Docs: prettify code examples. Bug 1284
[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
8d042305 48.set previousversion "4.87"
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
80fea873 552016
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
32a1dd3f 374.new
9b371988 375.cindex "documentation"
2aee48d6 376This edition of the Exim specification applies to version &version() of Exim.
9b371988 377Substantive changes from the &previousversion; edition are marked in some
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378renditions of the document; this paragraph is so marked if the rendition is
379capable of showing a change indicator.
32a1dd3f 380.wen
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381
382This document is very much a reference manual; it is not a tutorial. The reader
383is expected to have some familiarity with the SMTP mail transfer protocol and
384with general Unix system administration. Although there are some discussions
385and examples in places, the information is mostly organized in a way that makes
386it easy to look up, rather than in a natural order for sequential reading.
387Furthermore, the manual aims to cover every aspect of Exim in detail, including
388a number of rarely-used, special-purpose features that are unlikely to be of
389very wide interest.
390
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391.cindex "books about Exim"
392An &"easier"& discussion of Exim which provides more in-depth explanatory,
393introductory, and tutorial material can be found in a book entitled &'The Exim
595028e4 394SMTP Mail Server'& (second edition, 2007), published by UIT Cambridge
9b371988 395(&url(http://www.uit.co.uk/exim-book/)).
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396
397This book also contains a chapter that gives a general introduction to SMTP and
398Internet mail. Inevitably, however, the book is unlikely to be fully up-to-date
399with the latest release of Exim. (Note that the earlier book about Exim,
400published by O'Reilly, covers Exim 3, and many things have changed in Exim 4.)
401
9b371988 402.cindex "Debian" "information sources"
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403If you are using a Debian distribution of Exim, you will find information about
404Debian-specific features in the file
f89d2485 405&_/usr/share/doc/exim4-base/README.Debian_&.
9b371988 406The command &(man update-exim.conf)& is another source of Debian-specific
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407information.
408
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409.cindex "&_doc/NewStuff_&"
410.cindex "&_doc/ChangeLog_&"
411.cindex "change log"
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412As the program develops, there may be features in newer versions that have not
413yet made it into this document, which is updated only when the most significant
414digit of the fractional part of the version number changes. Specifications of
415new features that are not yet in this manual are placed in the file
9b371988 416&_doc/NewStuff_& in the Exim distribution.
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9b371988 418Some features may be classified as &"experimental"&. These may change
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419incompatibly while they are developing, or even be withdrawn. For this reason,
420they are not documented in this manual. Information about experimental features
9b371988 421can be found in the file &_doc/experimental.txt_&.
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422
423All changes to the program (whether new features, bug fixes, or other kinds of
9b371988 424change) are noted briefly in the file called &_doc/ChangeLog_&.
168e428f 425
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426.cindex "&_doc/spec.txt_&"
427This specification itself is available as an ASCII file in &_doc/spec.txt_& so
428that it can easily be searched with a text editor. Other files in the &_doc_&
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429directory are:
430
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431.table2 100pt
432.row &_OptionLists.txt_& "list of all options in alphabetical order"
433.row &_dbm.discuss.txt_& "discussion about DBM libraries"
434.row &_exim.8_& "a man page of Exim's command line options"
435.row &_experimental.txt_& "documentation of experimental features"
436.row &_filter.txt_& "specification of the filter language"
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437.row &_Exim3.upgrade_& "upgrade notes from release 2 to release 3"
438.row &_Exim4.upgrade_& "upgrade notes from release 3 to release 4"
439.endtable
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440
441The main specification and the specification of the filtering language are also
442available in other formats (HTML, PostScript, PDF, and Texinfo). Section
9b371988 443&<<SECTavail>>& below tells you how to get hold of these.
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444
445
446
f89d2485 447.section "FTP and web sites" "SECID2"
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448.cindex "web site"
449.cindex "FTP site"
068aaea8 450The primary site for Exim source distributions is currently the University of
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451Cambridge's FTP site, whose contents are described in &'Where to find the Exim
452distribution'& below. In addition, there is a web site and an FTP site at
453&%exim.org%&. These are now also hosted at the University of Cambridge. The
454&%exim.org%& site was previously hosted for a number of years by Energis
455Squared, formerly Planet Online Ltd, whose support I gratefully acknowledge.
456
457.cindex "wiki"
458.cindex "FAQ"
168e428f 459As well as Exim distribution tar files, the Exim web site contains a number of
f89d2485 460differently formatted versions of the documentation. A recent addition to the
7d0ab55c 461online information is the Exim wiki (&url(http://wiki.exim.org)),
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462which contains what used to be a separate FAQ, as well as various other
463examples, tips, and know-how that have been contributed by Exim users.
464
465.cindex Bugzilla
7d0ab55c 466An Exim Bugzilla exists at &url(http://bugs.exim.org). You can use
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467this to report bugs, and also to add items to the wish list. Please search
468first to check that you are not duplicating a previous entry.
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469
470
471
f89d2485 472.section "Mailing lists" "SECID3"
9b371988 473.cindex "mailing lists" "for Exim users"
f89d2485 474The following Exim mailing lists exist:
168e428f 475
9b371988 476.table2 140pt
d854d3a9 477.row &'exim-announce@exim.org'& "Moderated, low volume announcements list"
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478.row &'exim-users@exim.org'& "General discussion list"
479.row &'exim-dev@exim.org'& "Discussion of bugs, enhancements, etc."
d854d3a9 480.row &'exim-cvs@exim.org'& "Automated commit messages from the VCS"
9b371988 481.endtable
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482
483You can subscribe to these lists, change your existing subscriptions, and view
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484or search the archives via the mailing lists link on the Exim home page.
485.cindex "Debian" "mailing list for"
4f578862 486If you are using a Debian distribution of Exim, you may wish to subscribe to
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487the Debian-specific mailing list &'pkg-exim4-users@lists.alioth.debian.org'&
488via this web page:
489.display
490&url(http://lists.alioth.debian.org/mailman/listinfo/pkg-exim4-users)
491.endd
492Please ask Debian-specific questions on this list and not on the general Exim
493lists.
