Spec docs for IDNA2008 support
[exim.git] / doc / doc-docbook / spec.xfpt
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1. /////////////////////////////////////////////////////////////////////////////
2. This is the primary source of the Exim Manual. It is an xfpt document that is
3. converted into DocBook XML for subsequent conversion into printing and online
4. formats. The markup used herein is "standard" xfpt markup, with some extras.
5. The markup is summarized in a file called Markup.txt.
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6.
7. WARNING: When you use the .new macro, make sure it appears *before* any
8. adjacent index items; otherwise you get an empty "paragraph" which causes
9. unwanted vertical space.
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10. /////////////////////////////////////////////////////////////////////////////
11
12.include stdflags
13.include stdmacs
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14
15. /////////////////////////////////////////////////////////////////////////////
33393583 16. This outputs the standard DocBook boilerplate.
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17. /////////////////////////////////////////////////////////////////////////////
18
33393583 19.docbook
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20
21. /////////////////////////////////////////////////////////////////////////////
22. These lines are processing instructions for the Simple DocBook Processor that
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23. Philip Hazel has developed as a less cumbersome way of making PostScript and
24. PDFs than using xmlto and fop. They will be ignored by all other XML
25. processors.
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26. /////////////////////////////////////////////////////////////////////////////
27
28.literal xml
29<?sdop
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30 foot_right_recto="&chaptertitle; (&chapternumber;)"
31 foot_right_verso="&chaptertitle; (&chapternumber;)"
3cb1b51e 32 toc_chapter_blanks="yes,yes"
595028e4 33 table_warn_overflow="overprint"
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34?>
35.literal off
9b371988 36
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37. /////////////////////////////////////////////////////////////////////////////
38. This generate the outermost <book> element that wraps then entire document.
39. /////////////////////////////////////////////////////////////////////////////
40
41.book
42
43. /////////////////////////////////////////////////////////////////////////////
2aee48d6 44. These definitions set some parameters and save some typing.
7d837ca7 45. Update the Copyright year (only) when changing content.
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46. /////////////////////////////////////////////////////////////////////////////
47
fd047340 48.set previousversion "4.88"
2aee48d6 49.include ./local_params
f89d2485 50
33393583 51.set ACL "access control lists (ACLs)"
f89d2485 52.set I "&nbsp;&nbsp;&nbsp;&nbsp;"
33393583 53
7d837ca7 54.macro copyyear
d4e5e70b 552017
7d837ca7 56.endmacro
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57
58. /////////////////////////////////////////////////////////////////////////////
59. Additional xfpt markup used by this document, over and above the default
60. provided in the xfpt library.
61. /////////////////////////////////////////////////////////////////////////////
62
63. --- Override the &$ flag to automatically insert a $ with the variable name
64
65.flag &$ $& "<varname>$" "</varname>"
66
67. --- Short flags for daggers in option headings. They will always be inside
68. --- an italic string, but we want the daggers to be roman.
69
70.flag &!! "</emphasis>&dagger;<emphasis>"
71.flag &!? "</emphasis>&Dagger;<emphasis>"
72
73. --- A macro for an Exim option definition heading, generating a one-line
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74. --- table with four columns. For cases when the option name is given with
75. --- a space, so that it can be split, a fifth argument is used for the
76. --- index entry.
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77
78.macro option
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79.arg 5
80.oindex "&%$5%&"
81.endarg
82.arg -5
3cb1b51e 83.oindex "&%$1%&"
0a4e3112 84.endarg
f89d2485 85.itable all 0 0 4 8* left 6* center 6* center 6* right
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86.row "&%$1%&" "Use: &'$2'&" "Type: &'$3'&" "Default: &'$4'&"
87.endtable
88.endmacro
89
90. --- A macro for the common 2-column tables. The width of the first column
91. --- is suitable for the many tables at the start of the main options chapter;
92. --- the small number of other 2-column tables override it.
93
db9452a9 94.macro table2 196pt 254pt
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95.itable none 0 0 2 $1 left $2 left
96.endmacro
97
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98. --- A macro that generates .row, but puts &I; at the start of the first
99. --- argument, thus indenting it. Assume a minimum of two arguments, and
100. --- allow up to four arguments, which is as many as we'll ever need.
101
102.macro irow
103.arg 4
104.row "&I;$1" "$2" "$3" "$4"
105.endarg
106.arg -4
107.arg 3
108.row "&I;$1" "$2" "$3"
109.endarg
110.arg -3
111.row "&I;$1" "$2"
112.endarg
113.endarg
114.endmacro
115
116. --- Macros for option, variable, and concept index entries. For a "range"
117. --- style of entry, use .scindex for the start and .ecindex for the end. The
118. --- first argument of .scindex and the only argument of .ecindex must be the
119. --- ID that ties them together.
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120
121.macro cindex
122&<indexterm role="concept">&
123&<primary>&$1&</primary>&
124.arg 2
125&<secondary>&$2&</secondary>&
126.endarg
127&</indexterm>&
128.endmacro
129
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130.macro scindex
131&<indexterm role="concept" id="$1" class="startofrange">&
132&<primary>&$2&</primary>&
133.arg 3
134&<secondary>&$3&</secondary>&
135.endarg
136&</indexterm>&
137.endmacro
138
139.macro ecindex
140&<indexterm role="concept" startref="$1" class="endofrange"/>&
141.endmacro
142
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143.macro oindex
144&<indexterm role="option">&
145&<primary>&$1&</primary>&
146.arg 2
147&<secondary>&$2&</secondary>&
148.endarg
149&</indexterm>&
150.endmacro
151
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152.macro vindex
153&<indexterm role="variable">&
154&<primary>&$1&</primary>&
155.arg 2
156&<secondary>&$2&</secondary>&
157.endarg
158&</indexterm>&
159.endmacro
160
9b371988 161.macro index
f89d2485 162.echo "** Don't use .index; use .cindex or .oindex or .vindex"
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163.endmacro
164. ////////////////////////////////////////////////////////////////////////////
165
166
167. ////////////////////////////////////////////////////////////////////////////
168. The <bookinfo> element is removed from the XML before processing for Ascii
169. output formats.
170. ////////////////////////////////////////////////////////////////////////////
171
172.literal xml
173<bookinfo>
174<title>Specification of the Exim Mail Transfer Agent</title>
175<titleabbrev>The Exim MTA</titleabbrev>
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176<date>
177.fulldate
178</date>
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179<author><firstname>Exim</firstname><surname>Maintainers</surname></author>
180<authorinitials>EM</authorinitials>
9b371988 181<revhistory><revision>
99474a17 182.versiondatexml
7b4c60eb 183 <authorinitials>EM</authorinitials>
9b371988 184</revision></revhistory>
2aee48d6 185<copyright><year>
29343b08 186.copyyear
2aee48d6 187 </year><holder>University of Cambridge</holder></copyright>
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188</bookinfo>
189.literal off
190
191
192. /////////////////////////////////////////////////////////////////////////////
193. This chunk of literal XML implements index entries of the form "x, see y" and
194. "x, see also y". However, the DocBook DTD doesn't allow <indexterm> entries
195. at the top level, so we have to put the .chapter directive first.
196. /////////////////////////////////////////////////////////////////////////////
197
f89d2485 198.chapter "Introduction" "CHID1"
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199.literal xml
200
f89d2485 201<indexterm role="variable">
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202 <primary>$1, $2, etc.</primary>
203 <see><emphasis>numerical variables</emphasis></see>
204</indexterm>
205<indexterm role="concept">
206 <primary>address</primary>
207 <secondary>rewriting</secondary>
208 <see><emphasis>rewriting</emphasis></see>
209</indexterm>
210<indexterm role="concept">
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211 <primary>Bounce Address Tag Validation</primary>
212 <see><emphasis>BATV</emphasis></see>
213</indexterm>
214<indexterm role="concept">
215 <primary>Client SMTP Authorization</primary>
216 <see><emphasis>CSA</emphasis></see>
217</indexterm>
218<indexterm role="concept">
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219 <primary>CR character</primary>
220 <see><emphasis>carriage return</emphasis></see>
221</indexterm>
222<indexterm role="concept">
223 <primary>CRL</primary>
224 <see><emphasis>certificate revocation list</emphasis></see>
225</indexterm>
226<indexterm role="concept">
227 <primary>delivery</primary>
228 <secondary>failure report</secondary>
229 <see><emphasis>bounce message</emphasis></see>
230</indexterm>
231<indexterm role="concept">
232 <primary>dialup</primary>
233 <see><emphasis>intermittently connected hosts</emphasis></see>
234</indexterm>
235<indexterm role="concept">
236 <primary>exiscan</primary>
237 <see><emphasis>content scanning</emphasis></see>
238</indexterm>
239<indexterm role="concept">
240 <primary>failover</primary>
241 <see><emphasis>fallback</emphasis></see>
242</indexterm>
243<indexterm role="concept">
244 <primary>fallover</primary>
245 <see><emphasis>fallback</emphasis></see>
246</indexterm>
247<indexterm role="concept">
248 <primary>filter</primary>
249 <secondary>Sieve</secondary>
250 <see><emphasis>Sieve filter</emphasis></see>
251</indexterm>
252<indexterm role="concept">
253 <primary>ident</primary>
254 <see><emphasis>RFC 1413</emphasis></see>
255</indexterm>
256<indexterm role="concept">
257 <primary>LF character</primary>
258 <see><emphasis>linefeed</emphasis></see>
259</indexterm>
260<indexterm role="concept">
261 <primary>maximum</primary>
595028e4 262 <seealso><emphasis>limit</emphasis></seealso>
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263</indexterm>
264<indexterm role="concept">
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265 <primary>monitor</primary>
266 <see><emphasis>Exim monitor</emphasis></see>
267</indexterm>
268<indexterm role="concept">
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269 <primary>no_<emphasis>xxx</emphasis></primary>
270 <see>entry for xxx</see>
271</indexterm>
272<indexterm role="concept">
273 <primary>NUL</primary>
274 <see><emphasis>binary zero</emphasis></see>
275</indexterm>
276<indexterm role="concept">
277 <primary>passwd file</primary>
278 <see><emphasis>/etc/passwd</emphasis></see>
279</indexterm>
280<indexterm role="concept">
281 <primary>process id</primary>
282 <see><emphasis>pid</emphasis></see>
283</indexterm>
284<indexterm role="concept">
285 <primary>RBL</primary>
286 <see><emphasis>DNS list</emphasis></see>
287</indexterm>
288<indexterm role="concept">
289 <primary>redirection</primary>
290 <see><emphasis>address redirection</emphasis></see>
291</indexterm>
292<indexterm role="concept">
293 <primary>return path</primary>
294 <seealso><emphasis>envelope sender</emphasis></seealso>
295</indexterm>
296<indexterm role="concept">
297 <primary>scanning</primary>
298 <see><emphasis>content scanning</emphasis></see>
299</indexterm>
300<indexterm role="concept">
301 <primary>SSL</primary>
302 <see><emphasis>TLS</emphasis></see>
303</indexterm>
304<indexterm role="concept">
305 <primary>string</primary>
306 <secondary>expansion</secondary>
307 <see><emphasis>expansion</emphasis></see>
308</indexterm>
309<indexterm role="concept">
310 <primary>top bit</primary>
311 <see><emphasis>8-bit characters</emphasis></see>
312</indexterm>
313<indexterm role="concept">
314 <primary>variables</primary>
315 <see><emphasis>expansion, variables</emphasis></see>
316</indexterm>
317<indexterm role="concept">
318 <primary>zero, binary</primary>
319 <see><emphasis>binary zero</emphasis></see>
320</indexterm>
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321
322.literal off
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323
324
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325. /////////////////////////////////////////////////////////////////////////////
326. This is the real start of the first chapter. See the comment above as to why
327. we can't have the .chapter line here.
328. chapter "Introduction"
329. /////////////////////////////////////////////////////////////////////////////
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330
331Exim is a mail transfer agent (MTA) for hosts that are running Unix or
332Unix-like operating systems. It was designed on the assumption that it would be
333run on hosts that are permanently connected to the Internet. However, it can be
334used on intermittently connected hosts with suitable configuration adjustments.
335
336Configuration files currently exist for the following operating systems: AIX,
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337BSD/OS (aka BSDI), Darwin (Mac OS X), DGUX, Dragonfly, FreeBSD, GNU/Hurd,
338GNU/Linux, HI-OSF (Hitachi), HI-UX, HP-UX, IRIX, MIPS RISCOS, NetBSD, OpenBSD,
339OpenUNIX, QNX, SCO, SCO SVR4.2 (aka UNIX-SV), Solaris (aka SunOS5), SunOS4,
340Tru64-Unix (formerly Digital UNIX, formerly DEC-OSF1), Ultrix, and Unixware.
341Some of these operating systems are no longer current and cannot easily be
342tested, so the configuration files may no longer work in practice.
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343
344There are also configuration files for compiling Exim in the Cygwin environment
345that can be installed on systems running Windows. However, this document does
346not contain any information about running Exim in the Cygwin environment.
347
348The terms and conditions for the use and distribution of Exim are contained in
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349the file &_NOTICE_&. Exim is distributed under the terms of the GNU General
350Public Licence, a copy of which may be found in the file &_LICENCE_&.
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351
352The use, supply or promotion of Exim for the purpose of sending bulk,
353unsolicited electronic mail is incompatible with the basic aims of the program,
354which revolve around the free provision of a service that enhances the quality
355of personal communications. The author of Exim regards indiscriminate
356mass-mailing as an antisocial, irresponsible abuse of the Internet.
357
358Exim owes a great deal to Smail 3 and its author, Ron Karr. Without the
359experience of running and working on the Smail 3 code, I could never have
360contemplated starting to write a new MTA. Many of the ideas and user interfaces
361were originally taken from Smail 3, though the actual code of Exim is entirely
362new, and has developed far beyond the initial concept.
363
364Many people, both in Cambridge and around the world, have contributed to the
365development and the testing of Exim, and to porting it to various operating
366systems. I am grateful to them all. The distribution now contains a file called
9b371988 367&_ACKNOWLEDGMENTS_&, in which I have started recording the names of
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368contributors.
369
370
f89d2485 371.section "Exim documentation" "SECID1"
800d5176 372. Keep this example change bar when updating the documentation!
b52ed2b3 373
9b371988 374.cindex "documentation"
2aee48d6 375This edition of the Exim specification applies to version &version() of Exim.
9b371988 376Substantive changes from the &previousversion; edition are marked in some
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377renditions of the document; this paragraph is so marked if the rendition is
378capable of showing a change indicator.
379
380This document is very much a reference manual; it is not a tutorial. The reader
381is expected to have some familiarity with the SMTP mail transfer protocol and
382with general Unix system administration. Although there are some discussions
383and examples in places, the information is mostly organized in a way that makes
384it easy to look up, rather than in a natural order for sequential reading.
385Furthermore, the manual aims to cover every aspect of Exim in detail, including
386a number of rarely-used, special-purpose features that are unlikely to be of
387very wide interest.
388
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389.cindex "books about Exim"
390An &"easier"& discussion of Exim which provides more in-depth explanatory,
391introductory, and tutorial material can be found in a book entitled &'The Exim
595028e4 392SMTP Mail Server'& (second edition, 2007), published by UIT Cambridge
9b371988 393(&url(http://www.uit.co.uk/exim-book/)).
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394
395This book also contains a chapter that gives a general introduction to SMTP and
396Internet mail. Inevitably, however, the book is unlikely to be fully up-to-date
397with the latest release of Exim. (Note that the earlier book about Exim,
398published by O'Reilly, covers Exim 3, and many things have changed in Exim 4.)
399
9b371988 400.cindex "Debian" "information sources"
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401If you are using a Debian distribution of Exim, you will find information about
402Debian-specific features in the file
f89d2485 403&_/usr/share/doc/exim4-base/README.Debian_&.
9b371988 404The command &(man update-exim.conf)& is another source of Debian-specific
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405information.
406
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407.cindex "&_doc/NewStuff_&"
408.cindex "&_doc/ChangeLog_&"
409.cindex "change log"
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410As the program develops, there may be features in newer versions that have not
411yet made it into this document, which is updated only when the most significant
412digit of the fractional part of the version number changes. Specifications of
413new features that are not yet in this manual are placed in the file
9b371988 414&_doc/NewStuff_& in the Exim distribution.
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9b371988 416Some features may be classified as &"experimental"&. These may change
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417incompatibly while they are developing, or even be withdrawn. For this reason,
418they are not documented in this manual. Information about experimental features
9b371988 419can be found in the file &_doc/experimental.txt_&.
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420
421All changes to the program (whether new features, bug fixes, or other kinds of
9b371988 422change) are noted briefly in the file called &_doc/ChangeLog_&.
168e428f 423
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424.cindex "&_doc/spec.txt_&"
425This specification itself is available as an ASCII file in &_doc/spec.txt_& so
426that it can easily be searched with a text editor. Other files in the &_doc_&
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427directory are:
428
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429.table2 100pt
430.row &_OptionLists.txt_& "list of all options in alphabetical order"
431.row &_dbm.discuss.txt_& "discussion about DBM libraries"
432.row &_exim.8_& "a man page of Exim's command line options"
433.row &_experimental.txt_& "documentation of experimental features"
434.row &_filter.txt_& "specification of the filter language"
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435.row &_Exim3.upgrade_& "upgrade notes from release 2 to release 3"
436.row &_Exim4.upgrade_& "upgrade notes from release 3 to release 4"
2eec84ca 437.row &_openssl.txt_& "installing a current OpenSSL release"
9b371988 438.endtable
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439
440The main specification and the specification of the filtering language are also
441available in other formats (HTML, PostScript, PDF, and Texinfo). Section
9b371988 442&<<SECTavail>>& below tells you how to get hold of these.
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443
444
445
f89d2485 446.section "FTP and web sites" "SECID2"
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447.cindex "web site"
448.cindex "FTP site"
068aaea8 449The primary site for Exim source distributions is currently the University of
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450Cambridge's FTP site, whose contents are described in &'Where to find the Exim
451distribution'& below. In addition, there is a web site and an FTP site at
452&%exim.org%&. These are now also hosted at the University of Cambridge. The
453&%exim.org%& site was previously hosted for a number of years by Energis
454Squared, formerly Planet Online Ltd, whose support I gratefully acknowledge.
455
456.cindex "wiki"
457.cindex "FAQ"
168e428f 458As well as Exim distribution tar files, the Exim web site contains a number of
f89d2485 459differently formatted versions of the documentation. A recent addition to the
7d0ab55c 460online information is the Exim wiki (&url(http://wiki.exim.org)),
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461which contains what used to be a separate FAQ, as well as various other
462examples, tips, and know-how that have been contributed by Exim users.
