running details" .cindex "preconditions" "checking" .cindex "router" "result of running" As explained in the example above, a number of preconditions are checked before running a router. If any are not met, the router is skipped, and the address is passed to the next router. When all the preconditions on a router &'are'& met, the router is run. What happens next depends on the outcome, which is one of the following: .ilist &'accept'&: The router accepts the address, and either assigns it to a transport or generates one or more &"child"& addresses. Processing the original address ceases .oindex "&%unseen%&" unless the &%unseen%& option is set on the router. This option can be used to set up multiple deliveries with different routing (for example, for keeping archive copies of messages). When &%unseen%& is set, the address is passed to the next router. Normally, however, an &'accept'& return marks the end of routing. Any child addresses generated by the router are processed independently, starting with the first router by default. It is possible to change this by setting the &%redirect_router%& option to specify which router to start at for child addresses. Unlike &%pass_router%& (see below) the router specified by &%redirect_router%& may be anywhere in the router configuration. .next &'pass'&: The router recognizes the address, but cannot handle it itself. It requests that the address be passed to another router. By default, the address is passed to the next router, but this can be changed by setting the &%pass_router%& option. However, (unlike &%redirect_router%&) the named router must be below the current router (to avoid loops). .next &'decline'&: The router declines to accept the address because it does not recognize it at all. By default, the address is passed to the next router, but this can be prevented by setting the &%no_more%& option. When &%no_more%& is set, all the remaining routers are skipped. In effect, &%no_more%& converts &'decline'& into &'fail'&. .next &'fail'&: The router determines that the address should fail, and queues it for the generation of a bounce message. There is no further processing of the original address unless &%unseen%& is set on the router. .next &'defer'&: The router cannot handle the address at the present time. (A database may be offline, or a DNS lookup may have timed out.) No further processing of the address happens in this delivery attempt. It is tried again next time the message is considered for delivery. .next &'error'&: There is some error in the router (for example, a syntax error in its configuration). The action is as for defer. .endlist If an address reaches the end of the routers without having been accepted by any of them, it is bounced as unrouteable. The default error message in this situation is &"unrouteable address"&, but you can set your own message by making use of the &%cannot_route_message%& option. This can be set for any router; the value from the last router that &"saw"& the address is used. Sometimes while routing you want to fail a delivery when some conditions are met but others are not, instead of passing the address on for further routing. You can do this by having a second router that explicitly fails the delivery when the relevant conditions are met. The &(redirect)& router has a &"fail"& facility for this purpose. .section "Duplicate addresses" "SECID17" .cindex "case of local parts" .cindex "address duplicate, discarding" .cindex "duplicate addresses" Once routing is complete, Exim scans the addresses that are assigned to local and remote transports and discards any duplicates that it finds. During this check, local parts are treated case-sensitively. This happens only when actually delivering a message; when testing routers with &%-bt%&, all the routed addresses are shown. .section "Router preconditions" "SECTrouprecon" .cindex "router" "preconditions, order of processing" .cindex "preconditions" "order of processing" The preconditions that are tested for each router are listed below, in the order in which they are tested. The individual configuration options are described in more detail in chapter &<>&. .olist .cindex affix "router precondition" The &%local_part_prefix%& and &%local_part_suffix%& options can specify that the local parts handled by the router may or must have certain prefixes and/or suffixes. If a mandatory affix (prefix or suffix) is not present, the router is skipped. These conditions are tested first. When an affix is present, it is removed from the local part before further processing, including the evaluation of any other conditions. .next Routers can be designated for use only when not verifying an address, that is, only when routing it for delivery (or testing its delivery routing). If the &%verify%& option is set false, the router is skipped when Exim is verifying an address. Setting the &%verify%& option actually sets two options, &%verify_sender%& and &%verify_recipient%&, which independently control the use of the router for sender and recipient verification. You can set these options directly if you want a router to be used for only one type of verification. Note that cutthrough delivery is classed as a recipient verification for this purpose. .next If the &%address_test%& option is set false, the router is skipped when Exim is run with the &%-bt%& option to test an address routing. This can be helpful when the first router sends all new messages to a scanner of some sort; it makes it possible to use &%-bt%& to test subsequent delivery routing without having to simulate the effect of the scanner. .next Routers can be designated for use only when verifying an address, as opposed to routing it for delivery. The &%verify_only%& option controls this. Again, cutthrough delivery counts as a verification. .next Individual routers can be explicitly skipped when running the routers to check an address given in the SMTP EXPN command (see the &%expn%& option). .next If the &%domains%& option is set, the domain of the address must be in the set of domains that it defines. .cindex "tainted data" "de-tainting" .cindex "de-tainting" "using router domains option" A match verifies the variable &$domain$& (which carries tainted data) and assigns an untainted value to the &$domain_data$& variable. Such an untainted value is often needed in the transport. For specifics of the matching operation and the resulting untainted value, refer to section &<>&. When an untainted value is wanted, use this option rather than the generic &%condition%& option. .next .vindex "&$local_part_prefix$&" .vindex "&$local_part_prefix_v$&" .vindex "&$local_part$&" .vindex "&$local_part_suffix$&" .vindex "&$local_part_suffix_v$&" .cindex affix "router precondition" If the &%local_parts%& option is set, the local part of the address must be in the set of local parts that it defines. A match verifies the variable &$local_part$& (which carries tainted data) and assigns an untainted value to the &$local_part_data$& variable. Such an untainted value is often needed in the transport. For specifics of the matching operation and the resulting untainted value, refer to section &<>&. When an untainted value is wanted, use this option rather than the generic &%condition%& option. If &%local_part_prefix%& or &%local_part_suffix%& is in use, the prefix or suffix is removed from the local part before this check. If you want to do precondition tests on local parts that include affixes, you can do so by using a &%condition%& option (see below) that uses the variables &$local_part$&, &$local_part_prefix$&, &$local_part_prefix_v$&, &$local_part_suffix$& and &$local_part_suffix_v$& as necessary. .next .vindex "&$local_user_uid$&" .vindex "&$local_user_gid$&" .vindex "&$home$&" If the &%check_local_user%& option is set, the local part must be the name of an account on the local host. If this check succeeds, the uid and gid of the local user are placed in &$local_user_uid$& and &$local_user_gid$& and the user's home directory is placed in &$home$&; these values can be used in the remaining preconditions. .next If the &%router_home_directory%& option is set, it is expanded at this point, because it overrides the value of &$home$&. If this expansion were left till later, the value of &$home$& as set by &%check_local_user%& would be used in subsequent tests. Having two different values of &$home$& in the same router could lead to confusion. .next If the &%senders%& option is set, the envelope sender address must be in the set of addresses that it defines. .next If the &%require_files%& option is set, the existence or non-existence of specified files is tested. .next .cindex "customizing" "precondition" If the &%condition%& option is set, it is evaluated and tested. This option uses an expanded string to allow you to set up your own custom preconditions. Expanded strings are described in chapter &<>&. Note that while using this option for address matching technically works, it does not set any de-tainted values. Such values are often needed, either for router-specific options or for transport options. Using the &%domains%& and &%local_parts%& options is usually the most convenient way to obtain them. .endlist Note that &%require_files%& comes near the end of the list, so you cannot use it to check for the existence of a file in which to lookup up a domain, local part, or sender. However, as these options are all expanded, you can use the &%exists%& expansion condition to make such tests within each condition. The &%require_files%& option is intended for checking files that the router may be going to use internally, or which are needed by a specific transport (for example, &_.procmailrc_&). .section "Delivery in detail" "SECID18" .cindex "delivery" "in detail" When a message is to be delivered, the sequence of events is as follows: .olist If a system-wide filter file is specified, the message is passed to it. The filter may add recipients to the message, replace the recipients, discard the message, cause a new message to be generated, or cause the message delivery to fail. The format of the system filter file is the same as for Exim user filter files, described in the separate document entitled &'Exim's interfaces to mail filtering'&. .cindex "Sieve filter" "not available for system filter" (&*Note*&: Sieve cannot be used for system filter files.) Some additional features are available in system filters &-- see chapter &<>& for details. Note that a message is passed to the system filter only once per delivery attempt, however many recipients it has. However, if there are several delivery attempts because one or more addresses could not be immediately delivered, the system filter is run each time. The filter condition &%first_delivery%& can be used to detect the first run of the system filter. .next Each recipient address is offered to each configured router, in turn, subject to its preconditions, until one is able to handle it. If no router can handle the address, that is, if they all decline, the address is failed. Because routers can be targeted at particular domains, several locally handled domains can be processed entirely independently of each other. .next .cindex "routing" "loops in" .cindex "loop" "while routing" A router that accepts an address may assign it to a local or a remote transport. However, the transport is not run at this time. Instead, the address is placed on a list for the particular transport, which will be run later. Alternatively, the router may generate one or more new addresses (typically from alias, forward, or filter files). New addresses are fed back into this process from the top, but in order to avoid loops, a router ignores any address which has an identically-named ancestor that was processed by itself. .next When all the routing has been done, addresses that have been successfully handled are passed to their assigned transports. When local transports are doing real local deliveries, they handle only one address at a time, but if a local transport is being used as a pseudo-remote transport (for example, to collect batched SMTP messages for transmission by some other means) multiple addresses can be handled. Remote transports can always handle more than one address at a time, but can be configured not to do so, or to restrict multiple addresses to the same domain. .next Each local delivery to a file or a pipe runs in a separate process under a non-privileged uid, and these deliveries are run one at a time. Remote deliveries also run in separate processes, normally under a uid that is private to Exim (&"the Exim user"&), but in this case, several remote deliveries can be run in parallel. The maximum number of simultaneous remote deliveries for any one message is set by the &%remote_max_parallel%& option. The order in which deliveries are done is not defined, except that all local deliveries happen before any remote deliveries. .next .cindex "queue runner" When it encounters a local delivery during a queue run, Exim checks its retry database to see if there has been a previous temporary delivery failure for the address before running the local transport. If there was a previous failure, Exim does not attempt a new delivery until the retry time for the address is reached. However, this happens only for delivery attempts that are part of a queue run. Local deliveries are always attempted when delivery immediately follows message reception, even if retry times are set for them. This makes for better behaviour if one particular message is causing problems (for example, causing quota overflow, or provoking an error in a filter file). .next .cindex "delivery" "retry in remote transports" Remote transports do their own retry handling, since an address may be deliverable to one of a number of hosts, each of which may have a different retry time. If there have been previous temporary failures and no host has reached its retry time, no delivery is attempted, whether in a queue run or not. See chapter &<>& for details of retry strategies. .next If there were any permanent errors, a bounce message is returned to an appropriate address (the sender in the common case), with details of the error for each failing address. Exim can be configured to send copies of bounce messages to other addresses. .next .cindex "delivery" "deferral" If one or more addresses suffered a temporary failure, the message is left on the queue, to be tried again later. Delivery of these addresses is said to be &'deferred'&. .next When all the recipient addresses have either been delivered or bounced, handling of the message is complete. The spool files and message log are deleted, though the message log can optionally be preserved if required. .endlist .section "Retry mechanism" "SECID19" .cindex "delivery" "retry mechanism" .cindex "retry" "description of mechanism" .cindex "queue runner" Exim's mechanism for retrying messages that fail to get delivered at the first attempt is the queue runner process. You must either run an Exim daemon that uses the &%-q%& option with a time interval to start queue runners at regular intervals or use some other means (such as &'cron'&) to start them. If you do not arrange for queue runners to be run, messages that fail temporarily at the first attempt will remain in your queue forever. A queue runner process works its way through the queue, one message at a time, trying each delivery that has passed its retry time. You can run several queue runners at once. Exim uses a set of configured rules to determine when next to retry the failing address (see chapter &<>&). These rules also specify when Exim should give up trying to deliver to the address, at which point it generates a bounce message. If no retry rules are set for a particular host, address, and error combination, no retries are attempted, and temporary errors are treated as permanent. .subsection "Temporary delivery failure" SECID20 .cindex "delivery" "temporary failure" There are many reasons why a message may not be immediately deliverable to a particular address. Failure to connect to a remote machine (because it, or the connection to it, is down) is one of the most common. Temporary failures may be detected during routing as well as during the transport stage of delivery. Local deliveries may be delayed if NFS files are unavailable, or if a mailbox is on a file system where the user is over quota. Exim can be configured to impose its own quotas on local mailboxes; where system quotas are set they will also apply. If a host is unreachable for a period of time, a number of messages may be waiting for it by the time it recovers, and sending them in a single SMTP connection is clearly beneficial. Whenever a delivery to a remote host is deferred, .cindex "hints database" "deferred deliveries" Exim makes a note in its hints database, and whenever a successful SMTP delivery has happened, it looks to see if any other messages are waiting for the same host. If any are found, they are sent over the same SMTP connection, subject to a configuration limit as to the maximum number in any one connection. .subsection "Permanent delivery failure" SECID21 .cindex "delivery" "permanent failure" .cindex "bounce message" "when generated" When a message cannot be delivered to some or all of its intended recipients, a bounce message is generated. Temporary delivery failures turn into permanent errors when their timeout expires. All the addresses that fail in a given delivery attempt are listed in a single message. If the original message has many recipients, it is possible for some addresses to fail in one delivery attempt and others to fail subsequently, giving rise to more than one bounce message. The wording of bounce messages can be customized by the administrator. See chapter &<>& for details. .cindex "&'X-Failed-Recipients:'& header line" Bounce messages contain an &'X-Failed-Recipients:'& header line that lists the failed addresses, for the benefit of programs that try to analyse such messages automatically. .cindex "bounce message" "recipient of" A bounce message is normally sent to the sender of the original message, as obtained from the message's envelope. For incoming SMTP messages, this is the address given in the MAIL command. However, when an address is expanded via a forward or alias file, an alternative address can be specified for delivery failures of the generated addresses. For a mailing list expansion (see section &<>&) it is common to direct bounce messages to the manager of the list. .subsection "Failures to deliver bounce messages" SECID22 .cindex "bounce message" "failure to deliver" If a bounce message (either locally generated or received from a remote host) itself suffers a permanent delivery failure, the message is left in the queue, but it is frozen, awaiting the attention of an administrator. There are options that can be used to make Exim discard such failed messages, or to keep them for only a short time (see &%timeout_frozen_after%& and &%ignore_bounce_errors_after%&). . //////////////////////////////////////////////////////////////////////////// . //////////////////////////////////////////////////////////////////////////// .chapter "Building and installing Exim" "CHID3" .scindex IIDbuex "building