9b371988 494
f89d2485 495.section "Exim training" "SECID4"
9b371988 496.cindex "training courses"
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497Training courses in Cambridge (UK) used to be run annually by the author of
498Exim, before he retired. At the time of writing, there are no plans to run
499further Exim courses in Cambridge. However, if that changes, relevant
500information will be posted at &url(http://www-tus.csx.cam.ac.uk/courses/exim/).
168e428f 501
f89d2485 502.section "Bug reports" "SECID5"
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503.cindex "bug reports"
504.cindex "reporting bugs"
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505Reports of obvious bugs can be emailed to &'bugs@exim.org'& or reported
506via the Bugzilla (&url(http://bugs.exim.org)). However, if you are unsure
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507whether some behaviour is a bug or not, the best thing to do is to post a
508message to the &'exim-dev'& mailing list and have it discussed.
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509
510
511
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512.section "Where to find the Exim distribution" "SECTavail"
513.cindex "FTP site"
514.cindex "distribution" "ftp site"
168e428f 515The master ftp site for the Exim distribution is
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516.display
517&*ftp://ftp.csx.cam.ac.uk/pub/software/email/exim*&
518.endd
168e428f 519This is mirrored by
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520.display
521&*ftp://ftp.exim.org/pub/exim*&
522.endd
523The file references that follow are relative to the &_exim_& directories at
524these sites. There are now quite a number of independent mirror sites around
525the world. Those that I know about are listed in the file called &_Mirrors_&.
526
527Within the &_exim_& directory there are subdirectories called &_exim3_& (for
528previous Exim 3 distributions), &_exim4_& (for the latest Exim 4
529distributions), and &_Testing_& for testing versions. In the &_exim4_&
168e428f 530subdirectory, the current release can always be found in files called
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531.display
532&_exim-n.nn.tar.gz_&
533&_exim-n.nn.tar.bz2_&
534.endd
535where &'n.nn'& is the highest such version number in the directory. The two
168e428f 536files contain identical data; the only difference is the type of compression.
9b371988 537The &_.bz2_& file is usually a lot smaller than the &_.gz_& file.
168e428f 538
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539.cindex "distribution" "signing details"
540.cindex "distribution" "public key"
541.cindex "public key for signed distribution"
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542The distributions will be PGP signed by an individual key of the Release
543Coordinator. This key will have a uid containing an email address in the
544&'exim.org'& domain and will have signatures from other people, including
545other Exim maintainers. We expect that the key will be in the "strong set" of
546PGP keys. There should be a trust path to that key from Nigel Metheringham's
547PGP key, a version of which can be found in the release directory in the file
548&_nigel-pubkey.asc_&. All keys used will be available in public keyserver pools,
549such as &'pool.sks-keyservers.net'&.
550
551At time of last update, releases were being made by Phil Pennock and signed with
552key &'0x403043153903637F'&, although that key is expected to be replaced in 2013.
553A trust path from Nigel's key to Phil's can be observed at
554&url(https://www.security.spodhuis.org/exim-trustpath).
85b2d6f3 555
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556Releases have also been authorized to be performed by Todd Lyons who signs with
557key &'0xC4F4F94804D29EBA'&. A direct trust path exists between previous RE Phil
558Pennock and Todd Lyons through a common associate.
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559
560The signatures for the tar bundles are in:
9b371988 561.display
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562&_exim-n.nn.tar.gz.asc_&
563&_exim-n.nn.tar.bz2.asc_&
9b371988 564.endd
168e428f 565For each released version, the log of changes is made separately available in a
9b371988 566separate file in the directory &_ChangeLogs_& so that it is possible to
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567find out what has changed without having to download the entire distribution.
568
9b371988 569.cindex "documentation" "available formats"
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570The main distribution contains ASCII versions of this specification and other
571documentation; other formats of the documents are available in separate files
9b371988
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572inside the &_exim4_& directory of the FTP site:
573.display
574&_exim-html-n.nn.tar.gz_&
575&_exim-pdf-n.nn.tar.gz_&
576&_exim-postscript-n.nn.tar.gz_&
577&_exim-texinfo-n.nn.tar.gz_&
578.endd
579These tar files contain only the &_doc_& directory, not the complete
580distribution, and are also available in &_.bz2_& as well as &_.gz_& forms.
168e428f 581
168e428f 582
f89d2485 583.section "Limitations" "SECID6"
9b371988
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584.ilist
585.cindex "limitations of Exim"
586.cindex "bang paths" "not handled by Exim"
587Exim is designed for use as an Internet MTA, and therefore handles addresses in
588RFC 2822 domain format only. It cannot handle UUCP &"bang paths"&, though
589simple two-component bang paths can be converted by a straightforward rewriting
590configuration. This restriction does not prevent Exim from being interfaced to
591UUCP as a transport mechanism, provided that domain addresses are used.
592.next
593.cindex "domainless addresses"
594.cindex "address" "without domain"
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595Exim insists that every address it handles has a domain attached. For incoming
596local messages, domainless addresses are automatically qualified with a
597configured domain value. Configuration options specify from which remote
598systems unqualified addresses are acceptable. These are then qualified on
599arrival.
9b371988
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600.next
601.cindex "transport" "external"
602.cindex "external transports"
603The only external transport mechanisms that are currently implemented are SMTP
604and LMTP over a TCP/IP network (including support for IPv6). However, a pipe
168e428f 605transport is available, and there are facilities for writing messages to files
9b371988
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606and pipes, optionally in &'batched SMTP'& format; these facilities can be used
607to send messages to other transport mechanisms such as UUCP, provided they can
608handle domain-style addresses. Batched SMTP input is also catered for.