463
464.cindex Bugzilla
7d0ab55c 465An Exim Bugzilla exists at &url(http://bugs.exim.org). You can use
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466this to report bugs, and also to add items to the wish list. Please search
467first to check that you are not duplicating a previous entry.
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468
469
470
f89d2485 471.section "Mailing lists" "SECID3"
9b371988 472.cindex "mailing lists" "for Exim users"
f89d2485 473The following Exim mailing lists exist:
168e428f 474
9b371988 475.table2 140pt
d854d3a9 476.row &'exim-announce@exim.org'& "Moderated, low volume announcements list"
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477.row &'exim-users@exim.org'& "General discussion list"
478.row &'exim-dev@exim.org'& "Discussion of bugs, enhancements, etc."
d854d3a9 479.row &'exim-cvs@exim.org'& "Automated commit messages from the VCS"
9b371988 480.endtable
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481
482You can subscribe to these lists, change your existing subscriptions, and view
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483or search the archives via the mailing lists link on the Exim home page.
484.cindex "Debian" "mailing list for"
4f578862 485If you are using a Debian distribution of Exim, you may wish to subscribe to
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486the Debian-specific mailing list &'pkg-exim4-users@lists.alioth.debian.org'&
487via this web page:
488.display
489&url(http://lists.alioth.debian.org/mailman/listinfo/pkg-exim4-users)
490.endd
491Please ask Debian-specific questions on this list and not on the general Exim
492lists.
9b371988 493
f89d2485 494.section "Exim training" "SECID4"
9b371988 495.cindex "training courses"
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496Training courses in Cambridge (UK) used to be run annually by the author of
497Exim, before he retired. At the time of writing, there are no plans to run
498further Exim courses in Cambridge. However, if that changes, relevant
499information will be posted at &url(http://www-tus.csx.cam.ac.uk/courses/exim/).
168e428f 500
f89d2485 501.section "Bug reports" "SECID5"
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502.cindex "bug reports"
503.cindex "reporting bugs"
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504Reports of obvious bugs can be emailed to &'bugs@exim.org'& or reported
505via the Bugzilla (&url(http://bugs.exim.org)). However, if you are unsure
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506whether some behaviour is a bug or not, the best thing to do is to post a
507message to the &'exim-dev'& mailing list and have it discussed.
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508
509
510
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511.section "Where to find the Exim distribution" "SECTavail"
512.cindex "FTP site"
513.cindex "distribution" "ftp site"
168e428f 514The master ftp site for the Exim distribution is
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515.display
516&*ftp://ftp.csx.cam.ac.uk/pub/software/email/exim*&
517.endd
168e428f 518This is mirrored by
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519.display
520&*ftp://ftp.exim.org/pub/exim*&
521.endd
522The file references that follow are relative to the &_exim_& directories at
523these sites. There are now quite a number of independent mirror sites around
524the world. Those that I know about are listed in the file called &_Mirrors_&.
525
526Within the &_exim_& directory there are subdirectories called &_exim3_& (for
527previous Exim 3 distributions), &_exim4_& (for the latest Exim 4
528distributions), and &_Testing_& for testing versions. In the &_exim4_&
168e428f 529subdirectory, the current release can always be found in files called
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530.display
531&_exim-n.nn.tar.gz_&
532&_exim-n.nn.tar.bz2_&
533.endd
534where &'n.nn'& is the highest such version number in the directory. The two
168e428f 535files contain identical data; the only difference is the type of compression.
9b371988 536The &_.bz2_& file is usually a lot smaller than the &_.gz_& file.
168e428f 537
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538.cindex "distribution" "signing details"
539.cindex "distribution" "public key"
540.cindex "public key for signed distribution"
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541The distributions will be PGP signed by an individual key of the Release
542Coordinator. This key will have a uid containing an email address in the
543&'exim.org'& domain and will have signatures from other people, including
544other Exim maintainers. We expect that the key will be in the "strong set" of
545PGP keys. There should be a trust path to that key from Nigel Metheringham's
546PGP key, a version of which can be found in the release directory in the file
547&_nigel-pubkey.asc_&. All keys used will be available in public keyserver pools,
548such as &'pool.sks-keyservers.net'&.
549
550At time of last update, releases were being made by Phil Pennock and signed with
551key &'0x403043153903637F'&, although that key is expected to be replaced in 2013.
552A trust path from Nigel's key to Phil's can be observed at
553&url(https://www.security.spodhuis.org/exim-trustpath).
85b2d6f3 554
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555Releases have also been authorized to be performed by Todd Lyons who signs with
556key &'0xC4F4F94804D29EBA'&. A direct trust path exists between previous RE Phil
557Pennock and Todd Lyons through a common associate.
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558
559The signatures for the tar bundles are in:
9b371988 560.display
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561&_exim-n.nn.tar.gz.asc_&
562&_exim-n.nn.tar.bz2.asc_&
9b371988 563.endd
168e428f 564For each released version, the log of changes is made separately available in a
9b371988 565separate file in the directory &_ChangeLogs_& so that it is possible to
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566find out what has changed without having to download the entire distribution.
567
9b371988 568.cindex "documentation" "available formats"
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569The main distribution contains ASCII versions of this specification and other
570documentation; other formats of the documents are available in separate files
9b371988
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571inside the &_exim4_& directory of the FTP site:
572.display
573&_exim-html-n.nn.tar.gz_&
574&_exim-pdf-n.nn.tar.gz_&
575&_exim-postscript-n.nn.tar.gz_&
576&_exim-texinfo-n.nn.tar.gz_&
577.endd
578These tar files contain only the &_doc_& directory, not the complete
579distribution, and are also available in &_.bz2_& as well as &_.gz_& forms.
168e428f 580
168e428f 581
f89d2485 582.section "Limitations" "SECID6"
9b371988
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583.ilist
584.cindex "limitations of Exim"
585.cindex "bang paths" "not handled by Exim"
586Exim is designed for use as an Internet MTA, and therefore handles addresses in
587RFC 2822 domain format only. It cannot handle UUCP &"bang paths"&, though
588simple two-component bang paths can be converted by a straightforward rewriting
589configuration. This restriction does not prevent Exim from being interfaced to
590UUCP as a transport mechanism, provided that domain addresses are used.
591.next
592.cindex "domainless addresses"
593.cindex "address" "without domain"
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594Exim insists that every address it handles has a domain attached. For incoming
595local messages, domainless addresses are automatically qualified with a
596configured domain value. Configuration options specify from which remote
597systems unqualified addresses are acceptable. These are then qualified on
598arrival.
9b371988
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599.next
600.cindex "transport" "external"
601.cindex "external transports"
602The only external transport mechanisms that are currently implemented are SMTP
603and LMTP over a TCP/IP network (including support for IPv6). However, a pipe
168e428f 604transport is available, and there are facilities for writing messages to files
9b371988
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605and pipes, optionally in &'batched SMTP'& format; these facilities can be used
606to send messages to other transport mechanisms such as UUCP, provided they can
607handle domain-style addresses. Batched SMTP input is also catered for.
608.next
609Exim is not designed for storing mail for dial-in hosts. When the volumes of
610such mail are large, it is better to get the messages &"delivered"& into files
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611(that is, off Exim's queue) and subsequently passed on to the dial-in hosts by
612other means.
9b371988
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613.next
614Although Exim does have basic facilities for scanning incoming messages, these
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615are not comprehensive enough to do full virus or spam scanning. Such operations
616are best carried out using additional specialized software packages. If you
617compile Exim with the content-scanning extension, straightforward interfaces to
618a number of common scanners are provided.
9b371988 619.endlist
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620
621
f89d2485 622.section "Run time configuration" "SECID7"
168e428f
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623Exim's run time configuration is held in a single text file that is divided
624into a number of sections. The entries in this file consist of keywords and
625values, in the style of Smail 3 configuration files. A default configuration
626file which is suitable for simple online installations is provided in the
9b371988 627distribution, and is described in chapter &<<CHAPdefconfil>>& below.
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628
629
f89d2485 630.section "Calling interface" "SECID8"
9b371988 631.cindex "Sendmail compatibility" "command line interface"
168e428f 632Like many MTAs, Exim has adopted the Sendmail command line interface so that it
9b371988
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633can be a straight replacement for &_/usr/lib/sendmail_& or
634&_/usr/sbin/sendmail_& when sending mail, but you do not need to know anything
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635about Sendmail in order to run Exim. For actions other than sending messages,
636Sendmail-compatible options also exist, but those that produce output (for
9b371988 637example, &%-bp%&, which lists the messages on the queue) do so in Exim's own
168e428f 638format. There are also some additional options that are compatible with Smail
9b371988 6393, and some further options that are new to Exim. Chapter &<<CHAPcommandline>>&
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640documents all Exim's command line options. This information is automatically
641made into the man page that forms part of the Exim distribution.
642
643Control of messages on the queue can be done via certain privileged command
9b371988
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644line options. There is also an optional monitor program called &'eximon'&,
645which displays current information in an X window, and which contains a menu
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646interface to Exim's command line administration options.
647
648
649
f89d2485 650.section "Terminology" "SECID9"
9b371988
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651.cindex "terminology definitions"
652.cindex "body of message" "definition of"
653The &'body'& of a message is the actual data that the sender wants to transmit.
654It is the last part of a message, and is separated from the &'header'& (see
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655below) by a blank line.
656
9b371988 657.cindex "bounce message" "definition of"
168e428f 658When a message cannot be delivered, it is normally returned to the sender in a
9b371988
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659delivery failure message or a &"non-delivery report"& (NDR). The term
660&'bounce'& is commonly used for this action, and the error reports are often
661called &'bounce messages'&. This is a convenient shorthand for &"delivery
662failure error report"&. Such messages have an empty sender address in the
663message's &'envelope'& (see below) to ensure that they cannot themselves give
664rise to further bounce messages.
665
666The term &'default'& appears frequently in this manual. It is used to qualify a
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667value which is used in the absence of any setting in the configuration. It may
668also qualify an action which is taken unless a configuration setting specifies
669otherwise.
670
9b371988 671The term &'defer'& is used when the delivery of a message to a specific
168e428f 672destination cannot immediately take place for some reason (a remote host may be
9b371988 673down, or a user's local mailbox may be full). Such deliveries are &'deferred'&
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674until a later time.
675
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676The word &'domain'& is sometimes used to mean all but the first component of a
677host's name. It is &'not'& used in that sense here, where it normally refers to
678the part of an email address following the @ sign.
168e428f 679
f89d2485 680.cindex "envelope, definition of"
9b371988
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681.cindex "sender" "definition of"
682A message in transit has an associated &'envelope'&, as well as a header and a
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683body. The envelope contains a sender address (to which bounce messages should
684be delivered), and any number of recipient addresses. References to the
685sender or the recipients of a message usually mean the addresses in the
686envelope. An MTA uses these addresses for delivery, and for returning bounce
687messages, not the addresses that appear in the header lines.
688
f89d2485 689.cindex "message" "header, definition of"
9b371988
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690.cindex "header section" "definition of"
691The &'header'& of a message is the first part of a message's text, consisting
692of a number of lines, each of which has a name such as &'From:'&, &'To:'&,
693&'Subject:'&, etc. Long header lines can be split over several text lines by
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694indenting the continuations. The header is separated from the body by a blank
695line.
696
9b371988
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697.cindex "local part" "definition of"
698.cindex "domain" "definition of"
699The term &'local part'&, which is taken from RFC 2822, is used to refer to that
168e428f 700part of an email address that precedes the @ sign. The part that follows the
9b371988 701@ sign is called the &'domain'& or &'mail domain'&.
168e428f 702
9b371988 703.cindex "local delivery" "definition of"
f89d2485 704.cindex "remote delivery, definition of"
9b371988 705The terms &'local delivery'& and &'remote delivery'& are used to distinguish
168e428f 706delivery to a file or a pipe on the local host from delivery by SMTP over
068aaea8 707TCP/IP to another host. As far as Exim is concerned, all hosts other than the
9b371988 708host it is running on are &'remote'&.
168e428f 709
9b371988
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710.cindex "return path" "definition of"
711&'Return path'& is another name that is used for the sender address in a
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712message's envelope.
713
9b371988
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714.cindex "queue" "definition of"
715The term &'queue'& is used to refer to the set of messages awaiting delivery,
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716because this term is in widespread use in the context of MTAs. However, in
717Exim's case the reality is more like a pool than a queue, because there is
718normally no ordering of waiting messages.
719
9b371988
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720.cindex "queue runner" "definition of"
721The term &'queue runner'& is used to describe a process that scans the queue
168e428f 722and attempts to deliver those messages whose retry times have come. This term
9b371988 723is used by other MTAs, and also relates to the command &%runq%&, but in Exim
168e428f
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724the waiting messages are normally processed in an unpredictable order.
725
9b371988
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726.cindex "spool directory" "definition of"
727The term &'spool directory'& is used for a directory in which Exim keeps the
728messages on its queue &-- that is, those that it is in the process of
168e428f 729delivering. This should not be confused with the directory in which local
9b371988
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730mailboxes are stored, which is called a &"spool directory"& by some people. In
731the Exim documentation, &"spool"& is always used in the first sense.
168e428f
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732
733
734
735
736
737
9b371988
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738. ////////////////////////////////////////////////////////////////////////////
739. ////////////////////////////////////////////////////////////////////////////
168e428f 740
f89d2485 741.chapter "Incorporated code" "CHID2"
9b371988
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742.cindex "incorporated code"
743.cindex "regular expressions" "library"
744.cindex "PCRE"
1899bab2 745.cindex "OpenDMARC"
168e428f
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746A number of pieces of external code are included in the Exim distribution.
747
9b371988 748.ilist
210f147e
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749Regular expressions are supported in the main Exim program and in the
750Exim monitor using the freely-distributable PCRE library, copyright
40df1be3
TF
751&copy; University of Cambridge. The source to PCRE is no longer shipped with
752Exim, so you will need to use the version of PCRE shipped with your system,
753or obtain and install the full version of the library from
f89d2485 754&url(ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre).
9b371988 755.next
f89d2485 756.cindex "cdb" "acknowledgment"
168e428f
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757Support for the cdb (Constant DataBase) lookup method is provided by code
758contributed by Nigel Metheringham of (at the time he contributed it) Planet
9b371988
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759Online Ltd. The implementation is completely contained within the code of Exim.
760It does not link against an external cdb library. The code contains the
761following statements:
762
763.blockquote
764Copyright &copy; 1998 Nigel Metheringham, Planet Online Ltd
765
168e428f
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766This program is free software; you can redistribute it and/or modify it under
767the terms of the GNU General Public License as published by the Free Software
768Foundation; either version 2 of the License, or (at your option) any later
769version.
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770This code implements Dan Bernstein's Constant DataBase (cdb) spec. Information,
771the spec and sample code for cdb can be obtained from
f89d2485
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772&url(http://www.pobox.com/~djb/cdb.html). This implementation borrows
773some code from Dan Bernstein's implementation (which has no license
774restrictions applied to it).
9b371988
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775.endblockquote
776.next
777.cindex "SPA authentication"
778.cindex "Samba project"
779.cindex "Microsoft Secure Password Authentication"
780Client support for Microsoft's &'Secure Password Authentication'& is provided
168e428f
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781by code contributed by Marc Prud'hommeaux. Server support was contributed by
782Tom Kistner. This includes code taken from the Samba project, which is released
783under the Gnu GPL.
9b371988
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784.next
785.cindex "Cyrus"
786.cindex "&'pwcheck'& daemon"
787.cindex "&'pwauthd'& daemon"
788Support for calling the Cyrus &'pwcheck'& and &'saslauthd'& daemons is provided
168e428f
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789by code taken from the Cyrus-SASL library and adapted by Alexander S.
790Sabourenkov. The permission notice appears below, in accordance with the
791conditions expressed therein.
9b371988
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792
793.blockquote
794Copyright &copy; 2001 Carnegie Mellon University. All rights reserved.
795
168e428f
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796Redistribution and use in source and binary forms, with or without
797modification, are permitted provided that the following conditions
798are met:
168e428f 799
9b371988
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800.olist
801Redistributions of source code must retain the above copyright
802notice, this list of conditions and the following disclaimer.
803.next
804Redistributions in binary form must reproduce the above copyright
168e428f
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805notice, this list of conditions and the following disclaimer in
806the documentation and/or other materials provided with the
807distribution.
9b371988
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808.next
809The name &"Carnegie Mellon University"& must not be used to
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810endorse or promote products derived from this software without
811prior written permission. For permission or any other legal
812details, please contact
9b371988 813.display
068aaea8
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814 Office of Technology Transfer
815 Carnegie Mellon University
816 5000 Forbes Avenue
817 Pittsburgh, PA 15213-3890
818 (412) 268-4387, fax: (412) 268-7395
819 tech-transfer@andrew.cmu.edu
9b371988
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820.endd
821.next
822Redistributions of any form whatsoever must retain the following
168e428f 823acknowledgment:
9b371988
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824
825&"This product includes software developed by Computing Services
826at Carnegie Mellon University (&url(http://www.cmu.edu/computing/)."&
827
168e428f
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828CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO
829THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
830AND FITNESS, IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE
831FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
832WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
833AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
834OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
9b371988
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835.endlist
836.endblockquote
168e428f 837
9b371988 838.next
f89d2485 839.cindex "Exim monitor" "acknowledgment"
9b371988
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840.cindex "X-windows"
841.cindex "Athena"
168e428f
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842The Exim Monitor program, which is an X-Window application, includes
843modified versions of the Athena StripChart and TextPop widgets.
844This code is copyright by DEC and MIT, and their permission notice appears
845below, in accordance with the conditions expressed therein.
9b371988
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846
847.blockquote
168e428f
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848Copyright 1987, 1988 by Digital Equipment Corporation, Maynard, Massachusetts,
849and the Massachusetts Institute of Technology, Cambridge, Massachusetts.
9b371988 850
168e428f 851All Rights Reserved
9b371988 852
168e428f
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853Permission to use, copy, modify, and distribute this software and its
854documentation for any purpose and without fee is hereby granted,
855provided that the above copyright notice appear in all copies and that
856both that copyright notice and this permission notice appear in
857supporting documentation, and that the names of Digital or MIT not be
858used in advertising or publicity pertaining to distribution of the
859software without specific, written prior permission.
9b371988 860
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861DIGITAL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
862ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
863DIGITAL BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
864ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
865WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
866ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
867SOFTWARE.
9b371988 868.endblockquote
168e428f 869
9b371988 870.next
1899bab2
TL
871.cindex "opendmarc" "acknowledgment"
872The DMARC implementation uses the OpenDMARC library which is Copyrighted by
873The Trusted Domain Project. Portions of Exim source which use OpenDMARC
874derived code are indicated in the respective source files. The full OpenDMARC
875license is provided in the LICENSE.opendmarc file contained in the distributed
876source code.
