1 <?xml version="1.0" encoding="UTF-8"?>
2 <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
6 foot_right_recto="&chaptertitle;"
7 foot_right_verso="&chaptertitle;"
8 table_warn_overflow="overprint"
9 toc_chapter_blanks="yes,yes"
10 toc_title="Exim's interfaces to mail filtering"
14 <title>Exim's interfaces to mail filtering</title>
15 <titleabbrev>Exim filtering</titleabbrev>
19 <author><firstname>Philip</firstname><surname>Hazel</surname></author>
20 <authorinitials>PH</authorinitials>
21 <revhistory><revision>
22 <revnumber>4.97.1</revnumber>
23 <date>30 Dec 2023</date>
24 <authorinitials>PH</authorinitials>
25 </revision></revhistory>
28 </year><holder>The Exim Maintainers</holder></copyright>
30 <chapter id="CHAPforandfilt">
31 <title>Forwarding and filtering in Exim</title>
33 This document describes the user interfaces to Exim’s in-built mail filtering
34 facilities, and is copyright © The Exim Maintainers 2023. It
35 corresponds to Exim version 4.97.1.
38 <title>Introduction</title>
40 Most Unix mail transfer agents (programs that deliver mail) permit individual
41 users to specify automatic forwarding of their mail, usually by placing a list
42 of forwarding addresses in a file called <filename>.forward</filename> in their home
43 directories. Exim extends this facility by allowing the forwarding instructions
44 to be a set of rules rather than just a list of addresses, in effect providing
45 <quote><filename>.forward</filename> with conditions</quote>. Operating the set of rules is called
46 <emphasis>filtering</emphasis>, and the file that contains them is called a <emphasis>filter file</emphasis>.
49 Exim supports two different kinds of filter file. An <emphasis>Exim filter</emphasis> contains
50 instructions in a format that is unique to Exim. A <emphasis>Sieve filter</emphasis> contains
51 instructions in the Sieve format that is defined by RFC 3028. As this is a
52 standard format, Sieve filter files may already be familiar to some users.
53 Sieve files should also be portable between different environments. However,
54 the Exim filtering facility contains more features (such as variable
55 expansion), and better integration with the host environment (such as the use
56 of external processes and pipes).
59 The choice of which kind of filter to use can be left to the end-user, provided
60 that the system administrator has configured Exim appropriately for both kinds
61 of filter. However, if interoperability is important, Sieve is the only
65 The ability to use filtering or traditional forwarding has to be enabled by the
66 system administrator, and some of the individual facilities can be separately
67 enabled or disabled. A local document should be provided to describe exactly
68 what has been enabled. In the absence of this, consult your system
72 This document describes how to use a filter file and the format of its
73 contents. It is intended for use by end-users. Both Sieve filters and Exim
74 filters are covered. However, for Sieve filters, only issues that relate to the
75 Exim implementation are discussed, since Sieve itself is described elsewhere.
78 The contents of traditional <filename>.forward</filename> files are not described here. They
79 normally contain just a list of addresses, file names, or pipe commands,
80 separated by commas or newlines, but other types of item are also available.
81 The full details can be found in the chapter on the <command>redirect</command> router in the
82 Exim specification, which also describes how the system administrator can set
83 up and control the use of filtering.
87 <title>Filter operation</title>
89 It is important to realize that, in Exim, no deliveries are actually made while
90 a filter or traditional <filename>.forward</filename> file is being processed. Running a filter
91 or processing a traditional <filename>.forward</filename> file sets up future delivery
92 operations, but does not carry them out.
95 The result of filter or <filename>.forward</filename> file processing is a list of destinations
96 to which a message should be delivered. The deliveries themselves take place
97 later, along with all other deliveries for the message. This means that it is
98 not possible to test for successful deliveries while filtering. It also means
99 that any duplicate addresses that are generated are dropped, because Exim never
100 delivers the same message to the same address more than once.
103 <section id="SECTtesting">
104 <title>Testing a new filter file</title>
106 Filter files, especially the more complicated ones, should always be tested, as
107 it is easy to make mistakes. Exim provides a facility for preliminary testing
108 of a filter file before installing it. This tests the syntax of the file and
109 its basic operation, and can also be used with traditional <filename>.forward</filename> files.
112 Because a filter can do tests on the content of messages, a test message is
113 required. Suppose you have a new filter file called <filename>myfilter</filename> and a test
114 message in a file called <filename>test-message</filename>. Assuming that Exim is installed with
115 the conventional path name <filename>/usr/sbin/sendmail</filename> (some operating systems use
116 <filename>/usr/lib/sendmail</filename>), the following command can be used:
118 <literallayout class="monospaced">
119 /usr/sbin/sendmail -bf myfilter <test-message
122 The <option>-bf</option> option tells Exim that the following item on the command line is
123 the name of a filter file that is to be tested. There is also a <option>-bF</option> option,
124 which is similar, but which is used for testing system filter files, as opposed
125 to user filter files, and which is therefore of use only to the system
129 The test message is supplied on the standard input. If there are no
130 message-dependent tests in the filter, an empty file (<filename>/dev/null</filename>) can be
131 used. A supplied message must start with header lines or the <quote>From </quote> message
132 separator line that is found in many multi-message folder files. Note that
133 blank lines at the start terminate the header lines. A warning is given if no
134 header lines are read.
137 The result of running this command, provided no errors are detected in the
138 filter file, is a list of the actions that Exim would try to take if presented
139 with the message for real. For example, for an Exim filter, the output
141 <literallayout class="monospaced">
142 Deliver message to: gulliver@lilliput.fict.example
143 Save message to: /home/lemuel/mail/archive
146 means that one copy of the message would be sent to
147 <emphasis>gulliver@lilliput.fict.example</emphasis>, and another would be added to the file
148 <filename>/home/lemuel/mail/archive</filename>, if all went well.
151 The actions themselves are not attempted while testing a filter file in this
152 way; there is no check, for example, that any forwarding addresses are valid.
153 For an Exim filter, if you want to know why a particular action is being taken,
154 add the <option>-v</option> option to the command. This causes Exim to output the results of
155 any conditional tests and to indent its output according to the depth of
156 nesting of <command>if</command> commands. Further additional output from a filter test can be
157 generated by the <command>testprint</command> command, which is described below.
160 When Exim is outputting a list of the actions it would take, if any text
161 strings are included in the output, non-printing characters therein are
162 converted to escape sequences. In particular, if any text string contains a
163 newline character, this is shown as <quote>\n</quote> in the testing output.
166 When testing a filter in this way, Exim makes up an <quote>envelope</quote> for the
167 message. The recipient is by default the user running the command, and so is
168 the sender, but the command can be run with the <option>-f</option> option to supply a
169 different sender. For example,
171 <literallayout class="monospaced">
172 /usr/sbin/sendmail -bf myfilter \
173 -f islington@never.where <test-message
176 Alternatively, if the <option>-f</option> option is not used, but the first line of the
177 supplied message is a <quote>From </quote> separator from a message folder file (not the
178 same thing as a <emphasis>From:</emphasis> header line), the sender is taken from there. If
179 <option>-f</option> is present, the contents of any <quote>From </quote> line are ignored.
182 The <quote>return path</quote> is the same as the envelope sender, unless the message
183 contains a <emphasis>Return-path:</emphasis> header, in which case it is taken from there. You
184 need not worry about any of this unless you want to test out features of a
185 filter file that rely on the sender address or the return path.
188 It is possible to change the envelope recipient by specifying further options.
189 The <option>-bfd</option> option changes the domain of the recipient address, while the
190 <option>-bfl</option> option changes the <quote>local part</quote>, that is, the part before the @
191 sign. An adviser could make use of these to test someone else’s filter file.
194 The <option>-bfp</option> and <option>-bfs</option> options specify the prefix or suffix for the local
195 part. These are relevant only when support for multiple personal mailboxes is
196 implemented; see the description in section <xref linkend="SECTmbox"/> below.
200 <title>Installing a filter file</title>
202 A filter file is normally installed under the name <filename>.forward</filename> in your home
203 directory – it is distinguished from a conventional <filename>.forward</filename> file by its
204 first line (described below). However, the file name is configurable, and some
205 system administrators may choose to use some different name or location for
210 <title>Testing an installed filter file</title>
212 Testing a filter file before installation cannot find every potential problem;
213 for example, it does not actually run commands to which messages are piped.
214 Some <quote>live</quote> tests should therefore also be done once a filter is installed.
217 If at all possible, test your filter file by sending messages from some other
218 account. If you send a message to yourself from the filtered account, and
219 delivery fails, the error message will be sent back to the same account, which
220 may cause another delivery failure. It won’t cause an infinite sequence of such
221 messages, because delivery failure messages do not themselves generate further
222 messages. However, it does mean that the failure won’t be returned to you, and
223 also that the postmaster will have to investigate the stuck message.
226 If you have to test an Exim filter from the same account, a sensible precaution
227 is to include the line
229 <literallayout class="monospaced">
230 if error_message then finish endif
233 as the first filter command, at least while testing. This causes filtering to
234 be abandoned for a delivery failure message, and since no destinations are
235 generated, the message goes on to be delivered to the original address. Unless
236 there is a good reason for not doing so, it is recommended that the above test
237 be left in all Exim filter files. (This does not apply to Sieve files.)
241 <title>Details of filtering commands</title>
243 The filtering commands for Sieve and Exim filters are completely different in
244 syntax and semantics. The Sieve mechanism is defined in RFC 3028; in the next
245 chapter we describe how it is integrated into Exim. The subsequent chapter
246 covers Exim filtering commands in detail.