609.next
610Exim is not designed for storing mail for dial-in hosts. When the volumes of
611such mail are large, it is better to get the messages &"delivered"& into files
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612(that is, off Exim's queue) and subsequently passed on to the dial-in hosts by
613other means.
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614.next
615Although Exim does have basic facilities for scanning incoming messages, these
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616are not comprehensive enough to do full virus or spam scanning. Such operations
617are best carried out using additional specialized software packages. If you
618compile Exim with the content-scanning extension, straightforward interfaces to
619a number of common scanners are provided.
9b371988 620.endlist
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621
622
f89d2485 623.section "Run time configuration" "SECID7"
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624Exim's run time configuration is held in a single text file that is divided
625into a number of sections. The entries in this file consist of keywords and
626values, in the style of Smail 3 configuration files. A default configuration
627file which is suitable for simple online installations is provided in the
9b371988 628distribution, and is described in chapter &<<CHAPdefconfil>>& below.
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629
630
f89d2485 631.section "Calling interface" "SECID8"
9b371988 632.cindex "Sendmail compatibility" "command line interface"
168e428f 633Like many MTAs, Exim has adopted the Sendmail command line interface so that it
9b371988
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634can be a straight replacement for &_/usr/lib/sendmail_& or
635&_/usr/sbin/sendmail_& when sending mail, but you do not need to know anything
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636about Sendmail in order to run Exim. For actions other than sending messages,
637Sendmail-compatible options also exist, but those that produce output (for
9b371988 638example, &%-bp%&, which lists the messages on the queue) do so in Exim's own
168e428f 639format. There are also some additional options that are compatible with Smail
9b371988 6403, and some further options that are new to Exim. Chapter &<<CHAPcommandline>>&
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641documents all Exim's command line options. This information is automatically
642made into the man page that forms part of the Exim distribution.
643
644Control of messages on the queue can be done via certain privileged command
9b371988
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645line options. There is also an optional monitor program called &'eximon'&,
646which displays current information in an X window, and which contains a menu
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647interface to Exim's command line administration options.
648
649
650
f89d2485 651.section "Terminology" "SECID9"
9b371988
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652.cindex "terminology definitions"
653.cindex "body of message" "definition of"
654The &'body'& of a message is the actual data that the sender wants to transmit.
655It is the last part of a message, and is separated from the &'header'& (see
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656below) by a blank line.
657
9b371988 658.cindex "bounce message" "definition of"
168e428f 659When a message cannot be delivered, it is normally returned to the sender in a
9b371988
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660delivery failure message or a &"non-delivery report"& (NDR). The term
661&'bounce'& is commonly used for this action, and the error reports are often
662called &'bounce messages'&. This is a convenient shorthand for &"delivery
663failure error report"&. Such messages have an empty sender address in the
664message's &'envelope'& (see below) to ensure that they cannot themselves give
665rise to further bounce messages.
666
667The term &'default'& appears frequently in this manual. It is used to qualify a
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668value which is used in the absence of any setting in the configuration. It may
669also qualify an action which is taken unless a configuration setting specifies
670otherwise.
671
9b371988 672The term &'defer'& is used when the delivery of a message to a specific
168e428f 673destination cannot immediately take place for some reason (a remote host may be
9b371988 674down, or a user's local mailbox may be full). Such deliveries are &'deferred'&
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675until a later time.
676
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677The word &'domain'& is sometimes used to mean all but the first component of a
678host's name. It is &'not'& used in that sense here, where it normally refers to
679the part of an email address following the @ sign.
168e428f 680
f89d2485 681.cindex "envelope, definition of"
9b371988
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682.cindex "sender" "definition of"
683A message in transit has an associated &'envelope'&, as well as a header and a
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684body. The envelope contains a sender address (to which bounce messages should
685be delivered), and any number of recipient addresses. References to the
686sender or the recipients of a message usually mean the addresses in the
687envelope. An MTA uses these addresses for delivery, and for returning bounce
688messages, not the addresses that appear in the header lines.
689
f89d2485 690.cindex "message" "header, definition of"
9b371988
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691.cindex "header section" "definition of"
692The &'header'& of a message is the first part of a message's text, consisting
693of a number of lines, each of which has a name such as &'From:'&, &'To:'&,
694&'Subject:'&, etc. Long header lines can be split over several text lines by
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695indenting the continuations. The header is separated from the body by a blank
696line.
697
9b371988
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698.cindex "local part" "definition of"
699.cindex "domain" "definition of"
700The term &'local part'&, which is taken from RFC 2822, is used to refer to that
168e428f 701part of an email address that precedes the @ sign. The part that follows the
9b371988 702@ sign is called the &'domain'& or &'mail domain'&.
168e428f 703
9b371988 704.cindex "local delivery" "definition of"
f89d2485 705.cindex "remote delivery, definition of"
9b371988 706The terms &'local delivery'& and &'remote delivery'& are used to distinguish
168e428f 707delivery to a file or a pipe on the local host from delivery by SMTP over
068aaea8 708TCP/IP to another host. As far as Exim is concerned, all hosts other than the
9b371988 709host it is running on are &'remote'&.
168e428f 710
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711.cindex "return path" "definition of"
712&'Return path'& is another name that is used for the sender address in a
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713message's envelope.
714
9b371988
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715.cindex "queue" "definition of"
716The term &'queue'& is used to refer to the set of messages awaiting delivery,
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717because this term is in widespread use in the context of MTAs. However, in
718Exim's case the reality is more like a pool than a queue, because there is
719normally no ordering of waiting messages.
720
9b371988
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721.cindex "queue runner" "definition of"
722The term &'queue runner'& is used to describe a process that scans the queue
168e428f 723and attempts to deliver those messages whose retry times have come. This term
9b371988 724is used by other MTAs, and also relates to the command &%runq%&, but in Exim
168e428f
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725the waiting messages are normally processed in an unpredictable order.