877
878.next
9b371988 879Many people have contributed code fragments, some large, some small, that were
168e428f 880not covered by any specific licence requirements. It is assumed that the
f89d2485 881contributors are happy to see their code incorporated into Exim under the GPL.
9b371988 882.endlist
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883
884
885
886
887
9b371988
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888. ////////////////////////////////////////////////////////////////////////////
889. ////////////////////////////////////////////////////////////////////////////
168e428f 890
f89d2485 891.chapter "How Exim receives and delivers mail" "CHID11" &&&
9b371988 892 "Receiving and delivering mail"
168e428f
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893
894
f89d2485 895.section "Overall philosophy" "SECID10"
9b371988 896.cindex "design philosophy"
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897Exim is designed to work efficiently on systems that are permanently connected
898to the Internet and are handling a general mix of mail. In such circumstances,
899most messages can be delivered immediately. Consequently, Exim does not
900maintain independent queues of messages for specific domains or hosts, though
901it does try to send several messages in a single SMTP connection after a host
902has been down, and it also maintains per-host retry information.
903
904
f89d2485 905.section "Policy control" "SECID11"
9b371988 906.cindex "policy control" "overview"
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907Policy controls are now an important feature of MTAs that are connected to the
908Internet. Perhaps their most important job is to stop MTAs being abused as
9b371988
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909&"open relays"& by misguided individuals who send out vast amounts of
910unsolicited junk, and want to disguise its source. Exim provides flexible
911facilities for specifying policy controls on incoming mail:
168e428f 912
9b371988
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913.ilist
914.cindex "&ACL;" "introduction"
168e428f 915Exim 4 (unlike previous versions of Exim) implements policy controls on
9b371988 916incoming mail by means of &'Access Control Lists'& (ACLs). Each list is a
168e428f
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917series of statements that may either grant or deny access. ACLs can be used at
918several places in the SMTP dialogue while receiving a message from a remote
9b371988
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919host. However, the most common places are after each RCPT command, and at the
920very end of the message. The sysadmin can specify conditions for accepting or
921rejecting individual recipients or the entire message, respectively, at these
922two points (see chapter &<<CHAPACL>>&). Denial of access results in an SMTP
168e428f 923error code.
9b371988
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924.next
925An ACL is also available for locally generated, non-SMTP messages. In this
168e428f 926case, the only available actions are to accept or deny the entire message.
9b371988
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927.next
928When Exim is compiled with the content-scanning extension, facilities are
168e428f
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929provided in the ACL mechanism for passing the message to external virus and/or
930spam scanning software. The result of such a scan is passed back to the ACL,
931which can then use it to decide what to do with the message.
9b371988
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932.next
933When a message has been received, either from a remote host or from the local
f89d2485 934host, but before the final acknowledgment has been sent, a locally supplied C
9b371988
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935function called &[local_scan()]& can be run to inspect the message and decide
936whether to accept it or not (see chapter &<<CHAPlocalscan>>&). If the message
937is accepted, the list of recipients can be modified by the function.
938.next
939Using the &[local_scan()]& mechanism is another way of calling external scanner
940software. The &%SA-Exim%& add-on package works this way. It does not require
941Exim to be compiled with the content-scanning extension.
942.next
943After a message has been accepted, a further checking mechanism is available in
944the form of the &'system filter'& (see chapter &<<CHAPsystemfilter>>&). This
945runs at the start of every delivery process.
946.endlist
947
948
949
f89d2485 950.section "User filters" "SECID12"
9b371988
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951.cindex "filter" "introduction"
952.cindex "Sieve filter"
168e428f 953In a conventional Exim configuration, users are able to run private filters by
9b371988
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954setting up appropriate &_.forward_& files in their home directories. See
955chapter &<<CHAPredirect>>& (about the &(redirect)& router) for the
956configuration needed to support this, and the separate document entitled
957&'Exim's interfaces to mail filtering'& for user details. Two different kinds
958of filtering are available:
959
960.ilist
961Sieve filters are written in the standard filtering language that is defined
168e428f 962by RFC 3028.
9b371988
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963.next
964Exim filters are written in a syntax that is unique to Exim, but which is more
168e428f 965powerful than Sieve, which it pre-dates.
9b371988 966.endlist
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967
968User filters are run as part of the routing process, described below.
969
970
971
9b371988
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972.section "Message identification" "SECTmessiden"
973.cindex "message ids" "details of format"
974.cindex "format" "of message id"
975.cindex "id of message"
976.cindex "base62"
977.cindex "base36"
978.cindex "Darwin"
979.cindex "Cygwin"
980Every message handled by Exim is given a &'message id'& which is sixteen
168e428f 981characters long. It is divided into three parts, separated by hyphens, for
9b371988 982example &`16VDhn-0001bo-D3`&. Each part is a sequence of letters and digits,
168e428f
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983normally encoding numbers in base 62. However, in the Darwin operating
984system (Mac OS X) and when Exim is compiled to run under Cygwin, base 36
985(avoiding the use of lower case letters) is used instead, because the message
986id is used to construct file names, and the names of files in those systems are
068aaea8 987not always case-sensitive.
168e428f 988
9b371988 989.cindex "pid (process id)" "re-use of"
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990The detail of the contents of the message id have changed as Exim has evolved.
991Earlier versions relied on the operating system not re-using a process id (pid)
992within one second. On modern operating systems, this assumption can no longer
993be made, so the algorithm had to be changed. To retain backward compatibility,
994the format of the message id was retained, which is why the following rules are
995somewhat eccentric:
996
9b371988
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997.ilist
998The first six characters of the message id are the time at which the message
168e428f
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999started to be received, to a granularity of one second. That is, this field
1000contains the number of seconds since the start of the epoch (the normal Unix
1001way of representing the date and time of day).
9b371988
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1002.next
1003After the first hyphen, the next six characters are the id of the process that
168e428f 1004received the message.
9b371988
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1005.next
1006There are two different possibilities for the final two characters:
1007.olist
0a4e3112 1008.oindex "&%localhost_number%&"
9b371988 1009If &%localhost_number%& is not set, this value is the fractional part of the
168e428f
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1010time of reception, normally in units of 1/2000 of a second, but for systems
1011that must use base 36 instead of base 62 (because of case-insensitive file
1012systems), the units are 1/1000 of a second.
9b371988
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1013.next
1014If &%localhost_number%& is set, it is multiplied by 200 (100) and added to
168e428f
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1015the fractional part of the time, which in this case is in units of 1/200
1016(1/100) of a second.
9b371988
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1017.endlist
1018.endlist
168e428f
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1019
1020After a message has been received, Exim waits for the clock to tick at the
1021appropriate resolution before proceeding, so that if another message is
1022received by the same process, or by another process with the same (re-used)
1023pid, it is guaranteed that the time will be different. In most cases, the clock
1024will already have ticked while the message was being received.
1025
1026
f89d2485 1027.section "Receiving mail" "SECID13"
9b371988
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1028.cindex "receiving mail"
1029.cindex "message" "reception"
068aaea8
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1030The only way Exim can receive mail from another host is using SMTP over
1031TCP/IP, in which case the sender and recipient addresses are transferred using
168e428f
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1032SMTP commands. However, from a locally running process (such as a user's MUA),
1033there are several possibilities:
1034
9b371988
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1035.ilist
1036If the process runs Exim with the &%-bm%& option, the message is read
168e428f 1037non-interactively (usually via a pipe), with the recipients taken from the
9b371988
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1038command line, or from the body of the message if &%-t%& is also used.
1039.next
1040If the process runs Exim with the &%-bS%& option, the message is also read
168e428f
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1041non-interactively, but in this case the recipients are listed at the start of
1042the message in a series of SMTP RCPT commands, terminated by a DATA
9b371988 1043command. This is so-called &"batch SMTP"& format,
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1044but it isn't really SMTP. The SMTP commands are just another way of passing
1045envelope addresses in a non-interactive submission.
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1046.next
1047If the process runs Exim with the &%-bs%& option, the message is read
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1048interactively, using the SMTP protocol. A two-way pipe is normally used for
1049passing data between the local process and the Exim process.
9b371988 1050This is &"real"& SMTP and is handled in the same way as SMTP over TCP/IP. For
168e428f 1051example, the ACLs for SMTP commands are used for this form of submission.
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1052.next
1053A local process may also make a TCP/IP call to the host's loopback address
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1054(127.0.0.1) or any other of its IP addresses. When receiving messages, Exim
1055does not treat the loopback address specially. It treats all such connections
1056in the same way as connections from other hosts.
9b371988 1057.endlist
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1058
1059
f89d2485 1060.cindex "message sender, constructed by Exim"
9b371988 1061.cindex "sender" "constructed by Exim"
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1062In the three cases that do not involve TCP/IP, the sender address is
1063constructed from the login name of the user that called Exim and a default
9b371988 1064qualification domain (which can be set by the &%qualify_domain%& configuration
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1065option). For local or batch SMTP, a sender address that is passed using the
1066SMTP MAIL command is ignored. However, the system administrator may allow
9b371988 1067certain users (&"trusted users"&) to specify a different sender address
168e428f 1068unconditionally, or all users to specify certain forms of different sender
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1069address. The &%-f%& option or the SMTP MAIL command is used to specify these
1070different addresses. See section &<<SECTtrustedadmin>>& for details of trusted
1071users, and the &%untrusted_set_sender%& option for a way of allowing untrusted
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1072users to change sender addresses.
1073
1074Messages received by either of the non-interactive mechanisms are subject to
1075checking by the non-SMTP ACL, if one is defined. Messages received using SMTP
1076(either over TCP/IP, or interacting with a local process) can be checked by a
1077number of ACLs that operate at different times during the SMTP session. Either
1078individual recipients, or the entire message, can be rejected if local policy
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1079requirements are not met. The &[local_scan()]& function (see chapter
1080&<<CHAPlocalscan>>&) is run for all incoming messages.
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1081
1082Exim can be configured not to start a delivery process when a message is
1083received; this can be unconditional, or depend on the number of incoming SMTP
1084connections or the system load. In these situations, new messages wait on the
1085queue until a queue runner process picks them up. However, in standard
1086configurations under normal conditions, delivery is started as soon as a
1087message is received.
1088
1089
1090
1091
1092
f89d2485 1093.section "Handling an incoming message" "SECID14"
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1094.cindex "spool directory" "files that hold a message"
1095.cindex "file" "how a message is held"
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1096When Exim accepts a message, it writes two files in its spool directory. The
1097first contains the envelope information, the current status of the message, and
1098the header lines, and the second contains the body of the message. The names of
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1099the two spool files consist of the message id, followed by &`-H`& for the
1100file containing the envelope and header, and &`-D`& for the data file.
168e428f 1101
9b371988 1102.cindex "spool directory" "&_input_& sub-directory"
168e428f 1103By default all these message files are held in a single directory called
9b371988 1104&_input_& inside the general Exim spool directory. Some operating systems do
c0712871 1105not perform very well if the number of files in a directory gets large; to
9b371988 1106improve performance in such cases, the &%split_spool_directory%& option can be
168e428f 1107used. This causes Exim to split up the input files into 62 sub-directories
db9452a9 1108whose names are single letters or digits. When this is done, the queue is
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1109processed one sub-directory at a time instead of all at once, which can improve
1110overall performance even when there are not enough files in each directory to
db9452a9 1111affect file system performance.
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1112
1113The envelope information consists of the address of the message's sender and
1114the addresses of the recipients. This information is entirely separate from
1115any addresses contained in the header lines. The status of the message includes
1116a list of recipients who have already received the message. The format of the
9b371988 1117first spool file is described in chapter &<<CHAPspool>>&.
168e428f 1118
9b371988 1119.cindex "rewriting" "addresses"
168e428f 1120Address rewriting that is specified in the rewrite section of the configuration
9b371988 1121(see chapter &<<CHAPrewrite>>&) is done once and for all on incoming addresses,
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1122both in the header lines and the envelope, at the time the message is accepted.
1123If during the course of delivery additional addresses are generated (for
1124example, via aliasing), these new addresses are rewritten as soon as they are
1125generated. At the time a message is actually delivered (transported) further
1126rewriting can take place; because this is a transport option, it can be
1127different for different forms of delivery. It is also possible to specify the
1128addition or removal of certain header lines at the time the message is
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1129delivered (see chapters &<<CHAProutergeneric>>& and
1130&<<CHAPtransportgeneric>>&).
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1131
1132
1133
f89d2485 1134.section "Life of a message" "SECID15"
9b371988
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1135.cindex "message" "life of"
1136.cindex "message" "frozen"
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1137A message remains in the spool directory until it is completely delivered to
1138its recipients or to an error address, or until it is deleted by an
1139administrator or by the user who originally created it. In cases when delivery
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1140cannot proceed &-- for example, when a message can neither be delivered to its
1141recipients nor returned to its sender, the message is marked &"frozen"& on the
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1142spool, and no more deliveries are attempted.
1143
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1144.cindex "frozen messages" "thawing"
1145.cindex "message" "thawing frozen"
1146An administrator can &"thaw"& such messages when the problem has been
1147corrected, and can also freeze individual messages by hand if necessary. In
1148addition, an administrator can force a delivery error, causing a bounce message
1149to be sent.
1150
0a4e3112
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1151.oindex "&%timeout_frozen_after%&"
1152.oindex "&%ignore_bounce_errors_after%&"
9b371988
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1153There are options called &%ignore_bounce_errors_after%& and
1154&%timeout_frozen_after%&, which discard frozen messages after a certain time.
068aaea8 1155The first applies only to frozen bounces, the second to any frozen messages.
168e428f 1156
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1157.cindex "message" "log file for"
1158.cindex "log" "file for each message"
168e428f 1159While Exim is working on a message, it writes information about each delivery
068aaea8 1160attempt to its main log file. This includes successful, unsuccessful, and
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1161delayed deliveries for each recipient (see chapter &<<CHAPlog>>&). The log
1162lines are also written to a separate &'message log'& file for each message.
1163These logs are solely for the benefit of the administrator, and are normally
1164deleted along with the spool files when processing of a message is complete.
168e428f 1165The use of individual message logs can be disabled by setting
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1166&%no_message_logs%&; this might give an improvement in performance on very busy
1167systems.
168e428f 1168
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1169.cindex "journal file"
1170.cindex "file" "journal"
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1171All the information Exim itself needs to set up a delivery is kept in the first
1172spool file, along with the header lines. When a successful delivery occurs, the
1173address is immediately written at the end of a journal file, whose name is the
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1174message id followed by &`-J`&. At the end of a delivery run, if there are some
1175addresses left to be tried again later, the first spool file (the &`-H`& file)
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1176is updated to indicate which these are, and the journal file is then deleted.
1177Updating the spool file is done by writing a new file and renaming it, to
1178minimize the possibility of data loss.
1179
1180Should the system or the program crash after a successful delivery but before
1181the spool file has been updated, the journal is left lying around. The next
1182time Exim attempts to deliver the message, it reads the journal file and
1183updates the spool file before proceeding. This minimizes the chances of double
1184deliveries caused by crashes.
1185
1186
1187
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1188.section "Processing an address for delivery" "SECTprocaddress"
1189.cindex "drivers" "definition of"
1190.cindex "router" "definition of"
1191.cindex "transport" "definition of"
1192The main delivery processing elements of Exim are called &'routers'& and
1193&'transports'&, and collectively these are known as &'drivers'&. Code for a
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1194number of them is provided in the source distribution, and compile-time options
1195specify which ones are included in the binary. Run time options specify which
1196ones are actually used for delivering messages.
1197
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1198.cindex "drivers" "instance definition"
1199Each driver that is specified in the run time configuration is an &'instance'&
168e428f 1200of that particular driver type. Multiple instances are allowed; for example,
9b371988 1201you can set up several different &(smtp)& transports, each with different
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1202option values that might specify different ports or different timeouts. Each
1203instance has its own identifying name. In what follows we will normally use the
1204instance name when discussing one particular instance (that is, one specific
1205configuration of the driver), and the generic driver name when discussing
1206the driver's features in general.
1207
9b371988 1208A &'router'& is a driver that operates on an address, either determining how
068aaea8 1209its delivery should happen, by assigning it to a specific transport, or
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1210converting the address into one or more new addresses (for example, via an
1211alias file). A router may also explicitly choose to fail an address, causing it
1212to be bounced.
1213
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1214A &'transport'& is a driver that transmits a copy of the message from Exim's
1215spool to some destination. There are two kinds of transport: for a &'local'&
168e428f 1216transport, the destination is a file or a pipe on the local host, whereas for a
9b371988 1217&'remote'& transport the destination is some other host. A message is passed
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1218to a specific transport as a result of successful routing. If a message has
1219several recipients, it may be passed to a number of different transports.
1220
9b371988 1221.cindex "preconditions" "definition of"
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1222An address is processed by passing it to each configured router instance in
1223turn, subject to certain preconditions, until a router accepts the address or
1224specifies that it should be bounced. We will describe this process in more
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1225detail shortly. First, as a simple example, we consider how each recipient
1226address in a message is processed in a small configuration of three routers.
168e428f 1227
068aaea8 1228To make this a more concrete example, it is described in terms of some actual
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1229routers, but remember, this is only an example. You can configure Exim's
1230routers in many different ways, and there may be any number of routers in a
1231configuration.
1232
1233The first router that is specified in a configuration is often one that handles
1234addresses in domains that are not recognized specially by the local host. These
1235are typically addresses for arbitrary domains on the Internet. A precondition
1236is set up which looks for the special domains known to the host (for example,
9b371988 1237its own domain name), and the router is run for addresses that do &'not'&
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1238match. Typically, this is a router that looks up domains in the DNS in order to
1239find the hosts to which this address routes. If it succeeds, the address is
068aaea8 1240assigned to a suitable SMTP transport; if it does not succeed, the router is
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1241configured to fail the address.
1242
068aaea8 1243The second router is reached only when the domain is recognized as one that
9b371988 1244&"belongs"& to the local host. This router does redirection &-- also known as
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1245aliasing and forwarding. When it generates one or more new addresses from the
1246original, each of them is routed independently from the start. Otherwise, the
1247router may cause an address to fail, or it may simply decline to handle the
1248address, in which case the address is passed to the next router.
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1249
1250The final router in many configurations is one that checks to see if the
1251address belongs to a local mailbox. The precondition may involve a check to
1252see if the local part is the name of a login account, or it may look up the
1253local part in a file or a database. If its preconditions are not met, or if
1254the router declines, we have reached the end of the routers. When this happens,
1255the address is bounced.