251 <chapter id="CHAPsievefilter">
252 <title>Sieve filter files</title>
254 The code for Sieve filtering in Exim was contributed by Michael Haardt, and
255 most of the content of this chapter is taken from the notes he provided. Since
256 Sieve is an extensible language, it is important to understand <quote>Sieve</quote> in
257 this context as <quote>the specific implementation of Sieve for Exim</quote>.
260 This chapter does not contain a description of Sieve, since that can be found
261 in RFC 3028, which should be read in conjunction with these notes.
264 The Exim Sieve implementation offers the core as defined by RFC 3028,
265 comparison tests, the subaddress parameter, the <emphasis role="bold">copy</emphasis>, <emphasis role="bold">envelope</emphasis>,
266 <emphasis role="bold">fileinto</emphasis>, <emphasis role="bold">notify</emphasis>, and <emphasis role="bold">vacation</emphasis> extensions, but not the <emphasis role="bold">reject</emphasis>
269 <para revisionflag="changed">
270 Exim did not support message delivery notifications (MDNs) when Sieve handling
271 was introduced, so <emphasis role="bold">reject</emphasis> (which need them) could not be supported.
274 In order for Sieve to work properly in Exim, the system administrator needs to
275 make some adjustments to the Exim configuration. These are described in the
276 chapter on the <command>redirect</command> router in the full Exim specification.
279 <title>Recognition of Sieve filters</title>
281 A filter file is interpreted as a Sieve filter if its first line is
283 <literallayout class="monospaced">
287 This is what distinguishes it from a conventional <filename>.forward</filename> file or an Exim
292 <title>Saving to specified folders</title>
294 If the system administrator has set things up as suggested in the Exim
295 specification, and you use <command>keep</command> or <command>fileinto</command> to save a mail into a
296 folder, absolute files are stored where specified, relative files are stored
297 relative to <varname>$home</varname>, and <filename>inbox</filename> goes to the standard mailbox location.
301 <title>Strings containing header names</title>
303 RFC 3028 does not specify what happens if a string denoting a header field does
304 not contain a valid header name, for example, it contains a colon. This
305 implementation generates an error instead of ignoring the header field in order
306 to ease script debugging, which fits in with the common picture of Sieve.
310 <title>Exists test with empty list of headers</title>
312 The <emphasis role="bold">exists</emphasis> test succeeds only if all the specified headers exist. RFC 3028
313 does not explicitly specify what happens on an empty list of headers. This
314 implementation evaluates that condition as true, interpreting the RFC in a
319 <title>Header test with invalid MIME encoding in header</title>
321 Some MUAs process invalid base64 encoded data, generating junk. Others ignore
322 junk after seeing an equal sign in base64 encoded data. RFC 2047 does not
323 specify how to react in this case, other than stating that a client must not
324 forbid to process a message for that reason. RFC 2045 specifies that invalid
325 data should be ignored (apparently looking at end of line characters). It also
326 specifies that invalid data may lead to rejecting messages containing them (and
327 there it appears to talk about true encoding violations), which is a clear
328 contradiction to ignoring them.
331 RFC 3028 does not specify how to process incorrect MIME words. This
332 implementation treats them literally, as it does if the word is correct but its
333 character set cannot be converted to UTF-8.
337 <title>Address test for multiple addresses per header</title>
339 A header may contain multiple addresses. RFC 3028 does not explicitly specify
340 how to deal with them, but since the address test checks if anything matches
341 anything else, matching one address suffices to satisfy the condition. That
342 makes it impossible to test if a header contains a certain set of addresses and
343 no more, but it is more logical than letting the test fail if the header
344 contains an additional address besides the one the test checks for.
348 <title>Semantics of keep</title>
350 The <command>keep</command> command is equivalent to
352 <literallayout class="monospaced">
356 It saves the message and resets the implicit keep flag. It does not set the
357 implicit keep flag; there is no command to set it once it has been reset.
361 <title>Semantics of fileinto</title>
363 RFC 3028 does not specify whether <command>fileinto</command> should try to create a mail
364 folder if it does not exist. This implementation allows the sysadmin to
365 configure that aspect using the <command>appendfile</command> transport options
366 <option>create_directory</option>, <option>create_file</option>, and <option>file_must_exist</option>. See the
367 <command>appendfile</command> transport in the Exim specification for details.
371 <title>Semantics of redirect</title>
373 Sieve scripts are supposed to be interoperable between servers, so this
374 implementation does not allow mail to be redirected to unqualified addresses,
375 because the domain would depend on the system being used. On systems with
376 virtual mail domains, the default domain is probably not what the user expects
381 <title>String arguments</title>
383 There has been confusion if the string arguments to <command>require</command> are to be
384 matched case-sensitively or not. This implementation matches them with the
385 match type <command>:is</command> (default, see section 2.7.1 of the RFC) and the comparator
386 <command>i;ascii-casemap</command> (default, see section 2.7.3 of the RFC). The RFC defines
387 the command defaults clearly, so any different implementations violate RFC
388 3028. The same is valid for comparator names, also specified as strings.
392 <title>Number units</title>
394 There is a mistake in RFC 3028: the suffix G denotes gibi-, not tebibyte.
395 The mistake is obvious, because RFC 3028 specifies G to denote 2^30
396 (which is gibi, not tebi), and that is what this implementation uses as
397 the scaling factor for the suffix G.
401 <title>RFC compliance</title>
403 Exim requires the first line of a Sieve filter to be
405 <literallayout class="monospaced">
409 Of course the RFC does not specify that line. Do not expect examples to work
410 without adding it, though.
413 RFC 3028 requires the use of CRLF to terminate a line. The rationale was that
414 CRLF is universally used in network protocols to mark the end of the line. This
415 implementation does not embed Sieve in a network protocol, but uses Sieve
416 scripts as part of the Exim MTA. Since all parts of Exim use LF as the newline
417 character, this implementation does, too, by default, though the system
418 administrator may choose (at Exim compile time) to use CRLF instead.
421 Exim violates RFC 2822, section 3.6.8, by accepting 8-bit header names, so this
422 implementation repeats this violation to stay consistent with Exim. This is in
423 preparation for UTF-8 data.
426 Sieve scripts cannot contain NUL characters in strings, but mail headers could
427 contain MIME encoded NUL characters, which could never be matched by Sieve
428 scripts using exact comparisons. For that reason, this implementation extends
429 the Sieve quoted string syntax with \0 to describe a NUL character, violating
430 \0 being the same as 0 in RFC 3028. Even without using \0, the following tests
431 are all true in this implementation. Implementations that use C-style strings
432 will only evaluate the first test as true.
434 <literallayout class="monospaced">
435 Subject: =?iso-8859-1?q?abc=00def
437 header :contains "Subject" ["abc"]
438 header :contains "Subject" ["def"]
439 header :matches "Subject" ["abc?def"]
442 Note that by considering Sieve to be an MUA, RFC 2047 can be interpreted in a
443 way that NUL characters truncating strings is allowed for Sieve
444 implementations, although not recommended. It is further allowed to use encoded
445 NUL characters in headers, but that’s not recommended either. The above example
449 RFC 3028 states that if an implementation fails to convert a character set to
450 UTF-8, two strings cannot be equal if one contains octets greater than 127.
451 Assuming that all unknown character sets are one-byte character sets with the
452 lower 128 octets being US-ASCII is not sound, so this implementation violates
453 RFC 3028 and treats such MIME words literally. That way at least something
457 The folder specified by <command>fileinto</command> must not contain the character sequence
458 <quote>..</quote> to avoid security problems. RFC 3028 does not specify the syntax of
459 folders apart from <command>keep</command> being equivalent to
461 <literallayout class="monospaced">
465 This implementation uses <filename>inbox</filename> instead.
468 Sieve script errors currently cause messages to be silently filed into
469 <filename>inbox</filename>. RFC 3028 requires that the user is notified of that condition.
470 This may be implemented in the future by adding a header line to mails that
471 are filed into <filename>inbox</filename> due to an error in the filter.
476 <chapter id="CHAPeximfilter">
477 <title>Exim filter files</title>
479 This chapter contains a full description of the contents of Exim filter files.
482 <title>Format of Exim filter files</title>
484 Apart from leading white space, the first text in an Exim filter file must be
486 <literallayout class="monospaced">
490 This is what distinguishes it from a conventional <filename>.forward</filename> file or a Sieve
491 filter file. If the file does not have this initial line (or the equivalent for
492 a Sieve filter), it is treated as a conventional <filename>.forward</filename> file, both when
493 delivering mail and when using the <option>-bf</option> testing mechanism. The white space
494 in the line is optional, and any capitalization may be used. Further text on
495 the same line is treated as a comment. For example, you could have
497 <literallayout class="monospaced">
498 # Exim filter <<== do not edit or remove this line!
501 The remainder of the file is a sequence of filtering commands, which consist of
502 keywords and data values. For example, in the command
504 <literallayout class="monospaced">
505 deliver gulliver@lilliput.fict.example
508 the keyword is <literal>deliver</literal> and the data value is
509 <literal>gulliver@lilliput.fict.example</literal>. White space or line breaks separate the
510 components of a command, except in the case of conditions for the <command>if</command>
511 command, where round brackets (parentheses) also act as separators. Complete
512 commands are separated from each other by white space or line breaks; there are
513 no special terminators. Thus, several commands may appear on one line, or one
514 command may be spread over a number of lines.