Exim" .section "Unpacking" "SECID23" Exim is distributed as a gzipped or bzipped tar file which, when unpacked, creates a directory with the name of the current release (for example, &_exim-&version()_&) into which the following files are placed: .table2 140pt .irow &_ACKNOWLEDGMENTS_& "contains some acknowledgments" .irow &_CHANGES_& "contains a reference to where changes are &&& documented" .irow &_LICENCE_& "the GNU General Public Licence" .irow &_Makefile_& "top-level make file" .irow &_NOTICE_& "conditions for the use of Exim" .irow &_README_& "list of files, directories and simple build &&& instructions" .endtable Other files whose names begin with &_README_& may also be present. The following subdirectories are created: .table2 140pt .irow &_Local_& "an empty directory for local configuration files" .irow &_OS_& "OS-specific files" .irow &_doc_& "documentation files" .irow &_exim_monitor_& "source files for the Exim monitor" .irow &_scripts_& "scripts used in the build process" .irow &_src_& "remaining source files" .irow &_util_& "independent utilities" .endtable The main utility programs are contained in the &_src_& directory and are built with the Exim binary. The &_util_& directory contains a few optional scripts that may be useful to some sites. .section "Multiple machine architectures and operating systems" "SECID24" .cindex "building Exim" "multiple OS/architectures" The building process for Exim is arranged to make it easy to build binaries for a number of different architectures and operating systems from the same set of source files. Compilation does not take place in the &_src_& directory. Instead, a &'build directory'& is created for each architecture and operating system. .cindex "symbolic link" "to build directory" Symbolic links to the sources are installed in this directory, which is where the actual building takes place. In most cases, Exim can discover the machine architecture and operating system for itself, but the defaults can be overridden if necessary. .cindex compiler requirements .cindex compiler version A C99-capable compiler will be required for the build. .section "PCRE2 library" "SECTpcre" .cindex "PCRE2 library" Exim no longer has an embedded regular-expression library as the vast majority of modern systems include PCRE2 as a system library, although you may need to install the PCRE2 package or the PCRE2 development package for your operating system. If your system has a normal PCRE2 installation the Exim build process will need no further configuration. If the library or the headers are in an unusual location you will need to either set the PCRE2_LIBS and INCLUDE directives appropriately, or set PCRE2_CONFIG=yes to use the installed &(pcre-config)& command. If your operating system has no PCRE2 support then you will need to obtain and build the current PCRE2 from &url(https://github.com/PhilipHazel/pcre2/releases). More information on PCRE2 is available at &url(https://www.pcre.org/). .section "DBM libraries" "SECTdb" .cindex "DBM libraries" "discussion of" .cindex "hints database" "DBM files used for" Even if you do not use any DBM files in your configuration, Exim still needs a DBM library in order to operate, because it uses indexed files for its hints databases. Unfortunately, there are a number of DBM libraries in existence, and different operating systems often have different ones installed. .cindex "Solaris" "DBM library for" .cindex "IRIX, DBM library for" .cindex "BSD, DBM library for" .cindex "Linux, DBM library for" If you are using Solaris, IRIX, one of the modern BSD systems, or a modern Linux distribution, the DBM configuration should happen automatically, and you may be able to ignore this section. Otherwise, you may have to learn more than you would like about DBM libraries from what follows. .cindex "&'ndbm'& DBM library" Licensed versions of Unix normally contain a library of DBM functions operating via the &'ndbm'& interface, and this is what Exim expects by default. Free versions of Unix seem to vary in what they contain as standard. In particular, some early versions of Linux have no default DBM library, and different distributors have chosen to bundle different libraries with their packaged versions. However, the more recent releases seem to have standardized on the Berkeley DB library. .new Ownership of the Berkeley DB library has moved to a major corporation; development seems to have stalled and documentation is not freely available. This is probably not tenable for the long term use by Exim. .wen Different DBM libraries have different conventions for naming the files they use. When a program opens a file called &_dbmfile_&, there are several possibilities: .olist A traditional &'ndbm'& implementation, such as that supplied as part of Solaris, operates on two files called &_dbmfile.dir_& and &_dbmfile.pag_&. .next .cindex "&'gdbm'& DBM library" The GNU library, &'gdbm'&, operates on a single file. If used via its &'ndbm'& compatibility interface it makes two different hard links to it with names &_dbmfile.dir_& and &_dbmfile.pag_&, but if used via its native interface, the filename is used unmodified. .next .cindex "Berkeley DB library" The Berkeley DB package, if called via its &'ndbm'& compatibility interface, operates on a single file called &_dbmfile.db_&, but otherwise looks to the programmer exactly the same as the traditional &'ndbm'& implementation. .next If the Berkeley package is used in its native mode, it operates on a single file called &_dbmfile_&; the programmer's interface is somewhat different to the traditional &'ndbm'& interface. .next To complicate things further, there are several very different versions of the Berkeley DB package. Version 1.85 was stable for a very long time, releases 2.&'x'& and 3.&'x'& were current for a while, but the latest versions when Exim last revamped support were numbered 5.&'x'&. Maintenance of some of the earlier releases has ceased, and Exim no longer supports versions before 3.&'x'&. All versions of Berkeley DB could be obtained from &url(http://www.sleepycat.com/), which is now a redirect to their new owner's page with far newer versions listed. It is probably wise to plan to move your storage configurations away from Berkeley DB format, as today there are smaller and simpler alternatives more suited to Exim's usage model. .next .cindex "&'tdb'& DBM library" Yet another DBM library, called &'tdb'&, is available from &url(https://sourceforge.net/projects/tdb/files/). It has its own interface, and also operates on a single file. .next It is possible to use &url(https://www.sqlite.org/index.html,sqlite3) for the DBM library. .endlist .cindex "USE_DB" .cindex "DBM libraries" "configuration for building" Exim and its utilities can be compiled to use any of these interfaces. In order to use any version of the Berkeley DB package in native mode, you must set USE_DB in an appropriate configuration file (typically &_Local/Makefile_&). For example: .code USE_DB=yes .endd Similarly, for gdbm you set USE_GDBM, for tdb you set USE_TDB, and for sqlite3 you set USE_SQLITE. An error is diagnosed if you set more than one of these. You can set USE_NDBM if needed to override an operating system default. At the lowest level, the build-time configuration sets none of these options, thereby assuming an interface of type (1). However, some operating system configuration files (for example, those for the BSD operating systems and Linux) assume type (4) by setting USE_DB as their default, and the configuration files for Cygwin set USE_GDBM. Anything you set in &_Local/Makefile_&, however, overrides these system defaults. As well as setting USE_DB, USE_GDBM, or USE_TDB, it may also be necessary to set DBMLIB, to cause inclusion of the appropriate library, as in one of these lines: .code DBMLIB = -ldb DBMLIB = -ltdb DBMLIB = -lsqlite3 DBMLIB = -lgdbm -lgdbm_compat .endd The last of those was for a Linux having GDBM provide emulated NDBM facilities. Settings like that will work if the DBM library is installed in the standard place. Sometimes it is not, and the library's header file may also not be in the default path. You may need to set INCLUDE to specify where the header file is, and to specify the path to the library more fully in DBMLIB, as in this example: .code INCLUDE=-I/usr/local/include/db-4.1 DBMLIB=/usr/local/lib/db-4.1/libdb.a .endd There is further detailed discussion about the various DBM libraries in the file &_doc/dbm.discuss.txt_& in the Exim distribution. .new When moving from one DBM library to another, for the hints databases it suffices to just remove all the files in the directory named &"db/"& under the spool directory. This is because hints are only for optimisation and will be rebuilt during normal operations. Non-hints DBM databases (used by &"dbm"& lookups in the configuration) will need individual rebuilds for the new DBM library. This is not done automatically .wen .section "Pre-building configuration" "SECID25" .cindex "building Exim" "pre-building configuration" .cindex "configuration for building Exim" .cindex "&_Local/Makefile_&" .cindex "&_src/EDITME_&" Before building Exim, a local configuration file that specifies options independent of any operating system has to be created with the name &_Local/Makefile_&. A template for this file is supplied as the file &_src/EDITME_&, and it contains full descriptions of all the option settings therein. These descriptions are therefore not repeated here. If you are building Exim for the first time, the simplest thing to do is to copy &_src/EDITME_& to &_Local/Makefile_&, then read it and edit it appropriately. There are three settings that you must supply, because Exim will not build without them. They are the location of the runtime configuration file (CONFIGURE_FILE), the directory in which Exim binaries will be installed (BIN_DIRECTORY), and the identity of the Exim user (EXIM_USER and maybe EXIM_GROUP as well). The value of CONFIGURE_FILE can in fact be a colon-separated list of filenames; Exim uses the first of them that exists. There are a few other parameters that can be specified either at build time or at runtime, to enable the same binary to be used on a number of different machines. However, if the locations of Exim's spool directory and log file directory (if not within the spool directory) are fixed, it is recommended that you specify them in &_Local/Makefile_& instead of at runtime, so that errors detected early in Exim's execution (such as a malformed configuration file) can be logged. .cindex "content scanning" "specifying at build time" Exim's interfaces for calling virus and spam scanning software directly from access control lists are not compiled by default. If you want to include these facilities, you need to set .code WITH_CONTENT_SCAN=yes .endd in your &_Local/Makefile_&. For details of the facilities themselves, see chapter &<>&. .cindex "&_Local/eximon.conf_&" .cindex "&_exim_monitor/EDITME_&" If you are going to build the Exim monitor, a similar configuration process is required. The file &_exim_monitor/EDITME_& must be edited appropriately for your installation and saved under the name &_Local/eximon.conf_&. If you are happy with the default settings described in &_exim_monitor/EDITME_&, &_Local/eximon.conf_& can be empty, but it must exist. This is all the configuration that is needed in straightforward cases for known operating systems. However, the building process is set up so that it is easy to override options that are set by default or by operating-system-specific configuration files, for example, to change the C compiler, which defaults to &%gcc%&. See section &<>& below for details of how to do this. .section "Support for iconv()" "SECID26" .cindex "&[iconv()]& support" .cindex "RFC 2047" The contents of header lines in messages may be encoded according to the rules described in &url(https://www.rfc-editor.org/rfc/rfc2047,RFC 2047). This makes it possible to transmit characters that are not in the ASCII character set, and to label them as being in a particular character set. When Exim is inspecting header lines by means of the &%$h_%& mechanism, it decodes them, and translates them into a specified character set (default is set at build time). The translation is possible only if the operating system supports the &[iconv()]& function. However, some of the operating systems that supply &[iconv()]& do not support very many conversions. The GNU &%libiconv%& library (available from &url(https://www.gnu.org/software/libiconv/)) can be installed on such systems to remedy this deficiency, as well as on systems that do not supply &[iconv()]& at all. After installing &%libiconv%&, you should add .code HAVE_ICONV=yes .endd to your &_Local/Makefile_& and rebuild Exim. .section "Including TLS/SSL encryption support" "SECTinctlsssl" .cindex "TLS" "including support for TLS" .cindex "encryption" "including support for" .cindex "OpenSSL" "building Exim with" .cindex "GnuTLS" "building Exim with" Exim is usually built to support encrypted SMTP connections, using the STARTTLS command as per &url(https://www.rfc-editor.org/rfc/rfc2487,RFC 2487). It can also support clients that expect to start a TLS session immediately on connection to a non-standard port (see the &%tls_on_connect_ports%& runtime option and the &%-tls-on-connect%& command line option). If you want to build Exim with TLS support, you must first install either the OpenSSL or GnuTLS library. There is no cryptographic code in Exim itself for implementing SSL. If you do not want TLS support you should set .code DISABLE_TLS=yes .endd in &_Local/Makefile_&. If OpenSSL is installed, you should set .code USE_OPENSL=yes TLS_LIBS=-lssl -lcrypto .endd in &_Local/Makefile_&. You may also need to specify the locations of the OpenSSL library and include files. For example: .code USE_OPENSSL=yes TLS_LIBS=-L/usr/local/openssl/lib -lssl -lcrypto TLS_INCLUDE=-I/usr/local/openssl/include/ .endd .cindex "pkg-config" "OpenSSL" If you have &'pkg-config'& available, then instead you can just use: .code USE_OPENSSL=yes USE_OPENSSL_PC=openssl .endd .cindex "USE_GNUTLS" If GnuTLS is installed, you should set .code USE_GNUTLS=yes TLS_LIBS=-lgnutls -ltasn1 -lgcrypt .endd in &_Local/Makefile_&, and again you may need to specify the locations of the library and include files. For example: .code USE_GNUTLS=yes TLS_LIBS=-L/usr/gnu/lib -lgnutls -ltasn1 -lgcrypt TLS_INCLUDE=-I/usr/gnu/include .endd .cindex "pkg-config" "GnuTLS" If you have &'pkg-config'& available, then instead you can just use: .code USE_GNUTLS=yes USE_GNUTLS_PC=gnutls .endd You do not need to set TLS_INCLUDE if the relevant directory is already specified in INCLUDE. Details of how to configure Exim to make use of TLS are given in chapter &<>&. .section "Use of tcpwrappers" "SECID27" .cindex "tcpwrappers, building Exim to support" .cindex "USE_TCP_WRAPPERS" .cindex "TCP_WRAPPERS_DAEMON_NAME" .cindex "tcp_wrappers_daemon_name" Exim can be linked with the &'tcpwrappers'& library in order to check incoming SMTP calls using the &'tcpwrappers'& control files. This may be a convenient alternative to Exim's own checking facilities for installations that are already making use of &'tcpwrappers'& for other purposes. To do this, you should set USE_TCP_WRAPPERS in &_Local/Makefile_&, arrange for the file &_tcpd.h_& to be available at compile time, and also ensure that the library &_libwrap.a_& is available at link time, typically by including &%-lwrap%& in EXTRALIBS_EXIM. For example, if &'tcpwrappers'& is installed in &_/usr/local_&, you might have .code USE_TCP_WRAPPERS=yes CFLAGS=-O -I/usr/local/include EXTRALIBS_EXIM=-L/usr/local/lib -lwrap .endd in &_Local/Makefile_&. The daemon name to use in the &'tcpwrappers'& control files is &"exim"&. For example, the line .code exim : LOCAL 192.168.1. .friendly.domain.example .endd in your &_/etc/hosts.allow_& file allows connections from the local host, from the subnet 192.168.1.0/24, and from all hosts in &'friendly.domain.example'&. All other connections are denied. The daemon name used by &'tcpwrappers'& can be changed at build time by setting TCP_WRAPPERS_DAEMON_NAME in &_Local/Makefile_&, or by setting tcp_wrappers_daemon_name in the configure file. Consult the &'tcpwrappers'& documentation for further details. .section "Including support for IPv6" "SECID28" .cindex "IPv6" "including support for" Exim contains code for use on systems that have IPv6 support. Setting &`HAVE_IPV6=YES`& in &_Local/Makefile_& causes the IPv6 code to be included; it may also be necessary to set IPV6_INCLUDE and IPV6_LIBS on systems where the IPv6 support is not fully integrated into the normal include and library files. Two different types of DNS record for handling IPv6 addresses have been defined. AAAA records (analogous to A records for IPv4) are in use, and are currently seen as the mainstream. Another record type called A6 was proposed as better than AAAA because it had more flexibility. However, it was felt to be over-complex, and its status was reduced to &"experimental"&. Exim used to have a compile option for including A6 record support but this has now been withdrawn. .section "Dynamically loaded module support" "SECTdynamicmodules" .cindex "lookup modules" .cindex "router modules" .cindex "transport modules" .cindex "authenticator modules" .cindex "dynamic modules" .cindex ".so building" On some platforms, Exim supports not compiling all lookup types directly into the main binary, instead putting some into external modules which can be loaded on demand. This permits packagers to build Exim with support for lookups with extensive library dependencies without requiring all systems to install all of those dependencies. .new Any combination of lookup types can be built this way. Lookup types that provide several variants will be loaded as Exim starts. Types that provide only one method are not loaded until used by the runtime configuration. .wen For building set &`LOOKUP_MODULE_DIR`& to the directory into which the modules will be installed; Exim will only load modules from that directory, as a security measure. You will need to set &`CFLAGS_DYNAMIC`& if not already defined for your OS; see &_OS/Makefile-Linux_& for an example. Some other requirements for adjusting &`EXTRALIBS`& may also be necessary, see &_src/EDITME_& for details. Then, for each module to be loaded dynamically, define the relevant &`LOOKUP_`&<&'lookup_type'&> flags to have the value "2" instead of "yes". For example, this will build in lsearch but load sqlite and mysql support only if each is installed: .code LOOKUP_LSEARCH=yes LOOKUP_SQLITE=2 LOOKUP_MYSQL=2 .endd Set also &`LOOKUP_`&<&'lookup_type'&>&` INCLUDE`& and &`LOOKUP_`&<&'lookup_type'&>`_LIBS if needed for each lookup type, ensuring that duplicates are not present in more global values. .new Similarly, authenticator, router and transport drivers can be built as external modules. Modules will be searched for as demanded by the runtime configuration, permitting a smaller Exim binary. For building, as above but using &`AUTH_*`&, &`ROUTER_*`& and &`TRANSPORT_*`& instead of &`LOOKUP_*`&, .wen .section "The building process" "SECID29" .cindex "build directory" Once &_Local/Makefile_& (and &_Local/eximon.conf_&, if