1256
1257
1258
f89d2485 1259.section "Processing an address for verification" "SECID16"
9b371988
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1260.cindex "router" "for verification"
1261.cindex "verifying address" "overview"
168e428f 1262As well as being used to decide how to deliver to an address, Exim's routers
9b371988 1263are also used for &'address verification'&. Verification can be requested as
168e428f 1264one of the checks to be performed in an ACL for incoming messages, on both
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1265sender and recipient addresses, and it can be tested using the &%-bv%& and
1266&%-bvs%& command line options.
168e428f 1267
9b371988 1268When an address is being verified, the routers are run in &"verify mode"&. This
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1269does not affect the way the routers work, but it is a state that can be
1270detected. By this means, a router can be skipped or made to behave differently
1271when verifying. A common example is a configuration in which the first router
1272sends all messages to a message-scanning program, unless they have been
1273previously scanned. Thus, the first router accepts all addresses without any
9b371988 1274checking, making it useless for verifying. Normally, the &%no_verify%& option
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1275would be set for such a router, causing it to be skipped in verify mode.
1276
1277
1278
1279
9b371988
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1280.section "Running an individual router" "SECTrunindrou"
1281.cindex "router" "running details"
1282.cindex "preconditions" "checking"
1283.cindex "router" "result of running"
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1284As explained in the example above, a number of preconditions are checked before
1285running a router. If any are not met, the router is skipped, and the address is
9b371988 1286passed to the next router. When all the preconditions on a router &'are'& met,
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1287the router is run. What happens next depends on the outcome, which is one of
1288the following:
1289
9b371988
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1290.ilist
1291&'accept'&: The router accepts the address, and either assigns it to a
1292transport, or generates one or more &"child"& addresses. Processing the
1293original address ceases,
0a4e3112 1294.oindex "&%unseen%&"
9b371988 1295unless the &%unseen%& option is set on the router. This option
168e428f 1296can be used to set up multiple deliveries with different routing (for example,
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1297for keeping archive copies of messages). When &%unseen%& is set, the address is
1298passed to the next router. Normally, however, an &'accept'& return marks the
168e428f 1299end of routing.
9b371988 1300
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1301Any child addresses generated by the router are processed independently,
1302starting with the first router by default. It is possible to change this by
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1303setting the &%redirect_router%& option to specify which router to start at for
1304child addresses. Unlike &%pass_router%& (see below) the router specified by
1305&%redirect_router%& may be anywhere in the router configuration.
1306.next
1307&'pass'&: The router recognizes the address, but cannot handle it itself. It
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1308requests that the address be passed to another router. By default the address
1309is passed to the next router, but this can be changed by setting the
9b371988 1310&%pass_router%& option. However, (unlike &%redirect_router%&) the named router
168e428f 1311must be below the current router (to avoid loops).
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1312.next
1313&'decline'&: The router declines to accept the address because it does not
168e428f 1314recognize it at all. By default, the address is passed to the next router, but
9b371988
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1315this can be prevented by setting the &%no_more%& option. When &%no_more%& is
1316set, all the remaining routers are skipped. In effect, &%no_more%& converts
1317&'decline'& into &'fail'&.
1318.next
1319&'fail'&: The router determines that the address should fail, and queues it for
168e428f 1320the generation of a bounce message. There is no further processing of the
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1321original address unless &%unseen%& is set on the router.
1322.next
1323&'defer'&: The router cannot handle the address at the present time. (A
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1324database may be offline, or a DNS lookup may have timed out.) No further
1325processing of the address happens in this delivery attempt. It is tried again
1326next time the message is considered for delivery.
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1327.next
1328&'error'&: There is some error in the router (for example, a syntax error in
168e428f 1329its configuration). The action is as for defer.
9b371988 1330.endlist
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1331
1332If an address reaches the end of the routers without having been accepted by
068aaea8 1333any of them, it is bounced as unrouteable. The default error message in this
9b371988
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1334situation is &"unrouteable address"&, but you can set your own message by
1335making use of the &%cannot_route_message%& option. This can be set for any
1336router; the value from the last router that &"saw"& the address is used.
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1337
1338Sometimes while routing you want to fail a delivery when some conditions are
1339met but others are not, instead of passing the address on for further routing.
1340You can do this by having a second router that explicitly fails the delivery
9b371988 1341when the relevant conditions are met. The &(redirect)& router has a &"fail"&
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1342facility for this purpose.
1343
1344
f89d2485 1345.section "Duplicate addresses" "SECID17"
9b371988 1346.cindex "case of local parts"
f89d2485 1347.cindex "address duplicate, discarding"
db9452a9 1348.cindex "duplicate addresses"
068aaea8
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1349Once routing is complete, Exim scans the addresses that are assigned to local
1350and remote transports, and discards any duplicates that it finds. During this
3cb1b51e 1351check, local parts are treated as case-sensitive. This happens only when
db9452a9 1352actually delivering a message; when testing routers with &%-bt%&, all the
3cb1b51e 1353routed addresses are shown.
db9452a9 1354
068aaea8 1355
168e428f 1356
9b371988 1357.section "Router preconditions" "SECTrouprecon"
f89d2485 1358.cindex "router" "preconditions, order of processing"
9b371988 1359.cindex "preconditions" "order of processing"
168e428f
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1360The preconditions that are tested for each router are listed below, in the
1361order in which they are tested. The individual configuration options are
9b371988 1362described in more detail in chapter &<<CHAProutergeneric>>&.
168e428f 1363
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1364.ilist
1365The &%local_part_prefix%& and &%local_part_suffix%& options can specify that
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1366the local parts handled by the router may or must have certain prefixes and/or
1367suffixes. If a mandatory affix (prefix or suffix) is not present, the router is
1368skipped. These conditions are tested first. When an affix is present, it is
1369removed from the local part before further processing, including the evaluation
1370of any other conditions.
9b371988
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1371.next
1372Routers can be designated for use only when not verifying an address, that is,
168e428f 1373only when routing it for delivery (or testing its delivery routing). If the
9b371988 1374&%verify%& option is set false, the router is skipped when Exim is verifying an
168e428f 1375address.
9b371988
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1376Setting the &%verify%& option actually sets two options, &%verify_sender%& and
1377&%verify_recipient%&, which independently control the use of the router for
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1378sender and recipient verification. You can set these options directly if
1379you want a router to be used for only one type of verification.
6ece2e77 1380Note that cutthrough delivery is classed as a recipient verification for this purpose.
9b371988
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1381.next
1382If the &%address_test%& option is set false, the router is skipped when Exim is
1383run with the &%-bt%& option to test an address routing. This can be helpful
1384when the first router sends all new messages to a scanner of some sort; it
1385makes it possible to use &%-bt%& to test subsequent delivery routing without
1386having to simulate the effect of the scanner.
1387.next
1388Routers can be designated for use only when verifying an address, as
1389opposed to routing it for delivery. The &%verify_only%& option controls this.
6ece2e77 1390Again, cutthrough delivery counts as a verification.
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1391.next
1392Individual routers can be explicitly skipped when running the routers to
1393check an address given in the SMTP EXPN command (see the &%expn%& option).
1394.next
1395If the &%domains%& option is set, the domain of the address must be in the set
068aaea8 1396of domains that it defines.
9b371988 1397.next
f89d2485
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1398.vindex "&$local_part_prefix$&"
1399.vindex "&$local_part$&"
1400.vindex "&$local_part_suffix$&"
9b371988
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1401If the &%local_parts%& option is set, the local part of the address must be in
1402the set of local parts that it defines. If &%local_part_prefix%& or
1403&%local_part_suffix%& is in use, the prefix or suffix is removed from the local
168e428f 1404part before this check. If you want to do precondition tests on local parts
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1405that include affixes, you can do so by using a &%condition%& option (see below)
1406that uses the variables &$local_part$&, &$local_part_prefix$&, and
1407&$local_part_suffix$& as necessary.
1408.next
f89d2485
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1409.vindex "&$local_user_uid$&"
1410.vindex "&$local_user_gid$&"
1411.vindex "&$home$&"
9b371988 1412If the &%check_local_user%& option is set, the local part must be the name of
068aaea8 1413an account on the local host. If this check succeeds, the uid and gid of the
9b371988
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1414local user are placed in &$local_user_uid$& and &$local_user_gid$& and the
1415user's home directory is placed in &$home$&; these values can be used in the
1416remaining preconditions.
1417.next
1418If the &%router_home_directory%& option is set, it is expanded at this point,
1419because it overrides the value of &$home$&. If this expansion were left till
1420later, the value of &$home$& as set by &%check_local_user%& would be used in
1421subsequent tests. Having two different values of &$home$& in the same router
168e428f 1422could lead to confusion.
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1423.next
1424If the &%senders%& option is set, the envelope sender address must be in the
1425set of addresses that it defines.
1426.next
1427If the &%require_files%& option is set, the existence or non-existence of
168e428f 1428specified files is tested.
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1429.next
1430.cindex "customizing" "precondition"
1431If the &%condition%& option is set, it is evaluated and tested. This option
1432uses an expanded string to allow you to set up your own custom preconditions.
1433Expanded strings are described in chapter &<<CHAPexpand>>&.
1434.endlist
168e428f 1435
168e428f 1436
9b371988
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1437Note that &%require_files%& comes near the end of the list, so you cannot use
1438it to check for the existence of a file in which to lookup up a domain, local
168e428f 1439part, or sender. However, as these options are all expanded, you can use the
9b371988
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1440&%exists%& expansion condition to make such tests within each condition. The
1441&%require_files%& option is intended for checking files that the router may be
168e428f 1442going to use internally, or which are needed by a specific transport (for
9b371988 1443example, &_.procmailrc_&).
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1444
1445
1446
f89d2485 1447.section "Delivery in detail" "SECID18"
9b371988 1448.cindex "delivery" "in detail"
168e428f
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1449When a message is to be delivered, the sequence of events is as follows:
1450
9b371988
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1451.ilist
1452If a system-wide filter file is specified, the message is passed to it. The
168e428f
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1453filter may add recipients to the message, replace the recipients, discard the
1454message, cause a new message to be generated, or cause the message delivery to
1455fail. The format of the system filter file is the same as for Exim user filter
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1456files, described in the separate document entitled &'Exim's interfaces to mail
1457filtering'&.
1458.cindex "Sieve filter" "not available for system filter"
1459(&*Note*&: Sieve cannot be used for system filter files.)
1460
1461Some additional features are available in system filters &-- see chapter
1462&<<CHAPsystemfilter>>& for details. Note that a message is passed to the system
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1463filter only once per delivery attempt, however many recipients it has. However,
1464if there are several delivery attempts because one or more addresses could not
1465be immediately delivered, the system filter is run each time. The filter
9b371988 1466condition &%first_delivery%& can be used to detect the first run of the system
168e428f 1467filter.
9b371988
PH
1468.next
1469Each recipient address is offered to each configured router in turn, subject to
1470its preconditions, until one is able to handle it. If no router can handle the
1471address, that is, if they all decline, the address is failed. Because routers
1472can be targeted at particular domains, several locally handled domains can be
1473processed entirely independently of each other.
1474.next
1475.cindex "routing" "loops in"
1476.cindex "loop" "while routing"
1477A router that accepts an address may assign it to a local or a remote
1478transport. However, the transport is not run at this time. Instead, the address
1479is placed on a list for the particular transport, which will be run later.
068aaea8
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1480Alternatively, the router may generate one or more new addresses (typically
1481from alias, forward, or filter files). New addresses are fed back into this
1482process from the top, but in order to avoid loops, a router ignores any address
1483which has an identically-named ancestor that was processed by itself.
9b371988
PH
1484.next
1485When all the routing has been done, addresses that have been successfully
168e428f
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1486handled are passed to their assigned transports. When local transports are
1487doing real local deliveries, they handle only one address at a time, but if a
1488local transport is being used as a pseudo-remote transport (for example, to
1489collect batched SMTP messages for transmission by some other means) multiple
1490addresses can be handled. Remote transports can always handle more than one
1491address at a time, but can be configured not to do so, or to restrict multiple
1492addresses to the same domain.
9b371988
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1493.next
1494Each local delivery to a file or a pipe runs in a separate process under a
168e428f
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1495non-privileged uid, and these deliveries are run one at a time. Remote
1496deliveries also run in separate processes, normally under a uid that is private
9b371988 1497to Exim (&"the Exim user"&), but in this case, several remote deliveries can be
168e428f 1498run in parallel. The maximum number of simultaneous remote deliveries for any
9b371988 1499one message is set by the &%remote_max_parallel%& option.
168e428f
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1500The order in which deliveries are done is not defined, except that all local
1501deliveries happen before any remote deliveries.
9b371988
PH
1502.next
1503.cindex "queue runner"
168e428f
PH
1504When it encounters a local delivery during a queue run, Exim checks its retry
1505database to see if there has been a previous temporary delivery failure for the
1506address before running the local transport. If there was a previous failure,
1507Exim does not attempt a new delivery until the retry time for the address is
1508reached. However, this happens only for delivery attempts that are part of a
1509queue run. Local deliveries are always attempted when delivery immediately
1510follows message reception, even if retry times are set for them. This makes for
1511better behaviour if one particular message is causing problems (for example,
1512causing quota overflow, or provoking an error in a filter file).
9b371988
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1513.next
1514.cindex "delivery" "retry in remote transports"
168e428f
PH
1515Remote transports do their own retry handling, since an address may be
1516deliverable to one of a number of hosts, each of which may have a different
1517retry time. If there have been previous temporary failures and no host has
1518reached its retry time, no delivery is attempted, whether in a queue run or
9b371988
PH
1519not. See chapter &<<CHAPretry>>& for details of retry strategies.
1520.next
1521If there were any permanent errors, a bounce message is returned to an
168e428f
PH
1522appropriate address (the sender in the common case), with details of the error
1523for each failing address. Exim can be configured to send copies of bounce
1524messages to other addresses.
9b371988
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1525.next
1526.cindex "delivery" "deferral"
168e428f
PH
1527If one or more addresses suffered a temporary failure, the message is left on
1528the queue, to be tried again later. Delivery of these addresses is said to be
9b371988
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1529&'deferred'&.
1530.next
1531When all the recipient addresses have either been delivered or bounced,
168e428f
PH
1532handling of the message is complete. The spool files and message log are
1533deleted, though the message log can optionally be preserved if required.
9b371988 1534.endlist
168e428f
PH
1535
1536
1537
1538
f89d2485 1539.section "Retry mechanism" "SECID19"
9b371988
PH
1540.cindex "delivery" "retry mechanism"
1541.cindex "retry" "description of mechanism"
1542.cindex "queue runner"
168e428f
PH
1543Exim's mechanism for retrying messages that fail to get delivered at the first
1544attempt is the queue runner process. You must either run an Exim daemon that
9b371988
PH
1545uses the &%-q%& option with a time interval to start queue runners at regular
1546intervals, or use some other means (such as &'cron'&) to start them. If you do
168e428f
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1547not arrange for queue runners to be run, messages that fail temporarily at the
1548first attempt will remain on your queue for ever. A queue runner process works
068aaea8 1549its way through the queue, one message at a time, trying each delivery that has
168e428f
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1550passed its retry time.
1551You can run several queue runners at once.
1552
1553Exim uses a set of configured rules to determine when next to retry the failing
9b371988
PH
1554address (see chapter &<<CHAPretry>>&). These rules also specify when Exim
1555should give up trying to deliver to the address, at which point it generates a
1556bounce message. If no retry rules are set for a particular host, address, and
1557error combination, no retries are attempted, and temporary errors are treated
1558as permanent.
168e428f
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1559
1560
1561
f89d2485 1562.section "Temporary delivery failure" "SECID20"
9b371988 1563.cindex "delivery" "temporary failure"
168e428f
PH
1564There are many reasons why a message may not be immediately deliverable to a
1565particular address. Failure to connect to a remote machine (because it, or the
1566connection to it, is down) is one of the most common. Temporary failures may be
1567detected during routing as well as during the transport stage of delivery.
1568Local deliveries may be delayed if NFS files are unavailable, or if a mailbox
1569is on a file system where the user is over quota. Exim can be configured to
1570impose its own quotas on local mailboxes; where system quotas are set they will
1571also apply.
1572
1573If a host is unreachable for a period of time, a number of messages may be
1574waiting for it by the time it recovers, and sending them in a single SMTP
1575connection is clearly beneficial. Whenever a delivery to a remote host is
1576deferred,
fa41615d 1577.cindex "hints database" "deferred deliveries"
168e428f
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1578Exim makes a note in its hints database, and whenever a successful
1579SMTP delivery has happened, it looks to see if any other messages are waiting
1580for the same host. If any are found, they are sent over the same SMTP
1581connection, subject to a configuration limit as to the maximum number in any
1582one connection.
168e428f
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1583
1584
1585
f89d2485 1586.section "Permanent delivery failure" "SECID21"
9b371988
PH
1587.cindex "delivery" "permanent failure"
1588.cindex "bounce message" "when generated"
168e428f
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1589When a message cannot be delivered to some or all of its intended recipients, a
1590bounce message is generated. Temporary delivery failures turn into permanent
1591errors when their timeout expires. All the addresses that fail in a given
1592delivery attempt are listed in a single message. If the original message has
1593many recipients, it is possible for some addresses to fail in one delivery
1594attempt and others to fail subsequently, giving rise to more than one bounce
1595message. The wording of bounce messages can be customized by the administrator.
9b371988 1596See chapter &<<CHAPemsgcust>>& for details.
168e428f 1597
9b371988
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1598.cindex "&'X-Failed-Recipients:'& header line"
1599Bounce messages contain an &'X-Failed-Recipients:'& header line that lists the
168e428f
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1600failed addresses, for the benefit of programs that try to analyse such messages
1601automatically.
1602
9b371988 1603.cindex "bounce message" "recipient of"
168e428f
PH
1604A bounce message is normally sent to the sender of the original message, as
1605obtained from the message's envelope. For incoming SMTP messages, this is the
9b371988
PH
1606address given in the MAIL command. However, when an address is expanded via a
1607forward or alias file, an alternative address can be specified for delivery
1608failures of the generated addresses. For a mailing list expansion (see section
1609&<<SECTmailinglists>>&) it is common to direct bounce messages to the manager
1610of the list.
168e428f
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1611
1612
1613
f89d2485 1614.section "Failures to deliver bounce messages" "SECID22"
9b371988 1615.cindex "bounce message" "failure to deliver"
168e428f
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1616If a bounce message (either locally generated or received from a remote host)
1617itself suffers a permanent delivery failure, the message is left on the queue,
1618but it is frozen, awaiting the attention of an administrator. There are options
068aaea8 1619that can be used to make Exim discard such failed messages, or to keep them
9b371988
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1620for only a short time (see &%timeout_frozen_after%& and
1621&%ignore_bounce_errors_after%&).