517 If the character # follows a separator anywhere in a command, everything from
518 # up to the next newline is ignored. This provides a way of including comments
523 <title>Data values in filter commands</title>
525 There are two ways in which a data value can be input:
530 If the text contains no white space, it can be typed verbatim. However, if it
531 is part of a condition, it must also be free of round brackets (parentheses),
532 as these are used for grouping in conditions.
537 Otherwise, text must be enclosed in double quotation marks. In this case, the
538 character \ (backslash) is treated as an <quote>escape character</quote> within the
539 string, causing the following character or characters to be treated specially:
542 <literal>\n</literal> is replaced by a newline
543 <literal>\r</literal> is replaced by a carriage return
544 <literal>\t</literal> is replaced by a tab
549 Backslash followed by up to three octal digits is replaced by the character
550 specified by those digits, and <literal>\x</literal> followed by up to two hexadecimal digits
551 is treated similarly. Backslash followed by any other character is replaced by
552 the second character, so that in particular, <literal>\"</literal> becomes <literal>"</literal> and <literal>\\</literal>
553 becomes <literal>\</literal>. A data item enclosed in double quotes can be continued onto the
554 next line by ending the first line with a backslash. Any leading white space at
555 the start of the continuation line is ignored.
558 In addition to the escape character processing that occurs when strings are
559 enclosed in quotes, most data values are also subject to <emphasis>string expansion</emphasis>
560 (as described in the next section), in which case the characters <literal>$</literal> and
561 <literal>\</literal> are also significant. This means that if a single backslash is actually
562 required in such a string, and the string is also quoted, <literal>\\\\</literal> has to be
566 The maximum permitted length of a data string, before expansion, is 1024
570 <section id="SECTfilterstringexpansion">
571 <title>String expansion</title>
573 Most data values are expanded before use. Expansion consists of replacing
574 substrings beginning with <literal>$</literal> with other text. The full expansion facilities
575 available in Exim are extensive. If you want to know everything that Exim can
576 do with strings, you should consult the chapter on string expansion in the Exim
580 In filter files, by far the most common use of string expansion is the
581 substitution of the contents of a variable. For example, the substring
583 <literallayout class="monospaced">
587 is replaced by the address to which replies to the message should be sent. If
588 such a variable name is followed by a letter or digit or underscore, it must be
589 enclosed in curly brackets (braces), for example,
591 <literallayout class="monospaced">
595 If a <literal>$</literal> character is actually required in an expanded string, it must be
596 escaped with a backslash, and because backslash is also an escape character in
597 quoted input strings, it must be doubled in that case. The following two
598 examples illustrate two different ways of testing for a <literal>$</literal> character in a
601 <literallayout class="monospaced">
602 if $message_body contains \$ then ...
603 if $message_body contains "\\$" then ...
606 You can prevent part of a string from being expanded by enclosing it between
607 two occurrences of <literal>\N</literal>. For example,
609 <literallayout class="monospaced">
610 if $message_body contains \N$$$$\N then ...
613 tests for a run of four dollar characters.
617 <title>Some useful general variables</title>
619 A complete list of the available variables is given in the Exim documentation.
620 This shortened list contains the ones that are most likely to be useful in
621 personal filter files:
624 <varname>$body_linecount</varname>: The number of lines in the body of the message.
627 <varname>$body_zerocount</varname>: The number of binary zero characters in the body of the
631 <varname>$home</varname>: In conventional configurations, this variable normally contains the
632 user’s home directory. The system administrator can, however, change this.
635 <varname>$local_part</varname>: The part of the email address that precedes the @ sign –
636 normally the user’s login name. If support for multiple personal mailboxes is
637 enabled (see section <xref linkend="SECTmbox"/> below) and a prefix or suffix for the local
638 part was recognized, it is removed from the string in this variable.
641 <varname>$local_part_prefix</varname>: If support for multiple personal mailboxes is enabled
642 (see section <xref linkend="SECTmbox"/> below), and a local part prefix was recognized,
643 this variable contains the prefix. Otherwise it contains an empty string.
646 <varname>$local_part_suffix</varname>: If support for multiple personal mailboxes is enabled
647 (see section <xref linkend="SECTmbox"/> below), and a local part suffix was recognized,
648 this variable contains the suffix. Otherwise it contains an empty string.
651 <varname>$message_body</varname>: The initial portion of the body of the message. By default,
652 up to 500 characters are read into this variable, but the system administrator
653 can configure this to some other value. Newlines in the body are converted into
657 <varname>$message_body_end</varname>: The final portion of the body of the message, formatted
658 and limited in the same way as <varname>$message_body</varname>.
661 <varname>$message_body_size</varname>: The size of the body of the message, in bytes.
664 <varname>$message_exim_id</varname>: The message’s local identification string, which is unique
665 for each message handled by a single host.
668 <varname>$message_headers</varname>: The header lines of the message, concatenated into a
669 single string, with newline characters between them.
672 <varname>$message_size</varname>: The size of the entire message, in bytes.
675 <varname>$original_local_part</varname>: When an address that arrived with the message is
676 being processed, this contains the same value as the variable <varname>$local_part</varname>.
677 However, if an address generated by an alias, forward, or filter file is being
678 processed, this variable contains the local part of the original address.
681 <varname>$reply_address</varname>: The contents of the <emphasis>Reply-to:</emphasis> header, if the message
682 has one; otherwise the contents of the <emphasis>From:</emphasis> header. It is the address to
683 which normal replies to the message should be sent.
686 <varname>$return_path</varname>: The return path – that is, the sender field that will be
687 transmitted as part of the message’s envelope if the message is sent to another
688 host. This is the address to which delivery errors are sent. In many cases,
689 this variable has the same value as <varname>$sender_address</varname>, but if, for example,
690 an incoming message to a mailing list has been expanded, <varname>$return_path</varname> may
691 have been changed to contain the address of the list maintainer.
694 <varname>$sender_address</varname>: The sender address that was received in the envelope of
695 the message. This is not necessarily the same as the contents of the <emphasis>From:</emphasis>
696 or <emphasis>Sender:</emphasis> header lines. For delivery error messages (<quote>bounce messages</quote>)
697 there is no sender address, and this variable is empty.
700 <varname>$tod_full</varname>: A full version of the time and date, for example: Wed, 18 Oct
701 1995 09:51:40 +0100. The timezone is always given as a numerical offset from
705 <varname>$tod_log</varname>: The time and date in the format used for writing Exim’s log files,
706 without the timezone, for example: 1995-10-12 15:32:29.
709 <varname>$tod_zone</varname>: The local timezone offset, for example: +0100.
712 <section id="SECTheadervariables">
713 <title>Header variables</title>
715 There is a special set of expansion variables containing the header lines of
716 the message being processed. These variables have names beginning with
717 <varname>$header_</varname> followed by the name of the header line, terminated by a colon.
720 <literallayout class="monospaced">
725 The whole item, including the terminating colon, is replaced by the contents of
726 the message header line. If there is more than one header line with the same
727 name, their contents are concatenated. For header lines whose data consists of
728 a list of addresses (for example, <emphasis>From:</emphasis> and <emphasis>To:</emphasis>), a comma and newline
729 is inserted between each set of data. For all other header lines, just a
733 Leading and trailing white space is removed from header line data, and if there
734 are any MIME <quote>words</quote> that are encoded as defined by RFC 2047 (because they
735 contain non-ASCII characters), they are decoded and translated, if possible, to
736 a local character set. Translation is attempted only on operating systems that
737 have the <function>iconv()</function> function. This makes the header line look the same as it
738 would when displayed by an MUA. The default character set is ISO-8859-1, but
739 this can be changed by means of the <command>headers</command> command (see below).
742 If you want to see the actual characters that make up a header line, you can
743 specify <varname>$rheader_</varname> instead of <varname>$header_</varname>. This inserts the <quote>raw</quote>
744 header line, unmodified.
747 There is also an intermediate form, requested by <varname>$bheader_</varname>, which removes
748 leading and trailing space and decodes MIME <quote>words</quote>, but does not do any
749 character translation. If an attempt to decode what looks superficially like a
750 MIME <quote>word</quote> fails, the raw string is returned. If decoding produces a binary
751 zero character, it is replaced by a question mark.
754 The capitalization of the name following <varname>$header_</varname> is not significant.
755 Because any printing character except colon may appear in the name of a
756 message’s header (this is a requirement of RFC 2822, the document that
757 describes the format of a mail message) curly brackets must <emphasis>not</emphasis> be used in
758 this case, as they will be taken as part of the header name. Two shortcuts are
759 allowed in naming header variables:
764 The initiating <varname>$header_</varname>, <varname>$rheader_</varname>, or <varname>$bheader_</varname> can be
765 abbreviated to <varname>$h_</varname>, <varname>$rh_</varname>, or <varname>$bh_</varname>, respectively.
770 The terminating colon can be omitted if the next character is white space. The
771 white space character is retained in the expanded string. However, this is not
772 recommended, because it makes it easy to forget the colon when it really is
778 If the message does not contain a header of the given name, an empty string is
779 substituted. Thus it is important to spell the names of headers correctly. Do
780 not use <varname>$header_Reply_to</varname> when you really mean <varname>$header_Reply-to</varname>.
784 <title>User variables</title>
786 There are ten user variables with names <varname>$n0</varname> – <varname>$n9</varname> that can be
787 incremented by the <command>add</command> command (see section <xref linkend="SECTadd"/>). These can be
788 used for <quote>scoring</quote> messages in various ways. If Exim is configured to run a
789 <quote>system filter</quote> on every message, the values left in these variables are
790 copied into the variables <varname>$sn0</varname> – <varname>$sn9</varname> at the end of the system filter,
791 thus making them available to users’ filter files. How these values are used is
792 entirely up to the individual installation.