required) have been created, run &'make'& at the top level. It determines the architecture and operating system types, and creates a build directory if one does not exist. For example, on a Sun system running Solaris 8, the directory &_build-SunOS5-5.8-sparc_& is created. .cindex "symbolic link" "to source files" Symbolic links to relevant source files are installed in the build directory. If this is the first time &'make'& has been run, it calls a script that builds a make file inside the build directory, using the configuration files from the &_Local_& directory. The new make file is then passed to another instance of &'make'&. This does the real work, building a number of utility scripts, and then compiling and linking the binaries for the Exim monitor (if configured), a number of utility programs, and finally Exim itself. The command &`make makefile`& can be used to force a rebuild of the make file in the build directory, should this ever be necessary. If you have problems building Exim, check for any comments there may be in the &_README_& file concerning your operating system, and also take a look at the FAQ, where some common problems are covered. .section 'Output from &"make"&' "SECID283" The output produced by the &'make'& process for compile lines is often very unreadable, because these lines can be very long. For this reason, the normal output is suppressed by default, and instead output similar to that which appears when compiling the 2.6 Linux kernel is generated: just a short line for each module that is being compiled or linked. However, it is still possible to get the full output, by calling &'make'& like this: .code FULLECHO='' make -e .endd The value of FULLECHO defaults to &"@"&, the flag character that suppresses command reflection in &'make'&. When you ask for the full output, it is given in addition to the short output. .section "Overriding build-time options for Exim" "SECToverride" .cindex "build-time options, overriding" The main make file that is created at the beginning of the building process consists of the concatenation of a number of files which set configuration values, followed by a fixed set of &'make'& instructions. If a value is set more than once, the last setting overrides any previous ones. This provides a convenient way of overriding defaults. The files that are concatenated are, in order: .display &_OS/Makefile-Default_& &_OS/Makefile-_&<&'ostype'&> &_Local/Makefile_& &_Local/Makefile-_&<&'ostype'&> &_Local/Makefile-_&<&'archtype'&> &_Local/Makefile-_&<&'ostype'&>-<&'archtype'&> &_OS/Makefile-Base_& .endd .cindex "&_Local/Makefile_&" .cindex "building Exim" "operating system type" .cindex "building Exim" "architecture type" where <&'ostype'&> is the operating system type and <&'archtype'&> is the architecture type. &_Local/Makefile_& is required to exist, and the building process fails if it is absent. The other three &_Local_& files are optional, and are often not needed. The values used for <&'ostype'&> and <&'archtype'&> are obtained from scripts called &_scripts/os-type_& and &_scripts/arch-type_& respectively. If either of the environment variables EXIM_OSTYPE or EXIM_ARCHTYPE is set, their values are used, thereby providing a means of forcing particular settings. Otherwise, the scripts try to get values from the &%uname%& command. If this fails, the shell variables OSTYPE and ARCHTYPE are inspected. A number of &'ad hoc'& transformations are then applied, to produce the standard names that Exim expects. You can run these scripts directly from the shell in order to find out what values are being used on your system. &_OS/Makefile-Default_& contains comments about the variables that are set therein. Some (but not all) are mentioned below. If there is something that needs changing, review the contents of this file and the contents of the make file for your operating system (&_OS/Makefile-_&) to see what the default values are. .cindex "building Exim" "overriding default settings" If you need to change any of the values that are set in &_OS/Makefile-Default_& or in &_OS/Makefile-_&, or to add any new definitions, you do not need to change the original files. Instead, you should make the changes by putting the new values in an appropriate &_Local_& file. For example, .cindex "Tru64-Unix build-time settings" when building Exim in many releases of the Tru64-Unix (formerly Digital UNIX, formerly DEC-OSF1) operating system, it is necessary to specify that the C compiler is called &'cc'& rather than &'gcc'&. Also, the compiler must be called with the option &%-std1%&, to make it recognize some of the features of Standard C that Exim uses. (Most other compilers recognize Standard C by default.) To do this, you should create a file called &_Local/Makefile-OSF1_& containing the lines .code CC=cc CFLAGS=-std1 .endd If you are compiling for just one operating system, it may be easier to put these lines directly into &_Local/Makefile_&. Keeping all your local configuration settings separate from the distributed files makes it easy to transfer them to new versions of Exim simply by copying the contents of the &_Local_& directory. .cindex "NIS lookup type" "including support for" .cindex "NIS+ lookup type" "including support for" .cindex "LDAP" "including support for" .cindex "lookup" "inclusion in binary" Exim contains support for doing LDAP, NIS, NIS+, and other kinds of file lookup, but not all systems have these components installed, so the default is not to include the relevant code in the binary. All the different kinds of file and database lookup that Exim supports are implemented as separate code modules which are included only if the relevant compile-time options are set. In the case of LDAP, NIS, and NIS+, the settings for &_Local/Makefile_& are: .code LOOKUP_LDAP=yes LOOKUP_NIS=yes LOOKUP_NISPLUS=yes .endd and similar settings apply to the other lookup types. They are all listed in &_src/EDITME_&. In many cases the relevant include files and interface libraries need to be installed before compiling Exim. .cindex "cdb" "including support for" However, there are some optional lookup types (such as cdb) for which the code is entirely contained within Exim, and no external include files or libraries are required. When a lookup type is not included in the binary, attempts to configure Exim to use it cause runtime configuration errors. .cindex "pkg-config" "lookups" .cindex "pkg-config" "authenticators" Many systems now use a tool called &'pkg-config'& to encapsulate information about how to compile against a library; Exim has some initial support for being able to use pkg-config for lookups and authenticators. For any given makefile variable which starts &`LOOKUP_`& or &`AUTH_`&, you can add a new variable with the &`_PC`& suffix in the name and assign as the value the name of the package to be queried. The results of querying via the &'pkg-config'& command will be added to the appropriate Makefile variables with &`+=`& directives, so your version of &'make'& will need to support that syntax. For instance: .code LOOKUP_SQLITE=yes LOOKUP_SQLITE_PC=sqlite3 AUTH_GSASL=yes AUTH_GSASL_PC=libgsasl AUTH_HEIMDAL_GSSAPI=yes AUTH_HEIMDAL_GSSAPI_PC=heimdal-gssapi .endd .cindex "Perl" "including support for" Exim can be linked with an embedded Perl interpreter, allowing Perl subroutines to be called during string expansion. To enable this facility, .code EXIM_PERL=perl.o .endd must be defined in &_Local/Makefile_&. Details of this facility are given in chapter &<>&. .cindex "X11 libraries, location of" The location of the X11 libraries is something that varies a lot between operating systems, and there may be different versions of X11 to cope with. Exim itself makes no use of X11, but if you are compiling the Exim monitor, the X11 libraries must be available. The following three variables are set in &_OS/Makefile-Default_&: .code X11=/usr/X11R6 XINCLUDE=-I$(X11)/include XLFLAGS=-L$(X11)/lib .endd These are overridden in some of the operating-system configuration files. For example, in &_OS/Makefile-SunOS5_& there is .code X11=/usr/openwin XINCLUDE=-I$(X11)/include XLFLAGS=-L$(X11)/lib -R$(X11)/lib .endd If you need to override the default setting for your operating system, place a definition of all three of these variables into your &_Local/Makefile-_& file. .cindex "EXTRALIBS" If you need to add any extra libraries to the link steps, these can be put in a variable called EXTRALIBS, which appears in all the link commands, but by default is not defined. In contrast, EXTRALIBS_EXIM is used only on the command for linking the main Exim binary, and not for any associated utilities. .cindex "DBM libraries" "configuration for building" There is also DBMLIB, which appears in the link commands for binaries that use DBM functions (see also section &<>&). Finally, there is EXTRALIBS_EXIMON, which appears only in the link step for the Exim monitor binary, and which can be used, for example, to include additional X11 libraries. .cindex "configuration file" "editing" The make file copes with rebuilding Exim correctly if any of the configuration files are edited. However, if an optional configuration file is deleted, it is necessary to touch the associated non-optional file (that is, &_Local/Makefile_& or &_Local/eximon.conf_&) before rebuilding. .section "OS-specific header files" "SECID30" .cindex "&_os.h_&" .cindex "building Exim" "OS-specific C header files" The &_OS_& directory contains a number of files with names of the form &_os.h-_&. These are system-specific C header files that should not normally need to be changed. There is a list of macro settings that are recognized in the file &_OS/os.configuring_&, which should be consulted if you are porting Exim to a new operating system. .section "Overriding build-time options for the monitor" "SECID31" .cindex "building Eximon" A similar process is used for overriding things when building the Exim monitor, where the files that are involved are .display &_OS/eximon.conf-Default_& &_OS/eximon.conf-_&<&'ostype'&> &_Local/eximon.conf_& &_Local/eximon.conf-_&<&'ostype'&> &_Local/eximon.conf-_&<&'archtype'&> &_Local/eximon.conf-_&<&'ostype'&>-<&'archtype'&> .endd .cindex "&_Local/eximon.conf_&" As with Exim itself, the final three files need not exist, and in this case the &_OS/eximon.conf-_& file is also optional. The default values in &_OS/eximon.conf-Default_& can be overridden dynamically by setting environment variables of the same name, preceded by EXIMON_. For example, setting EXIMON_LOG_DEPTH in the environment overrides the value of LOG_DEPTH at runtime. .ecindex IIDbuex .section "Installing Exim binaries and scripts" "SECID32" .cindex "installing Exim" .cindex "BIN_DIRECTORY" The command &`make install`& runs the &(exim_install)& script with no arguments. The script copies binaries and utility scripts into the directory whose name is specified by the BIN_DIRECTORY setting in &_Local/Makefile_&. .cindex "setuid" "installing Exim with" The install script copies files only if they are newer than the files they are going to replace. The Exim binary is required to be owned by root and have the &'setuid'& bit set, for normal configurations. Therefore, you must run &`make install`& as root so that it can set up the Exim binary in this way. However, in some special situations (for example, if a host is doing no local deliveries) it may be possible to run Exim without making the binary setuid root (see chapter &<>& for details). .cindex "CONFIGURE_FILE" Exim's runtime configuration file is named by the CONFIGURE_FILE setting in &_Local/Makefile_&. If this names a single file, and the file does not exist, the default configuration file &_src/configure.default_& is copied there by the installation script. If a runtime configuration file already exists, it is left alone. If CONFIGURE_FILE is a colon-separated list, naming several alternative files, no default is installed. .cindex "system aliases file" .cindex "&_/etc/aliases_&" One change is made to the default configuration file when it is installed: the default configuration contains a router that references a system aliases file. The path to this file is set to the value specified by SYSTEM_ALIASES_FILE in &_Local/Makefile_& (&_/etc/aliases_& by default). If the system aliases file does not exist, the installation script creates it, and outputs a comment to the user. The created file contains no aliases, but it does contain comments about the aliases a site should normally have. Mail aliases have traditionally been kept in &_/etc/aliases_&. However, some operating systems are now using &_/etc/mail/aliases_&. You should check if yours is one of these, and change Exim's configuration if necessary. The default configuration uses the local host's name as the only local domain, and is set up to do local deliveries into the shared directory &_/var/mail_&, running as the local user. System aliases and &_.forward_& files in users' home directories are supported, but no NIS or NIS+ support is configured. Domains other than the name of the local host are routed using the DNS, with delivery over SMTP. It is possible to install Exim for special purposes (such as building a binary distribution) in a private part of the file system. You can do this by a command such as .code make DESTDIR=/some/directory/ install .endd This has the effect of pre-pending the specified directory to all the file paths, except the name of the system aliases file that appears in the default configuration. (If a default alias file is created, its name &'is'& modified.) For backwards compatibility, ROOT is used if DESTDIR is not set, but this usage is deprecated. .cindex "installing Exim" "what is not installed" Running &'make install'& does not copy the Exim 4 conversion script &'convert4r4'&. You will probably run this only once if you are upgrading from Exim 3. None of the documentation files in the &_doc_& directory are copied, except for the info files when you have set INFO_DIRECTORY, as described in section &<>& below. For the utility programs, old versions are renamed by adding the suffix &_.O_& to their names. The Exim binary itself, however, is handled differently. It is installed under a name that includes the version number and the compile number, for example, &_exim-&version()-1_&. The script then arranges for a symbolic link called &_exim_& to point to the binary. If you are updating a previous version of Exim, the script takes care to ensure that the name &_exim_& is never absent from the directory (as seen by other processes). .cindex "installing Exim" "testing the script" If you want to see what the &'make install'& will do before running it for real, you can pass the &%-n%& option to the installation script by this command: .code make INSTALL_ARG=-n install .endd The contents of the variable INSTALL_ARG are passed to the installation script. You do not need to be root to run this test. Alternatively, you can run the installation script directly, but this must be from within the build directory. For example, from the top-level Exim directory you could use this command: .code (cd build-SunOS5-5.5.1-sparc; ../scripts/exim_install -n) .endd .cindex "installing Exim" "install script options" There are two other options that can be supplied to the installation script. .ilist &%-no_chown%& bypasses the call to change the owner of the installed binary to root, and the call to make it a setuid binary. .next &%-no_symlink%& bypasses the setting up of the symbolic link &_exim_& to the installed binary. .endlist INSTALL_ARG can be used to pass these options to the script. For example: .code make INSTALL_ARG=-no_symlink install .endd The installation script can also be given arguments specifying which files are to be copied. For example, to install just the Exim binary, and nothing else, without creating the symbolic link, you could use: .code make INSTALL_ARG='-no_symlink exim' install .endd .section "Installing info documentation" "SECTinsinfdoc" .cindex "installing Exim" "&'info'& documentation" Not all systems use the GNU &'info'& system for documentation, and for this reason, the Texinfo source of Exim's documentation is not included in the main distribution. Instead it is available separately from the FTP site (see section &<>&). If you have defined INFO_DIRECTORY in &_Local/Makefile_& and the Texinfo source of the documentation is found in the source tree, running &`make install`& automatically builds the info files and installs them. .section "Setting up the spool directory" "SECID33" .cindex "spool directory" "creating" When it starts up, Exim tries to create its spool directory if it does not exist. The Exim uid and gid are used for the owner and group of the spool directory. Sub-directories are automatically created in the spool directory as necessary. .section "Testing" "SECID34" .cindex "testing" "installation" Having installed Exim, you can check that the runtime configuration file is syntactically valid by running the following command, which assumes that the Exim binary directory is within your PATH environment variable: .code exim -bV .endd If there are any errors in the configuration file, Exim outputs error messages. Otherwise it outputs the version number and build date, the DBM library that is being used, and information about which drivers and other optional code modules are included in the binary. Some simple routing tests can be done by using the address testing option. For example, .display &`exim -bt`& <&'local username'&> .endd should verify that it recognizes a local mailbox, and .display &`exim -bt`& <&'remote address'&> .endd a remote one. Then try getting it to deliver mail, both locally and remotely. This can be done by passing messages directly to Exim, without going through a user agent. For example: .code exim -v postmaster@your.domain.example From: user@your.domain.example To: postmaster@your.domain.example Subject: Testing Exim This is a test message. ^D .endd The &%-v%& option causes Exim to output some verification of what it is doing. In this case you should see copies of three log lines, one for the message's arrival, one for its delivery, and one containing &"Completed"&. .cindex "delivery" "problems with" If you encounter problems, look at Exim's log files (&'mainlog'& and &'paniclog'&) to see if there is any relevant information there. Another source of information is running Exim with debugging turned on, by specifying the &%-d%& option. If a message is stuck on Exim's spool, you can force a delivery with debugging turned on by a command of the form .display &`exim -d -M`& <&'exim-message-id'&> .endd You must be root or an &"admin user"& in order to do this. The &%-d%& option produces rather a lot of output, but you can cut this down to specific areas. For example, if you use &%-d-all+route%& only the debugging information relevant to routing is included. (See the &%-d%& option in chapter &<>& for more details.) .cindex '&"sticky"& bit' .cindex "lock files" One specific problem that has shown up on some sites is the inability to do local deliveries into a shared mailbox directory, because it does not have the &"sticky bit"& set on it. By default, Exim tries to create a lock file before writing to a mailbox file, and if