168e428f
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1622
1623
1624
1625
1626
9b371988
PH
1627. ////////////////////////////////////////////////////////////////////////////
1628. ////////////////////////////////////////////////////////////////////////////
168e428f 1629
f89d2485 1630.chapter "Building and installing Exim" "CHID3"
4f578862 1631.scindex IIDbuex "building Exim"
168e428f 1632
f89d2485
PH
1633.section "Unpacking" "SECID23"
1634Exim is distributed as a gzipped or bzipped tar file which, when unpacked,
168e428f 1635creates a directory with the name of the current release (for example,
2aee48d6 1636&_exim-&version()_&) into which the following files are placed:
9b371988
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1637
1638.table2 140pt
f89d2485
PH
1639.irow &_ACKNOWLEDGMENTS_& "contains some acknowledgments"
1640.irow &_CHANGES_& "contains a reference to where changes are &&&
1641 documented"
1642.irow &_LICENCE_& "the GNU General Public Licence"
1643.irow &_Makefile_& "top-level make file"
1644.irow &_NOTICE_& "conditions for the use of Exim"
1645.irow &_README_& "list of files, directories and simple build &&&
1646 instructions"
9b371988
PH
1647.endtable
1648
1649Other files whose names begin with &_README_& may also be present. The
168e428f
PH
1650following subdirectories are created:
1651
9b371988 1652.table2 140pt
f89d2485
PH
1653.irow &_Local_& "an empty directory for local configuration files"
1654.irow &_OS_& "OS-specific files"
1655.irow &_doc_& "documentation files"
1656.irow &_exim_monitor_& "source files for the Exim monitor"
1657.irow &_scripts_& "scripts used in the build process"
1658.irow &_src_& "remaining source files"
1659.irow &_util_& "independent utilities"
9b371988
PH
1660.endtable
1661
1662The main utility programs are contained in the &_src_& directory, and are built
1663with the Exim binary. The &_util_& directory contains a few optional scripts
168e428f
PH
1664that may be useful to some sites.
1665
1666
f89d2485 1667.section "Multiple machine architectures and operating systems" "SECID24"
9b371988 1668.cindex "building Exim" "multiple OS/architectures"
168e428f
PH
1669The building process for Exim is arranged to make it easy to build binaries for
1670a number of different architectures and operating systems from the same set of
9b371988
PH
1671source files. Compilation does not take place in the &_src_& directory.
1672Instead, a &'build directory'& is created for each architecture and operating
1673system.
1674.cindex "symbolic link" "to build directory"
168e428f 1675Symbolic links to the sources are installed in this directory, which is where
9b371988
PH
1676the actual building takes place. In most cases, Exim can discover the machine
1677architecture and operating system for itself, but the defaults can be
1678overridden if necessary.
168e428f 1679
168e428f 1680
8473d4ee 1681.section "PCRE library" "SECTpcre"
210f147e
NM
1682.cindex "PCRE library"
1683Exim no longer has an embedded PCRE library as the vast majority of
1684modern systems include PCRE as a system library, although you may need
1685to install the PCRE or PCRE development package for your operating
1686system. If your system has a normal PCRE installation the Exim build
1687process will need no further configuration. If the library or the
6a6084f8
PP
1688headers are in an unusual location you will need to either set the PCRE_LIBS
1689and INCLUDE directives appropriately,
1690or set PCRE_CONFIG=yes to use the installed &(pcre-config)& command.
1691If your operating system has no
210f147e
NM
1692PCRE support then you will need to obtain and build the current PCRE
1693from &url(ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/).
6a6084f8 1694More information on PCRE is available at &url(http://www.pcre.org/).
210f147e 1695
9b371988
PH
1696.section "DBM libraries" "SECTdb"
1697.cindex "DBM libraries" "discussion of"
1698.cindex "hints database" "DBM files used for"
168e428f
PH
1699Even if you do not use any DBM files in your configuration, Exim still needs a
1700DBM library in order to operate, because it uses indexed files for its hints
1701databases. Unfortunately, there are a number of DBM libraries in existence, and
1702different operating systems often have different ones installed.
1703
9b371988 1704.cindex "Solaris" "DBM library for"
f89d2485
PH
1705.cindex "IRIX, DBM library for"
1706.cindex "BSD, DBM library for"
1707.cindex "Linux, DBM library for"
168e428f
PH
1708If you are using Solaris, IRIX, one of the modern BSD systems, or a modern
1709Linux distribution, the DBM configuration should happen automatically, and you
1710may be able to ignore this section. Otherwise, you may have to learn more than
1711you would like about DBM libraries from what follows.
1712
9b371988 1713.cindex "&'ndbm'& DBM library"
168e428f 1714Licensed versions of Unix normally contain a library of DBM functions operating
9b371988 1715via the &'ndbm'& interface, and this is what Exim expects by default. Free
168e428f
PH
1716versions of Unix seem to vary in what they contain as standard. In particular,
1717some early versions of Linux have no default DBM library, and different
1718distributors have chosen to bundle different libraries with their packaged
f89d2485 1719versions. However, the more recent releases seem to have standardized on the
168e428f
PH
1720Berkeley DB library.
1721
1722Different DBM libraries have different conventions for naming the files they
9b371988 1723use. When a program opens a file called &_dbmfile_&, there are several
168e428f
PH
1724possibilities:
1725
9b371988
PH
1726.olist
1727A traditional &'ndbm'& implementation, such as that supplied as part of
1728Solaris, operates on two files called &_dbmfile.dir_& and &_dbmfile.pag_&.
1729.next
1730.cindex "&'gdbm'& DBM library"
1731The GNU library, &'gdbm'&, operates on a single file. If used via its &'ndbm'&
168e428f 1732compatibility interface it makes two different hard links to it with names
9b371988 1733&_dbmfile.dir_& and &_dbmfile.pag_&, but if used via its native interface, the
168e428f 1734file name is used unmodified.
9b371988
PH
1735.next
1736.cindex "Berkeley DB library"
1737The Berkeley DB package, if called via its &'ndbm'& compatibility interface,
1738operates on a single file called &_dbmfile.db_&, but otherwise looks to the
1739programmer exactly the same as the traditional &'ndbm'& implementation.
1740.next
1741If the Berkeley package is used in its native mode, it operates on a single
1742file called &_dbmfile_&; the programmer's interface is somewhat different to
1743the traditional &'ndbm'& interface.
1744.next
1745To complicate things further, there are several very different versions of the
168e428f 1746Berkeley DB package. Version 1.85 was stable for a very long time, releases
9b371988
PH
17472.&'x'& and 3.&'x'& were current for a while, but the latest versions are now
1748numbered 4.&'x'&. Maintenance of some of the earlier releases has ceased. All
168e428f 1749versions of Berkeley DB can be obtained from
9b371988
PH
1750&url(http://www.sleepycat.com/).
1751.next
1752.cindex "&'tdb'& DBM library"
1753Yet another DBM library, called &'tdb'&, is available from
1754&url(http://download.sourceforge.net/tdb). It has its own interface, and also
1755operates on a single file.
1756.endlist
1757
1758.cindex "USE_DB"
1759.cindex "DBM libraries" "configuration for building"
168e428f
PH
1760Exim and its utilities can be compiled to use any of these interfaces. In order
1761to use any version of the Berkeley DB package in native mode, you must set
1762USE_DB in an appropriate configuration file (typically
9b371988
PH
1763&_Local/Makefile_&). For example:
1764.code
1765USE_DB=yes
1766.endd
168e428f
PH
1767Similarly, for gdbm you set USE_GDBM, and for tdb you set USE_TDB. An
1768error is diagnosed if you set more than one of these.
1769
1770At the lowest level, the build-time configuration sets none of these options,
1771thereby assuming an interface of type (1). However, some operating system
1772configuration files (for example, those for the BSD operating systems and
1773Linux) assume type (4) by setting USE_DB as their default, and the
1774configuration files for Cygwin set USE_GDBM. Anything you set in
9b371988 1775&_Local/Makefile_&, however, overrides these system defaults.
168e428f
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1776
1777As well as setting USE_DB, USE_GDBM, or USE_TDB, it may also be
1778necessary to set DBMLIB, to cause inclusion of the appropriate library, as
1779in one of these lines:
9b371988
PH
1780.code
1781DBMLIB = -ldb
1782DBMLIB = -ltdb
1783.endd
168e428f
PH
1784Settings like that will work if the DBM library is installed in the standard
1785place. Sometimes it is not, and the library's header file may also not be in
1786the default path. You may need to set INCLUDE to specify where the header
1787file is, and to specify the path to the library more fully in DBMLIB, as in
1788this example:
9b371988
PH
1789.code
1790INCLUDE=-I/usr/local/include/db-4.1
1791DBMLIB=/usr/local/lib/db-4.1/libdb.a
1792.endd
168e428f 1793There is further detailed discussion about the various DBM libraries in the
9b371988 1794file &_doc/dbm.discuss.txt_& in the Exim distribution.
168e428f
PH
1795
1796
1797
f89d2485 1798.section "Pre-building configuration" "SECID25"
9b371988
PH
1799.cindex "building Exim" "pre-building configuration"
1800.cindex "configuration for building Exim"
1801.cindex "&_Local/Makefile_&"
1802.cindex "&_src/EDITME_&"
168e428f
PH
1803Before building Exim, a local configuration file that specifies options
1804independent of any operating system has to be created with the name
9b371988
PH
1805&_Local/Makefile_&. A template for this file is supplied as the file
1806&_src/EDITME_&, and it contains full descriptions of all the option settings
168e428f
PH
1807therein. These descriptions are therefore not repeated here. If you are
1808building Exim for the first time, the simplest thing to do is to copy
9b371988 1809&_src/EDITME_& to &_Local/Makefile_&, then read it and edit it appropriately.
168e428f
PH
1810
1811There are three settings that you must supply, because Exim will not build
1812without them. They are the location of the run time configuration file
1813(CONFIGURE_FILE), the directory in which Exim binaries will be installed
1814(BIN_DIRECTORY), and the identity of the Exim user (EXIM_USER and
1815maybe EXIM_GROUP as well). The value of CONFIGURE_FILE can in fact be
1816a colon-separated list of file names; Exim uses the first of them that exists.
1817
1818There are a few other parameters that can be specified either at build time or
1819at run time, to enable the same binary to be used on a number of different
1820machines. However, if the locations of Exim's spool directory and log file
1821directory (if not within the spool directory) are fixed, it is recommended that
9b371988 1822you specify them in &_Local/Makefile_& instead of at run time, so that errors
168e428f
PH
1823detected early in Exim's execution (such as a malformed configuration file) can
1824be logged.
1825
9b371988 1826.cindex "content scanning" "specifying at build time"
068aaea8 1827Exim's interfaces for calling virus and spam scanning software directly from
168e428f
PH
1828access control lists are not compiled by default. If you want to include these
1829facilities, you need to set
9b371988
PH
1830.code
1831WITH_CONTENT_SCAN=yes
1832.endd
1833in your &_Local/Makefile_&. For details of the facilities themselves, see
1834chapter &<<CHAPexiscan>>&.
168e428f
PH
1835
1836
9b371988 1837.cindex "&_Local/eximon.conf_&"
3cb1b51e 1838.cindex "&_exim_monitor/EDITME_&"
168e428f 1839If you are going to build the Exim monitor, a similar configuration process is
9b371988
PH
1840required. The file &_exim_monitor/EDITME_& must be edited appropriately for
1841your installation and saved under the name &_Local/eximon.conf_&. If you are
1842happy with the default settings described in &_exim_monitor/EDITME_&,
1843&_Local/eximon.conf_& can be empty, but it must exist.
168e428f
PH
1844
1845This is all the configuration that is needed in straightforward cases for known
1846operating systems. However, the building process is set up so that it is easy
1847to override options that are set by default or by operating-system-specific
1848configuration files, for example to change the name of the C compiler, which
9b371988
PH
1849defaults to &%gcc%&. See section &<<SECToverride>>& below for details of how to
1850do this.
168e428f
PH
1851
1852
1853
f89d2485 1854.section "Support for iconv()" "SECID26"
9b371988
PH
1855.cindex "&[iconv()]& support"
1856.cindex "RFC 2047"
168e428f
PH
1857The contents of header lines in messages may be encoded according to the rules
1858described RFC 2047. This makes it possible to transmit characters that are not
1859in the ASCII character set, and to label them as being in a particular
9b371988 1860character set. When Exim is inspecting header lines by means of the &%$h_%&
168e428f 1861mechanism, it decodes them, and translates them into a specified character set
1459a03d 1862(default is set at build time). The translation is possible only if the operating system
9b371988
PH
1863supports the &[iconv()]& function.
1864
1865However, some of the operating systems that supply &[iconv()]& do not support
1866very many conversions. The GNU &%libiconv%& library (available from
1867&url(http://www.gnu.org/software/libiconv/)) can be installed on such
1868systems to remedy this deficiency, as well as on systems that do not supply
1869&[iconv()]& at all. After installing &%libiconv%&, you should add
1870.code
1871HAVE_ICONV=yes
1872.endd
1873to your &_Local/Makefile_& and rebuild Exim.
1874
1875
1876
1877.section "Including TLS/SSL encryption support" "SECTinctlsssl"
1878.cindex "TLS" "including support for TLS"
1879.cindex "encryption" "including support for"
1880.cindex "SUPPORT_TLS"
1881.cindex "OpenSSL" "building Exim with"
1882.cindex "GnuTLS" "building Exim with"
168e428f
PH
1883Exim can be built to support encrypted SMTP connections, using the STARTTLS
1884command as per RFC 2487. It can also support legacy clients that expect to
1885start a TLS session immediately on connection to a non-standard port (see the
9b371988 1886&%tls_on_connect_ports%& runtime option and the &%-tls-on-connect%& command
168e428f
PH
1887line option).
1888
1889If you want to build Exim with TLS support, you must first install either the
1890OpenSSL or GnuTLS library. There is no cryptographic code in Exim itself for
1891implementing SSL.
1892
1893If OpenSSL is installed, you should set
9b371988
PH
1894.code
1895SUPPORT_TLS=yes
1896TLS_LIBS=-lssl -lcrypto
1897.endd
1898in &_Local/Makefile_&. You may also need to specify the locations of the
168e428f 1899OpenSSL library and include files. For example:
9b371988
PH
1900.code
1901SUPPORT_TLS=yes
1902TLS_LIBS=-L/usr/local/openssl/lib -lssl -lcrypto
1903TLS_INCLUDE=-I/usr/local/openssl/include/
1904.endd
7e6a8985
PP
1905.cindex "pkg-config" "OpenSSL"
1906If you have &'pkg-config'& available, then instead you can just use:
1907.code
1908SUPPORT_TLS=yes
1909USE_OPENSSL_PC=openssl
1910.endd
9b371988 1911.cindex "USE_GNUTLS"
168e428f 1912If GnuTLS is installed, you should set
9b371988
PH
1913.code
1914SUPPORT_TLS=yes
1915USE_GNUTLS=yes
1916TLS_LIBS=-lgnutls -ltasn1 -lgcrypt
1917.endd
1918in &_Local/Makefile_&, and again you may need to specify the locations of the
168e428f 1919library and include files. For example:
9b371988
PH
1920.code
1921SUPPORT_TLS=yes
1922USE_GNUTLS=yes
1923TLS_LIBS=-L/usr/gnu/lib -lgnutls -ltasn1 -lgcrypt
1924TLS_INCLUDE=-I/usr/gnu/include
1925.endd
7e6a8985
PP
1926.cindex "pkg-config" "GnuTLS"
1927If you have &'pkg-config'& available, then instead you can just use:
1928.code
1929SUPPORT_TLS=yes
1930USE_GNUTLS=yes
1931USE_GNUTLS_PC=gnutls
1932.endd
7e6a8985 1933
168e428f 1934You do not need to set TLS_INCLUDE if the relevant directory is already
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1935specified in INCLUDE. Details of how to configure Exim to make use of TLS are
1936given in chapter &<<CHAPTLS>>&.
168e428f
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1937
1938
1939
1940
b52ed2b3
NM
1941.section "Use of tcpwrappers" "SECID27"
1942
f89d2485 1943.cindex "tcpwrappers, building Exim to support"
9b371988 1944.cindex "USE_TCP_WRAPPERS"
5dc43717
JJ
1945.cindex "TCP_WRAPPERS_DAEMON_NAME"
1946.cindex "tcp_wrappers_daemon_name"
9b371988
PH
1947Exim can be linked with the &'tcpwrappers'& library in order to check incoming
1948SMTP calls using the &'tcpwrappers'& control files. This may be a convenient
168e428f 1949alternative to Exim's own checking facilities for installations that are
9b371988
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1950already making use of &'tcpwrappers'& for other purposes. To do this, you
1951should set USE_TCP_WRAPPERS in &_Local/Makefile_&, arrange for the file
1952&_tcpd.h_& to be available at compile time, and also ensure that the library
1953&_libwrap.a_& is available at link time, typically by including &%-lwrap%& in
1954EXTRALIBS_EXIM. For example, if &'tcpwrappers'& is installed in &_/usr/local_&,
1955you might have
1956.code
1957USE_TCP_WRAPPERS=yes
1958CFLAGS=-O -I/usr/local/include
1959EXTRALIBS_EXIM=-L/usr/local/lib -lwrap
1960.endd
5dc43717
JJ
1961in &_Local/Makefile_&. The daemon name to use in the &'tcpwrappers'& control
1962files is &"exim"&. For example, the line
9b371988
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1963.code
1964exim : LOCAL 192.168.1. .friendly.domain.example
1965.endd
1966in your &_/etc/hosts.allow_& file allows connections from the local host, from
1967the subnet 192.168.1.0/24, and from all hosts in &'friendly.domain.example'&.
5dc43717
JJ
1968All other connections are denied. The daemon name used by &'tcpwrappers'&
1969can be changed at build time by setting TCP_WRAPPERS_DAEMON_NAME in
a543079f 1970&_Local/Makefile_&, or by setting tcp_wrappers_daemon_name in the
5dc43717 1971configure file. Consult the &'tcpwrappers'& documentation for
168e428f 1972further details.
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1973
1974
f89d2485 1975.section "Including support for IPv6" "SECID28"
9b371988 1976.cindex "IPv6" "including support for"
168e428f 1977Exim contains code for use on systems that have IPv6 support. Setting
9b371988 1978&`HAVE_IPV6=YES`& in &_Local/Makefile_& causes the IPv6 code to be included;
168e428f
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1979it may also be necessary to set IPV6_INCLUDE and IPV6_LIBS on systems
1980where the IPv6 support is not fully integrated into the normal include and
1981library files.