796 <title>Current directory</title>
798 The contents of your filter file should not make any assumptions about the
799 current directory. It is best to use absolute paths for file names; you can
800 normally make use of the <varname>$home</varname> variable to refer to your home directory. The
801 <command>save</command> command automatically inserts <varname>$home</varname> at the start of non-absolute
805 <section id="SECTsigdel">
806 <title>Significant deliveries</title>
808 When in the course of delivery a message is processed by a filter file, what
809 happens next, that is, after the filter file has been processed, depends on
810 whether or not the filter sets up any <emphasis>significant deliveries</emphasis>. If at least
811 one significant delivery is set up, the filter is considered to have handled
812 the entire delivery arrangements for the current address, and no further
813 processing of the address takes place. If, however, no significant deliveries
814 are set up, Exim continues processing the current address as if there were no
815 filter file, and typically sets up a delivery of a copy of the message into a
816 local mailbox. In particular, this happens in the special case of a filter file
817 containing only comments.
820 The delivery commands <command>deliver</command>, <command>save</command>, and <command>pipe</command> are by default
821 significant. However, if such a command is preceded by the word <quote>unseen</quote>, its
822 delivery is not considered to be significant. In contrast, other commands such
823 as <command>mail</command> and <command>vacation</command> do not set up significant deliveries unless
824 preceded by the word <quote>seen</quote>. The following example commands set up
825 significant deliveries:
827 <literallayout class="monospaced">
828 deliver jack@beanstalk.example
829 pipe $home/bin/mymailscript
830 seen mail subject "message discarded"
834 The following example commands do not set up significant deliveries:
836 <literallayout class="monospaced">
837 unseen deliver jack@beanstalk.example
838 unseen pipe $home/bin/mymailscript
839 mail subject "message discarded"
843 <section id="SEC222">
844 <title>Filter commands</title>
846 The filter commands that are described in subsequent sections are listed
847 below, with the section in which they are described in brackets:
849 <informaltable frame="none">
850 <tgroup cols="2" colsep="0" rowsep="0">
851 <colspec colwidth="100pt" align="left"/>
852 <colspec colwidth="300pt" align="left"/>
855 <entry><command>add</command></entry>
856 <entry> increment a user variable (section <xref linkend="SECTadd"/>)</entry>
859 <entry><command>deliver</command></entry>
860 <entry> deliver to an email address (section <xref linkend="SECTdeliver"/>)</entry>
863 <entry><command>fail</command></entry>
864 <entry> force delivery failure (sysadmin use) (section <xref linkend="SECTfail"/>)</entry>
867 <entry><command>finish</command></entry>
868 <entry> end processing (section <xref linkend="SECTfinish"/>)</entry>
871 <entry><command>freeze</command></entry>
872 <entry> freeze message (sysadmin use) (section <xref linkend="SECTfreeze"/>)</entry>
875 <entry><command>headers</command></entry>
876 <entry> set the header character set (section <xref linkend="SECTheaders"/>)</entry>
879 <entry><command>if</command></entry>
880 <entry> test condition(s) (section <xref linkend="SECTif"/>)</entry>
883 <entry><command>logfile</command></entry>
884 <entry> define log file (section <xref linkend="SECTlog"/>)</entry>
887 <entry><command>logwrite</command></entry>
888 <entry> write to log file (section <xref linkend="SECTlog"/>)</entry>
891 <entry><command>mail</command></entry>
892 <entry> send a reply message (section <xref linkend="SECTmail"/>)</entry>
895 <entry><command>pipe</command></entry>
896 <entry> pipe to a command (section <xref linkend="SECTpipe"/>)</entry>
899 <entry><command>save</command></entry>
900 <entry> save to a file (section <xref linkend="SECTsave"/>)</entry>
903 <entry><command>testprint</command></entry>
904 <entry> print while testing (section <xref linkend="SECTtestprint"/>)</entry>
907 <entry><command>vacation</command></entry>
908 <entry> tailored form of <command>mail</command> (section <xref linkend="SECTmail"/>)</entry>
914 The <command>headers</command> command has additional parameters that can be used only in a
915 system filter. The <command>fail</command> and <command>freeze</command> commands are available only when
916 Exim’s filtering facilities are being used as a system filter, and are
917 therefore usable only by the system administrator and not by ordinary users.
918 They are mentioned only briefly in this document; for more information, see the
919 main Exim specification.
922 <section id="SECTadd">
923 <title>The add command</title>
925 <literal> add </literal><<emphasis>number</emphasis>><literal> to </literal><<emphasis>user variable</emphasis>>
926 <literal>e.g. add 2 to n3</literal>
929 There are 10 user variables of this type, with names <varname>$n0</varname> – <varname>$n9</varname>. Their
930 values can be obtained by the normal expansion syntax (for example <varname>$n3</varname>) in
931 other commands. At the start of filtering, these variables all contain zero.
932 Both arguments of the <command>add</command> command are expanded before use, making it
933 possible to add variables to each other. Subtraction can be obtained by adding
937 <section id="SECTdeliver">
938 <title>The deliver command</title>
940 <literal> deliver</literal> <<emphasis>mail address</emphasis>>
941 <literal>e.g. deliver "Dr Livingstone <David@somewhere.africa.example>"</literal>
944 This command provides a forwarding operation. The delivery that it sets up is
945 significant unless the command is preceded by <quote>unseen</quote> (see section
946 <xref linkend="SECTsigdel"/>). The message is sent on to the given address, exactly as
947 happens if the address had appeared in a traditional <filename>.forward</filename> file. If you
948 want to deliver the message to a number of different addresses, you can use
949 more than one <command>deliver</command> command (each one may have only one address).
950 However, duplicate addresses are discarded.
953 To deliver a copy of the message to your normal mailbox, your login name can be
954 given as the address. Once an address has been processed by the filtering
955 mechanism, an identical generated address will not be so processed again, so
956 doing this does not cause a loop.
959 However, if you have a mail alias, you should <emphasis>not</emphasis> refer to it here. For
960 example, if the mail address <emphasis>L.Gulliver</emphasis> is aliased to <emphasis>lg303</emphasis> then all
961 references in Gulliver’s <filename>.forward</filename> file should be to <emphasis>lg303</emphasis>. A reference
962 to the alias will not work for messages that are addressed to that alias,
963 since, like <filename>.forward</filename> file processing, aliasing is performed only once on an
964 address, in order to avoid looping.
967 Following the new address, an optional second address, preceded by
968 <quote>errors_to</quote> may appear. This changes the address to which delivery errors on
969 the forwarded message will be sent. Instead of going to the message’s original
970 sender, they go to this new address. For ordinary users, the only value that is
971 permitted for this address is the user whose filter file is being processed.
972 For example, the user <emphasis>lg303</emphasis> whose mailbox is in the domain
973 <emphasis>lilliput.example</emphasis> could have a filter file that contains
975 <literallayout class="monospaced">
976 deliver jon@elsewhere.example errors_to lg303@lilliput.example
979 Clearly, using this feature makes sense only in situations where not all
980 messages are being forwarded. In particular, bounce messages must not be
981 forwarded in this way, as this is likely to create a mail loop if something
985 <section id="SECTsave">
986 <title>The save command</title>
988 <literal> save </literal><<emphasis>file name</emphasis>>
989 <literal>e.g. save $home/mail/bookfolder</literal>
992 This command specifies that a copy of the message is to be appended to the
993 given file (that is, the file is to be used as a mail folder). The delivery
994 that <command>save</command> sets up is significant unless the command is preceded by
995 <quote>unseen</quote> (see section <xref linkend="SECTsigdel"/>).
998 More than one <command>save</command> command may be obeyed; each one causes a copy of the
999 message to be written to its argument file, provided they are different
1000 (duplicate <command>save</command> commands are ignored).
1003 If the file name does not start with a / character, the contents of the
1004 <varname>$home</varname> variable are prepended, unless it is empty, or the system
1005 administrator has disabled this feature. In conventional configurations, this
1006 variable is normally set in a user filter to the user’s home directory, but the
1007 system administrator may set it to some other path. In some configurations,
1008 <varname>$home</varname> may be unset, or prepending may be disabled, in which case a
1009 non-absolute path name may be generated. Such configurations convert this to an
1010 absolute path when the delivery takes place. In a system filter, <varname>$home</varname> is
1014 The user must of course have permission to write to the file, and the writing
1015 of the file takes place in a process that is running as the user, under the
1016 user’s primary group. Any secondary groups to which the user may belong are not
1017 normally taken into account, though the system administrator can configure Exim
1018 to set them up. In addition, the ability to use this command at all is
1019 controlled by the system administrator – it may be forbidden on some systems.
1022 An optional mode value may be given after the file name. The value for the mode
1023 is interpreted as an octal number, even if it does not begin with a zero. For
1026 <literallayout class="monospaced">
1027 save /some/folder 640
1030 This makes it possible for users to override the system-wide mode setting for
1031 file deliveries, which is normally 600. If an existing file does not have the
1032 correct mode, it is changed.
1035 An alternative form of delivery may be enabled on your system, in which each
1036 message is delivered into a new file in a given directory. If this is the case,
1037 this functionality can be requested by giving the directory name terminated by
1038 a slash after the <command>save</command> command, for example
1040 <literallayout class="monospaced">
1041 save separated/messages/
1044 There are several different formats for such deliveries; check with your system
1045 administrator or local documentation to find out which (if any) are available
1046 on your system. If this functionality is not enabled, the use of a path name
1047 ending in a slash causes an error.