726
9b371988
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727.cindex "spool directory" "definition of"
728The term &'spool directory'& is used for a directory in which Exim keeps the
729messages on its queue &-- that is, those that it is in the process of
168e428f 730delivering. This should not be confused with the directory in which local
9b371988
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731mailboxes are stored, which is called a &"spool directory"& by some people. In
732the Exim documentation, &"spool"& is always used in the first sense.
168e428f
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733
734
735
736
737
738
9b371988
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739. ////////////////////////////////////////////////////////////////////////////
740. ////////////////////////////////////////////////////////////////////////////
168e428f 741
f89d2485 742.chapter "Incorporated code" "CHID2"
9b371988
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743.cindex "incorporated code"
744.cindex "regular expressions" "library"
745.cindex "PCRE"
1899bab2 746.cindex "OpenDMARC"
168e428f
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747A number of pieces of external code are included in the Exim distribution.
748
9b371988 749.ilist
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750Regular expressions are supported in the main Exim program and in the
751Exim monitor using the freely-distributable PCRE library, copyright
40df1be3
TF
752&copy; University of Cambridge. The source to PCRE is no longer shipped with
753Exim, so you will need to use the version of PCRE shipped with your system,
754or obtain and install the full version of the library from
f89d2485 755&url(ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre).
9b371988 756.next
f89d2485 757.cindex "cdb" "acknowledgment"
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758Support for the cdb (Constant DataBase) lookup method is provided by code
759contributed by Nigel Metheringham of (at the time he contributed it) Planet
9b371988
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760Online Ltd. The implementation is completely contained within the code of Exim.
761It does not link against an external cdb library. The code contains the
762following statements:
763
764.blockquote
765Copyright &copy; 1998 Nigel Metheringham, Planet Online Ltd
766
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767This program is free software; you can redistribute it and/or modify it under
768the terms of the GNU General Public License as published by the Free Software
769Foundation; either version 2 of the License, or (at your option) any later
770version.
168e428f
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771This code implements Dan Bernstein's Constant DataBase (cdb) spec. Information,
772the spec and sample code for cdb can be obtained from
f89d2485
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773&url(http://www.pobox.com/~djb/cdb.html). This implementation borrows
774some code from Dan Bernstein's implementation (which has no license
775restrictions applied to it).
9b371988
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776.endblockquote
777.next
778.cindex "SPA authentication"
779.cindex "Samba project"
780.cindex "Microsoft Secure Password Authentication"
781Client support for Microsoft's &'Secure Password Authentication'& is provided
168e428f
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782by code contributed by Marc Prud'hommeaux. Server support was contributed by
783Tom Kistner. This includes code taken from the Samba project, which is released
784under the Gnu GPL.
9b371988
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785.next
786.cindex "Cyrus"
787.cindex "&'pwcheck'& daemon"
788.cindex "&'pwauthd'& daemon"
789Support for calling the Cyrus &'pwcheck'& and &'saslauthd'& daemons is provided
168e428f
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790by code taken from the Cyrus-SASL library and adapted by Alexander S.
791Sabourenkov. The permission notice appears below, in accordance with the
792conditions expressed therein.
9b371988
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793
794.blockquote
795Copyright &copy; 2001 Carnegie Mellon University. All rights reserved.
796
168e428f
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797Redistribution and use in source and binary forms, with or without
798modification, are permitted provided that the following conditions
799are met:
168e428f 800
9b371988
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801.olist
802Redistributions of source code must retain the above copyright
803notice, this list of conditions and the following disclaimer.
804.next
805Redistributions in binary form must reproduce the above copyright
168e428f
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806notice, this list of conditions and the following disclaimer in
807the documentation and/or other materials provided with the
808distribution.
9b371988
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809.next
810The name &"Carnegie Mellon University"& must not be used to
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811endorse or promote products derived from this software without
812prior written permission. For permission or any other legal
813details, please contact
9b371988 814.display
068aaea8
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815 Office of Technology Transfer
816 Carnegie Mellon University
817 5000 Forbes Avenue
818 Pittsburgh, PA 15213-3890
819 (412) 268-4387, fax: (412) 268-7395
820 tech-transfer@andrew.cmu.edu
9b371988
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821.endd
822.next
823Redistributions of any form whatsoever must retain the following
168e428f 824acknowledgment:
9b371988
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825
826&"This product includes software developed by Computing Services
827at Carnegie Mellon University (&url(http://www.cmu.edu/computing/)."&
828
168e428f
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829CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO
830THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
831AND FITNESS, IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE
832FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
833WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
834AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
835OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
9b371988
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836.endlist
837.endblockquote
168e428f 838
9b371988 839.next
f89d2485 840.cindex "Exim monitor" "acknowledgment"
9b371988
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841.cindex "X-windows"
842.cindex "Athena"
168e428f
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843The Exim Monitor program, which is an X-Window application, includes
844modified versions of the Athena StripChart and TextPop widgets.
845This code is copyright by DEC and MIT, and their permission notice appears
846below, in accordance with the conditions expressed therein.
9b371988
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847
848.blockquote
168e428f
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849Copyright 1987, 1988 by Digital Equipment Corporation, Maynard, Massachusetts,
850and the Massachusetts Institute of Technology, Cambridge, Massachusetts.
9b371988 851
168e428f 852All Rights Reserved
9b371988 853
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854Permission to use, copy, modify, and distribute this software and its
855documentation for any purpose and without fee is hereby granted,
856provided that the above copyright notice appear in all copies and that
857both that copyright notice and this permission notice appear in
858supporting documentation, and that the names of Digital or MIT not be
859used in advertising or publicity pertaining to distribution of the
860software without specific, written prior permission.
9b371988 861
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862DIGITAL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
863ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
864DIGITAL BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
865ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
866WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
867ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
868SOFTWARE.