it cannot create the lock file, the delivery is deferred. You can get round this either by setting the &"sticky bit"& on the directory, or by setting a specific group for local deliveries and allowing that group to create files in the directory (see the comments above the &(local_delivery)& transport in the default configuration file). Another approach is to configure Exim not to use lock files, but just to rely on &[fcntl()]& locking instead. However, you should do this only if all user agents also use &[fcntl()]& locking. For further discussion of locking issues, see chapter &<>&. One thing that cannot be tested on a system that is already running an MTA is the receipt of incoming SMTP mail on the standard SMTP port. However, the &%-oX%& option can be used to run an Exim daemon that listens on some other port, or &'inetd'& can be used to do this. The &%-bh%& option and the &'exim_checkaccess'& utility can be used to check out policy controls on incoming SMTP mail. Testing a new version on a system that is already running Exim can most easily be done by building a binary with a different CONFIGURE_FILE setting. From within the runtime configuration, all other file and directory names that Exim uses can be altered, in order to keep it entirely clear of the production version. .section "Replacing another MTA with Exim" "SECID35" .cindex "replacing another MTA" Building and installing Exim for the first time does not of itself put it in general use. The name by which the system's MTA is called by mail user agents is either &_/usr/sbin/sendmail_&, or &_/usr/lib/sendmail_& (depending on the operating system), and it is necessary to make this name point to the &'exim'& binary in order to get the user agents to pass messages to Exim. This is normally done by renaming any existing file and making &_/usr/sbin/sendmail_& or &_/usr/lib/sendmail_& .cindex "symbolic link" "to &'exim'& binary" a symbolic link to the &'exim'& binary. It is a good idea to remove any setuid privilege and executable status from the old MTA. It is then necessary to stop and restart the mailer daemon, if one is running. .cindex "FreeBSD, MTA indirection" .cindex "&_/etc/mail/mailer.conf_&" Some operating systems have introduced alternative ways of switching MTAs. For example, if you are running FreeBSD, you need to edit the file &_/etc/mail/mailer.conf_& instead of setting up a symbolic link as just described. A typical example of the contents of this file for running Exim is as follows: .code sendmail /usr/exim/bin/exim send-mail /usr/exim/bin/exim mailq /usr/exim/bin/exim -bp newaliases /usr/bin/true .endd Once you have set up the symbolic link, or edited &_/etc/mail/mailer.conf_&, your Exim installation is &"live"&. Check it by sending a message from your favourite user agent. You should consider what to tell your users about the change of MTA. Exim may have different capabilities to what was previously running, and there are various operational differences such as the text of messages produced by command line options and in bounce messages. If you allow your users to make use of Exim's filtering capabilities, you should make the document entitled &'Exim's interface to mail filtering'& available to them. .section "Running the daemon" SECTdaemonLaunch The most common command line for launching the Exim daemon looks like .code exim -bd -q5m .endd This starts a daemon which .ilist listens for incoming smtp connections, launching handler processes for each new one .next starts a queue-runner process every five minutes, to inspect queued messages and run delivery attempts on any that have arrived at their retry time .endlist Should a queue run take longer than the time between queue-runner starts, they will run in parallel. Numbers of jobs of the various types are subject to policy controls defined in the configuration. .section "Upgrading Exim" "SECID36" .cindex "upgrading Exim" If you are already running Exim on your host, building and installing a new version automatically makes it available to MUAs, or any other programs that call the MTA directly. However, if you are running an Exim daemon, you do need .cindex restart "on HUP signal" .cindex signal "HUP, to restart" to send it a HUP signal, to make it re-execute itself, and thereby pick up the new binary. You do not need to stop processing mail in order to install a new version of Exim. The install script does not modify an existing runtime configuration file. .section "Stopping the Exim daemon on Solaris" "SECID37" .cindex "Solaris" "stopping Exim on" The standard command for stopping the mailer daemon on Solaris is .code /etc/init.d/sendmail stop .endd If &_/usr/lib/sendmail_& has been turned into a symbolic link, this script fails to stop Exim because it uses the command &'ps -e'& and greps the output for the text &"sendmail"&; this is not present because the actual program name (that is, &"exim"&) is given by the &'ps'& command with these options. A solution is to replace the line that finds the process id with something like .code pid=`cat /var/spool/exim/exim-daemon.pid` .endd to obtain the daemon's pid directly from the file that Exim saves it in. Note, however, that stopping the daemon does not &"stop Exim"&. Messages can still be received from local processes, and if automatic delivery is configured (the normal case), deliveries will still occur. . //////////////////////////////////////////////////////////////////////////// . //////////////////////////////////////////////////////////////////////////// .chapter "The Exim command line" "CHAPcommandline" .scindex IIDclo1 "command line" "options" .scindex IIDclo2 "options" "command line" Exim's command line takes the standard Unix form of a sequence of options, each starting with a hyphen character, followed by a number of arguments. The options are compatible with the main options of Sendmail, and there are also some additional options, some of which are compatible with Smail 3. Certain combinations of options do not make sense, and provoke an error if used. The form of the arguments depends on which options are set. .section "Setting options by program name" "SECID38" .cindex "&'mailq'&" If Exim is called under the name &'mailq'&, it behaves as if the option &%-bp%& were present before any other options. The &%-bp%& option requests a listing of the contents of the mail queue on the standard output. This feature is for compatibility with some systems that contain a command of that name in one of the standard libraries, symbolically linked to &_/usr/sbin/sendmail_& or &_/usr/lib/sendmail_&. .cindex "&'rsmtp'&" If Exim is called under the name &'rsmtp'& it behaves as if the option &%-bS%& were present before any other options, for compatibility with Smail. The &%-bS%& option is used for reading in a number of messages in batched SMTP format. .cindex "&'rmail'&" If Exim is called under the name &'rmail'& it behaves as if the &%-i%& and &%-oee%& options were present before any other options, for compatibility with Smail. The name &'rmail'& is used as an interface by some UUCP systems. .cindex "&'runq'&" .cindex "queue runner" If Exim is called under the name &'runq'& it behaves as if the option &%-q%& were present before any other options, for compatibility with Smail. The &%-q%& option causes a single queue runner process to be started. .cindex "&'newaliases'&" .cindex "alias file" "building" .cindex "Sendmail compatibility" "calling Exim as &'newaliases'&" If Exim is called under the name &'newaliases'& it behaves as if the option &%-bi%& were present before any other options, for compatibility with Sendmail. This option is used for rebuilding Sendmail's alias file. Exim does not have the concept of a single alias file, but can be configured to run a given command if called with the &%-bi%& option. .section "Trusted and admin users" "SECTtrustedadmin" Some Exim options are available only to &'trusted users'& and others are available only to &'admin users'&. In the description below, the phrases &"Exim user"& and &"Exim group"& mean the user and group defined by EXIM_USER and EXIM_GROUP in &_Local/Makefile_& or set by the &%exim_user%& and &%exim_group%& options. These do not necessarily have to use the name &"exim"&. .ilist .cindex "trusted users" "definition of" .cindex "user" "trusted definition of" The trusted users are root, the Exim user, any user listed in the &%trusted_users%& configuration option, and any user whose current group or any supplementary group is one of those listed in the &%trusted_groups%& configuration option. Note that the Exim group is not automatically trusted. .cindex '&"From"& line' .cindex "envelope from" .cindex "envelope sender" Trusted users are always permitted to use the &%-f%& option or a leading &"From&~"& line to specify the envelope sender of a message that is passed to Exim through the local interface (see the &%-bm%& and &%-f%& options below). See the &%untrusted_set_sender%& option for a way of permitting non-trusted users to set envelope senders. .chindex From: .chindex Sender: For a trusted user, there is never any check on the contents of the &'From:'& header line, and a &'Sender:'& line is never added. Furthermore, any existing &'Sender:'& line in incoming local (non-TCP/IP) messages is not removed. Trusted users may also specify a host name, host address, interface address, protocol name, ident value, and authentication data when submitting a message locally. Thus, they are able to insert messages into Exim's queue locally that have the characteristics of messages received from a remote host. Untrusted users may in some circumstances use &%-f%&, but can never set the other values that are available to trusted users. .next .cindex "user" "admin definition of" .cindex "admin user" "definition of" The admin users are root, the Exim user, and any user that is a member of the Exim group or of any group listed in the &%admin_groups%& configuration option. The current group does not have to be one of these groups. Admin users are permitted to list the queue, and to carry out certain operations on messages, for example, to force delivery failures. It is also necessary to be an admin user in order to see the full information provided by the Exim monitor, and full debugging output. By default, the use of the &%-M%&, &%-q%&, &%-R%&, and &%-S%& options to cause Exim to attempt delivery of messages on its queue is restricted to admin users. However, this restriction can be relaxed by setting the &%prod_requires_admin%& option false (that is, specifying &%no_prod_requires_admin%&). Similarly, the use of the &%-bp%& option to list all the messages in the queue is restricted to admin users unless &%queue_list_requires_admin%& is set false. .endlist &*Warning*&: If you configure your system so that admin users are able to edit Exim's configuration file, you are giving those users an easy way of getting root. There is further discussion of this issue at the start of chapter &<>&. .section "Command line options" "SECID39" Exim's command line options are described in alphabetical order below. If none of the options that specifies a specific action (such as starting the daemon or a queue runner, or testing an address, or receiving a message in a specific format, or listing the queue) are present, and there is at least one argument on the command line, &%-bm%& (accept a local message on the standard input, with the arguments specifying the recipients) is assumed. Otherwise, Exim outputs a brief message about itself and exits. . //////////////////////////////////////////////////////////////////////////// . Insert a stylized XML comment here, to identify the start of the command line . options. This is for the benefit of the Perl script that automatically . creates a man page for the options. . //////////////////////////////////////////////////////////////////////////// .literal xml .literal off .vlist .cmdopt "--" "--" .cindex "options" "command line; terminating" This is a pseudo-option whose only purpose is to terminate the options and therefore to cause subsequent command line items to be treated as arguments rather than options, even if they begin with hyphens. .cmdopt --help This option causes Exim to output a few sentences stating what it is. The same output is generated if the Exim binary is called with no options and no arguments. .cmdopt --version This option is an alias for &%-bV%& and causes version information to be displayed. .vitem &%-Ac%& &&& &%-Am%& .oindex "&%-Ac%&" .oindex "&%-Am%&" These options are used by Sendmail for selecting configuration files and are ignored by Exim. .cmdopt -B <&'type'&> .oindex "&%-B%&" .cindex "8-bit characters" .cindex "Sendmail compatibility" "8-bit characters" This is a Sendmail option for selecting 7 or 8 bit processing. Exim is 8-bit clean; it ignores this option. .cmdopt -bd .cindex "daemon" .cindex "SMTP" "listener" .cindex "queue runner" This option runs Exim as a daemon, awaiting incoming SMTP connections. Usually the &%-bd%& option is combined with the &%-q%&<&'time'&> option, to specify that the daemon should also initiate periodic queue runs. The &%-bd%& option can be used only by an admin user. If either of the &%-d%& (debugging) or &%-v%& (verifying) options are set, the daemon does not disconnect from the controlling terminal. When running this way, it can be stopped by pressing ctrl-C. By default, Exim listens for incoming connections to the standard SMTP port on all the host's running interfaces. However, it is possible to listen on other ports, on multiple ports, and only on specific interfaces. Chapter &<>& contains a description of the options that control this. When a listening daemon .cindex "daemon" "process id (pid)" .cindex "pid (process id)" "of daemon" is started without the use of &%-oX%& (that is, without overriding the normal configuration), it writes its process id to a file called &_exim-daemon.pid_& in Exim's spool directory. This location can be overridden by setting PID_FILE_PATH in &_Local/Makefile_&. The file is written while Exim is still running as root. When &%-oX%& is used on the command line to start a listening daemon, the process id is not written to the normal pid file path. However, &%-oP%& can be used to specify a path on the command line if a pid file is required. The SIGHUP signal .cindex "SIGHUP" .cindex restart "on HUP signal" .cindex signal "HUP, to restart" .cindex "daemon" "restarting" .cindex signal "to reload configuration" .cindex daemon "reload configuration" .cindex reload configuration can be used to cause the daemon to re-execute itself. This should be done whenever Exim's configuration file, or any file that is incorporated into it by means of the &%.include%& facility, is changed, and also whenever a new version of Exim is installed. It is not necessary to do this when other files that are referenced from the configuration (for example, alias files) are changed, because these are reread each time they are used. Either a SIGTERM or a SIGINT signal should be used to cause the daemon to cleanly shut down. Subprocesses handling recceiving or delivering messages, or for scanning the queue, will not be affected by the termination of the daemon process. .cmdopt -bdf This option has the same effect as &%-bd%& except that it never disconnects from the controlling terminal, even when no debugging is specified. .cmdopt -be .cindex "testing" "string expansion" .cindex "expansion" "testing" Run Exim in expansion testing mode. Exim discards its root privilege, to prevent ordinary users from using this mode to read otherwise inaccessible files. If no arguments are given, Exim runs interactively, prompting for lines of data. Otherwise, it processes each argument in turn. If Exim was built with USE_READLINE=yes in &_Local/Makefile_&, it tries to load the &%libreadline%& library dynamically whenever the &%-be%& option is used without command line arguments. If successful, it uses the &[readline()]& function, which provides extensive line-editing facilities, for reading the test data. A line history is supported. Long expansion expressions can be split over several lines by using backslash continuations. As in Exim's runtime configuration, white space at the start of continuation lines is ignored. Each argument or data line is passed through the string expansion mechanism, and the result is output. Variable values from the configuration file (for example, &$qualify_domain$&) are available, but no message-specific values (such as &$message_exim_id$&) are set, because no message is being processed (but see &%-bem%& and &%-Mset%&). &*Note*&: If you use this mechanism to test lookups, and you change the data files or databases you are using, you must exit and restart Exim before trying the same lookup again. Otherwise, because each Exim process caches the results of lookups, you will just get the same result as before. Macro processing is done on lines before string-expansion: new macros can be defined and macros will be expanded. Because macros in the config file are often used for secrets, those are only available to admin users. The word &"set"& at the start of a line, followed by a single space, is recognised specially as defining a value for a variable. .cindex "tainted data" "expansion testing" If the sequence &",t"& is inserted before the space, the value is marked as tainted. The syntax is otherwise the same as the ACL modifier &"set ="&. .cmdopt -bem <&'filename'&> .cindex "testing" "string expansion" .cindex "expansion" "testing" This option operates like &%-be%& except that it must be followed by the name of a file. For example: .code exim -bem /tmp/testmessage .endd The file is read as a message (as if receiving a locally-submitted non-SMTP message) before any of the test expansions are done. Thus, message-specific variables such as &$message_size$& and &$header_from:$& are available. However, no &'Received:'& header is added to the message. If the &%-t%& option is set, recipients are read from the headers in the normal way, and are shown in the &$recipients$& variable. Note that recipients cannot be given on the command line, because further arguments are taken as strings to expand (just like &%-be%&). .cmdopt -bF <&'filename'&> .cindex "system filter" "testing" .cindex "testing" "system filter" This option is the same as &%-bf%& except that it assumes that the filter being tested is a system filter. The additional commands that are available only in system filters are recognized. .cmdopt -bf <&'filename'&> .cindex "filter" "testing" .cindex "testing" "filter file" .cindex "forward file" "testing" .cindex "testing" "forward file" .cindex "Sieve filter" "testing" This option runs Exim in user filter testing mode; the file is the filter file to be tested, and a test message must be supplied on the standard input. If there are no message-dependent tests in the filter, an empty file can be supplied. If you want to test a system filter file, use &%-bF%& instead of &%-bf%&. You can use both &%-bF%& and &%-bf%& on the same command, in order to test a system filter and a user filter in the same run. For example: .code exim -bF /system/filter -bf /user/filter >& to &<>& for a description of the possible contents of non-filter redirection lists. The