1050 <section id="SECTpipe">
1051 <title>The pipe command</title>
1053 <literal> pipe </literal><<emphasis>command</emphasis>>
1054 <literal>e.g. pipe "$home/bin/countmail $sender_address"</literal>
1057 This command specifies that the message is to be delivered to the specified
1058 command using a pipe. The delivery that it sets up is significant unless the
1059 command is preceded by <quote>unseen</quote> (see section <xref linkend="SECTsigdel"/>). Remember,
1060 however, that no deliveries are done while the filter is being processed. All
1061 deliveries happen later on. Therefore, the result of running the pipe is not
1062 available to the filter.
1065 When the deliveries are done, a separate process is run, and a copy of the
1066 message is passed on its standard input. The process runs as the user, under
1067 the user’s primary group. Any secondary groups to which the user may belong are
1068 not normally taken into account, though the system administrator can configure
1069 Exim to set them up. More than one <command>pipe</command> command may appear; each one causes
1070 a copy of the message to be written to its argument pipe, provided they are
1071 different (duplicate <command>pipe</command> commands are ignored).
1074 When the time comes to transport the message, the command supplied to <command>pipe</command>
1075 is split up by Exim into a command name and a number of arguments. These are
1076 delimited by white space except for arguments enclosed in double quotes, in
1077 which case backslash is interpreted as an escape, or in single quotes, in which
1078 case no escaping is recognized. Note that as the whole command is normally
1079 supplied in double quotes, a second level of quoting is required for internal
1080 double quotes. For example:
1082 <literallayout class="monospaced">
1083 pipe "$home/myscript \"size is $message_size\""
1086 String expansion is performed on the separate components after the line has
1087 been split up, and the command is then run directly by Exim; it is not run
1088 under a shell. Therefore, substitution cannot change the number of arguments,
1089 nor can quotes, backslashes or other shell metacharacters in variables cause
1093 Documentation for some programs that are normally run via this kind of pipe
1094 often suggest that the command should start with
1096 <literallayout class="monospaced">
1100 This is a shell command, and should <emphasis>not</emphasis> be present in Exim filter files,
1101 since it does not normally run the command under a shell.
1104 However, there is an option that the administrator can set to cause a shell to
1105 be used. In this case, the entire command is expanded as a single string and
1106 passed to the shell for interpretation. It is recommended that this be avoided
1107 if at all possible, since it can lead to problems when inserted variables
1108 contain shell metacharacters.
1111 The default PATH set up for the command is determined by the system
1112 administrator, usually containing at least <filename>/bin</filename> and <filename>/usr/bin</filename> so that
1113 common commands are available without having to specify an absolute file name.
1114 However, it is possible for the system administrator to restrict the pipe
1115 facility so that the command name must not contain any / characters, and must
1116 be found in one of the directories in the configured PATH. It is also possible
1117 for the system administrator to lock out the use of the <command>pipe</command> command
1121 When the command is run, a number of environment variables are set up. The
1122 complete list for pipe deliveries may be found in the Exim reference manual.
1123 Those that may be useful for pipe deliveries from user filter files are:
1126 <literal>DOMAIN </literal> the domain of the address
1127 <literal>HOME </literal> your home directory
1128 <literal>LOCAL_PART </literal> see below
1129 <literal>LOCAL_PART_PREFIX </literal> see below
1130 <literal>LOCAL_PART_SUFFIX </literal> see below
1131 <literal>LOGNAME </literal> your login name
1132 <literal>MESSAGE_ID </literal> the unique id of the message
1133 <literal>PATH </literal> the command search path
1134 <literal>RECIPIENT </literal> the complete recipient address
1135 <literal>SENDER </literal> the sender of the message
1136 <literal>SHELL </literal> <literal>/bin/sh</literal>
1137 <literal>USER </literal> see below
1140 LOCAL_PART, LOGNAME, and USER are all set to the same value, namely, your login
1141 id. LOCAL_PART_PREFIX and LOCAL_PART_SUFFIX may be set if Exim is configured to
1142 recognize prefixes or suffixes in the local parts of addresses. For example, a
1143 message addressed to <emphasis>pat-suf2@domain.example</emphasis> may cause the filter for user
1144 <emphasis>pat</emphasis> to be run. If this sets up a pipe delivery, LOCAL_PART_SUFFIX is
1145 <literal>-suf2</literal> when the pipe command runs. The system administrator has to configure
1146 Exim specially for this feature to be available.
1149 If you run a command that is a shell script, be very careful in your use of
1150 data from the incoming message in the commands in your script. RFC 2822 is very
1151 generous in the characters that are permitted to appear in mail addresses, and
1152 in particular, an address may begin with a vertical bar or a slash. For this
1153 reason you should always use quotes round any arguments that involve data from
1154 the message, like this:
1156 <literallayout class="monospaced">
1157 /some/command '$SENDER'
1160 so that inserted shell meta-characters do not cause unwanted effects.
1163 Remember that, as was explained earlier, the pipe command is not run at the
1164 time the filter file is interpreted. The filter just defines what deliveries
1165 are required for one particular addressee of a message. The deliveries
1166 themselves happen later, once Exim has decided everything that needs to be done
1170 A consequence of this is that you cannot inspect the return code from the pipe
1171 command from within the filter. Nevertheless, the code returned by the command
1172 is important, because Exim uses it to decide whether the delivery has succeeded
1176 The command should return a zero completion code if all has gone well. Most
1177 non-zero codes are treated by Exim as indicating a failure of the pipe. This is
1178 treated as a delivery failure, causing the message to be returned to its
1179 sender. However, there are some completion codes that are treated as temporary
1180 errors. The message remains on Exim’s spool disk, and the delivery is tried
1181 again later, though it will ultimately time out if the delivery failures go on
1182 too long. The completion codes to which this applies can be specified by the
1183 system administrator; the default values are 73 and 75.
1186 The pipe command should not normally write anything to its standard output or
1187 standard error file descriptors. If it does, whatever is written is normally
1188 returned to the sender of the message as a delivery error, though this action
1189 can be varied by the system administrator.
1192 <section id="SECTmail">
1193 <title>Mail commands</title>
1195 There are two commands that cause the creation of a new mail message, neither
1196 of which count as a significant delivery unless the command is preceded by the
1197 word <quote>seen</quote> (see section <xref linkend="SECTsigdel"/>). This is a powerful facility, but
1198 it should be used with care, because of the danger of creating infinite
1199 sequences of messages. The system administrator can forbid the use of these
1200 commands altogether.
1203 To help prevent runaway message sequences, these commands have no effect when
1204 the incoming message is a bounce (delivery error) message, and messages sent by
1205 this means are treated as if they were reporting delivery errors. Thus, they
1206 should never themselves cause a bounce message to be returned. The basic
1207 mail-sending command is
1210 <literal>mail [to </literal><<emphasis>address-list</emphasis>><literal>]</literal>
1211 <literal> [cc </literal><<emphasis>address-list</emphasis>><literal>]</literal>
1212 <literal> [bcc </literal><<emphasis>address-list</emphasis>><literal>]</literal>
1213 <literal> [from </literal><<emphasis>address</emphasis>><literal>]</literal>
1214 <literal> [reply_to </literal><<emphasis>address</emphasis>><literal>]</literal>
1215 <literal> [subject </literal><<emphasis>text</emphasis>><literal>]</literal>
1216 <literal> [extra_headers </literal><<emphasis>text</emphasis>><literal>]</literal>
1217 <literal> [text </literal><<emphasis>text</emphasis>><literal>]</literal>
1218 <literal> [[expand] file </literal><<emphasis>filename</emphasis>><literal>]</literal>
1219 <literal> [return message]</literal>
1220 <literal> [log </literal><<emphasis>log file name</emphasis>><literal>]</literal>
1221 <literal> [once </literal><<emphasis>note file name</emphasis>><literal>]</literal>
1222 <literal> [once_repeat </literal><<emphasis>time interval</emphasis>><literal>]</literal>
1223 <literal>e.g. mail text "Your message about $h_subject: has been received"</literal>
1226 Each <<emphasis>address-list</emphasis>> can contain a number of addresses, separated by commas,
1227 in the format of a <emphasis>To:</emphasis> or <emphasis>Cc:</emphasis> header line. In fact, the text you supply
1228 here is copied exactly into the appropriate header line. It may contain
1229 additional information as well as email addresses. For example:
1231 <literallayout class="monospaced">
1232 mail to "Julius Caesar <jc@rome.example>, \
1233 <ma@rome.example> (Mark A.)"
1236 Similarly, the texts supplied for <option>from</option> and <option>reply_to</option> are copied into
1237 their respective header lines.
1240 As a convenience for use in one common case, there is also a command called
1241 <command>vacation</command>. It behaves in the same way as <command>mail</command>, except that the defaults
1242 for the <option>subject</option>, <option>file</option>, <option>log</option>, <option>once</option>, and <option>once_repeat</option> options
1245 <literallayout class="monospaced">
1246 subject "On vacation"
1247 expand file .vacation.msg
1253 respectively. These are the same file names and repeat period used by the
1254 traditional Unix <command>vacation</command> command. The defaults can be overridden by
1255 explicit settings, but if a file name is given its contents are expanded only
1256 if explicitly requested.
1259 <emphasis role="bold">Warning</emphasis>: The <command>vacation</command> command should always be used conditionally,
1260 subject to at least the <command>personal</command> condition (see section <xref linkend="SECTpersonal"/>
1261 below) so as not to send automatic replies to non-personal messages from
1262 mailing lists or elsewhere. Sending an automatic response to a mailing list or
1263 a mailing list manager is an Internet Sin.