9b371988 869.endblockquote
168e428f 870
9b371988 871.next
1899bab2
TL
872.cindex "opendmarc" "acknowledgment"
873The DMARC implementation uses the OpenDMARC library which is Copyrighted by
874The Trusted Domain Project. Portions of Exim source which use OpenDMARC
875derived code are indicated in the respective source files. The full OpenDMARC
876license is provided in the LICENSE.opendmarc file contained in the distributed
877source code.
878
879.next
9b371988 880Many people have contributed code fragments, some large, some small, that were
168e428f 881not covered by any specific licence requirements. It is assumed that the
f89d2485 882contributors are happy to see their code incorporated into Exim under the GPL.
9b371988 883.endlist
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884
885
886
887
888
9b371988
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889. ////////////////////////////////////////////////////////////////////////////
890. ////////////////////////////////////////////////////////////////////////////
168e428f 891
f89d2485 892.chapter "How Exim receives and delivers mail" "CHID11" &&&
9b371988 893 "Receiving and delivering mail"
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894
895
f89d2485 896.section "Overall philosophy" "SECID10"
9b371988 897.cindex "design philosophy"
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898Exim is designed to work efficiently on systems that are permanently connected
899to the Internet and are handling a general mix of mail. In such circumstances,
900most messages can be delivered immediately. Consequently, Exim does not
901maintain independent queues of messages for specific domains or hosts, though
902it does try to send several messages in a single SMTP connection after a host
903has been down, and it also maintains per-host retry information.
904
905
f89d2485 906.section "Policy control" "SECID11"
9b371988 907.cindex "policy control" "overview"
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908Policy controls are now an important feature of MTAs that are connected to the
909Internet. Perhaps their most important job is to stop MTAs being abused as
9b371988
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910&"open relays"& by misguided individuals who send out vast amounts of
911unsolicited junk, and want to disguise its source. Exim provides flexible
912facilities for specifying policy controls on incoming mail:
168e428f 913
9b371988
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914.ilist
915.cindex "&ACL;" "introduction"
168e428f 916Exim 4 (unlike previous versions of Exim) implements policy controls on
9b371988 917incoming mail by means of &'Access Control Lists'& (ACLs). Each list is a
168e428f
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918series of statements that may either grant or deny access. ACLs can be used at
919several places in the SMTP dialogue while receiving a message from a remote
9b371988
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920host. However, the most common places are after each RCPT command, and at the
921very end of the message. The sysadmin can specify conditions for accepting or
922rejecting individual recipients or the entire message, respectively, at these
923two points (see chapter &<<CHAPACL>>&). Denial of access results in an SMTP
168e428f 924error code.
9b371988
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925.next
926An ACL is also available for locally generated, non-SMTP messages. In this
168e428f 927case, the only available actions are to accept or deny the entire message.
9b371988
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928.next
929When Exim is compiled with the content-scanning extension, facilities are
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930provided in the ACL mechanism for passing the message to external virus and/or
931spam scanning software. The result of such a scan is passed back to the ACL,
932which can then use it to decide what to do with the message.
9b371988
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933.next
934When a message has been received, either from a remote host or from the local
f89d2485 935host, but before the final acknowledgment has been sent, a locally supplied C
9b371988
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936function called &[local_scan()]& can be run to inspect the message and decide
937whether to accept it or not (see chapter &<<CHAPlocalscan>>&). If the message
938is accepted, the list of recipients can be modified by the function.
939.next
940Using the &[local_scan()]& mechanism is another way of calling external scanner
941software. The &%SA-Exim%& add-on package works this way. It does not require
942Exim to be compiled with the content-scanning extension.
943.next
944After a message has been accepted, a further checking mechanism is available in
945the form of the &'system filter'& (see chapter &<<CHAPsystemfilter>>&). This
946runs at the start of every delivery process.
947.endlist
948
949
950
f89d2485 951.section "User filters" "SECID12"
9b371988
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952.cindex "filter" "introduction"
953.cindex "Sieve filter"
168e428f 954In a conventional Exim configuration, users are able to run private filters by
9b371988
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955setting up appropriate &_.forward_& files in their home directories. See
956chapter &<<CHAPredirect>>& (about the &(redirect)& router) for the
957configuration needed to support this, and the separate document entitled
958&'Exim's interfaces to mail filtering'& for user details. Two different kinds
959of filtering are available:
960
961.ilist
962Sieve filters are written in the standard filtering language that is defined
168e428f 963by RFC 3028.
9b371988
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964.next
965Exim filters are written in a syntax that is unique to Exim, but which is more
168e428f 966powerful than Sieve, which it pre-dates.
9b371988 967.endlist
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968
969User filters are run as part of the routing process, described below.
970
971
972
9b371988
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973.section "Message identification" "SECTmessiden"
974.cindex "message ids" "details of format"
975.cindex "format" "of message id"
976.cindex "id of message"
977.cindex "base62"
978.cindex "base36"
979.cindex "Darwin"
980.cindex "Cygwin"
981Every message handled by Exim is given a &'message id'& which is sixteen
168e428f 982characters long. It is divided into three parts, separated by hyphens, for
9b371988 983example &`16VDhn-0001bo-D3`&. Each part is a sequence of letters and digits,
168e428f
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984normally encoding numbers in base 62. However, in the Darwin operating
985system (Mac OS X) and when Exim is compiled to run under Cygwin, base 36
986(avoiding the use of lower case letters) is used instead, because the message
987id is used to construct file names, and the names of files in those systems are
068aaea8 988not always case-sensitive.
168e428f 989
9b371988 990.cindex "pid (process id)" "re-use of"
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991The detail of the contents of the message id have changed as Exim has evolved.
992Earlier versions relied on the operating system not re-using a process id (pid)
993within one second. On modern operating systems, this assumption can no longer
994be made, so the algorithm had to be changed. To retain backward compatibility,
995the format of the message id was retained, which is why the following rules are
996somewhat eccentric:
997
9b371988
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998.ilist
999The first six characters of the message id are the time at which the message
168e428f
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1000started to be received, to a granularity of one second. That is, this field
1001contains the number of seconds since the start of the epoch (the normal Unix
1002way of representing the date and time of day).