result of an Exim command that uses &%-bf%&, provided no errors are detected, is a list of the actions that Exim would try to take if presented with the message for real. More details of filter testing are given in the separate document entitled &'Exim's interfaces to mail filtering'&. When testing a filter file, .cindex "&""From""& line" .cindex "envelope from" .cindex "envelope sender" .oindex "&%-f%&" "for filter testing" the envelope sender can be set by the &%-f%& option, or by a &"From&~"& line at the start of the test message. Various parameters that would normally be taken from the envelope recipient address of the message can be set by means of additional command line options (see the next four options). .cmdopt -bfd <&'domain'&> .vindex "&$qualify_domain$&" This sets the domain of the recipient address when a filter file is being tested by means of the &%-bf%& option. The default is the value of &$qualify_domain$&. .cmdopt -bfl <&'local&~part'&> This sets the local part of the recipient address when a filter file is being tested by means of the &%-bf%& option. The default is the username of the process that calls Exim. A local part should be specified with any prefix or suffix stripped, because that is how it appears to the filter when a message is actually being delivered. .cmdopt -bfp <&'prefix'&> .cindex affix "filter testing" This sets the prefix of the local part of the recipient address when a filter file is being tested by means of the &%-bf%& option. The default is an empty prefix. .cmdopt -bfs <&'suffix'&> .cindex affix "filter testing" This sets the suffix of the local part of the recipient address when a filter file is being tested by means of the &%-bf%& option. The default is an empty suffix. .cmdopt -bh <&'IP&~address'&> .cindex "testing" "incoming SMTP" .cindex "SMTP" "testing incoming" .cindex "testing" "relay control" .cindex "relaying" "testing configuration" .cindex "policy control" "testing" .cindex "debugging" "&%-bh%& option" This option runs a fake SMTP session as if from the given IP address, using the standard input and output. The IP address may include a port number at the end, after a full stop. For example: .code exim -bh 10.9.8.7.1234 exim -bh fe80::a00:20ff:fe86:a061.5678 .endd When an IPv6 address is given, it is converted into canonical form. In the case of the second example above, the value of &$sender_host_address$& after conversion to the canonical form is &`fe80:0000:0000:0a00:20ff:fe86:a061.5678`&. Comments as to what is going on are written to the standard error file. These include lines beginning with &"LOG"& for anything that would have been logged. This facility is provided for testing configuration options for incoming messages, to make sure they implement the required policy. For example, you can test your relay controls using &%-bh%&. &*Warning 1*&: .cindex "RFC 1413" You can test features of the configuration that rely on ident (&url(https://www.rfc-editor.org/rfc/rfc2487,RFC 1413)) information by using the &%-oMt%& option. However, Exim cannot actually perform an ident callout when testing using &%-bh%& because there is no incoming SMTP connection. &*Warning 2*&: Address verification callouts (see section &<>&) are also skipped when testing using &%-bh%&. If you want these callouts to occur, use &%-bhc%& instead. Messages supplied during the testing session are discarded, and nothing is written to any of the real log files. There may be pauses when DNS (and other) lookups are taking place, and of course these may time out. The &%-oMi%& option can be used to specify a specific IP interface and port if this is important, and &%-oMaa%& and &%-oMai%& can be used to set parameters as if the SMTP session were authenticated. The &'exim_checkaccess'& utility is a &"packaged"& version of &%-bh%& whose output just states whether a given recipient address from a given host is acceptable or not. See section &<>&. Features such as authentication and encryption, where the client input is not plain text, cannot easily be tested with &%-bh%&. Instead, you should use a specialized SMTP test program such as &url(https://www.jetmore.org/john/code/swaks/,swaks,swaks). .cmdopt -bhc <&'IP&~address'&> This option operates in the same way as &%-bh%&, except that address verification callouts are performed if required. This includes consulting and updating the callout cache database. .cmdopt -bi .cindex "alias file" "building" .cindex "building alias file" .cindex "Sendmail compatibility" "&%-bi%& option" Sendmail interprets the &%-bi%& option as a request to rebuild its alias file. Exim does not have the concept of a single alias file, and so it cannot mimic this behaviour. However, calls to &_/usr/lib/sendmail_& with the &%-bi%& option tend to appear in various scripts such as NIS make files, so the option must be recognized. If &%-bi%& is encountered, the command specified by the &%bi_command%& configuration option is run, under the uid and gid of the caller of Exim. If the &%-oA%& option is used, its value is passed to the command as an argument. The command set by &%bi_command%& may not contain arguments. The command can use the &'exim_dbmbuild'& utility, or some other means, to rebuild alias files if this is required. If the &%bi_command%& option is not set, calling Exim with &%-bi%& is a no-op. . // Keep :help first, then the rest in alphabetical order .cmdopt -bI:help .cindex "querying exim information" We shall provide various options starting &`-bI:`& for querying Exim for information. The output of many of these will be intended for machine consumption. This one is not. The &%-bI:help%& option asks Exim for a synopsis of supported options beginning &`-bI:`&. Use of any of these options shall cause Exim to exit after producing the requested output. .cmdopt -bI:dscp .cindex "DSCP" "values" This option causes Exim to emit an alphabetically sorted list of all recognised DSCP names. .cmdopt -bI:sieve .cindex "Sieve filter" "capabilities" This option causes Exim to emit an alphabetically sorted list of all supported Sieve protocol extensions on stdout, one per line. This is anticipated to be useful for ManageSieve (&url(https://datatracker.ietf.org/doc/html/rfc5804.html,RFC 5804)) implementations, in providing that protocol's &`SIEVE`& capability response line. As the precise list may depend upon compile-time build options, which this option will adapt to, this is the only way to guarantee a correct response. .cmdopt -bm .cindex "local message reception" This option runs an Exim receiving process that accepts an incoming, locally-generated message on the standard input. The recipients are given as the command arguments (except when &%-t%& is also present &-- see below). Each argument can be a comma-separated list of &url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822) addresses. This is the default option for selecting the overall action of an Exim call; it is assumed if no other conflicting option is present. If any addresses in the message are unqualified (have no domain), they are qualified by the values of the &%qualify_domain%& or &%qualify_recipient%& options, as appropriate. The &%-bnq%& option (see below) provides a way of suppressing this for special cases. Policy checks on the contents of local messages can be enforced by means of the non-SMTP ACL. See section &<>& for details. .cindex "return code" "for &%-bm%&" The return code is zero if the message is successfully accepted. Otherwise, the action is controlled by the &%-oe%&&'x'& option setting &-- see below. The format .cindex "message" "format" .cindex "format" "message" .cindex "&""From""& line" .cindex "UUCP" "&""From""& line" .cindex "Sendmail compatibility" "&""From""& line" of the message must be as defined in &url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822), except that, for compatibility with Sendmail and Smail, a line in one of the forms .code From sender Fri Jan 5 12:55 GMT 1997 From sender Fri, 5 Jan 97 12:55:01 .endd (with the weekday optional, and possibly with additional text after the date) is permitted to appear at the start of the message. There appears to be no authoritative specification of the format of this line. Exim recognizes it by matching against the regular expression defined by the &%uucp_from_pattern%& option, which can be changed if necessary. .oindex "&%-f%&" "overriding &""From""& line" The specified sender is treated as if it were given as the argument to the &%-f%& option, but if a &%-f%& option is also present, its argument is used in preference to the address taken from the message. The caller of Exim must be a trusted user for the sender of a message to be set in this way. .cmdopt -bmalware <&'filename'&> .cindex "testing", "malware" .cindex "malware scan test" This debugging option causes Exim to scan the given file or directory (depending on the used scanner interface), using the malware scanning framework. The option of &%av_scanner%& influences this option, so if &%av_scanner%&'s value is dependent upon an expansion then the expansion should have defaults which apply to this invocation. ACLs are not invoked, so if &%av_scanner%& references an ACL variable then that variable will never be populated and &%-bmalware%& will fail. Exim will have changed working directory before resolving the filename, so using fully qualified pathnames is advisable. Exim will be running as the Exim user when it tries to open the file, rather than as the invoking user. This option requires admin privileges. The &%-bmalware%& option will not be extended to be more generally useful, there are better tools for file-scanning. This option exists to help administrators verify their Exim and AV scanner configuration. .cmdopt -bnq .cindex "address qualification, suppressing" By default, Exim automatically qualifies unqualified addresses (those without domains) that appear in messages that are submitted locally (that is, not over TCP/IP). This qualification applies both to addresses in envelopes, and addresses in header lines. Sender addresses are qualified using &%qualify_domain%&, and recipient addresses using &%qualify_recipient%& (which defaults to the value of &%qualify_domain%&). Sometimes, qualification is not wanted. For example, if &%-bS%& (batch SMTP) is being used to re-submit messages that originally came from remote hosts after content scanning, you probably do not want to qualify unqualified addresses in header lines. (Such lines will be present only if you have not enabled a header syntax check in the appropriate ACL.) The &%-bnq%& option suppresses all qualification of unqualified addresses in messages that originate on the local host. When this is used, unqualified addresses in the envelope provoke errors (causing message rejection) and unqualified addresses in header lines are left alone. .cmdopt -bP .cindex "configuration options" "extracting" .cindex "options" "configuration &-- extracting" If this option is given with no arguments, it causes the values of all Exim's main configuration options to be written to the standard output. The values of one or more specific options can be requested by giving their names as arguments, for example: .code exim -bP qualify_domain hold_domains .endd .cindex "hiding configuration option values" .cindex "configuration options" "hiding value of" .cindex "options" "hiding value of" However, any option setting that is preceded by the word &"hide"& in the configuration file is not shown in full, except to an admin user. For other users, the output is as in this example: .code mysql_servers = .endd If &%config%& is given as an argument, the config is output, as it was parsed, any include file resolved, any comment removed. If &%config_file%& is given as an argument, the name of the runtime configuration file is output. (&%configure_file%& works too, for backward compatibility.) If a list of configuration files was supplied, the value that is output here is the name of the file that was actually used. .cindex "options" "hiding name of" If the &%-n%& flag is given, then for most modes of &%-bP%& operation the name will not be output. .cindex "daemon" "process id (pid)" .cindex "pid (process id)" "of daemon" If &%log_file_path%& or &%pid_file_path%& are given, the names of the directories where log files and daemon pid files are written are output, respectively. If these values are unset, log files are written in a sub-directory of the spool directory called &%log%&, and the pid file is written directly into the spool directory. If &%-bP%& is followed by a name preceded by &`+`&, for example, .code exim -bP +local_domains .endd it searches for a matching named list of any type (domain, host, address, or local part) and outputs what it finds. .cindex "options" "router &-- extracting" .cindex "options" "transport &-- extracting" .cindex "options" "authenticator &-- extracting" If one of the words &%router%&, &%transport%&, or &%authenticator%& is given, followed by the name of an appropriate driver instance, the option settings for that driver are output. For example: .code exim -bP transport local_delivery .endd The generic driver options are output first, followed by the driver's private options. A list of the names of drivers of a particular type can be obtained by using one of the words &%router_list%&, &%transport_list%&, or &%authenticator_list%&, and a complete list of all drivers with their option settings can be obtained by using &%routers%&, &%transports%&, or &%authenticators%&. .cindex "environment" If &%environment%& is given as an argument, the set of environment variables is output, line by line. Using the &%-n%& flag suppresses the value of the variables. .cindex "options" "macro &-- extracting" If invoked by an admin user, then &%macro%&, &%macro_list%& and &%macros%& are available, similarly to the drivers. Because macros are sometimes used for storing passwords, this option is restricted. The output format is one item per line. For the "-bP macro " form, if no such macro is found the exit status will be nonzero. .cmdopt -bp .cindex "queue" "listing messages in" .cindex "listing" "messages in the queue" This option requests a listing of the contents of the mail queue on the standard output. If the &%-bp%& option is followed by a list of message ids, just those messages are listed. By default, this option can be used only by an admin user. However, the &%queue_list_requires_admin%& option can be set false to allow any user to see the queue. Each message in the queue is displayed as in the following example: .code 25m 2.9K 0t5C6f-0000c8-00 red.king@looking-glass.fict.example .endd .cindex "message" "size in queue listing" .cindex "size" "of message" The first line contains the length of time the message has been in the queue (in this case 25 minutes), the size of the message (2.9K), the unique local identifier for the message, and the message sender, as contained in the envelope. For bounce messages, the sender address is empty, and appears as &"<>"&. If the message was submitted locally by an untrusted user who overrode the default sender address, the user's login name is shown in parentheses before the sender address. .cindex "frozen messages" "in queue listing" If the message is frozen (attempts to deliver it are suspended) then the text &"*** frozen ***"& is displayed at the end of this line. The recipients of the message (taken from the envelope, not the headers) are displayed on subsequent lines. Those addresses to which the message has already been delivered are marked with the letter D. If an original address gets expanded into several addresses via an alias or forward file, the original is displayed with a D only when deliveries for all of its child addresses are complete. .cmdopt -bpa This option operates like &%-bp%&, but in addition it shows delivered addresses that were generated from the original top level address(es) in each message by alias or forwarding operations. These addresses are flagged with &"+D"& instead of just &"D"&. .cmdopt -bpc .cindex "queue" "count of messages on" This option counts the number of messages in the queue, and writes the total to the standard output. It is restricted to admin users, unless &%queue_list_requires_admin%& is set false. .cmdopt -bpi .cindex queue "list of message IDs" This option operates like &%-bp%&, but only outputs message ids (one per line). .cmdopt -bpr This option operates like &%-bp%&, but the output is not sorted into chronological order of message arrival. This can speed it up when there are lots of messages in the queue, and is particularly useful if the output is going to be post-processed in a way that doesn't need the sorting. .cmdopt -bpra This option is a combination of &%-bpr%& and &%-bpa%&. .cmdopt -bpri This option is a combination of &%-bpr%& and &%-bpi%&. .cmdopt -bpru This option is a combination of &%-bpr%& and &%-bpu%&. .cmdopt -bpu This option operates like &%-bp%& but shows only undelivered top-level addresses for each message displayed. Addresses generated by aliasing or forwarding are not shown, unless the message was deferred after processing by a router with the &%one_time%& option set. .cmdopt -brt .cindex "testing" "retry configuration" .cindex "retry" "configuration testing" This option is for testing retry rules, and it must be followed by up to three arguments. It causes Exim to look for a retry rule that matches the values and to write it to the standard output. For example: .code exim -brt bach.comp.mus.example Retry rule: *.comp.mus.example F,2h,15m; F,4d,30m; .endd See chapter &<>& for a description of Exim's retry rules. The first argument, which is required, can be a complete address in the form &'local_part@domain'&, or it can be just a domain name. If the second argument contains a dot, it is interpreted as an optional second domain name; if no retry rule is found for the first argument, the second is tried. This ties in with Exim's behaviour when looking for retry rules for remote hosts &-- if no rule is found that matches the host, one that matches the mail domain is sought. Finally, an argument that is the name of a specific delivery error, as used in setting up retry rules, can be given. For example: .code exim -brt haydn.comp.mus.example quota_3d Retry rule: *@haydn.comp.mus.example quota_3d F,1h,15m .endd .cmdopt -brw .cindex "testing" "rewriting" .cindex "rewriting" "testing" This option is for testing address rewriting rules, and it must be followed by a single argument, consisting of either a local part without a domain, or a complete address with a fully qualified domain. Exim outputs how this address would be rewritten for each possible place it might appear. See chapter &<>& for further details. .cmdopt -bS .cindex "SMTP" "batched incoming" .cindex "batched SMTP input" This option is used for batched SMTP input, which is an alternative interface for non-interactive local message submission. A number of messages can be submitted in a single run. However, despite its name, this is not really SMTP input. Exim reads each message's envelope from SMTP commands on the standard input, but generates no responses. If the caller is trusted, or &%untrusted_set_sender%& is set, the senders in the SMTP MAIL commands are believed; otherwise the sender