1982
1983Two different types of DNS record for handling IPv6 addresses have been
f89d2485 1984defined. AAAA records (analogous to A records for IPv4) are in use, and are
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1985currently seen as the mainstream. Another record type called A6 was proposed
1986as better than AAAA because it had more flexibility. However, it was felt to be
badb25a9 1987over-complex, and its status was reduced to &"experimental"&.
badb25a9 1988Exim used to
cc00f4af
JH
1989have a compile option for including A6 record support but this has now been
1990withdrawn.
168e428f
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1991
1992
1993
0a349494
PP
1994.section "Dynamically loaded lookup module support" "SECTdynamicmodules"
1995.cindex "lookup modules"
1996.cindex "dynamic modules"
1997.cindex ".so building"
1998On some platforms, Exim supports not compiling all lookup types directly into
1999the main binary, instead putting some into external modules which can be loaded
2000on demand.
2001This permits packagers to build Exim with support for lookups with extensive
2002library dependencies without requiring all users to install all of those
2003dependencies.
2004Most, but not all, lookup types can be built this way.
2005
2006Set &`LOOKUP_MODULE_DIR`& to the directory into which the modules will be
2007installed; Exim will only load modules from that directory, as a security
2008measure. You will need to set &`CFLAGS_DYNAMIC`& if not already defined
2009for your OS; see &_OS/Makefile-Linux_& for an example.
2010Some other requirements for adjusting &`EXTRALIBS`& may also be necessary,
2011see &_src/EDITME_& for details.
2012
2013Then, for each module to be loaded dynamically, define the relevant
2014&`LOOKUP_`&<&'lookup_type'&> flags to have the value "2" instead of "yes".
2015For example, this will build in lsearch but load sqlite and mysql support
2016on demand:
2017.code
2018LOOKUP_LSEARCH=yes
2019LOOKUP_SQLITE=2
2020LOOKUP_MYSQL=2
2021.endd
5d758a46 2022
0a349494 2023
f89d2485 2024.section "The building process" "SECID29"
9b371988
PH
2025.cindex "build directory"
2026Once &_Local/Makefile_& (and &_Local/eximon.conf_&, if required) have been
2027created, run &'make'& at the top level. It determines the architecture and
168e428f
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2028operating system types, and creates a build directory if one does not exist.
2029For example, on a Sun system running Solaris 8, the directory
9b371988
PH
2030&_build-SunOS5-5.8-sparc_& is created.
2031.cindex "symbolic link" "to source files"
168e428f
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2032Symbolic links to relevant source files are installed in the build directory.
2033
9b371988 2034If this is the first time &'make'& has been run, it calls a script that builds
168e428f 2035a make file inside the build directory, using the configuration files from the
9b371988
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2036&_Local_& directory. The new make file is then passed to another instance of
2037&'make'&. This does the real work, building a number of utility scripts, and
168e428f 2038then compiling and linking the binaries for the Exim monitor (if configured), a
9b371988
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2039number of utility programs, and finally Exim itself. The command &`make
2040makefile`& can be used to force a rebuild of the make file in the build
168e428f
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2041directory, should this ever be necessary.
2042
2043If you have problems building Exim, check for any comments there may be in the
9b371988 2044&_README_& file concerning your operating system, and also take a look at the
168e428f
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2045FAQ, where some common problems are covered.
2046
2047
2048
f89d2485 2049.section 'Output from &"make"&' "SECID283"
9b371988 2050The output produced by the &'make'& process for compile lines is often very
068aaea8
PH
2051unreadable, because these lines can be very long. For this reason, the normal
2052output is suppressed by default, and instead output similar to that which
2053appears when compiling the 2.6 Linux kernel is generated: just a short line for
2054each module that is being compiled or linked. However, it is still possible to
9b371988
PH
2055get the full output, by calling &'make'& like this:
2056.code
2057FULLECHO='' make -e
2058.endd
2059The value of FULLECHO defaults to &"@"&, the flag character that suppresses
2060command reflection in &'make'&. When you ask for the full output, it is
3cb1b51e 2061given in addition to the short output.
068aaea8
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2062
2063
2064
9b371988 2065.section "Overriding build-time options for Exim" "SECToverride"
f89d2485 2066.cindex "build-time options, overriding"
168e428f
PH
2067The main make file that is created at the beginning of the building process
2068consists of the concatenation of a number of files which set configuration
9b371988 2069values, followed by a fixed set of &'make'& instructions. If a value is set
168e428f
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2070more than once, the last setting overrides any previous ones. This provides a
2071convenient way of overriding defaults. The files that are concatenated are, in
2072order:
9b371988
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2073.display
2074&_OS/Makefile-Default_&
2075&_OS/Makefile-_&<&'ostype'&>
2076&_Local/Makefile_&
2077&_Local/Makefile-_&<&'ostype'&>
2078&_Local/Makefile-_&<&'archtype'&>
2079&_Local/Makefile-_&<&'ostype'&>-<&'archtype'&>
2080&_OS/Makefile-Base_&
2081.endd
2082.cindex "&_Local/Makefile_&"
2083.cindex "building Exim" "operating system type"
2084.cindex "building Exim" "architecture type"
2085where <&'ostype'&> is the operating system type and <&'archtype'&> is the
2086architecture type. &_Local/Makefile_& is required to exist, and the building
2087process fails if it is absent. The other three &_Local_& files are optional,
168e428f
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2088and are often not needed.
2089
9b371988
PH
2090The values used for <&'ostype'&> and <&'archtype'&> are obtained from scripts
2091called &_scripts/os-type_& and &_scripts/arch-type_& respectively. If either of
168e428f
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2092the environment variables EXIM_OSTYPE or EXIM_ARCHTYPE is set, their
2093values are used, thereby providing a means of forcing particular settings.
9b371988 2094Otherwise, the scripts try to get values from the &%uname%& command. If this
168e428f 2095fails, the shell variables OSTYPE and ARCHTYPE are inspected. A number
9b371988 2096of &'ad hoc'& transformations are then applied, to produce the standard names
168e428f
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2097that Exim expects. You can run these scripts directly from the shell in order
2098to find out what values are being used on your system.
2099
2100
9b371988 2101&_OS/Makefile-Default_& contains comments about the variables that are set
168e428f
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2102therein. Some (but not all) are mentioned below. If there is something that
2103needs changing, review the contents of this file and the contents of the make
9b371988 2104file for your operating system (&_OS/Makefile-<ostype>_&) to see what the
168e428f
PH
2105default values are.
2106
2107
9b371988
PH
2108.cindex "building Exim" "overriding default settings"
2109If you need to change any of the values that are set in &_OS/Makefile-Default_&
2110or in &_OS/Makefile-<ostype>_&, or to add any new definitions, you do not
168e428f 2111need to change the original files. Instead, you should make the changes by
9b371988
PH
2112putting the new values in an appropriate &_Local_& file. For example,
2113.cindex "Tru64-Unix build-time settings"
168e428f
PH
2114when building Exim in many releases of the Tru64-Unix (formerly Digital UNIX,
2115formerly DEC-OSF1) operating system, it is necessary to specify that the C
9b371988
PH
2116compiler is called &'cc'& rather than &'gcc'&. Also, the compiler must be
2117called with the option &%-std1%&, to make it recognize some of the features of
168e428f 2118Standard C that Exim uses. (Most other compilers recognize Standard C by
9b371988 2119default.) To do this, you should create a file called &_Local/Makefile-OSF1_&
168e428f 2120containing the lines
9b371988
PH
2121.code
2122CC=cc
2123CFLAGS=-std1
2124.endd
168e428f 2125If you are compiling for just one operating system, it may be easier to put
9b371988 2126these lines directly into &_Local/Makefile_&.
168e428f
PH
2127
2128Keeping all your local configuration settings separate from the distributed
2129files makes it easy to transfer them to new versions of Exim simply by copying
9b371988 2130the contents of the &_Local_& directory.
168e428f
PH
2131
2132
9b371988
PH
2133.cindex "NIS lookup type" "including support for"
2134.cindex "NIS+ lookup type" "including support for"
2135.cindex "LDAP" "including support for"
2136.cindex "lookup" "inclusion in binary"
168e428f
PH
2137Exim contains support for doing LDAP, NIS, NIS+, and other kinds of file
2138lookup, but not all systems have these components installed, so the default is
2139not to include the relevant code in the binary. All the different kinds of file
2140and database lookup that Exim supports are implemented as separate code modules
2141which are included only if the relevant compile-time options are set. In the
9b371988
PH
2142case of LDAP, NIS, and NIS+, the settings for &_Local/Makefile_& are:
2143.code
2144LOOKUP_LDAP=yes
2145LOOKUP_NIS=yes
2146LOOKUP_NISPLUS=yes
2147.endd
168e428f 2148and similar settings apply to the other lookup types. They are all listed in
9b371988 2149&_src/EDITME_&. In many cases the relevant include files and interface
168e428f 2150libraries need to be installed before compiling Exim.
9b371988 2151.cindex "cdb" "including support for"
068aaea8
PH
2152However, there are some optional lookup types (such as cdb) for which
2153the code is entirely contained within Exim, and no external include
168e428f
PH
2154files or libraries are required. When a lookup type is not included in the
2155binary, attempts to configure Exim to use it cause run time configuration
2156errors.
2157
7e6a8985
PP
2158.cindex "pkg-config" "lookups"
2159.cindex "pkg-config" "authenticators"
252e0c7b
PP
2160Many systems now use a tool called &'pkg-config'& to encapsulate information
2161about how to compile against a library; Exim has some initial support for
2162being able to use pkg-config for lookups and authenticators. For any given
2163makefile variable which starts &`LOOKUP_`& or &`AUTH_`&, you can add a new
2164variable with the &`_PC`& suffix in the name and assign as the value the
2165name of the package to be queried. The results of querying via the
2166&'pkg-config'& command will be added to the appropriate Makefile variables
2167with &`+=`& directives, so your version of &'make'& will need to support that
2168syntax. For instance:
2169.code
2170LOOKUP_SQLITE=yes
2171LOOKUP_SQLITE_PC=sqlite3
2172AUTH_GSASL=yes
2173AUTH_GSASL_PC=libgsasl
2174AUTH_HEIMDAL_GSSAPI=yes
2175AUTH_HEIMDAL_GSSAPI_PC=heimdal-gssapi
2176.endd
252e0c7b 2177
9b371988 2178.cindex "Perl" "including support for"
168e428f
PH
2179Exim can be linked with an embedded Perl interpreter, allowing Perl
2180subroutines to be called during string expansion. To enable this facility,
9b371988
PH
2181.code
2182EXIM_PERL=perl.o
2183.endd
2184must be defined in &_Local/Makefile_&. Details of this facility are given in
2185chapter &<<CHAPperl>>&.
168e428f 2186
f89d2485 2187.cindex "X11 libraries, location of"
168e428f 2188The location of the X11 libraries is something that varies a lot between
068aaea8 2189operating systems, and there may be different versions of X11 to cope
168e428f
PH
2190with. Exim itself makes no use of X11, but if you are compiling the Exim
2191monitor, the X11 libraries must be available.
9b371988
PH
2192The following three variables are set in &_OS/Makefile-Default_&:
2193.code
2194X11=/usr/X11R6
2195XINCLUDE=-I$(X11)/include
2196XLFLAGS=-L$(X11)/lib
2197.endd
168e428f 2198These are overridden in some of the operating-system configuration files. For
9b371988
PH
2199example, in &_OS/Makefile-SunOS5_& there is
2200.code
2201X11=/usr/openwin
2202XINCLUDE=-I$(X11)/include
2203XLFLAGS=-L$(X11)/lib -R$(X11)/lib
2204.endd
168e428f
PH
2205If you need to override the default setting for your operating system, place a
2206definition of all three of these variables into your
9b371988 2207&_Local/Makefile-<ostype>_& file.
168e428f 2208
9b371988 2209.cindex "EXTRALIBS"
168e428f
PH
2210If you need to add any extra libraries to the link steps, these can be put in a
2211variable called EXTRALIBS, which appears in all the link commands, but by
2212default is not defined. In contrast, EXTRALIBS_EXIM is used only on the
2213command for linking the main Exim binary, and not for any associated utilities.
2214
9b371988 2215.cindex "DBM libraries" "configuration for building"
168e428f 2216There is also DBMLIB, which appears in the link commands for binaries that
9b371988 2217use DBM functions (see also section &<<SECTdb>>&). Finally, there is
168e428f
PH
2218EXTRALIBS_EXIMON, which appears only in the link step for the Exim monitor
2219binary, and which can be used, for example, to include additional X11
2220libraries.
2221
9b371988 2222.cindex "configuration file" "editing"
168e428f
PH
2223The make file copes with rebuilding Exim correctly if any of the configuration
2224files are edited. However, if an optional configuration file is deleted, it is
9b371988
PH
2225necessary to touch the associated non-optional file (that is,
2226&_Local/Makefile_& or &_Local/eximon.conf_&) before rebuilding.
168e428f
PH
2227
2228
f89d2485 2229.section "OS-specific header files" "SECID30"
9b371988
PH
2230.cindex "&_os.h_&"
2231.cindex "building Exim" "OS-specific C header files"
2232The &_OS_& directory contains a number of files with names of the form
2233&_os.h-<ostype>_&. These are system-specific C header files that should not
168e428f 2234normally need to be changed. There is a list of macro settings that are
9b371988 2235recognized in the file &_OS/os.configuring_&, which should be consulted if you
168e428f
PH
2236are porting Exim to a new operating system.
2237
2238
2239
f89d2485
PH
2240.section "Overriding build-time options for the monitor" "SECID31"
2241.cindex "building Eximon"
168e428f
PH
2242A similar process is used for overriding things when building the Exim monitor,
2243where the files that are involved are
9b371988
PH
2244.display
2245&_OS/eximon.conf-Default_&
2246&_OS/eximon.conf-_&<&'ostype'&>
2247&_Local/eximon.conf_&
2248&_Local/eximon.conf-_&<&'ostype'&>
2249&_Local/eximon.conf-_&<&'archtype'&>
2250&_Local/eximon.conf-_&<&'ostype'&>-<&'archtype'&>
2251.endd
2252.cindex "&_Local/eximon.conf_&"
168e428f 2253As with Exim itself, the final three files need not exist, and in this case the
9b371988
PH
2254&_OS/eximon.conf-<ostype>_& file is also optional. The default values in
2255&_OS/eximon.conf-Default_& can be overridden dynamically by setting environment
168e428f
PH
2256variables of the same name, preceded by EXIMON_. For example, setting
2257EXIMON_LOG_DEPTH in the environment overrides the value of
2258LOG_DEPTH at run time.
4f578862 2259.ecindex IIDbuex
168e428f
PH
2260
2261
f89d2485 2262.section "Installing Exim binaries and scripts" "SECID32"
9b371988
PH
2263.cindex "installing Exim"
2264.cindex "BIN_DIRECTORY"
2265The command &`make install`& runs the &(exim_install)& script with no
2266arguments. The script copies binaries and utility scripts into the directory
2267whose name is specified by the BIN_DIRECTORY setting in &_Local/Makefile_&.
2268.cindex "setuid" "installing Exim with"
068aaea8
PH
2269The install script copies files only if they are newer than the files they are
2270going to replace. The Exim binary is required to be owned by root and have the
9b371988
PH
2271&'setuid'& bit set, for normal configurations. Therefore, you must run &`make
2272install`& as root so that it can set up the Exim binary in this way. However, in
068aaea8
PH
2273some special situations (for example, if a host is doing no local deliveries)
2274it may be possible to run Exim without making the binary setuid root (see
9b371988 2275chapter &<<CHAPsecurity>>& for details).
168e428f 2276
9b371988 2277.cindex "CONFIGURE_FILE"
168e428f 2278Exim's run time configuration file is named by the CONFIGURE_FILE setting
9b371988
PH
2279in &_Local/Makefile_&. If this names a single file, and the file does not
2280exist, the default configuration file &_src/configure.default_& is copied there
168e428f
PH
2281by the installation script. If a run time configuration file already exists, it
2282is left alone. If CONFIGURE_FILE is a colon-separated list, naming several
2283alternative files, no default is installed.
2284
9b371988
PH
2285.cindex "system aliases file"
2286.cindex "&_/etc/aliases_&"
168e428f
PH
2287One change is made to the default configuration file when it is installed: the
2288default configuration contains a router that references a system aliases file.
2289The path to this file is set to the value specified by
9b371988 2290SYSTEM_ALIASES_FILE in &_Local/Makefile_& (&_/etc/aliases_& by default).
168e428f
PH
2291If the system aliases file does not exist, the installation script creates it,
2292and outputs a comment to the user.
2293
2294The created file contains no aliases, but it does contain comments about the
2295aliases a site should normally have. Mail aliases have traditionally been
9b371988
PH
2296kept in &_/etc/aliases_&. However, some operating systems are now using
2297&_/etc/mail/aliases_&. You should check if yours is one of these, and change
168e428f
PH
2298Exim's configuration if necessary.
2299
2300The default configuration uses the local host's name as the only local domain,
9b371988
PH
2301and is set up to do local deliveries into the shared directory &_/var/mail_&,
2302running as the local user. System aliases and &_.forward_& files in users' home
168e428f
PH
2303directories are supported, but no NIS or NIS+ support is configured. Domains
2304other than the name of the local host are routed using the DNS, with delivery
2305over SMTP.
2306
168e428f
PH
2307It is possible to install Exim for special purposes (such as building a binary
2308distribution) in a private part of the file system. You can do this by a
2309command such as
9b371988
PH
2310.code
2311make DESTDIR=/some/directory/ install
2312.endd
168e428f
PH
2313This has the effect of pre-pending the specified directory to all the file
2314paths, except the name of the system aliases file that appears in the default
9b371988 2315configuration. (If a default alias file is created, its name &'is'& modified.)
168e428f
PH
2316For backwards compatibility, ROOT is used if DESTDIR is not set,
2317but this usage is deprecated.
2318
9b371988
PH
2319.cindex "installing Exim" "what is not installed"
2320Running &'make install'& does not copy the Exim 4 conversion script
40df1be3
TF
2321&'convert4r4'&. You will probably run this only once if you are
2322upgrading from Exim 3. None of the documentation files in the &_doc_&
168e428f 2323directory are copied, except for the info files when you have set
9b371988 2324INFO_DIRECTORY, as described in section &<<SECTinsinfdoc>>& below.