1266 For both commands, the key/value argument pairs can appear in any order. At
1267 least one of <option>text</option> or <option>file</option> must appear (except with <command>vacation</command>, where
1268 there is a default for <option>file</option>); if both are present, the text string appears
1269 first in the message. If <option>expand</option> precedes <option>file</option>, each line of the file is
1270 subject to string expansion before it is included in the message.
1273 Several lines of text can be supplied to <option>text</option> by including the escape
1274 sequence <quote>\n</quote> in the string wherever a newline is required. If the command is
1275 output during filter file testing, newlines in the text are shown as <quote>\n</quote>.
1278 Note that the keyword for creating a <emphasis>Reply-To:</emphasis> header is <option>reply_to</option>,
1279 because Exim keywords may contain underscores, but not hyphens. If the <option>from</option>
1280 keyword is present and the given address does not match the user who owns the
1281 forward file, Exim normally adds a <emphasis>Sender:</emphasis> header to the message, though it
1282 can be configured not to do this.
1285 The <option>extra_headers</option> keyword allows you to add custom header lines to the
1286 message. The text supplied must be one or more syntactically valid RFC 2822
1287 header lines. You can use <quote>\n</quote> within quoted text to specify newlines between
1288 headers, and also to define continued header lines. For example:
1290 <literallayout class="monospaced">
1291 extra_headers "h1: first\nh2: second\n continued\nh3: third"
1294 No newline should appear at the end of the final header line.
1297 If no <option>to</option> argument appears, the message is sent to the address in the
1298 <varname>$reply_address</varname> variable (see section <xref linkend="SECTfilterstringexpansion"/> above).
1299 An <emphasis>In-Reply-To:</emphasis> header is automatically included in the created message,
1300 giving a reference to the message identification of the incoming message.
1303 If <option>return message</option> is specified, the incoming message that caused the filter
1304 file to be run is added to the end of the message, subject to a maximum size
1308 If a log file is specified, a line is added to it for each message sent.
1311 If a <option>once</option> file is specified, it is used to hold a database for remembering
1312 who has received a message, and no more than one message is ever sent to any
1313 particular address, unless <option>once_repeat</option> is set. This specifies a time
1314 interval after which another copy of the message is sent. The interval is
1315 specified as a sequence of numbers, each followed by the initial letter of one
1316 of <quote>seconds</quote>, <quote>minutes</quote>, <quote>hours</quote>, <quote>days</quote>, or <quote>weeks</quote>. For example,
1318 <literallayout class="monospaced">
1322 causes a new message to be sent if at least 5 days and 4 hours have elapsed
1323 since the last one was sent. There must be no white space in a time interval.
1326 Commonly, the file name specified for <option>once</option> is used as the base name for
1327 direct-access (DBM) file operations. There are a number of different DBM
1328 libraries in existence. Some operating systems provide one as a default, but
1329 even in this case a different one may have been used when building Exim. With
1330 some DBM libraries, specifying <option>once</option> results in two files being created,
1331 with the suffixes <filename>.dir</filename> and <filename>.pag</filename> being added to the given name. With
1332 some others a single file with the suffix <filename>.db</filename> is used, or the name is used
1336 Using a DBM file for implementing the <option>once</option> feature means that the file
1337 grows as large as necessary. This is not usually a problem, but some system
1338 administrators want to put a limit on it. The facility can be configured not to
1339 use a DBM file, but instead, to use a regular file with a maximum size. The
1340 data in such a file is searched sequentially, and if the file fills up, the
1341 oldest entry is deleted to make way for a new one. This means that some
1342 correspondents may receive a second copy of the message after an unpredictable
1343 interval. Consult your local information to see if your system is configured
1347 More than one <command>mail</command> or <command>vacation</command> command may be obeyed in a single filter
1348 run; they are all honoured, even when they are to the same recipient.
1351 <section id="SECTlog">
1352 <title>Logging commands</title>
1354 A log can be kept of actions taken by a filter file. This facility is normally
1355 available in conventional configurations, but there are some situations where
1356 it might not be. Also, the system administrator may choose to disable it. Check
1357 your local information if in doubt.
1360 Logging takes place while the filter file is being interpreted. It does not
1361 queue up for later like the delivery commands. The reason for this is so that a
1362 log file need be opened only once for several write operations. There are two
1363 commands, neither of which constitutes a significant delivery. The first
1364 defines a file to which logging output is subsequently written:
1367 <literal> logfile </literal><<emphasis>file name</emphasis>>
1368 <literal>e.g. logfile $home/filter.log</literal>
1371 The file name must be fully qualified. You can use <varname>$home</varname>, as in this
1372 example, to refer to your home directory. The file name may optionally be
1373 followed by a mode for the file, which is used if the file has to be created.
1376 <literallayout class="monospaced">
1377 logfile $home/filter.log 0644
1380 The number is interpreted as octal, even if it does not begin with a zero.
1381 The default for the mode is 600. It is suggested that the <command>logfile</command> command
1382 normally appear as the first command in a filter file. Once a log file has
1383 been obeyed, the <command>logwrite</command> command can be used to write to it:
1386 <literal> logwrite "</literal><<emphasis>some text string</emphasis>><literal>"</literal>
1387 <literal>e.g. logwrite "$tod_log $message_id processed"</literal>
1390 It is possible to have more than one <command>logfile</command> command, to specify writing to
1391 different log files in different circumstances.
1392 A previously opened log is closed on a subsequent <command>logfile</command> command.
1393 Writing takes place at the end
1394 of the file, and a newline character is added to the end of each string if
1395 there isn’t one already there. Newlines can be put in the middle of the string
1396 by using the <quote>\n</quote> escape sequence. Lines from simultaneous deliveries may get
1397 interleaved in the file, as there is no interlocking, so you should plan your
1398 logging with this in mind. However, data should not get lost.
1401 <section id="SECTfinish">
1402 <title>The finish command</title>
1404 The command <command>finish</command>, which has no arguments, causes Exim to stop
1405 interpreting the filter file. This is not a significant action unless preceded
1406 by <quote>seen</quote>. A filter file containing only <quote>seen finish</quote> is a black hole.
1409 <section id="SECTtestprint">
1410 <title>The testprint command</title>
1412 It is sometimes helpful to be able to print out the values of variables when
1413 testing filter files. The command
1416 <literal> testprint </literal><<emphasis>text</emphasis>>
1417 <literal>e.g. testprint "home=$home reply_address=$reply_address"</literal>
1420 does nothing when mail is being delivered. However, when the filtering code is
1421 being tested by means of the <option>-bf</option> option (see section <xref linkend="SECTtesting"/>
1422 above), the value of the string is written to the standard output.
1425 <section id="SECTfail">
1426 <title>The fail command</title>
1428 When Exim’s filtering facilities are being used as a system filter, the
1429 <command>fail</command> command is available, to force delivery failure. Because this command
1430 is normally usable only by the system administrator, and not enabled for use by
1431 ordinary users, it is described in more detail in the main Exim specification
1432 rather than in this document.
1435 <section id="SECTfreeze">
1436 <title>The freeze command</title>
1438 When Exim’s filtering facilities are being used as a system filter, the
1439 <command>freeze</command> command is available, to freeze a message on the queue. Because this
1440 command is normally usable only by the system administrator, and not enabled
1441 for use by ordinary users, it is described in more detail in the main Exim
1442 specification rather than in this document.
1445 <section id="SECTheaders">
1446 <title>The headers command</title>
1448 The <command>headers</command> command can be used to change the target character set that is
1449 used when translating the contents of encoded header lines for insertion by the
1450 <varname>$header_</varname> mechanism (see section <xref linkend="SECTheadervariables"/> above). The
1451 default can be set in the Exim configuration; if not specified, ISO-8859-1 is
1452 used. The only currently supported format for the <command>headers</command> command in user
1453 filters is as in this example:
1455 <literallayout class="monospaced">
1456 headers charset "UTF-8"
1459 That is, <command>headers</command> is followed by the word <quote>charset</quote> and then the name of a
1460 character set. This particular example would be useful if you wanted to compare
1461 the contents of a header to a UTF-8 string.
1464 In system filter files, the <command>headers</command> command can be used to add or remove
1465 header lines from the message. These features are described in the main Exim
1469 <section id="SECTif">
1470 <title>Obeying commands conditionally</title>
1472 Most of the power of filtering comes from the ability to test conditions and
1473 obey different commands depending on the outcome. The <command>if</command> command is used to
1474 specify conditional execution, and its general form is
1477 <literal>if </literal><<emphasis>condition</emphasis>>
1478 <literal>then </literal><<emphasis>commands</emphasis>>
1479 <literal>elif </literal><<emphasis>condition</emphasis>>
1480 <literal>then </literal><<emphasis>commands</emphasis>>
1481 <literal>else </literal><<emphasis>commands</emphasis>>
1482 <literal>endif</literal>
1485 There may be any number of <command>elif</command> and <command>then</command> sections (including none) and
1486 the <command>else</command> section is also optional. Any number of commands, including nested
1487 <command>if</command> commands, may appear in any of the <<emphasis>commands</emphasis>> sections.