9b371988
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1003.next
1004After the first hyphen, the next six characters are the id of the process that
168e428f 1005received the message.
9b371988
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1006.next
1007There are two different possibilities for the final two characters:
1008.olist
0a4e3112 1009.oindex "&%localhost_number%&"
9b371988 1010If &%localhost_number%& is not set, this value is the fractional part of the
168e428f
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1011time of reception, normally in units of 1/2000 of a second, but for systems
1012that must use base 36 instead of base 62 (because of case-insensitive file
1013systems), the units are 1/1000 of a second.
9b371988
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1014.next
1015If &%localhost_number%& is set, it is multiplied by 200 (100) and added to
168e428f
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1016the fractional part of the time, which in this case is in units of 1/200
1017(1/100) of a second.
9b371988
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1018.endlist
1019.endlist
168e428f
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1020
1021After a message has been received, Exim waits for the clock to tick at the
1022appropriate resolution before proceeding, so that if another message is
1023received by the same process, or by another process with the same (re-used)
1024pid, it is guaranteed that the time will be different. In most cases, the clock
1025will already have ticked while the message was being received.
1026
1027
f89d2485 1028.section "Receiving mail" "SECID13"
9b371988
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1029.cindex "receiving mail"
1030.cindex "message" "reception"
068aaea8
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1031The only way Exim can receive mail from another host is using SMTP over
1032TCP/IP, in which case the sender and recipient addresses are transferred using
168e428f
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1033SMTP commands. However, from a locally running process (such as a user's MUA),
1034there are several possibilities:
1035
9b371988
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1036.ilist
1037If the process runs Exim with the &%-bm%& option, the message is read
168e428f 1038non-interactively (usually via a pipe), with the recipients taken from the
9b371988
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1039command line, or from the body of the message if &%-t%& is also used.
1040.next
1041If the process runs Exim with the &%-bS%& option, the message is also read
168e428f
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1042non-interactively, but in this case the recipients are listed at the start of
1043the message in a series of SMTP RCPT commands, terminated by a DATA
9b371988 1044command. This is so-called &"batch SMTP"& format,
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1045but it isn't really SMTP. The SMTP commands are just another way of passing
1046envelope addresses in a non-interactive submission.
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1047.next
1048If the process runs Exim with the &%-bs%& option, the message is read
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1049interactively, using the SMTP protocol. A two-way pipe is normally used for
1050passing data between the local process and the Exim process.
9b371988 1051This is &"real"& SMTP and is handled in the same way as SMTP over TCP/IP. For
168e428f 1052example, the ACLs for SMTP commands are used for this form of submission.
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1053.next
1054A local process may also make a TCP/IP call to the host's loopback address
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1055(127.0.0.1) or any other of its IP addresses. When receiving messages, Exim
1056does not treat the loopback address specially. It treats all such connections
1057in the same way as connections from other hosts.
9b371988 1058.endlist
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1059
1060
f89d2485 1061.cindex "message sender, constructed by Exim"
9b371988 1062.cindex "sender" "constructed by Exim"
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1063In the three cases that do not involve TCP/IP, the sender address is
1064constructed from the login name of the user that called Exim and a default
9b371988 1065qualification domain (which can be set by the &%qualify_domain%& configuration
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1066option). For local or batch SMTP, a sender address that is passed using the
1067SMTP MAIL command is ignored. However, the system administrator may allow
9b371988 1068certain users (&"trusted users"&) to specify a different sender address
168e428f 1069unconditionally, or all users to specify certain forms of different sender
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1070address. The &%-f%& option or the SMTP MAIL command is used to specify these
1071different addresses. See section &<<SECTtrustedadmin>>& for details of trusted
1072users, and the &%untrusted_set_sender%& option for a way of allowing untrusted
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1073users to change sender addresses.
1074
1075Messages received by either of the non-interactive mechanisms are subject to
1076checking by the non-SMTP ACL, if one is defined. Messages received using SMTP
1077(either over TCP/IP, or interacting with a local process) can be checked by a
1078number of ACLs that operate at different times during the SMTP session. Either
1079individual recipients, or the entire message, can be rejected if local policy
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1080requirements are not met. The &[local_scan()]& function (see chapter
1081&<<CHAPlocalscan>>&) is run for all incoming messages.
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1082
1083Exim can be configured not to start a delivery process when a message is
1084received; this can be unconditional, or depend on the number of incoming SMTP
1085connections or the system load. In these situations, new messages wait on the
1086queue until a queue runner process picks them up. However, in standard
1087configurations under normal conditions, delivery is started as soon as a
1088message is received.
1089
1090
1091
1092
1093
f89d2485 1094.section "Handling an incoming message" "SECID14"
9b371988
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1095.cindex "spool directory" "files that hold a message"
1096.cindex "file" "how a message is held"
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1097When Exim accepts a message, it writes two files in its spool directory. The
1098first contains the envelope information, the current status of the message, and
1099the header lines, and the second contains the body of the message. The names of
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1100the two spool files consist of the message id, followed by &`-H`& for the
1101file containing the envelope and header, and &`-D`& for the data file.
168e428f 1102
9b371988 1103.cindex "spool directory" "&_input_& sub-directory"
168e428f 1104By default all these message files are held in a single directory called
9b371988 1105&_input_& inside the general Exim spool directory. Some operating systems do
c0712871 1106not perform very well if the number of files in a directory gets large; to
9b371988 1107improve performance in such cases, the &%split_spool_directory%& option can be
168e428f 1108used. This causes Exim to split up the input files into 62 sub-directories
db9452a9 1109whose names are single letters or digits. When this is done, the queue is
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1110processed one sub-directory at a time instead of all at once, which can improve
1111overall performance even when there are not enough files in each directory to
db9452a9 1112affect file system performance.