is always the caller of Exim. The message itself is read from the standard input, in SMTP format (leading dots doubled), terminated by a line containing just a single dot. An error is provoked if the terminating dot is missing. A further message may then follow. As for other local message submissions, the contents of incoming batch SMTP messages can be checked using the non-SMTP ACL (see section &<>&). Unqualified addresses are automatically qualified using &%qualify_domain%& and &%qualify_recipient%&, as appropriate, unless the &%-bnq%& option is used. Some other SMTP commands are recognized in the input. HELO and EHLO act as RSET; VRFY, EXPN, ETRN, ATRN, and HELP act as NOOP; QUIT quits, ignoring the rest of the standard input. .cindex "return code" "for &%-bS%&" If any error is encountered, reports are written to the standard output and error streams, and Exim gives up immediately. The return code is 0 if no error was detected; it is 1 if one or more messages were accepted before the error was detected; otherwise it is 2. More details of input using batched SMTP are given in section &<>&. .cmdopt -bs .cindex "SMTP" "local input" .cindex "local SMTP input" This option causes Exim to accept one or more messages by reading SMTP commands on the standard input, and producing SMTP replies on the standard output. SMTP policy controls, as defined in ACLs (see chapter &<>&) are applied. Some user agents use this interface as a way of passing locally-generated messages to the MTA. In .cindex "sender" "source of" this usage, if the caller of Exim is trusted, or &%untrusted_set_sender%& is set, the senders of messages are taken from the SMTP MAIL commands. Otherwise the content of these commands is ignored and the sender is set up as the calling user. Unqualified addresses are automatically qualified using &%qualify_domain%& and &%qualify_recipient%&, as appropriate, unless the &%-bnq%& option is used. .cindex "inetd" The &%-bs%& option is also used to run Exim from &'inetd'&, as an alternative to using a listening daemon. Exim can distinguish the two cases by checking whether the standard input is a TCP/IP socket. When Exim is called from &'inetd'&, the source of the mail is assumed to be remote, and the comments above concerning senders and qualification do not apply. In this situation, Exim behaves in exactly the same way as it does when receiving a message via the listening daemon. .cmdopt -bt .cindex "testing" "addresses" .cindex "address" "testing" This option runs Exim in address testing mode, in which each argument is taken as a recipient address to be tested for deliverability. The results are written to the standard output. If a test fails, and the caller is not an admin user, no details of the failure are output, because these might contain sensitive information such as usernames and passwords for database lookups. If no arguments are given, Exim runs in an interactive manner, prompting with a right angle bracket for addresses to be tested. Unlike the &%-be%& test option, you cannot arrange for Exim to use the &[readline()]& function, because it is running as &'root'& and there are security issues. Each address is handled as if it were the recipient address of a message (compare the &%-bv%& option). It is passed to the routers and the result is written to the standard output. However, any router that has &%no_address_test%& set is bypassed. This can make &%-bt%& easier to use for genuine routing tests if your first router passes everything to a scanner program. .cindex "return code" "for &%-bt%&" The return code is 2 if any address failed outright; it is 1 if no address failed outright but at least one could not be resolved for some reason. Return code 0 is given only when all addresses succeed. .cindex "duplicate addresses" &*Note*&: When actually delivering a message, Exim removes duplicate recipient addresses after routing is complete, so that only one delivery takes place. This does not happen when testing with &%-bt%&; the full results of routing are always shown. &*Warning*&: &%-bt%& can only do relatively simple testing. If any of the routers in the configuration makes any tests on the sender address of a message, .oindex "&%-f%&" "for address testing" you can use the &%-f%& option to set an appropriate sender when running &%-bt%& tests. Without it, the sender is assumed to be the calling user at the default qualifying domain. However, if you have set up (for example) routers whose behaviour depends on the contents of an incoming message, you cannot test those conditions using &%-bt%&. The &%-N%& option provides a possible way of doing such tests. .cmdopt -bV .cindex "version number of Exim" This option causes Exim to write the current version number, compilation number, and compilation date of the &'exim'& binary to the standard output. It also lists the DBM library that is being used, the optional modules (such as specific lookup types), the drivers that are included in the binary, and the name of the runtime configuration file that is in use. As part of its operation, &%-bV%& causes Exim to read and syntax check its configuration file. However, this is a static check only. It cannot check values that are to be expanded. For example, although a misspelt ACL verb is detected, an error in the verb's arguments is not. You cannot rely on &%-bV%& alone to discover (for example) all the typos in the configuration; some realistic testing is needed. The &%-bh%& and &%-N%& options provide more dynamic testing facilities. .cmdopt -bv .cindex "verifying address" "using &%-bv%&" .cindex "address" "verification" This option runs Exim in address verification mode, in which each argument is taken as a recipient address to be verified by the routers. (This does not involve any verification callouts). During normal operation, verification happens mostly as a consequence processing a &%verify%& condition in an ACL (see chapter &<>&). If you want to test an entire ACL, possibly including callouts, see the &%-bh%& and &%-bhc%& options. If verification fails, and the caller is not an admin user, no details of the failure are output, because these might contain sensitive information such as usernames and passwords for database lookups. If no arguments are given, Exim runs in an interactive manner, prompting with a right angle bracket for addresses to be verified. Unlike the &%-be%& test option, you cannot arrange for Exim to use the &[readline()]& function, because it is running as &'exim'& and there are security issues. Verification differs from address testing (the &%-bt%& option) in that routers that have &%no_verify%& set are skipped, and if the address is accepted by a router that has &%fail_verify%& set, verification fails. The address is verified as a recipient if &%-bv%& is used; to test verification for a sender address, &%-bvs%& should be used. If the &%-v%& option is not set, the output consists of a single line for each address, stating whether it was verified or not, and giving a reason in the latter case. Without &%-v%&, generating more than one address by redirection causes verification to end successfully, without considering the generated addresses. However, if just one address is generated, processing continues, and the generated address must verify successfully for the overall verification to succeed. When &%-v%& is set, more details are given of how the address has been handled, and in the case of address redirection, all the generated addresses are also considered. Verification may succeed for some and fail for others. The .cindex "return code" "for &%-bv%&" return code is 2 if any address failed outright; it is 1 if no address failed outright but at least one could not be resolved for some reason. Return code 0 is given only when all addresses succeed. If any of the routers in the configuration makes any tests on the sender address of a message, you should use the &%-f%& option to set an appropriate sender when running &%-bv%& tests. Without it, the sender is assumed to be the calling user at the default qualifying domain. .cmdopt -bvs This option acts like &%-bv%&, but verifies the address as a sender rather than a recipient address. This affects any rewriting and qualification that might happen. .cmdopt -bw .cindex "daemon" .cindex "inetd" .cindex "inetd" "wait mode" This option runs Exim as a daemon, awaiting incoming SMTP connections, similarly to the &%-bd%& option. All port specifications on the command-line and in the configuration file are ignored. Queue-running may not be specified. In this mode, Exim expects to be passed a socket as fd 0 (stdin) which is listening for connections. This permits the system to start up and have inetd (or equivalent) listen on the SMTP ports, starting an Exim daemon for each port only when the first connection is received. If the option is given as &%-bw%&<&'time'&> then the time is a timeout, after which the daemon will exit, which should cause inetd to listen once more. .cmdopt -C <&'filelist'&> .cindex "configuration file" "alternate" .cindex "CONFIGURE_FILE" .cindex "alternate configuration file" This option causes Exim to find the runtime configuration file from the given list instead of from the list specified by the CONFIGURE_FILE compile-time setting. Usually, the list will consist of just a single filename, but it can be a colon-separated list of names. In this case, the first file that exists is used. Failure to open an existing file stops Exim from proceeding any further along the list, and an error is generated. When this option is used by a caller other than root, and the list is different from the compiled-in list, Exim gives up its root privilege immediately, and runs with the real and effective uid and gid set to those of the caller. However, if a TRUSTED_CONFIG_LIST file is defined in &_Local/Makefile_&, that file contains a list of full pathnames, one per line, for configuration files which are trusted. Root privilege is retained for any configuration file so listed, as long as the caller is the Exim user (or the user specified in the CONFIGURE_OWNER option, if any), and as long as the configuration file is not writeable by inappropriate users or groups. Leaving TRUSTED_CONFIG_LIST unset precludes the possibility of testing a configuration using &%-C%& right through message reception and delivery, even if the caller is root. The reception works, but by that time, Exim is running as the Exim user, so when it re-executes to regain privilege for the delivery, the use of &%-C%& causes privilege to be lost. However, root can test reception and delivery using two separate commands (one to put a message in the queue, using &%-odq%&, and another to do the delivery, using &%-M%&). If ALT_CONFIG_PREFIX is defined &_in Local/Makefile_&, it specifies a prefix string with which any file named in a &%-C%& command line option must start. In addition, the filename must not contain the sequence &`/../`&. However, if the value of the &%-C%& option is identical to the value of CONFIGURE_FILE in &_Local/Makefile_&, Exim ignores &%-C%& and proceeds as usual. There is no default setting for ALT_CONFIG_PREFIX; when it is unset, any filename can be used with &%-C%&. ALT_CONFIG_PREFIX can be used to confine alternative configuration files to a directory to which only root has access. This prevents someone who has broken into the Exim account from running a privileged Exim with an arbitrary configuration file. The &%-C%& facility is useful for ensuring that configuration files are syntactically correct, but cannot be used for test deliveries, unless the caller is privileged, or unless it is an exotic configuration that does not require privilege. No check is made on the owner or group of the files specified by this option. .vitem &%-D%&<&'macro'&>=<&'value'&> .oindex "&%-D%&" .cindex "macro" "setting on command line" This option can be used to override macro definitions in the configuration file (see section &<>&). However, like &%-C%&, if it is used by an unprivileged caller, it causes Exim to give up its root privilege. If DISABLE_D_OPTION is defined in &_Local/Makefile_&, the use of &%-D%& is completely disabled, and its use causes an immediate error exit. If WHITELIST_D_MACROS is defined in &_Local/Makefile_& then it should be a colon-separated list of macros which are considered safe and, if &%-D%& only supplies macros from this list, and the values are acceptable, then Exim will not give up root privilege if the caller is root, the Exim run-time user, or the CONFIGURE_OWNER, if set. This is a transition mechanism and is expected to be removed in the future. Acceptable values for the macros satisfy the regexp: &`^[A-Za-z0-9_/.-]*$`& The entire option (including equals sign if present) must all be within one command line item. &%-D%& can be used to set the value of a macro to the empty string, in which case the equals sign is optional. These two commands are synonymous: .code exim -DABC ... exim -DABC= ... .endd To include spaces in a macro definition item, quotes must be used. If you use quotes, spaces are permitted around the macro name and the equals sign. For example: .code exim '-D ABC = something' ... .endd &%-D%& may be repeated up to 10 times on a command line. Only macro names up to 22 letters long can be set. .vitem &%-d%&<&'debug&~options'&> .oindex "&%-d%&" .cindex "debugging" "list of selectors" .cindex "debugging" "&%-d%& option" This option causes debugging information to be written to the standard error stream. It is restricted to admin users because debugging output may show database queries that contain password information. Also, the details of users' filter files should be protected. If a non-admin user uses &%-d%&, Exim writes an error message to the standard error stream and exits with a non-zero return code. When &%-d%& is used, &%-v%& is assumed. If &%-d%& is given on its own, a lot of standard debugging data is output. This can be reduced, or increased to include some more rarely needed information, by directly following &%-d%& with a string made up of names preceded by plus or minus characters. These add or remove sets of debugging data, respectively. For example, &%-d+filter%& adds filter debugging, whereas &%-d-all+filter%& selects only filter debugging. Note that no spaces are allowed in the debug setting. The available debugging categories are: .itable none 0 0 2 20* left 80* left .irow acl "ACL interpretation" .irow auth "authenticators" .irow deliver "general delivery logic" .irow dns "DNS lookups (see also resolver)" .irow dnsbl "DNS black list (aka RBL) code" .irow exec "arguments for &[execv()]& calls" .irow expand "detailed debugging for string expansions" .irow filter "filter handling" .irow hints_lookup "hints data lookups" .irow host_lookup "all types of name-to-IP address handling" .irow ident "ident lookup" .irow interface "lists of local interfaces" .irow lists "matching things in lists" .irow load "system load checks" .irow local_scan "can be used by &[local_scan()]& (see chapter &&& &<>&)" .irow lookup "general lookup code and all lookups" .irow memory "memory handling" .irow noutf8 "modifier: avoid UTF-8 line-drawing" .irow pid "modifier: add pid to debug output lines" .irow process_info "setting info for the process log" .irow queue_run "queue runs" .irow receive "general message reception logic" .irow resolver "turn on the DNS resolver's debugging output" .irow retry "retry handling" .irow rewrite "address rewriting"" .irow route "address routing" .irow timestamp "modifier: add timestamp to debug output lines" .irow tls "TLS logic" .irow transport "transports" .irow uid "changes of uid/gid and looking up uid/gid" .irow verify "address verification logic" .irow all "almost all of the above (see below), and also &%-v%&" .endtable The &`all`& option excludes &`memory`& when used as &`+all`&, but includes it for &`-all`&. The reason for this is that &`+all`& is something that people tend to use when generating debug output for Exim maintainers. If &`+memory`& is included, an awful lot of output that is very rarely of interest is generated, so it now has to be explicitly requested. However, &`-all`& does turn everything off. .cindex "resolver, debugging output" .cindex "DNS resolver, debugging output" The &`resolver`& option produces output only if the DNS resolver was compiled with DEBUG enabled. This is not the case in some operating systems. Also, unfortunately, debugging output from the DNS resolver is written to stdout rather than stderr. The default (&%-d%& with no argument) omits &`expand`&, &`filter`&, &`interface`&, &`load`&, &`memory`&, &`pid`&, &`resolver`&, and &`timestamp`&. However, the &`pid`& selector is forced when debugging is turned on for a daemon, which then passes it on to any re-executed Exims. Exim also automatically adds the pid to debug lines when several remote deliveries are run in parallel. The &`timestamp`& selector causes the current time to be inserted at the start of all debug output lines. This can be useful when trying to track down delays in processing. .cindex debugging "UTF-8 in" .cindex UTF-8 "in debug output" The &`noutf8`& selector disables the use of UTF-8 line-drawing characters to group related information. When disabled. ascii-art is used instead. Using the &`+all`& option does not set this modifier, If the &%debug_print%& option is set in any driver, it produces output whenever any debugging is selected, or if &%-v%& is used. .vitem &%-dd%&<&'debug&~options'&> .oindex "&%-dd%&" This option behaves exactly like &%-d%& except when used on a command that starts a daemon process. In that case, debugging is turned off for the subprocesses that the daemon creates. Thus, it is useful for monitoring the behaviour of the daemon without creating as much output as full debugging does. .cmdopt -dropcr This is an obsolete option that is now a no-op. It used to affect the way Exim handled CR and LF characters in incoming messages. What happens now is described in section &<>&. .cmdopt -E .cindex "bounce message" "generating" This option specifies that an incoming message is a locally-generated delivery failure report. It is used internally by Exim when handling delivery failures and is not intended for external use. Its only effect is to stop Exim generating certain messages to the postmaster, as otherwise message cascades could occur in some situations. As part of the same option, a message id may follow the characters &%-E%&. If it does, the log entry for the receipt of the new message contains the id, following &"R="&, as a cross-reference. .vitem &%-e%&&'x'& .oindex "&%-e%&&'x'&" There are a number of Sendmail options starting with &%-oe%& which seem to be called by various programs without the leading &%o%& in the option. For example, the &%vacation%& program uses &%-eq%&. Exim treats all options of the form &%-e%&&'x'& as synonymous with the corresponding &%-oe%&&'x'& options. .cmdopt -F <&'string'&> .cindex "sender" "name" .cindex "name" "of sender" This option sets the sender's full name for use when a locally-generated message is being accepted. In the absence of this option, the user's &'gecos'& entry from the password data is used. As users are generally permitted to alter their &'gecos'& entries, no security