1490 Conditions can be combined by using the words <command>and</command> and <command>or</command>, and round
1491 brackets (parentheses) can be used to specify how several conditions are to
1492 combine. Without brackets, <command>and</command> is more binding than <command>or</command>. For example:
1494 <literallayout class="monospaced">
1496 $h_subject: contains "Make money" or
1497 $h_precedence: is "junk" or
1498 ($h_sender: matches ^\\d{8}@ and not personal) or
1499 $message_body contains "this is not spam"
1505 A condition can be preceded by <command>not</command> to negate it, and there are also some
1506 negative forms of condition that are more English-like.
1509 <section id="SEC23">
1510 <title>String testing conditions</title>
1512 There are a number of conditions that operate on text strings, using the words
1513 <quote>begins</quote>, <quote>ends</quote>, <quote>is</quote>, <quote>contains</quote> and <quote>matches</quote>. If you want to
1514 apply the same test to more than one header line, you can easily concatenate
1515 them into a single string for testing, as in this example:
1517 <literallayout class="monospaced">
1518 if "$h_to:, $h_cc:" contains me@domain.example then ...
1521 If a string-testing condition name is written in lower case, the testing
1522 of letters is done without regard to case; if it is written in upper case
1523 (for example, <quote>CONTAINS</quote>), the case of letters is taken into account.
1526 <literal> </literal><<emphasis>text1</emphasis>><literal> begins </literal><<emphasis>text2</emphasis>>
1527 <literal> </literal><<emphasis>text1</emphasis>><literal> does not begin </literal><<emphasis>text2</emphasis>>
1528 <literal>e.g. $header_from: begins "Friend@"</literal>
1531 A <quote>begins</quote> test checks for the presence of the second string at the start of
1532 the first, both strings having been expanded.
1535 <literal> </literal><<emphasis>text1</emphasis>><literal> ends </literal><<emphasis>text2</emphasis>>
1536 <literal> </literal><<emphasis>text1</emphasis>><literal> does not end </literal><<emphasis>text2</emphasis>>
1537 <literal>e.g. $header_from: ends "public.com.example"</literal>
1540 An <quote>ends</quote> test checks for the presence of the second string at the end of
1541 the first, both strings having been expanded.
1544 <literal> </literal><<emphasis>text1</emphasis>><literal> is </literal><<emphasis>text2</emphasis>>
1545 <literal> </literal><<emphasis>text1</emphasis>><literal> is not </literal><<emphasis>text2</emphasis>>
1546 <literal>e.g. $local_part_suffix is "-foo"</literal>
1549 An <quote>is</quote> test does an exact match between the strings, having first expanded
1553 <literal> </literal><<emphasis>text1</emphasis>><literal> contains </literal><<emphasis>text2</emphasis>>
1554 <literal> </literal><<emphasis>text1</emphasis>><literal> does not contain </literal><<emphasis>text2</emphasis>>
1555 <literal>e.g. $header_subject: contains "evolution"</literal>
1558 A <quote>contains</quote> test does a partial string match, having expanded both strings.
1561 <literal> </literal><<emphasis>text1</emphasis>><literal> matches </literal><<emphasis>text2</emphasis>>
1562 <literal> </literal><<emphasis>text1</emphasis>><literal> does not match </literal><<emphasis>text2</emphasis>>
1563 <literal>e.g. $sender_address matches "(bill|john)@"</literal>
1566 For a <quote>matches</quote> test, after expansion of both strings, the second one is
1567 interpreted as a regular expression. Exim uses the PCRE2 regular expression
1568 library, which provides regular expressions that are compatible with Perl.
1571 The match succeeds if the regular expression matches any part of the first
1572 string. If you want a regular expression to match only at the start or end of
1573 the subject string, you must encode that requirement explicitly, using the
1574 <literal>^</literal> or <literal>$</literal> metacharacters. The above example, which is not so constrained,
1575 matches all these addresses:
1577 <literallayout class="monospaced">
1580 spoonbill@example.com
1581 littlejohn@example.com
1584 To match only the first two, you could use this:
1586 <literallayout class="monospaced">
1587 if $sender_address matches "^(bill|john)@" then ...
1590 Care must be taken if you need a backslash in a regular expression, because
1591 backslashes are interpreted as escape characters both by the string expansion
1592 code and by Exim’s normal processing of strings in quotes. For example, if you
1593 want to test the sender address for a domain ending in <emphasis>.com</emphasis> the regular
1596 <literallayout class="monospaced">
1600 The backslash and dollar sign in that expression have to be escaped when used
1601 in a filter command, as otherwise they would be interpreted by the expansion
1602 code. Thus, what you actually write is
1604 <literallayout class="monospaced">
1605 if $sender_address matches \\.com\$
1608 An alternative way of handling this is to make use of the <literal>\N</literal> expansion
1609 flag for suppressing expansion:
1611 <literallayout class="monospaced">
1612 if $sender_address matches \N\.com$\N
1615 Everything between the two occurrences of <literal>\N</literal> is copied without change by
1616 the string expander (and in fact you do not need the final one, because it is
1617 at the end of the string). If the regular expression is given in quotes
1618 (mandatory only if it contains white space) you have to write either
1620 <literallayout class="monospaced">
1621 if $sender_address matches "\\\\.com\\$"
1626 <literallayout class="monospaced">
1627 if $sender_address matches "\\N\\.com$\\N"
1630 If the regular expression contains bracketed sub-expressions, numeric
1631 variable substitutions such as <varname>$1</varname> can be used in the subsequent actions
1632 after a successful match. If the match fails, the values of the numeric
1633 variables remain unchanged. Previous values are not restored after <command>endif</command>.
1634 In other words, only one set of values is ever available. If the condition
1635 contains several sub-conditions connected by <command>and</command> or <command>or</command>, it is the
1636 strings extracted from the last successful match that are available in
1637 subsequent actions. Numeric variables from any one sub-condition are also
1638 available for use in subsequent sub-conditions, because string expansion of a
1639 condition occurs just before it is tested.
1642 <section id="SEC24">
1643 <title>Numeric testing conditions</title>
1645 The following conditions are available for performing numerical tests:
1648 <literal> </literal><<emphasis>number1</emphasis>><literal> is above </literal><<emphasis>number2</emphasis>>
1649 <literal> </literal><<emphasis>number1</emphasis>><literal> is not above </literal><<emphasis>number2</emphasis>>
1650 <literal> </literal><<emphasis>number1</emphasis>><literal> is below </literal><<emphasis>number2</emphasis>>
1651 <literal> </literal><<emphasis>number1</emphasis>><literal> is not below </literal><<emphasis>number2</emphasis>>
1652 <literal>e.g. $message_size is not above 10k</literal>
1655 The <<emphasis>number</emphasis>> arguments must expand to strings of digits, optionally
1656 followed by one of the letters K or M (upper case or lower case) which cause
1657 multiplication by 1024 and 1024x1024 respectively.
1660 <section id="SEC25">
1661 <title>Testing for significant deliveries</title>
1663 You can use the <command>delivered</command> condition to test whether or not any previously
1664 obeyed filter commands have set up a significant delivery. For example:
1666 <literallayout class="monospaced">
1667 if not delivered then save mail/anomalous endif
1670 <quote>Delivered</quote> is perhaps a poor choice of name for this condition, because the
1671 message has not actually been delivered; rather, a delivery has been set up for
1675 <section id="SEC26">
1676 <title>Testing for error messages</title>
1678 The condition <command>error_message</command> is true if the incoming message is a bounce
1679 (mail delivery error) message. Putting the command
1681 <literallayout class="monospaced">
1682 if error_message then finish endif
1685 at the head of your filter file is a useful insurance against things going
1686 wrong in such a way that you cannot receive delivery error reports. <emphasis role="bold">Note</emphasis>:
1687 <command>error_message</command> is a condition, not an expansion variable, and therefore is
1688 not preceded by <literal>$</literal>.
1691 <section id="SEC27">
1692 <title>Testing a list of addresses</title>
1694 There is a facility for looping through a list of addresses and applying a
1695 condition to each of them. It takes the form
1698 <literal>foranyaddress </literal><<emphasis>string</emphasis>><literal> (</literal><<emphasis>condition</emphasis>><literal>)</literal>
1701 where <<emphasis>string</emphasis>> is interpreted as a list of RFC 2822 addresses, as in a
1702 typical header line, and <<emphasis>condition</emphasis>> is any valid filter condition or
1703 combination of conditions. The <quote>group</quote> syntax that is defined for certain
1704 header lines that contain addresses is supported.
1707 The parentheses surrounding the condition are mandatory, to delimit it from
1708 possible further sub-conditions of the enclosing <command>if</command> command. Within the
1709 condition, the expansion variable <varname>$thisaddress</varname> is set to the non-comment
1710 portion of each of the addresses in the string in turn. For example, if the
1713 <literallayout class="monospaced">
1714 B.Simpson <bart@sfld.example>, lisa@sfld.example (his sister)
1717 then <varname>$thisaddress</varname> would take on the values <literal>bart@sfld.example</literal> and
1718 <literal>lisa@sfld.example</literal> in turn.
1721 If there are no valid addresses in the list, the whole condition is false. If
1722 the internal condition is true for any one address, the overall condition is
1723 true and the loop ends. If the internal condition is false for all addresses in
1724 the list, the overall condition is false. This example tests for the presence
1725 of an eight-digit local part in any address in a <emphasis>To:</emphasis> header:
1727 <literallayout class="monospaced">
1728 if foranyaddress $h_to: ( $thisaddress matches ^\\d{8}@ ) then ...