168e428f 2325
9b371988 2326For the utility programs, old versions are renamed by adding the suffix &_.O_&
168e428f
PH
2327to their names. The Exim binary itself, however, is handled differently. It is
2328installed under a name that includes the version number and the compile number,
2aee48d6 2329for example &_exim-&version()-1_&. The script then arranges for a symbolic link
9b371988
PH
2330called &_exim_& to point to the binary. If you are updating a previous version
2331of Exim, the script takes care to ensure that the name &_exim_& is never absent
168e428f
PH
2332from the directory (as seen by other processes).
2333
9b371988
PH
2334.cindex "installing Exim" "testing the script"
2335If you want to see what the &'make install'& will do before running it for
2336real, you can pass the &%-n%& option to the installation script by this
2337command:
2338.code
2339make INSTALL_ARG=-n install
2340.endd
168e428f
PH
2341The contents of the variable INSTALL_ARG are passed to the installation
2342script. You do not need to be root to run this test. Alternatively, you can run
2343the installation script directly, but this must be from within the build
2344directory. For example, from the top-level Exim directory you could use this
2345command:
9b371988
PH
2346.code
2347(cd build-SunOS5-5.5.1-sparc; ../scripts/exim_install -n)
2348.endd
2349.cindex "installing Exim" "install script options"
168e428f
PH
2350There are two other options that can be supplied to the installation script.
2351
9b371988
PH
2352.ilist
2353&%-no_chown%& bypasses the call to change the owner of the installed binary
168e428f 2354to root, and the call to make it a setuid binary.
9b371988
PH
2355.next
2356&%-no_symlink%& bypasses the setting up of the symbolic link &_exim_& to the
168e428f 2357installed binary.
9b371988 2358.endlist
168e428f
PH
2359
2360INSTALL_ARG can be used to pass these options to the script. For example:
9b371988
PH
2361.code
2362make INSTALL_ARG=-no_symlink install
2363.endd
168e428f
PH
2364The installation script can also be given arguments specifying which files are
2365to be copied. For example, to install just the Exim binary, and nothing else,
2366without creating the symbolic link, you could use:
9b371988
PH
2367.code
2368make INSTALL_ARG='-no_symlink exim' install
2369.endd
168e428f
PH
2370
2371
2372
9b371988
PH
2373.section "Installing info documentation" "SECTinsinfdoc"
2374.cindex "installing Exim" "&'info'& documentation"
2375Not all systems use the GNU &'info'& system for documentation, and for this
168e428f
PH
2376reason, the Texinfo source of Exim's documentation is not included in the main
2377distribution. Instead it is available separately from the ftp site (see section
9b371988 2378&<<SECTavail>>&).
168e428f 2379
9b371988
PH
2380If you have defined INFO_DIRECTORY in &_Local/Makefile_& and the Texinfo
2381source of the documentation is found in the source tree, running &`make
2382install`& automatically builds the info files and installs them.
168e428f
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2383
2384
2385
f89d2485 2386.section "Setting up the spool directory" "SECID33"
9b371988 2387.cindex "spool directory" "creating"
168e428f
PH
2388When it starts up, Exim tries to create its spool directory if it does not
2389exist. The Exim uid and gid are used for the owner and group of the spool
2390directory. Sub-directories are automatically created in the spool directory as
2391necessary.
2392
2393
2394
2395
f89d2485 2396.section "Testing" "SECID34"
9b371988 2397.cindex "testing" "installation"
168e428f
PH
2398Having installed Exim, you can check that the run time configuration file is
2399syntactically valid by running the following command, which assumes that the
2400Exim binary directory is within your PATH environment variable:
9b371988
PH
2401.code
2402exim -bV
2403.endd
168e428f
PH
2404If there are any errors in the configuration file, Exim outputs error messages.
2405Otherwise it outputs the version number and build date,
2406the DBM library that is being used, and information about which drivers and
2407other optional code modules are included in the binary.
2408Some simple routing tests can be done by using the address testing option. For
2409example,
9b371988
PH
2410.display
2411&`exim -bt`& <&'local username'&>
2412.endd
168e428f 2413should verify that it recognizes a local mailbox, and
9b371988
PH
2414.display
2415&`exim -bt`& <&'remote address'&>
2416.endd
168e428f
PH
2417a remote one. Then try getting it to deliver mail, both locally and remotely.
2418This can be done by passing messages directly to Exim, without going through a
2419user agent. For example:
9b371988 2420.code
068aaea8
PH
2421exim -v postmaster@your.domain.example
2422From: user@your.domain.example
2423To: postmaster@your.domain.example
2424Subject: Testing Exim
168e428f 2425
068aaea8
PH
2426This is a test message.
2427^D
9b371988
PH
2428.endd
2429The &%-v%& option causes Exim to output some verification of what it is doing.
168e428f 2430In this case you should see copies of three log lines, one for the message's
9b371988 2431arrival, one for its delivery, and one containing &"Completed"&.
168e428f 2432
9b371988
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2433.cindex "delivery" "problems with"
2434If you encounter problems, look at Exim's log files (&'mainlog'& and
2435&'paniclog'&) to see if there is any relevant information there. Another source
168e428f 2436of information is running Exim with debugging turned on, by specifying the
9b371988 2437&%-d%& option. If a message is stuck on Exim's spool, you can force a delivery
168e428f 2438with debugging turned on by a command of the form
9b371988
PH
2439.display
2440&`exim -d -M`& <&'exim-message-id'&>
2441.endd
2442You must be root or an &"admin user"& in order to do this. The &%-d%& option
168e428f 2443produces rather a lot of output, but you can cut this down to specific areas.
9b371988
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2444For example, if you use &%-d-all+route%& only the debugging information
2445relevant to routing is included. (See the &%-d%& option in chapter
2446&<<CHAPcommandline>>& for more details.)
168e428f 2447
9b371988
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2448.cindex '&"sticky"& bit'
2449.cindex "lock files"
168e428f
PH
2450One specific problem that has shown up on some sites is the inability to do
2451local deliveries into a shared mailbox directory, because it does not have the
9b371988 2452&"sticky bit"& set on it. By default, Exim tries to create a lock file before
168e428f 2453writing to a mailbox file, and if it cannot create the lock file, the delivery
9b371988 2454is deferred. You can get round this either by setting the &"sticky bit"& on the
168e428f
PH
2455directory, or by setting a specific group for local deliveries and allowing
2456that group to create files in the directory (see the comments above the
9b371988 2457&(local_delivery)& transport in the default configuration file). Another
168e428f 2458approach is to configure Exim not to use lock files, but just to rely on
9b371988
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2459&[fcntl()]& locking instead. However, you should do this only if all user
2460agents also use &[fcntl()]& locking. For further discussion of locking issues,
2461see chapter &<<CHAPappendfile>>&.
168e428f
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2462
2463One thing that cannot be tested on a system that is already running an MTA is
2464the receipt of incoming SMTP mail on the standard SMTP port. However, the
9b371988
PH
2465&%-oX%& option can be used to run an Exim daemon that listens on some other
2466port, or &'inetd'& can be used to do this. The &%-bh%& option and the
2467&'exim_checkaccess'& utility can be used to check out policy controls on
168e428f
PH
2468incoming SMTP mail.
2469
2470Testing a new version on a system that is already running Exim can most easily
2471be done by building a binary with a different CONFIGURE_FILE setting. From
2472within the run time configuration, all other file and directory names
2473that Exim uses can be altered, in order to keep it entirely clear of the
2474production version.
2475
2476
f89d2485 2477.section "Replacing another MTA with Exim" "SECID35"
9b371988 2478.cindex "replacing another MTA"
168e428f
PH
2479Building and installing Exim for the first time does not of itself put it in
2480general use. The name by which the system's MTA is called by mail user agents
9b371988
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2481is either &_/usr/sbin/sendmail_&, or &_/usr/lib/sendmail_& (depending on the
2482operating system), and it is necessary to make this name point to the &'exim'&
168e428f 2483binary in order to get the user agents to pass messages to Exim. This is
9b371988
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2484normally done by renaming any existing file and making &_/usr/sbin/sendmail_&
2485or &_/usr/lib/sendmail_&
2486.cindex "symbolic link" "to &'exim'& binary"
2487a symbolic link to the &'exim'& binary. It is a good idea to remove any setuid
168e428f
PH
2488privilege and executable status from the old MTA. It is then necessary to stop
2489and restart the mailer daemon, if one is running.
2490
f89d2485 2491.cindex "FreeBSD, MTA indirection"
9b371988 2492.cindex "&_/etc/mail/mailer.conf_&"
168e428f
PH
2493Some operating systems have introduced alternative ways of switching MTAs. For
2494example, if you are running FreeBSD, you need to edit the file
9b371988 2495&_/etc/mail/mailer.conf_& instead of setting up a symbolic link as just
168e428f
PH
2496described. A typical example of the contents of this file for running Exim is
2497as follows:
9b371988
PH
2498.code
2499sendmail /usr/exim/bin/exim
2500send-mail /usr/exim/bin/exim
2501mailq /usr/exim/bin/exim -bp
2502newaliases /usr/bin/true
2503.endd
2504Once you have set up the symbolic link, or edited &_/etc/mail/mailer.conf_&,
2505your Exim installation is &"live"&. Check it by sending a message from your
168e428f
PH
2506favourite user agent.
2507
2508You should consider what to tell your users about the change of MTA. Exim may
2509have different capabilities to what was previously running, and there are
2510various operational differences such as the text of messages produced by
2511command line options and in bounce messages. If you allow your users to make
2512use of Exim's filtering capabilities, you should make the document entitled
9b371988 2513&'Exim's interface to mail filtering'& available to them.
168e428f
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2514
2515
2516
f89d2485 2517.section "Upgrading Exim" "SECID36"
9b371988 2518.cindex "upgrading Exim"
168e428f
PH
2519If you are already running Exim on your host, building and installing a new
2520version automatically makes it available to MUAs, or any other programs that
2521call the MTA directly. However, if you are running an Exim daemon, you do need
9b371988
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2522to send it a HUP signal, to make it re-execute itself, and thereby pick up the
2523new binary. You do not need to stop processing mail in order to install a new
068aaea8
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2524version of Exim. The install script does not modify an existing runtime
2525configuration file.
2526
168e428f
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2527
2528
2529
f89d2485 2530.section "Stopping the Exim daemon on Solaris" "SECID37"
9b371988 2531.cindex "Solaris" "stopping Exim on"
168e428f 2532The standard command for stopping the mailer daemon on Solaris is
9b371988
PH
2533.code
2534/etc/init.d/sendmail stop
2535.endd
2536If &_/usr/lib/sendmail_& has been turned into a symbolic link, this script
2537fails to stop Exim because it uses the command &'ps -e'& and greps the output
2538for the text &"sendmail"&; this is not present because the actual program name
2539(that is, &"exim"&) is given by the &'ps'& command with these options. A
2540solution is to replace the line that finds the process id with something like
2541.code
2542pid=`cat /var/spool/exim/exim-daemon.pid`
2543.endd
168e428f
PH
2544to obtain the daemon's pid directly from the file that Exim saves it in.
2545
9b371988 2546Note, however, that stopping the daemon does not &"stop Exim"&. Messages can
168e428f
PH
2547still be received from local processes, and if automatic delivery is configured
2548(the normal case), deliveries will still occur.
2549
2550
2551
2552
9b371988
PH
2553. ////////////////////////////////////////////////////////////////////////////
2554. ////////////////////////////////////////////////////////////////////////////
168e428f 2555
9b371988 2556.chapter "The Exim command line" "CHAPcommandline"
4f578862
PH
2557.scindex IIDclo1 "command line" "options"
2558.scindex IIDclo2 "options" "command line"
168e428f
PH
2559Exim's command line takes the standard Unix form of a sequence of options,
2560each starting with a hyphen character, followed by a number of arguments. The
2561options are compatible with the main options of Sendmail, and there are also
2562some additional options, some of which are compatible with Smail 3. Certain
2563combinations of options do not make sense, and provoke an error if used.
2564The form of the arguments depends on which options are set.
2565
2566
f89d2485 2567.section "Setting options by program name" "SECID38"
9b371988
PH
2568.cindex "&'mailq'&"
2569If Exim is called under the name &'mailq'&, it behaves as if the option &%-bp%&
168e428f 2570were present before any other options.
9b371988 2571The &%-bp%& option requests a listing of the contents of the mail queue on the
168e428f
PH
2572standard output.
2573This feature is for compatibility with some systems that contain a command of
2574that name in one of the standard libraries, symbolically linked to
9b371988
PH
2575&_/usr/sbin/sendmail_& or &_/usr/lib/sendmail_&.
2576
2577.cindex "&'rsmtp'&"
2578If Exim is called under the name &'rsmtp'& it behaves as if the option &%-bS%&
2579were present before any other options, for compatibility with Smail. The
2580&%-bS%& option is used for reading in a number of messages in batched SMTP
2581format.
2582
2583.cindex "&'rmail'&"
2584If Exim is called under the name &'rmail'& it behaves as if the &%-i%& and
2585&%-oee%& options were present before any other options, for compatibility with
2586Smail. The name &'rmail'& is used as an interface by some UUCP systems.
2587
2588.cindex "&'runq'&"
2589.cindex "queue runner"
2590If Exim is called under the name &'runq'& it behaves as if the option &%-q%&
2591were present before any other options, for compatibility with Smail. The &%-q%&
168e428f
PH
2592option causes a single queue runner process to be started.
2593
9b371988
PH
2594.cindex "&'newaliases'&"
2595.cindex "alias file" "building"
2596.cindex "Sendmail compatibility" "calling Exim as &'newaliases'&"
2597If Exim is called under the name &'newaliases'& it behaves as if the option
2598&%-bi%& were present before any other options, for compatibility with Sendmail.
168e428f
PH
2599This option is used for rebuilding Sendmail's alias file. Exim does not have
2600the concept of a single alias file, but can be configured to run a given
9b371988 2601command if called with the &%-bi%& option.
168e428f
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2602
2603
9b371988
PH
2604.section "Trusted and admin users" "SECTtrustedadmin"
2605Some Exim options are available only to &'trusted users'& and others are
2606available only to &'admin users'&. In the description below, the phrases &"Exim
2607user"& and &"Exim group"& mean the user and group defined by EXIM_USER and
2608EXIM_GROUP in &_Local/Makefile_& or set by the &%exim_user%& and
2609&%exim_group%& options. These do not necessarily have to use the name &"exim"&.
168e428f 2610
9b371988 2611.ilist
f89d2485 2612.cindex "trusted users" "definition of"
9b371988 2613.cindex "user" "trusted definition of"
168e428f 2614The trusted users are root, the Exim user, any user listed in the
9b371988
PH
2615&%trusted_users%& configuration option, and any user whose current group or any
2616supplementary group is one of those listed in the &%trusted_groups%&
168e428f 2617configuration option. Note that the Exim group is not automatically trusted.
9b371988
PH
2618
2619.cindex '&"From"& line'
2620.cindex "envelope sender"
2621Trusted users are always permitted to use the &%-f%& option or a leading
2622&"From&~"& line to specify the envelope sender of a message that is passed to
2623Exim through the local interface (see the &%-bm%& and &%-f%& options below).
2624See the &%untrusted_set_sender%& option for a way of permitting non-trusted
2625users to set envelope senders.
2626
2627.cindex "&'From:'& header line"
2628.cindex "&'Sender:'& header line"
1e4519cc
JH
2629.cindex "header lines" "From:"
2630.cindex "header lines" "Sender:"
9b371988
PH
2631For a trusted user, there is never any check on the contents of the &'From:'&
2632header line, and a &'Sender:'& line is never added. Furthermore, any existing
2633&'Sender:'& line in incoming local (non-TCP/IP) messages is not removed.
2634
168e428f
PH
2635Trusted users may also specify a host name, host address, interface address,
2636protocol name, ident value, and authentication data when submitting a message
2637locally. Thus, they are able to insert messages into Exim's queue locally that
2638have the characteristics of messages received from a remote host. Untrusted
9b371988 2639users may in some circumstances use &%-f%&, but can never set the other values
168e428f 2640that are available to trusted users.
9b371988
PH
2641.next
2642.cindex "user" "admin definition of"
2643.cindex "admin user" "definition of"
168e428f 2644The admin users are root, the Exim user, and any user that is a member of the
9b371988 2645Exim group or of any group listed in the &%admin_groups%& configuration option.
168e428f 2646The current group does not have to be one of these groups.
9b371988 2647
168e428f
PH
2648Admin users are permitted to list the queue, and to carry out certain
2649operations on messages, for example, to force delivery failures. It is also
2650necessary to be an admin user in order to see the full information provided by
2651the Exim monitor, and full debugging output.
9b371988
PH
2652
2653By default, the use of the &%-M%&, &%-q%&, &%-R%&, and &%-S%& options to cause
2654Exim to attempt delivery of messages on its queue is restricted to admin users.
2655However, this restriction can be relaxed by setting the &%prod_requires_admin%&
2656option false (that is, specifying &%no_prod_requires_admin%&).
2657
2658Similarly, the use of the &%-bp%& option to list all the messages in the queue
2659is restricted to admin users unless &%queue_list_requires_admin%& is set
168e428f 2660false.
9b371988 2661.endlist
168e428f
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2662
2663
9b371988 2664&*Warning*&: If you configure your system so that admin users are able to
168e428f
PH
2665edit Exim's configuration file, you are giving those users an easy way of
2666getting root. There is further discussion of this issue at the start of chapter
9b371988 2667&<<CHAPconf>>&.
168e428f
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2668
2669
2670
2671
f89d2485 2672.section "Command line options" "SECID39"
db9452a9
PH
2673Exim's command line options are described in alphabetical order below. If none
2674of the options that specifies a specific action (such as starting the daemon or
2675a queue runner, or testing an address, or receiving a message in a specific
2676format, or listing the queue) are present, and there is at least one argument
2677on the command line, &%-bm%& (accept a local message on the standard input,
2678with the arguments specifying the recipients) is assumed. Otherwise, Exim
2679outputs a brief message about itself and exits.
168e428f 2680
9b371988
PH
2681. ////////////////////////////////////////////////////////////////////////////
2682. Insert a stylized XML comment here, to identify the start of the command line
2683. options. This is for the benefit of the Perl script that automatically
2684. creates a man page for the options.
2685. ////////////////////////////////////////////////////////////////////////////
168e428f 2686
9b371988 2687.literal xml
168e428f 2688<!-- === Start of command line options === -->
9b371988 2689.literal off
168e428f
PH
2690
2691
9b371988
PH
2692.vlist
2693.vitem &%--%&
2694.oindex "--"
2695.cindex "options" "command line; terminating"
168e428f
PH
2696This is a pseudo-option whose only purpose is to terminate the options and
2697therefore to cause subsequent command line items to be treated as arguments
2698rather than options, even if they begin with hyphens.