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1113
1114The envelope information consists of the address of the message's sender and
1115the addresses of the recipients. This information is entirely separate from
1116any addresses contained in the header lines. The status of the message includes
1117a list of recipients who have already received the message. The format of the
9b371988 1118first spool file is described in chapter &<<CHAPspool>>&.
168e428f 1119
9b371988 1120.cindex "rewriting" "addresses"
168e428f 1121Address rewriting that is specified in the rewrite section of the configuration
9b371988 1122(see chapter &<<CHAPrewrite>>&) is done once and for all on incoming addresses,
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1123both in the header lines and the envelope, at the time the message is accepted.
1124If during the course of delivery additional addresses are generated (for
1125example, via aliasing), these new addresses are rewritten as soon as they are
1126generated. At the time a message is actually delivered (transported) further
1127rewriting can take place; because this is a transport option, it can be
1128different for different forms of delivery. It is also possible to specify the
1129addition or removal of certain header lines at the time the message is
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1130delivered (see chapters &<<CHAProutergeneric>>& and
1131&<<CHAPtransportgeneric>>&).
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1132
1133
1134
f89d2485 1135.section "Life of a message" "SECID15"
9b371988
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1136.cindex "message" "life of"
1137.cindex "message" "frozen"
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1138A message remains in the spool directory until it is completely delivered to
1139its recipients or to an error address, or until it is deleted by an
1140administrator or by the user who originally created it. In cases when delivery
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1141cannot proceed &-- for example, when a message can neither be delivered to its
1142recipients nor returned to its sender, the message is marked &"frozen"& on the
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1143spool, and no more deliveries are attempted.
1144
9b371988
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1145.cindex "frozen messages" "thawing"
1146.cindex "message" "thawing frozen"
1147An administrator can &"thaw"& such messages when the problem has been
1148corrected, and can also freeze individual messages by hand if necessary. In
1149addition, an administrator can force a delivery error, causing a bounce message
1150to be sent.
1151
0a4e3112
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1152.oindex "&%timeout_frozen_after%&"
1153.oindex "&%ignore_bounce_errors_after%&"
9b371988
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1154There are options called &%ignore_bounce_errors_after%& and
1155&%timeout_frozen_after%&, which discard frozen messages after a certain time.
068aaea8 1156The first applies only to frozen bounces, the second to any frozen messages.
168e428f 1157
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1158.cindex "message" "log file for"
1159.cindex "log" "file for each message"
168e428f 1160While Exim is working on a message, it writes information about each delivery
068aaea8 1161attempt to its main log file. This includes successful, unsuccessful, and
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1162delayed deliveries for each recipient (see chapter &<<CHAPlog>>&). The log
1163lines are also written to a separate &'message log'& file for each message.
1164These logs are solely for the benefit of the administrator, and are normally
1165deleted along with the spool files when processing of a message is complete.
168e428f 1166The use of individual message logs can be disabled by setting
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1167&%no_message_logs%&; this might give an improvement in performance on very busy
1168systems.
168e428f 1169
9b371988
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1170.cindex "journal file"
1171.cindex "file" "journal"
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1172All the information Exim itself needs to set up a delivery is kept in the first
1173spool file, along with the header lines. When a successful delivery occurs, the
1174address is immediately written at the end of a journal file, whose name is the
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1175message id followed by &`-J`&. At the end of a delivery run, if there are some
1176addresses left to be tried again later, the first spool file (the &`-H`& file)
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1177is updated to indicate which these are, and the journal file is then deleted.
1178Updating the spool file is done by writing a new file and renaming it, to
1179minimize the possibility of data loss.
1180
1181Should the system or the program crash after a successful delivery but before
1182the spool file has been updated, the journal is left lying around. The next
1183time Exim attempts to deliver the message, it reads the journal file and
1184updates the spool file before proceeding. This minimizes the chances of double
1185deliveries caused by crashes.
1186
1187
1188
9b371988
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1189.section "Processing an address for delivery" "SECTprocaddress"
1190.cindex "drivers" "definition of"
1191.cindex "router" "definition of"
1192.cindex "transport" "definition of"
1193The main delivery processing elements of Exim are called &'routers'& and
1194&'transports'&, and collectively these are known as &'drivers'&. Code for a
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1195number of them is provided in the source distribution, and compile-time options
1196specify which ones are included in the binary. Run time options specify which
1197ones are actually used for delivering messages.
1198
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1199.cindex "drivers" "instance definition"
1200Each driver that is specified in the run time configuration is an &'instance'&
168e428f 1201of that particular driver type. Multiple instances are allowed; for example,
9b371988 1202you can set up several different &(smtp)& transports, each with different
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1203option values that might specify different ports or different timeouts. Each
1204instance has its own identifying name. In what follows we will normally use the
1205instance name when discussing one particular instance (that is, one specific
1206configuration of the driver), and the generic driver name when discussing
1207the driver's features in general.
1208
9b371988 1209A &'router'& is a driver that operates on an address, either determining how
068aaea8 1210its delivery should happen, by assigning it to a specific transport, or
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1211converting the address into one or more new addresses (for example, via an
1212alias file). A router may also explicitly choose to fail an address, causing it
1213to be bounced.
1214
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1215A &'transport'& is a driver that transmits a copy of the message from Exim's
1216spool to some destination. There are two kinds of transport: for a &'local'&
168e428f 1217transport, the destination is a file or a pipe on the local host, whereas for a
9b371988 1218&'remote'& transport the destination is some other host. A message is passed
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1219to a specific transport as a result of successful routing. If a message has
1220several recipients, it may be passed to a number of different transports.
1221
9b371988 1222.cindex "preconditions" "definition of"
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1223An address is processed by passing it to each configured router instance in
1224turn, subject to certain preconditions, until a router accepts the address or
1225specifies that it should be bounced. We will describe this process in more
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1226detail shortly. First, as a simple example, we consider how each recipient
1227address in a message is processed in a small configuration of three routers.