1731 When the overall condition is true, the value of <varname>$thisaddress</varname> in the
1732 commands that follow <command>then</command> is the last value it took on inside the loop. At
1733 the end of the <command>if</command> command, the value of <varname>$thisaddress</varname> is reset to what it
1734 was before. It is best to avoid the use of multiple occurrences of
1735 <command>foranyaddress</command>, nested or otherwise, in a single <command>if</command> command, if the
1736 value of <varname>$thisaddress</varname> is to be used afterwards, because it isn’t always
1737 clear what the value will be. Nested <command>if</command> commands should be used instead.
1740 Header lines can be joined together if a check is to be applied to more than
1741 one of them. For example:
1743 <literallayout class="monospaced">
1744 if foranyaddress $h_to:,$h_cc: ....
1747 This scans through the addresses in both the <emphasis>To:</emphasis> and the <emphasis>Cc:</emphasis> headers.
1750 <section id="SECTpersonal">
1751 <title>Testing for personal mail</title>
1753 A common requirement is to distinguish between incoming personal mail and mail
1754 from a mailing list, or from a robot or other automatic process (for example, a
1755 bounce message). In particular, this test is normally required for <quote>vacation
1759 The <command>personal</command> condition checks that the message is not a bounce message and
1760 that the current user’s email address appears in the <emphasis>To:</emphasis> header. It also
1761 checks that the sender is not the current user or one of a number of common
1762 daemons, and that there are no header lines starting <emphasis>List-</emphasis> in the message.
1763 Finally, it checks the content of the <emphasis>Precedence:</emphasis> header line, if there is
1767 You should always use the <command>personal</command> condition when generating automatic
1768 responses. This example shows the use of <command>personal</command> in a filter file that is
1769 sending out vacation messages:
1771 <literallayout class="monospaced">
1773 mail to $reply_address
1774 subject "I am on holiday"
1775 file $home/vacation/message
1776 once $home/vacation/once
1781 It is tempting, when writing commands like the above, to quote the original
1782 subject in the reply. For example:
1784 <literallayout class="monospaced">
1785 subject "Re: $h_subject:"
1788 There is a danger in doing this, however. It may allow a third party to
1789 subscribe you to an opt-in mailing list, provided that the list accepts bounce
1790 messages as subscription confirmations. (Messages sent from filters are always
1791 sent as bounce messages.) Well-managed lists require a non-bounce message to
1792 confirm a subscription, so the danger is relatively small.
1795 If prefixes or suffixes are in use for local parts – something which depends
1796 on the configuration of Exim (see section <xref linkend="SECTmbox"/> below) – the tests
1797 for the current user are done with the full address (including the prefix and
1798 suffix, if any) as well as with the prefix and suffix removed. If the system is
1799 configured to rewrite local parts of mail addresses, for example, to rewrite
1800 <literal>dag46</literal> as <literal>Dirk.Gently</literal>, the rewritten form of the address is also used in
1804 <section id="SEC28">
1805 <title>Alias addresses for the personal condition</title>
1807 It is quite common for people who have mail accounts on a number of different
1808 systems to forward all their mail to one system, and in this case a check for
1809 personal mail should test all their various mail addresses. To allow for this,
1810 the <command>personal</command> condition keyword can be followed by
1813 <literal>alias </literal><<emphasis>address</emphasis>>
1816 any number of times, for example:
1818 <literallayout class="monospaced">
1819 if personal alias smith@else.where.example
1820 alias jones@other.place.example
1824 The alias addresses are treated as alternatives to the current user’s email
1825 address when testing the contents of header lines.
1828 <section id="SEC29">
1829 <title>Details of the personal condition</title>
1831 The basic <command>personal</command> test is roughly equivalent to the following:
1833 <literallayout class="monospaced">
1834 not error_message and
1835 $message_headers does not contain "\nList-Id:" and
1836 $message_headers does not contain "\nList-Help:" and
1837 $message_headers does not contain "\nList-Subscribe:" and
1838 $message_headers does not contain "\nList-Unsubscribe:" and
1839 $message_headers does not contain "\nList-Post:" and
1840 $message_headers does not contain "\nList-Owner:" and
1841 $message_headers does not contain "\nList-Archive:" and
1843 "${if def:h_auto-submitted:{present}{absent}}" is "absent" or
1844 $header_auto-submitted: is "no"
1846 $header_precedence: does not contain "bulk" and
1847 $header_precedence: does not contain "list" and
1848 $header_precedence: does not contain "junk" and
1849 foranyaddress $header_to:
1850 ( $thisaddress contains "$local_part$domain" ) and
1851 not foranyaddress $header_from:
1853 $thisaddress contains "$local_part@$domain" or
1854 $thisaddress contains "server@" or
1855 $thisaddress contains "daemon@" or
1856 $thisaddress contains "root@" or
1857 $thisaddress contains "listserv@" or
1858 $thisaddress contains "majordomo@" or
1859 $thisaddress contains "-request@" or
1860 $thisaddress matches "^owner-[^@]+@"
1864 The variable <varname>$local_part</varname> contains the local part of the mail address of
1865 the user whose filter file is being run – it is normally your login id. The
1866 <varname>$domain</varname> variable contains the mail domain. As explained above, if aliases
1867 or rewriting are defined, or if prefixes or suffixes are in use, the tests for
1868 the current user are also done with alternative addresses.
1871 <section id="SEC30">
1872 <title>Testing delivery status</title>
1874 There are two conditions that are intended mainly for use in system filter
1875 files, but which are available in users’ filter files as well. The condition
1876 <command>first_delivery</command> is true if this is the first process that is attempting to
1877 deliver the message, and false otherwise. This indicator is not reset until the
1878 first delivery process successfully terminates; if there is a crash or a power
1879 failure (for example), the next delivery attempt is also a <quote>first delivery</quote>.
1882 In a user filter file <command>first_delivery</command> will be false if there was previously
1883 an error in the filter, or if a delivery for the user failed owing to, for
1884 example, a quota error, or if forwarding to a remote address was deferred for
1888 The condition <command>manually_thawed</command> is true if the message was <quote>frozen</quote> for
1889 some reason, and was subsequently released by the system administrator. It is
1890 unlikely to be of use in users’ filter files.
1893 <section id="SECTmbox">
1894 <title>Multiple personal mailboxes</title>
1895 <titleabbrev>SEC31</titleabbrev>
1897 The system administrator can configure Exim so that users can set up variants
1898 on their email addresses and handle them separately. Consult your system
1899 administrator or local documentation to see if this facility is enabled on your
1900 system, and if so, what the details are.
1903 The facility involves the use of a prefix or a suffix on an email address. For
1904 example, all mail addressed to <emphasis>lg303-</emphasis><<emphasis>something</emphasis>> would be the property
1905 of user <emphasis>lg303</emphasis>, who could determine how it was to be handled, depending on
1906 the value of <<emphasis>something</emphasis>>.
1909 There are two possible ways in which this can be set up. The first possibility
1910 is the use of multiple <filename>.forward</filename> files. In this case, mail to <emphasis>lg303-foo</emphasis>,
1911 for example, is handled by looking for a file called <filename>.forward-foo</filename> in
1912 <emphasis>lg303</emphasis>’s home directory. If such a file does not exist, delivery fails
1913 and the message is returned to its sender.
1916 The alternative approach is to pass all messages through a single <filename>.forward</filename>
1917 file, which must be a filter file so that it can distinguish between the
1918 different cases by referencing the variables <varname>$local_part_prefix</varname> or
1919 <varname>$local_part_suffix</varname>, as in the final example in section <xref linkend="SECTex"/> below.
1922 It is possible to configure Exim to support both schemes at once. In this case,
1923 a specific <filename>.forward-foo</filename> file is first sought; if it is not found, the basic
1924 <filename>.forward</filename> file is used.
1927 The <command>personal</command> test (see section <xref linkend="SECTpersonal"/>) includes prefixes and
1928 suffixes in its checking.
1931 <section id="SEC43">
1932 <title>Ignoring delivery errors</title>
1934 As was explained above, filtering just sets up addresses for delivery – no
1935 deliveries are actually done while a filter file is active. If any of the
1936 generated addresses subsequently suffers a delivery failure, an error message
1937 is generated in the normal way. However, if a filter command that sets up a
1938 delivery is preceded by the word <quote>noerror</quote>, errors for that delivery,
1939 and any deliveries consequent on it (that is, from alias, forwarding, or
1940 filter files it invokes) are ignored.
1943 <section id="SECTex">
1944 <title>Examples of Exim filter commands</title>
1948 <literallayout class="monospaced">
1950 deliver baggins@rivendell.middle-earth.example
1953 Vacation handling using traditional means, assuming that the <filename>.vacation.msg</filename>
1954 and other files have been set up in your home directory:
1956 <literallayout class="monospaced">
1958 unseen pipe "/usr/ucb/vacation \"$local_part\""
1961 Vacation handling inside Exim, having first created a file called
1962 <filename>.vacation.msg</filename> in your home directory:
1964 <literallayout class="monospaced">
1966 if personal then vacation endif
1969 File some messages by subject:
1971 <literallayout class="monospaced">
1973 if $header_subject: contains "empire" or
1974 $header_subject: contains "foundation"
1980 Save all non-urgent messages by weekday:
1982 <literallayout class="monospaced">
1984 if $header_subject: does not contain "urgent" and
1985 $tod_full matches "^(...),"
1991 Throw away all mail from one site, except from postmaster:
1993 <literallayout class="monospaced">
1995 if $reply_address contains "@spam.site.example" and
1996 $reply_address does not contain "postmaster@"
2002 Handle multiple personal mailboxes:
2004 <literallayout class="monospaced">
2006 if $local_part_suffix is "-foo"
2009 elif $local_part_suffix is "-bar"
git://git.exim.org / exim-website.git / blob