2699
9b371988
PH
2700.vitem &%--help%&
2701.oindex "&%--help%&"
168e428f
PH
2702This option causes Exim to output a few sentences stating what it is.
2703The same output is generated if the Exim binary is called with no options and
2704no arguments.
2705
4b2241d2
PP
2706.vitem &%--version%&
2707.oindex "&%--version%&"
2708This option is an alias for &%-bV%& and causes version information to be
2709displayed.
2710
a3fb9793
PP
2711.vitem &%-Ac%& &&&
2712 &%-Am%&
2713.oindex "&%-Ac%&"
2714.oindex "&%-Am%&"
2715These options are used by Sendmail for selecting configuration files and are
2716ignored by Exim.
a3fb9793 2717
9b371988
PH
2718.vitem &%-B%&<&'type'&>
2719.oindex "&%-B%&"
2720.cindex "8-bit characters"
2721.cindex "Sendmail compatibility" "8-bit characters"
168e428f
PH
2722This is a Sendmail option for selecting 7 or 8 bit processing. Exim is 8-bit
2723clean; it ignores this option.
2724
9b371988
PH
2725.vitem &%-bd%&
2726.oindex "&%-bd%&"
2727.cindex "daemon"
f89d2485 2728.cindex "SMTP" "listener"
9b371988 2729.cindex "queue runner"
168e428f 2730This option runs Exim as a daemon, awaiting incoming SMTP connections. Usually
9b371988
PH
2731the &%-bd%& option is combined with the &%-q%&<&'time'&> option, to specify
2732that the daemon should also initiate periodic queue runs.
2733
2734The &%-bd%& option can be used only by an admin user. If either of the &%-d%&
2735(debugging) or &%-v%& (verifying) options are set, the daemon does not
168e428f
PH
2736disconnect from the controlling terminal. When running this way, it can be
2737stopped by pressing ctrl-C.
9b371988 2738
168e428f
PH
2739By default, Exim listens for incoming connections to the standard SMTP port on
2740all the host's running interfaces. However, it is possible to listen on other
2741ports, on multiple ports, and only on specific interfaces. Chapter
9b371988
PH
2742&<<CHAPinterfaces>>& contains a description of the options that control this.
2743
168e428f 2744When a listening daemon
9b371988
PH
2745.cindex "daemon" "process id (pid)"
2746.cindex "pid (process id)" "of daemon"
2747is started without the use of &%-oX%& (that is, without overriding the normal
2748configuration), it writes its process id to a file called &_exim-daemon.pid_&
2749in Exim's spool directory. This location can be overridden by setting
2750PID_FILE_PATH in &_Local/Makefile_&. The file is written while Exim is still
168e428f 2751running as root.
9b371988
PH
2752
2753When &%-oX%& is used on the command line to start a listening daemon, the
2754process id is not written to the normal pid file path. However, &%-oP%& can be
168e428f 2755used to specify a path on the command line if a pid file is required.
9b371988 2756
168e428f 2757The SIGHUP signal
9b371988 2758.cindex "SIGHUP"
3cb1b51e
PH
2759.cindex "daemon" "restarting"
2760can be used to cause the daemon to re-execute itself. This should be done
2761whenever Exim's configuration file, or any file that is incorporated into it by
2762means of the &%.include%& facility, is changed, and also whenever a new version
2763of Exim is installed. It is not necessary to do this when other files that are
9b371988
PH
2764referenced from the configuration (for example, alias files) are changed,
2765because these are reread each time they are used.
2766
2767.vitem &%-bdf%&
2768.oindex "&%-bdf%&"
2769This option has the same effect as &%-bd%& except that it never disconnects
2770from the controlling terminal, even when no debugging is specified.
2771
2772.vitem &%-be%&
2773.oindex "&%-be%&"
2774.cindex "testing" "string expansion"
2775.cindex "expansion" "testing"
168e428f
PH
2776Run Exim in expansion testing mode. Exim discards its root privilege, to
2777prevent ordinary users from using this mode to read otherwise inaccessible
2778files. If no arguments are given, Exim runs interactively, prompting for lines
4f578862 2779of data. Otherwise, it processes each argument in turn.
9b371988
PH
2780
2781If Exim was built with USE_READLINE=yes in &_Local/Makefile_&, it tries
2782to load the &%libreadline%& library dynamically whenever the &%-be%& option is
2783used without command line arguments. If successful, it uses the &[readline()]&
168e428f
PH
2784function, which provides extensive line-editing facilities, for reading the
2785test data. A line history is supported.
9b371988 2786
168e428f 2787Long expansion expressions can be split over several lines by using backslash
068aaea8 2788continuations. As in Exim's run time configuration, white space at the start of
168e428f
PH
2789continuation lines is ignored. Each argument or data line is passed through the
2790string expansion mechanism, and the result is output. Variable values from the
9b371988 2791configuration file (for example, &$qualify_domain$&) are available, but no
374dc194 2792message-specific values (such as &$message_exim_id$&) are set, because no message
f89d2485 2793is being processed (but see &%-bem%& and &%-Mset%&).
168e428f 2794
9b371988
PH
2795&*Note*&: If you use this mechanism to test lookups, and you change the data
2796files or databases you are using, you must exit and restart Exim before trying
2797the same lookup again. Otherwise, because each Exim process caches the results
2798of lookups, you will just get the same result as before.
9b371988 2799
3cb1b51e
PH
2800.vitem &%-bem%&&~<&'filename'&>
2801.oindex "&%-bem%&"
2802.cindex "testing" "string expansion"
2803.cindex "expansion" "testing"
2804This option operates like &%-be%& except that it must be followed by the name
2805of a file. For example:
2806.code
2807exim -bem /tmp/testmessage
2808.endd
2809The file is read as a message (as if receiving a locally-submitted non-SMTP
2810message) before any of the test expansions are done. Thus, message-specific
2811variables such as &$message_size$& and &$header_from:$& are available. However,
2812no &'Received:'& header is added to the message. If the &%-t%& option is set,
2813recipients are read from the headers in the normal way, and are shown in the
2814&$recipients$& variable. Note that recipients cannot be given on the command
2815line, because further arguments are taken as strings to expand (just like
2816&%-be%&).
3cb1b51e 2817
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2818.vitem &%-bF%&&~<&'filename'&>
2819.oindex "&%-bF%&"
2820.cindex "system filter" "testing"
2821.cindex "testing" "system filter"
2822This option is the same as &%-bf%& except that it assumes that the filter being
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PH
2823tested is a system filter. The additional commands that are available only in
2824system filters are recognized.
2825
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PH
2826.vitem &%-bf%&&~<&'filename'&>
2827.oindex "&%-bf%&"
2828.cindex "filter" "testing"
2829.cindex "testing" "filter file"
2830.cindex "forward file" "testing"
2831.cindex "testing" "forward file"
2832.cindex "Sieve filter" "testing"
168e428f
PH
2833This option runs Exim in user filter testing mode; the file is the filter file
2834to be tested, and a test message must be supplied on the standard input. If
2835there are no message-dependent tests in the filter, an empty file can be
2836supplied.
168e428f 2837
9b371988
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2838If you want to test a system filter file, use &%-bF%& instead of &%-bf%&. You
2839can use both &%-bF%& and &%-bf%& on the same command, in order to test a system
2840filter and a user filter in the same run. For example:
2841.code
2842exim -bF /system/filter -bf /user/filter </test/message
2843.endd
168e428f
PH
2844This is helpful when the system filter adds header lines or sets filter
2845variables that are used by the user filter.
168e428f 2846
9b371988
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2847If the test filter file does not begin with one of the special lines
2848.code
2849# Exim filter
2850# Sieve filter
2851.endd
2852it is taken to be a normal &_.forward_& file, and is tested for validity under
2853that interpretation. See sections &<<SECTitenonfilred>>& to
2854&<<SECTspecitredli>>& for a description of the possible contents of non-filter
2855redirection lists.
2856
2857The result of an Exim command that uses &%-bf%&, provided no errors are
168e428f
PH
2858detected, is a list of the actions that Exim would try to take if presented
2859with the message for real. More details of filter testing are given in the
9b371988
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2860separate document entitled &'Exim's interfaces to mail filtering'&.
2861
168e428f 2862When testing a filter file,
9b371988
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2863.cindex "&""From""& line"
2864.cindex "envelope sender"
f89d2485 2865.oindex "&%-f%&" "for filter testing"
9b371988
PH
2866the envelope sender can be set by the &%-f%& option,
2867or by a &"From&~"& line at the start of the test message. Various parameters
2868that would normally be taken from the envelope recipient address of the message
2869can be set by means of additional command line options (see the next four
2870options).
2871
2872.vitem &%-bfd%&&~<&'domain'&>
2873.oindex "&%-bfd%&"
f89d2485 2874.vindex "&$qualify_domain$&"
168e428f 2875This sets the domain of the recipient address when a filter file is being
9b371988
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2876tested by means of the &%-bf%& option. The default is the value of
2877&$qualify_domain$&.
168e428f 2878
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2879.vitem &%-bfl%&&~<&'local&~part'&>
2880.oindex "&%-bfl%&"
168e428f 2881This sets the local part of the recipient address when a filter file is being
9b371988 2882tested by means of the &%-bf%& option. The default is the username of the
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2883process that calls Exim. A local part should be specified with any prefix or
2884suffix stripped, because that is how it appears to the filter when a message is
2885actually being delivered.
2886
9b371988
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2887.vitem &%-bfp%&&~<&'prefix'&>
2888.oindex "&%-bfp%&"
168e428f 2889This sets the prefix of the local part of the recipient address when a filter
9b371988 2890file is being tested by means of the &%-bf%& option. The default is an empty
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2891prefix.
2892
9b371988
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2893.vitem &%-bfs%&&~<&'suffix'&>
2894.oindex "&%-bfs%&"
168e428f 2895This sets the suffix of the local part of the recipient address when a filter
9b371988 2896file is being tested by means of the &%-bf%& option. The default is an empty
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2897suffix.
2898
9b371988
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2899.vitem &%-bh%&&~<&'IP&~address'&>
2900.oindex "&%-bh%&"
2901.cindex "testing" "incoming SMTP"
2902.cindex "SMTP" "testing incoming"
2903.cindex "testing" "relay control"
2904.cindex "relaying" "testing configuration"
2905.cindex "policy control" "testing"
2906.cindex "debugging" "&%-bh%& option"
168e428f
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2907This option runs a fake SMTP session as if from the given IP address, using the
2908standard input and output. The IP address may include a port number at the end,
2909after a full stop. For example:
9b371988
PH
2910.code
2911exim -bh 10.9.8.7.1234
2912exim -bh fe80::a00:20ff:fe86:a061.5678
2913.endd
168e428f 2914When an IPv6 address is given, it is converted into canonical form. In the case
9b371988
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2915of the second example above, the value of &$sender_host_address$& after
2916conversion to the canonical form is
2917&`fe80:0000:0000:0a00:20ff:fe86:a061.5678`&.
2918
168e428f 2919Comments as to what is going on are written to the standard error file. These
9b371988 2920include lines beginning with &"LOG"& for anything that would have been logged.
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2921This facility is provided for testing configuration options for incoming
2922messages, to make sure they implement the required policy. For example, you can
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2923test your relay controls using &%-bh%&.
2924
2925&*Warning 1*&:
2926.cindex "RFC 1413"
db9452a9
PH
2927You can test features of the configuration that rely on ident (RFC 1413)
2928information by using the &%-oMt%& option. However, Exim cannot actually perform
2929an ident callout when testing using &%-bh%& because there is no incoming SMTP
2930connection.
9b371988
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2931
2932&*Warning 2*&: Address verification callouts (see section &<<SECTcallver>>&)
2933are also skipped when testing using &%-bh%&. If you want these callouts to
2934occur, use &%-bhc%& instead.
2935
168e428f
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2936Messages supplied during the testing session are discarded, and nothing is
2937written to any of the real log files. There may be pauses when DNS (and other)
9b371988 2938lookups are taking place, and of course these may time out. The &%-oMi%& option
db9452a9
PH
2939can be used to specify a specific IP interface and port if this is important,
2940and &%-oMaa%& and &%-oMai%& can be used to set parameters as if the SMTP
2941session were authenticated.
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2942
2943The &'exim_checkaccess'& utility is a &"packaged"& version of &%-bh%& whose
168e428f 2944output just states whether a given recipient address from a given host is
9b371988 2945acceptable or not. See section &<<SECTcheckaccess>>&.
168e428f 2946
3cb1b51e 2947Features such as authentication and encryption, where the client input is not
f89d2485
PH
2948plain text, cannot easily be tested with &%-bh%&. Instead, you should use a
2949specialized SMTP test program such as
3cb1b51e 2950&url(http://jetmore.org/john/code/#swaks,swaks).
3cb1b51e 2951
9b371988
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2952.vitem &%-bhc%&&~<&'IP&~address'&>
2953.oindex "&%-bhc%&"
2954This option operates in the same way as &%-bh%&, except that address
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PH
2955verification callouts are performed if required. This includes consulting and
2956updating the callout cache database.
2957
9b371988
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2958.vitem &%-bi%&
2959.oindex "&%-bi%&"
2960.cindex "alias file" "building"
2961.cindex "building alias file"
2962.cindex "Sendmail compatibility" "&%-bi%& option"
2963Sendmail interprets the &%-bi%& option as a request to rebuild its alias file.
168e428f 2964Exim does not have the concept of a single alias file, and so it cannot mimic
9b371988 2965this behaviour. However, calls to &_/usr/lib/sendmail_& with the &%-bi%& option
168e428f
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2966tend to appear in various scripts such as NIS make files, so the option must be
2967recognized.
9b371988
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2968
2969If &%-bi%& is encountered, the command specified by the &%bi_command%&
168e428f 2970configuration option is run, under the uid and gid of the caller of Exim. If
9b371988
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2971the &%-oA%& option is used, its value is passed to the command as an argument.
2972The command set by &%bi_command%& may not contain arguments. The command can
2973use the &'exim_dbmbuild'& utility, or some other means, to rebuild alias files
2974if this is required. If the &%bi_command%& option is not set, calling Exim with
2975&%-bi%& is a no-op.
2976
36a3ae5f 2977. // Keep :help first, then the rest in alphabetical order
98a90c36
PP
2978.vitem &%-bI:help%&
2979.oindex "&%-bI:help%&"
2980.cindex "querying exim information"
2981We shall provide various options starting &`-bI:`& for querying Exim for
2982information. The output of many of these will be intended for machine
2983consumption. This one is not. The &%-bI:help%& option asks Exim for a
2984synopsis of supported options beginning &`-bI:`&. Use of any of these
2985options shall cause Exim to exit after producing the requested output.
2986
36a3ae5f
PP
2987.vitem &%-bI:dscp%&
2988.oindex "&%-bI:dscp%&"
2989.cindex "DSCP" "values"
2990This option causes Exim to emit an alphabetically sorted list of all
2991recognised DSCP names.
2992
98a90c36
PP
2993.vitem &%-bI:sieve%&
2994.oindex "&%-bI:sieve%&"
2995.cindex "Sieve filter" "capabilities"
2996This option causes Exim to emit an alphabetically sorted list of all supported
2997Sieve protocol extensions on stdout, one per line. This is anticipated to be
2998useful for ManageSieve (RFC 5804) implementations, in providing that protocol's
2999&`SIEVE`& capability response line. As the precise list may depend upon
3000compile-time build options, which this option will adapt to, this is the only
3001way to guarantee a correct response.
3002
9b371988
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3003.vitem &%-bm%&
3004.oindex "&%-bm%&"
3005.cindex "local message reception"
168e428f 3006This option runs an Exim receiving process that accepts an incoming,
a543079f 3007locally-generated message on the standard input. The recipients are given as the
9b371988 3008command arguments (except when &%-t%& is also present &-- see below). Each
168e428f
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3009argument can be a comma-separated list of RFC 2822 addresses. This is the
3010default option for selecting the overall action of an Exim call; it is assumed
3011if no other conflicting option is present.
9b371988 3012
168e428f 3013If any addresses in the message are unqualified (have no domain), they are
9b371988
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3014qualified by the values of the &%qualify_domain%& or &%qualify_recipient%&
3015options, as appropriate. The &%-bnq%& option (see below) provides a way of
168e428f 3016suppressing this for special cases.
9b371988 3017
168e428f 3018Policy checks on the contents of local messages can be enforced by means of
9b371988
PH
3019the non-SMTP ACL. See chapter &<<CHAPACL>>& for details.
3020
3021.cindex "return code" "for &%-bm%&"
3022The return code is zero if the message is successfully accepted. Otherwise, the
3023action is controlled by the &%-oe%&&'x'& option setting &-- see below.
3024
168e428f 3025The format
9b371988
PH
3026.cindex "message" "format"
3027.cindex "format" "message"
3028.cindex "&""From""& line"
3029.cindex "UUCP" "&""From""& line"
3030.cindex "Sendmail compatibility" "&""From""& line"
168e428f
PH
3031of the message must be as defined in RFC 2822, except that, for
3032compatibility with Sendmail and Smail, a line in one of the forms
9b371988
PH
3033.code
3034From sender Fri Jan 5 12:55 GMT 1997
3035From sender Fri, 5 Jan 97 12:55:01
3036.endd
168e428f
PH
3037(with the weekday optional, and possibly with additional text after the date)
3038is permitted to appear at the start of the message. There appears to be no
3039authoritative specification of the format of this line. Exim recognizes it by
9b371988 3040matching against the regular expression defined by the &%uucp_from_pattern%&
168e428f 3041option, which can be changed if necessary.
9b371988 3042
f89d2485
PH
3043.oindex "&%-f%&" "overriding &""From""& line"
3044The specified sender is treated as if it were given as the argument to the
9b371988 3045&%-f%& option, but if a &%-f%& option is also present, its argument is used in
168e428f
PH
3046preference to the address taken from the message. The caller of Exim must be a
3047trusted user for the sender of a message to be set in this way.
3048
5b257915
PP
3049.vitem &%-bmalware%&&~<&'filename'&>
3050.oindex "&%-bmalware%&"
3051.cindex "testing", "malware"
3052.cindex "malware scan test"
60f914bc
HSHR
3053This debugging option causes Exim to scan the given file or directory
3054(depending on the used scanner interface),
5b257915
PP
3055using the malware scanning framework. The option of &%av_scanner%& influences
3056this option, so if &%av_scanner%&'s value is dependent upon an expansion then
3057the expansion should have defaults which apply to this invocation. ACLs are
3058not invoked, so if &%av_scanner%& references an ACL variable then that variable
3059will never be populated and &%-bmalware%& will fail.
3060
3061Exim will have changed working directory before resolving the filename, so