considerations are involved. White space between &%-F%& and the <&'string'&> is optional. .cmdopt -f <&'address'&> .cindex "sender" "address" .cindex "address" "sender" .cindex "trusted users" .cindex "envelope from" .cindex "envelope sender" .cindex "user" "trusted" This option sets the address of the envelope sender of a locally-generated message (also known as the return path). The option can normally be used only by a trusted user, but &%untrusted_set_sender%& can be set to allow untrusted users to use it. Processes running as root or the Exim user are always trusted. Other trusted users are defined by the &%trusted_users%& or &%trusted_groups%& options. In the absence of &%-f%&, or if the caller is not trusted, the sender of a local message is set to the caller's login name at the default qualify domain. There is one exception to the restriction on the use of &%-f%&: an empty sender can be specified by any user, trusted or not, to create a message that can never provoke a bounce. An empty sender can be specified either as an empty string, or as a pair of angle brackets with nothing between them, as in these examples of shell commands: .code exim -f '<>' user@domain exim -f "" user@domain .endd In addition, the use of &%-f%& is not restricted when testing a filter file with &%-bf%& or when testing or verifying addresses using the &%-bt%& or &%-bv%& options. Allowing untrusted users to change the sender address does not of itself make it possible to send anonymous mail. Exim still checks that the &'From:'& header refers to the local user, and if it does not, it adds a &'Sender:'& header, though this can be overridden by setting &%no_local_from_check%&. White .cindex "&""From""& line" space between &%-f%& and the <&'address'&> is optional (that is, they can be given as two arguments or one combined argument). The sender of a locally-generated message can also be set (when permitted) by an initial &"From&~"& line in the message &-- see the description of &%-bm%& above &-- but if &%-f%& is also present, it overrides &"From&~"&. .cmdopt -G .cindex "submission fixups, suppressing (command-line)" This option is equivalent to an ACL applying: .code control = suppress_local_fixups .endd for every message received. Note that Sendmail will complain about such bad formatting, where Exim silently just does not fix it up. This may change in future. As this affects audit information, the caller must be a trusted user to use this option. .cmdopt -h <&'number'&> .cindex "Sendmail compatibility" "&%-h%& option ignored" This option is accepted for compatibility with Sendmail, but has no effect. (In Sendmail it overrides the &"hop count"& obtained by counting &'Received:'& headers.) .cmdopt -i .cindex "Solaris" "&'mail'& command" .cindex "dot" "in incoming non-SMTP message" This option, which has the same effect as &%-oi%&, specifies that a dot on a line by itself should not terminate an incoming, non-SMTP message. Solaris 2.4 (SunOS 5.4) Sendmail has a similar &%-i%& processing option &url(https://docs.oracle.com/cd/E19457-01/801-6680-1M/801-6680-1M.pdf), p. 1M-529), and therefore a &%-oi%& command line option, which both are used by its &'mailx'& command. .cmdopt -L <&'tag'&> .cindex "syslog" "process name; set with flag" This option is equivalent to setting &%syslog_processname%& in the config file and setting &%log_file_path%& to &`syslog`&. Its use is restricted to administrators. The configuration file has to be read and parsed, to determine access rights, before this is set and takes effect, so early configuration file errors will not honour this flag. The tag should not be longer than 32 characters. .cmdopt -M <&'message&~id'&>&~<&'message&~id'&>&~... .cindex "forcing delivery" .cindex "delivery" "forcing attempt" .cindex "frozen messages" "forcing delivery" This option requests Exim to run a delivery attempt on each message in turn. If any of the messages are frozen, they are automatically thawed before the delivery attempt. The settings of &%queue_domains%&, &%queue_smtp_domains%&, and &%hold_domains%& are ignored. Retry .cindex "hints database" "overriding retry hints" hints for any of the addresses are overridden &-- Exim tries to deliver even if the normal retry time has not yet been reached. This option requires the caller to be an admin user. However, there is an option called &%prod_requires_admin%& which can be set false to relax this restriction (and also the same requirement for the &%-q%&, &%-R%&, and &%-S%& options). The deliveries happen synchronously, that is, the original Exim process does not terminate until all the delivery attempts have finished. No output is produced unless there is a serious error. If you want to see what is happening, use the &%-v%& option as well, or inspect Exim's main log. .cmdopt -Mar <&'message&~id'&>&~<&'address'&>&~<&'address'&>&~... .cindex "message" "adding recipients" .cindex "recipient" "adding" This option requests Exim to add the addresses to the list of recipients of the message (&"ar"& for &"add recipients"&). The first argument must be a message id, and the remaining ones must be email addresses. However, if the message is active (in the middle of a delivery attempt), it is not altered. This option can be used only by an admin user. .vitem "&%-MC%&&~<&'transport'&>&~<&'hostname'&>&&& &~<&'host&~IP'&>&&& &~<&'sequence&~number'&>&&& &~<&'message&~id'&>" .oindex "&%-MC%&" .cindex "SMTP" "passed connection" .cindex "SMTP" "multiple deliveries" .cindex "multiple SMTP deliveries" This option is not intended for use by external callers. It is used internally by Exim to invoke another instance of itself to deliver a waiting message using an existing SMTP connection, which is passed as the standard input. Details are given in chapter &<>&. This must be the final option, and the caller must be root or the Exim user in order to use it. .cmdopt -MCA This option is not intended for use by external callers. It is used internally by Exim in conjunction with the &%-MC%& option. It signifies that the connection to the remote host has been authenticated. .cmdopt -MCD This option is not intended for use by external callers. It is used internally by Exim in conjunction with the &%-MC%& option. It signifies that the remote host supports the ESMTP &_DSN_& extension. .cmdopt -MCd This option is not intended for use by external callers. It is used internally by Exim in conjunction with the &%-d%& option to pass on an information string on the purpose of the process. .cmdopt -MCG <&'queue&~name'&> This option is not intended for use by external callers. It is used internally by Exim in conjunction with the &%-MC%& option. It signifies that an alternate queue is used, named by the following argument. .cmdopt -MCK This option is not intended for use by external callers. It is used internally by Exim in conjunction with the &%-MC%& option. It signifies that a remote host supports the ESMTP &_CHUNKING_& extension. .cmdopt -MCL This option is not intended for use by external callers. It is used internally by Exim in conjunction with the &%-MC%& option. It signifies that the server to which Exim is connected advertised limits on numbers of mails, recipients or recipient domains. The limits are given by the following three arguments. .cmdopt -MCP This option is not intended for use by external callers. It is used internally by Exim in conjunction with the &%-MC%& option. It signifies that the server to which Exim is connected supports pipelining. .cmdopt -MCp This option is not intended for use by external callers. It is used internally by Exim in conjunction with the &%-MC%& option. It signifies that the connection t a remote server is via a SOCKS proxy, using addresses and ports given by the following four arguments. .cmdopt -MCQ <&'process&~id'&>&~<&'pipe&~fd'&> This option is not intended for use by external callers. It is used internally by Exim in conjunction with the &%-MC%& option when the original delivery was started by a queue runner. It passes on the process id of the queue runner, together with the file descriptor number of an open pipe. Closure of the pipe signals the final completion of the sequence of processes that are passing messages through the same SMTP connection. .cmdopt -MCq <&'recipient&~address'&>&~<&'size'&> This option is not intended for use by external callers. It is used internally by Exim to implement quota checking for local users. .cmdopt -MCS This option is not intended for use by external callers. It is used internally by Exim in conjunction with the &%-MC%& option, and passes on the fact that the ESMTP SIZE option should be used on messages delivered down the existing connection. .cmdopt -MCT This option is not intended for use by external callers. It is used internally by Exim in conjunction with the &%-MC%& option, and passes on the fact that the host to which Exim is connected supports TLS encryption. .vitem &%-MCr%&&~<&'SNI'&> &&& &%-MCs%&&~<&'SNI'&> .oindex "&%-MCs%&" .oindex "&%-MCr%&" These options are not intended for use by external callers. It is used internally by Exim in conjunction with the &%-MCt%& option, and passes on the fact that a TLS Server Name Indication was sent as part of the channel establishment. The argument gives the SNI string. The "r" variant indicates a DANE-verified connection. .cmdopt -MCt <&'IP&~address'&>&~<&'port'&>&~<&'cipher'&> This option is not intended for use by external callers. It is used internally by Exim in conjunction with the &%-MC%& option, and passes on the fact that the connection is being proxied by a parent process for handling TLS encryption. The arguments give the local address and port being proxied, and the TLS cipher. .cmdopt -Mc <&'message&~id'&>&~<&'message&~id'&>&~... .cindex "hints database" "not overridden by &%-Mc%&" .cindex "delivery" "manually started &-- not forced" This option requests Exim to run a delivery attempt on each message, in turn, but unlike the &%-M%& option, it does check for retry hints, and respects any that are found. This option is not very useful to external callers. It is provided mainly for internal use by Exim when it needs to re-invoke itself in order to regain root privilege for a delivery (see chapter &<>&). However, &%-Mc%& can be useful when testing, in order to run a delivery that respects retry times and other options such as &%hold_domains%& that are overridden when &%-M%& is used. Such a delivery does not count as a queue run. If you want to run a specific delivery as if in a queue run, you should use &%-q%& with a message id argument. A distinction between queue run deliveries and other deliveries is made in one or two places. .cmdopt -Mes <&'message&~id'&>&~<&'address'&> .cindex "message" "changing sender" .cindex "sender" "changing" This option requests Exim to change the sender address in the message to the given address, which must be a fully qualified address or &"<>"& (&"es"& for &"edit sender"&). There must be exactly two arguments. The first argument must be a message id, and the second one an email address. However, if the message is active (in the middle of a delivery attempt), its status is not altered. This option can be used only by an admin user. .cmdopt -Mf <&'message&~id'&>&~<&'message&~id'&>&~... .cindex "freezing messages" .cindex "message" "manually freezing" This option requests Exim to mark each listed message as &"frozen"&. This prevents any delivery attempts taking place until the message is &"thawed"&, either manually or as a result of the &%auto_thaw%& configuration option. However, if any of the messages are active (in the middle of a delivery attempt), their status is not altered. This option can be used only by an admin user. .cmdopt -Mg <&'message&~id'&>&~<&'message&~id'&>&~... .cindex "giving up on messages" .cindex "message" "abandoning delivery attempts" .cindex "delivery" "abandoning further attempts" This option requests Exim to give up trying to deliver the listed messages, including any that are frozen. However, if any of the messages are active, their status is not altered. For non-bounce messages, a delivery error message is sent to the sender. Bounce messages are just discarded. This option can be used only by an admin user. .cmdopt -MG <&'queue&~name'&>&~<&'message&~id'&>&~<&'message&~id'&>&~... .cindex queue named .cindex "named queues" "moving messages" .cindex "queue" "moving messages" This option requests that each listed message be moved from its current queue to the given named queue. The destination queue name argument is required, but can be an empty string to define the default queue. If the messages are not currently located in the default queue, a &%-qG%& option will be required to define the source queue. .cmdopt -Mmad <&'message&~id'&>&~<&'message&~id'&>&~... .cindex "delivery" "cancelling all" This option requests Exim to mark all the recipient addresses in the messages as already delivered (&"mad"& for &"mark all delivered"&). However, if any message is active (in the middle of a delivery attempt), its status is not altered. This option can be used only by an admin user. .cmdopt -Mmd <&'message&~id'&>&~<&'address'&>&~<&'address'&>&~... .cindex "delivery" "cancelling by address" .cindex "recipient" "removing" .cindex "removing recipients" This option requests Exim to mark the given addresses as already delivered (&"md"& for &"mark delivered"&). The first argument must be a message id, and the remaining ones must be email addresses. These are matched to recipient addresses in the message in a case-sensitive manner. If the message is active (in the middle of a delivery attempt), its status is not altered. This option can be used only by an admin user. .cmdopt -Mrm <&'message&~id'&>&~<&'message&~id'&>&~... .cindex "removing messages" .cindex "abandoning mail" .cindex "message" "manually discarding" This option requests Exim to remove the given messages from the queue. No bounce messages are sent; each message is simply forgotten. However, if any of the messages are active, their status is not altered. This option can be used only by an admin user or by the user who originally caused the message to be placed in the queue. . .new . .vitem &%-MS%& . .oindex "&%-MS%&" . .cindex REQUIRETLS . This option is used to request REQUIRETLS processing on the message. . It is used internally by Exim in conjunction with -E when generating . a bounce message. . .wen .cmdopt -Mset <&'message&~id'&> .cindex "testing" "string expansion" .cindex "expansion" "testing" This option is useful only in conjunction with &%-be%& (that is, when testing string expansions). Exim loads the given message from its spool before doing the test expansions, thus setting message-specific variables such as &$message_size$& and the header variables. The &$recipients$& variable is made available. This feature is provided to make it easier to test expansions that make use of these variables. However, this option can be used only by an admin user. See also &%-bem%&. .cmdopt -Mt <&'message&~id'&>&~<&'message&~id'&>&~... .cindex "thawing messages" .cindex "unfreezing messages" .cindex "frozen messages" "thawing" .cindex "message" "thawing frozen" This option requests Exim to &"thaw"& any of the listed messages that are &"frozen"&, so that delivery attempts can resume. However, if any of the messages are active, their status is not altered. This option can be used only by an admin user. .cmdopt -Mvb <&'message&~id'&> .cindex "listing" "message body" .cindex "message" "listing body of" This option causes the contents of the message body (-D) spool file to be written to the standard output. This option can be used only by an admin user. .cmdopt -Mvc <&'message&~id'&> .cindex "message" "listing in RFC 2822 format" .cindex "listing" "message in RFC 2822 format" This option causes a copy of the complete message (header lines plus body) to be written to the standard output in &url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822) format. This option can be used only by an admin user. .cmdopt -Mvh <&'message&~id'&> .cindex "listing" "message headers" .cindex "header lines" "listing" .cindex "message" "listing header lines" This option causes the contents of the message headers (-H) spool file to be written to the standard output. This option can be used only by an admin user. .cmdopt -Mvl <&'message&~id'&> .cindex "listing" "message log" .cindex "message" "listing message log" This option causes the contents of the message log spool file to be written to the standard output. This option can be used only by an admin user. .cmdopt -m This is a synonym for &%-om%& that is accepted by Sendmail (&url(https://docs.oracle.com/cd/E19457-01/801-6680-1M/801-6680-1M.pdf) p. 1M-258), so Exim treats it that way too. .cmdopt -N .cindex "debugging" "&%-N%& option" .cindex "debugging" "suppressing delivery" This is a debugging option that inhibits delivery of a message at the transport level. It implies &%-v%&. Exim goes through many of the motions of delivery &-- it just doesn't actually transport the message, but instead behaves as if it had successfully done so. However, it does not make any updates to the retry database, and the log entries for deliveries are flagged with &"*>"& rather than &"=>"&. Because &%-N%& discards any message to which it applies, only root or the Exim user are allowed to use it with &%-bd%&, &%-q%&, &%-R%& or &%-M%&. In other words, an ordinary user can use it only when supplying an incoming message to which it will apply. Although transportation never fails when &%-N%& is set, an address may be deferred because of a configuration problem on a transport, or a routing problem. Once &%-N%& has been used for a delivery attempt, it sticks to the message, and applies to any subsequent delivery attempts that may happen for that message. .cmdopt -n This option is interpreted by Sendmail to mean &"no aliasing"&. For normal modes of operation, it is ignored by Exim. When combined with &%-bP%& it makes the output more terse (suppresses option names, environment values and config pretty printing). .cmdopt -O <&'data'&> This option is interpreted by Sendmail to mean &`set option`&. It is ignored by Exim. .cmdopt -oA <&'file&~name'&> .cindex "Sendmail compatibility" "&%-oA%& option" This option is used by Sendmail in conjunction with &%-bi%& to specify an alternative alias filename. Exim handles &%-bi%& differently; see the description above. .cmdopt -oB <&'n'&> .cindex "SMTP" "passed connection" .cindex "SMTP" "multiple deliveries" .cindex "multiple SMTP deliveries" This is a debugging option which limits the maximum number of messages that can be delivered down one SMTP connection, overriding the value set in any &(smtp)& transport. If <&'n'&> is omitted, the limit is set to 1. .cmdopt -odb .cindex "background delivery" .cindex "delivery" "in the background" This option applies to all modes in which Exim accepts incoming messages, including the listening daemon. It requests &"background"& delivery of such messages, which means that the accepting process automatically starts a delivery process for each message received, but does not wait for the delivery processes to finish. When all the messages have been received, the reception process exits, leaving the delivery processes to finish in their own time. The standard output and error streams are closed at the start of each delivery process. This is the default action if none of the &%-od%& options are present. If one of the queueing options in the configuration file (&%queue_only%& or &%queue_only_file%&, for example) is in effect, &%-odb%& overrides it if &%queue_only_override%& is set true, which is the default setting. If &%queue_only_override%& is set false, &%-odb%& has no effect. .cmdopt -odf .cindex "foreground delivery" .cindex "delivery" "in the foreground" This option requests &"foreground"& (synchronous) delivery when Exim has accepted a locally-generated message. (For the daemon it is exactly the same as &%-odb%&.) A delivery process is automatically started to deliver the message, and Exim waits for it to complete before proceeding. The original Exim reception process does not finish until the delivery process for the final message has ended. The standard error stream is left open during deliveries. However, like &%-odb%&, this option has no effect if &%queue_only_override%& is false and one of the queueing options in the configuration file is in effect. If there is a temporary delivery error during foreground delivery, the message is left in the queue for later delivery, and the original reception process exits. See chapter &<>& for a way of setting up a restricted configuration that never queues messages. .cmdopt -odi This option is synonymous with &%-odf%&. It is provided for compatibility with Sendmail. .cmdopt -odq .cindex "non-immediate delivery" .cindex "delivery" "suppressing immediate" .cindex "queueing incoming messages" This option applies to all modes in which Exim accepts incoming messages, including the listening daemon. It specifies that the accepting process should not automatically start a delivery process for each message received. Messages are placed in the queue, and remain there until a subsequent queue runner process encounters them. There are several configuration options (such as &%queue_only%&) that can be used to queue incoming messages under certain conditions. This option overrides all of them and also &%-odqs%&. It always forces queueing. .cmdopt -odqs .cindex "SMTP" "delaying delivery" .cindex "first pass routing" This option is a hybrid between &%-odb%&/&%-odi%& and &%-odq%&. However, like &%-odb%& and &%-odi%&, this option has no effect if &%queue_only_override%& is false and one of the queueing options in the configuration file is in effect. When &%-odqs%& does operate, a delivery process is started for each incoming message, in the background by default, but in the foreground if &%-odi%& is also present. The recipient addresses are routed, and local deliveries are done in the normal way. However, if any SMTP deliveries are required, they are not done at this time, so the message remains in the queue until a subsequent queue runner process encounters it. Because routing was done, Exim knows which messages are waiting for which hosts, and so a number of messages for the same host can be sent in a single SMTP connection. The &%queue_smtp_domains%& configuration option has the same effect for specific domains. See also the &%-qq%& option. .cmdopt -oee .cindex "error" "reporting" If an error is detected while a non-SMTP message is being received (for example, a malformed address), the error is reported to the sender in a mail message. .cindex "return code" "for &%-oee%&" Provided this error message is successfully sent, the Exim receiving process exits with a return code of zero. If not, the return code is 2 if the problem is that the original message has no recipients, or 1 for any other error. This is the default &%-oe%&&'x'& option if Exim is called as &'rmail'&. .cmdopt -oem .cindex "error" "reporting" .cindex "return code" "for &%-oem%&" This is the same as &%-oee%&, except that Exim always exits with a non-zero return code, whether or not the error message was successfully sent. This is the default &%-oe%&&'x'& option, unless Exim is called as &'rmail'&. .cmdopt -oep .cindex "error" "reporting" If an error is detected while a non-SMTP message is being received, the error is reported by writing a message to the standard error file (stderr). .cindex "return code" "for &%-oep%&" The return code is 1 for all errors. .cmdopt -oeq .cindex "error" "reporting" This option is supported for compatibility with Sendmail, but has the same effect as &%-oep%&. .cmdopt -oew .cindex "error" "reporting" This option is supported for compatibility with Sendmail, but has the same effect as &%-oem%&. .cmdopt -oi .cindex "dot" "in incoming non-SMTP message" This option, which has the same effect as &%-i%&, specifies that a dot on a line by itself should not terminate an incoming, non-SMTP message. Otherwise, a single dot does terminate, though Exim does no special processing for other lines that start with a dot. This option is set by default if Exim is called as &'rmail'&. See also &%-ti%&. .cmdopt -oitrue This option is treated as synonymous with &%-oi%&. .cmdopt -oMa <&'host&~address'&> .cindex "sender" "host address, specifying for local message" A number of options starting with &%-oM%& can be used to set values associated with remote hosts on locally-submitted messages (that is, messages not received over TCP/IP). These options can be used by any caller in conjunction with the &%-bh%&, &%-be%&, &%-bf%&, &%-bF%&, &%-bt%&, or &%-bv%& testing options. In other circumstances, they are ignored unless the caller is trusted. The &%-oMa%& option sets the sender host address. This may include a port number at the end, after a full stop (period). For example: .code exim -bs -oMa 10.9.8.7.1234 .endd An alternative syntax is to enclose the IP address in square brackets, followed by a colon and the port number: .code exim -bs -oMa [10.9.8.7]:1234 .endd The IP address is placed in the &$sender_host_address$& variable, and the port, if present, in &$sender_host_port$&. If both &%-oMa%& and &%-bh%& are present on the command line, the sender host IP address is taken from whichever one is last. .cmdopt -oMaa <&'name'&> .cindex "authentication" "name, specifying for local message" See &%-oMa%& above for general remarks about the &%-oM%& options. The &%-oMaa%& option sets the value of &$sender_host_authenticated$& (the authenticator name). See chapter &<>& for a discussion of SMTP authentication. This option can be used with &%-bh%& and &%-bs%& to set up an authenticated SMTP session without actually using the SMTP AUTH command. .cmdopt -oMai <&'string'&> .cindex "authentication" "id, specifying for local message" See &%-oMa%& above for general remarks about the &%-oM%& options. The &%-oMai%& option sets the value of &$authenticated_id$& (the id that was authenticated). This overrides the default value (the caller's login id, except with &%-bh%&, where there is no default) for messages from local sources. See chapter &<>& for a discussion of authenticated ids. .cmdopt -oMas <&'address'&> .cindex "authentication" "sender, specifying for local message" See &%-oMa%& above for general remarks about the &%-oM%& options. The &%-oMas%& option sets the authenticated sender value in &$authenticated_sender$&. It overrides the sender address that is created from the caller's login id for messages from local sources, except when &%-bh%& is used, when there is no default. For both &%-bh%& and &%-bs%&, an authenticated sender that is specified on a MAIL command overrides this value. See chapter &<>& for a discussion of authenticated senders. .cmdopt -oMi <&'interface&~address'&> .cindex "interface" "address, specifying for local message" See &%-oMa%& above for general remarks about the &%-oM%& options. The &%-oMi%& option sets the IP interface address value. A port number may be included, using the same syntax as for &%-oMa%&. The interface address is placed in &$received_ip_address$& and the port number, if present, in &$received_port$&. .cmdopt -oMm <&'message&~reference'&> .cindex "message reference" "message reference, specifying for local message" See &%-oMa%& above for general remarks about the &%-oM%& options. The &%-oMm%& option sets the message reference, e.g. message-id, and is logged during delivery. This is useful when some kind of audit trail is required to tie messages together. The format of the message reference is checked and will abort if the format is invalid. The option will only be accepted if exim is running in trusted mode, not as any regular user. The best example of a message reference is when Exim sends a bounce message. The message reference is the message-id of the original message for which Exim is sending the bounce. .cmdopt -oMr <&'protocol&~name'&> .cindex "protocol, specifying for local message" .vindex "&$received_protocol$&" See &%-oMa%& above for general remarks about the &%-oM%& options. The &%-oMr%& option sets the received protocol value that is stored in &$received_protocol$&. However, it does not apply (and is ignored) when &%-bh%& or &%-bs%& is used. For &%-bh%&, the protocol is forced to one of the standard SMTP protocol names (see the description of &$received_protocol$& in section &<>&). For &%-bs%&, the protocol is always &"local-"& followed by one of those same names. For &%-bS%& (batched SMTP) however, the protocol can be set by &%-oMr%&. Repeated use of this option is not supported. .cmdopt -oMs <&'host&~name'&> .cindex "sender" "host name, specifying for local message" See &%-oMa%& above for general remarks about the &%-oM%& options. The &%-oMs%& option sets the sender host name in &$sender_host_name$&. When this option is present, Exim does not attempt to look up a host name from an IP address; it uses the name it is given. .cmdopt -oMt <&'ident&~string'&> .cindex "sender" "ident string, specifying for local message" See &%-oMa%& above for general remarks about the &%-oM%& options. The &%-oMt%& option sets the sender ident value in &$sender_ident$&. The default setting for local callers is the login id of the calling process, except when &%-bh%& is used, when there is no default. .cmdopt -om .cindex "Sendmail compatibility" "&%-om%& option ignored" In Sendmail, this option means &"me too"&, indicating that the sender of a message should receive a copy of the message if the sender appears in an alias expansion. Exim always does this, so the option does nothing. .cmdopt -oo .cindex "Sendmail compatibility" "&%-oo%& option ignored" This option is ignored. In Sendmail it specifies &"old style headers"&, whatever that means. .cmdopt -oP <&'path'&> .cindex "pid (process id)" "of daemon" .cindex "daemon" "process id (pid)" This option is useful only in conjunction with &%-bd%& or &%-q%& with a time value. The option specifies the file to which the process id of the daemon is written. When &%-oX%& is used with &%-bd%&, or when &%-q%& with a time is used without &%-bd%&, this is the only way of causing Exim to write a pid file, because in those cases, the normal pid file is not used. .cmdopt -oPX .cindex "pid (process id)" "of daemon" .cindex "daemon" "process id (pid)" This option is not intended for general use. The daemon uses it when terminating due to a SIGTEM, possibly in combination with &%-oP%&&~<&'path'&>. It causes the pid file to be removed. .cmdopt -or <&'time'&> .cindex "timeout" "for non-SMTP input" This option sets a timeout value for incoming non-SMTP messages. If it is not set, Exim will wait forever for the standard input. The value can also be set by the &%receive_timeout%& option. The format used for specifying times is described in section &<>&. .cmdopt -os <&'time'&> .cindex "timeout" "for SMTP input" .cindex "SMTP" "input timeout" This option sets a timeout value for incoming SMTP messages. The timeout applies to each SMTP command and block of data. The value can also be set by the &%smtp_receive_timeout%& option; it defaults to 5 minutes. The format used for specifying times is described in section &<>&. .cmdopt -ov This option has exactly the same effect as &%-v%&. .cmdopt -oX <&'number&~or&~string'&> .cindex "TCP/IP" "setting listening ports" .cindex "TCP/IP" "setting listening interfaces" .cindex "port" "receiving TCP/IP" This option is relevant only when the &%-bd%& (start listening daemon) option is also given. It controls which ports and interfaces the daemon uses. Details of the syntax, and how it interacts with configuration file options, are given in chapter &<>&. When &%-oX%& is used to start a daemon, no pid file is written unless &%-oP%& is also present to specify a pid filename. .cmdopt -oY .cindex "daemon notifier socket" This option controls the creation of an inter-process communications endpoint by the Exim daemon. It is only relevant when the &%-bd%& (start listening daemon) option is also given. Normally the daemon creates this socket, unless a &%-oX%& and &*no*& &%-oP%& option is also present. If this option is given then the socket will not be created. This is required if the system is running multiple daemons, in which case it should be used on all. The features supported by the socket will not be available in such cases. The socket is currently used for .ilist fast ramp-up of queue runner processes .next caching compiled regexes .next obtaining a current queue size .endlist .cmdopt -pd .cindex "Perl" "starting the interpreter" This option applies when an embedded Perl interpreter is linked with Exim (see chapter &<>&). It overrides the setting of the &%perl_at_start%& option, forcing the starting of the interpreter to be delayed until it is needed. .cmdopt -ps .cindex "Perl" "starting the interpreter" This option applies when an embedded Perl interpreter is linked with Exim (see chapter &<>&). It overrides the setting of the &%perl_at_start%& option, forcing the starting of the interpreter to occur as soon as Exim is started. .vitem &%-p%&<&'rval'&>:<&'sval'&> .oindex "&%-p%&" For compatibility with Sendmail, this option is equivalent to .display &`-oMr`& <&'rval'&> &`-oMs`& <&'sval'&> .endd It sets the incoming protocol and host name (for trusted callers). The host name and its colon can be omitted when only the protocol is to be set. Note the Exim already has two private options, &%-pd%& and &%-ps%&, that refer to embedded Perl. It is therefore impossible to set a protocol value of &`d`& or &`s`& using this option (but that does not seem a real limitation). Repeated use of this option is not supported. .cmdopt -q .cindex "queue runner" "starting manually" This option is normally restricted to admin users. However, there is a configuration option called &%prod_requires_admin%& which can be set false to relax this restriction (and also the same requirement for the &%-M%&, &%-R%&, and &%-S%& options). .cindex "queue runner" "description of operation" If other commandline options do not specify an action, the &%-q%& option starts one queue runner process. This scans the queue of waiting messages, and runs a delivery process for each one in turn. It waits for each delivery process to finish before starting the next one. A delivery process may not actually do any deliveries if the retry times for the addresses have not been reached. Use &%-qf%& (see below) if you want to override this. If .cindex "SMTP" "passed connection" .cindex "SMTP" "multiple deliveries" .cindex "multiple SMTP deliveries" the delivery process spawns other processes to deliver other messages down passed SMTP connections, the queue runner waits for these to finish before proceeding. When all the queued messages have been considered, the original queue runner process terminates. In other words, a single pass is made over the waiting mail, one message at a time. Use &%-q%& with a time (see below) if you want this to be repeated periodically. Exim processes the waiting messages in an unpredictable order. It isn't very random, but it is likely to be different each time, which is all that matters. If one particular message screws up a remote MTA, other messages to the same MTA have a chance of getting through if they get tried first. It is possible to cause the messages to be processed in lexical message id order, which is essentially the order in which they arrived, by setting the &%queue_run_in_order%& option, but this is not recommended for normal use. .vitem &%-q%&<&'qflags'&> The &%-q%& option may be followed by one or more flag letters that change its behaviour. They are all optional, but if more than one is present, they must appear in the correct order. Each flag is described in a separate item below. .vitem &%-qq...%& .oindex "&%-qq%&" .cindex "queue" "double scanning" .cindex "queue" "routing" .cindex "routing" "whole queue before delivery" .cindex "first pass routing" .cindex "queue runner" "two phase" An option starting with &%-qq%& requests a two-stage queue run. In the first stage, the queue is scanned as if the &%queue_smtp_domains%& option matched every domain. Addresses are routed, local deliveries happen, but no remote transports are run. Performance will be best if the &%queue_run_in_order%& option is false. If that is so and the &%queue_fast_ramp%& option is true and a daemon-notifier socket is available then in the first phase of the run, once a threshold number of messages are routed for a given host, a delivery process is forked in parallel with the rest of the scan. .cindex "hints database" "remembering routing" The hints database that remembers which messages are waiting for specific hosts is updated, as if delivery to those hosts had been deferred. After the first queue scan complete, a second, normal queue scan is done, with routing and delivery taking place as normal. Messages that are routed to the same host should mostly be delivered down a single SMTP .cindex "SMTP" "passed connection" .cindex "SMTP" "multiple deliveries" .cindex "multiple SMTP deliveries" connection because of the hints that were set up during the first queue scan. Two-phase queue runs should be used on systems which, even intermittently, have a large queue (such as mailing-list operators). They may also be useful for hosts that are connected to the Internet intermittently. .vitem &%-q[q]i...%& .oindex "&%-qi%&" .cindex "queue" "initial delivery" If the &'i'& flag is present, the queue runner runs delivery processes only for those messages that haven't previously been tried. (&'i'& stands for &"initial delivery"&.) This can be helpful if you are putting messages in the queue using &%-odq%& and want a queue runner just to process the new messages. .vitem &%-q[q][i]f...%& .oindex "&%-qf%&" .cindex "queue" "forcing delivery" .cindex "delivery" "forcing in queue run" If one &'f'& flag is present, a delivery attempt is forced for each non-frozen message, whereas without &'f'& only those non-frozen addresses that have passed their retry times are tried. .vitem &%-q[q][i]ff...%& .oindex "&%-qff%&" .cindex "frozen messages" "forcing delivery" If &'ff'& is present, a delivery attempt is forced for every message, whether frozen or not. .vitem &%-q[q][i][f[f]]l%& .oindex "&%-ql%&" .cindex "queue" "local deliveries only" The &'l'& (the letter &"ell"&) flag specifies that only local deliveries are to be done. If a message requires any remote deliveries, it remains in the queue for later delivery. .vitem &%-q[q][i][f[f]][l][G[/