168e428f 1228
068aaea8 1229To make this a more concrete example, it is described in terms of some actual
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1230routers, but remember, this is only an example. You can configure Exim's
1231routers in many different ways, and there may be any number of routers in a
1232configuration.
1233
1234The first router that is specified in a configuration is often one that handles
1235addresses in domains that are not recognized specially by the local host. These
1236are typically addresses for arbitrary domains on the Internet. A precondition
1237is set up which looks for the special domains known to the host (for example,
9b371988 1238its own domain name), and the router is run for addresses that do &'not'&
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1239match. Typically, this is a router that looks up domains in the DNS in order to
1240find the hosts to which this address routes. If it succeeds, the address is
068aaea8 1241assigned to a suitable SMTP transport; if it does not succeed, the router is
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1242configured to fail the address.
1243
068aaea8 1244The second router is reached only when the domain is recognized as one that
9b371988 1245&"belongs"& to the local host. This router does redirection &-- also known as
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1246aliasing and forwarding. When it generates one or more new addresses from the
1247original, each of them is routed independently from the start. Otherwise, the
1248router may cause an address to fail, or it may simply decline to handle the
1249address, in which case the address is passed to the next router.
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1250
1251The final router in many configurations is one that checks to see if the
1252address belongs to a local mailbox. The precondition may involve a check to
1253see if the local part is the name of a login account, or it may look up the
1254local part in a file or a database. If its preconditions are not met, or if
1255the router declines, we have reached the end of the routers. When this happens,
1256the address is bounced.
1257
1258
1259
f89d2485 1260.section "Processing an address for verification" "SECID16"
9b371988
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1261.cindex "router" "for verification"
1262.cindex "verifying address" "overview"
168e428f 1263As well as being used to decide how to deliver to an address, Exim's routers
9b371988 1264are also used for &'address verification'&. Verification can be requested as
168e428f 1265one of the checks to be performed in an ACL for incoming messages, on both
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1266sender and recipient addresses, and it can be tested using the &%-bv%& and
1267&%-bvs%& command line options.
168e428f 1268
9b371988 1269When an address is being verified, the routers are run in &"verify mode"&. This
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1270does not affect the way the routers work, but it is a state that can be
1271detected. By this means, a router can be skipped or made to behave differently
1272when verifying. A common example is a configuration in which the first router
1273sends all messages to a message-scanning program, unless they have been
1274previously scanned. Thus, the first router accepts all addresses without any
9b371988 1275checking, making it useless for verifying. Normally, the &%no_verify%& option
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1276would be set for such a router, causing it to be skipped in verify mode.
1277
1278
1279
1280
9b371988
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1281.section "Running an individual router" "SECTrunindrou"
1282.cindex "router" "running details"
1283.cindex "preconditions" "checking"
1284.cindex "router" "result of running"
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1285As explained in the example above, a number of preconditions are checked before
1286running a router. If any are not met, the router is skipped, and the address is
9b371988 1287passed to the next router. When all the preconditions on a router &'are'& met,
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1288the router is run. What happens next depends on the outcome, which is one of
1289the following:
1290
9b371988
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1291.ilist
1292&'accept'&: The router accepts the address, and either assigns it to a
1293transport, or generates one or more &"child"& addresses. Processing the
1294original address ceases,
0a4e3112 1295.oindex "&%unseen%&"
9b371988 1296unless the &%unseen%& option is set on the router. This option
168e428f 1297can be used to set up multiple deliveries with different routing (for example,
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1298for keeping archive copies of messages). When &%unseen%& is set, the address is
1299passed to the next router. Normally, however, an &'accept'& return marks the
168e428f 1300end of routing.
9b371988 1301
068aaea8
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1302Any child addresses generated by the router are processed independently,
1303starting with the first router by default. It is possible to change this by
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1304setting the &%redirect_router%& option to specify which router to start at for
1305child addresses. Unlike &%pass_router%& (see below) the router specified by
1306&%redirect_router%& may be anywhere in the router configuration.
1307.next
1308&'pass'&: The router recognizes the address, but cannot handle it itself. It
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1309requests that the address be passed to another router. By default the address
1310is passed to the next router, but this can be changed by setting the
9b371988 1311&%pass_router%& option. However, (unlike &%redirect_router%&) the named router
168e428f 1312must be below the current router (to avoid loops).
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1313.next
1314&'decline'&: The router declines to accept the address because it does not
168e428f 1315recognize it at all. By default, the address is passed to the next router, but
9b371988
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1316this can be prevented by setting the &%no_more%& option. When &%no_more%& is
1317set, all the remaining routers are skipped. In effect, &%no_more%& converts
1318&'decline'& into &'fail'&.
1319.next
1320&'fail'&: The router determines that the address should fail, and queues it for
168e428f 1321the generation of a bounce message. There is no further processing of the
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1322original address unless &%unseen%& is set on the router.
1323.next
1324&'defer'&: The router cannot handle the address at the present time. (A
068aaea8
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1325database may be offline, or a DNS lookup may have timed out.) No further
1326processing of the address happens in this delivery attempt. It is tried again
1327next time the message is considered for delivery.
9b371988
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1328.next
1329&'error'&: There is some error in the router (for example, a syntax error in
168e428f 1330its configuration). The action is as for defer.
9b371988 1331.endlist
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1332
1333If an address reaches the end of the routers without having been accepted by
068aaea8 1334any of them, it is bounced as unrouteable. The default error message in this
9b371988
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1335situation is &"unrouteable address"&, but you can set your own message by
1336making use of the &%cannot_route_message%& option. This can be set for any
1337router; the value from the last router that &"saw"& the address is used.
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1338
1339Sometimes while routing you want to fail a delivery when some conditions are
1340met but others are not, instead of passing the address on for further routing.
1341You can do this by having a second router that explicitly fails the delivery
9b371988 1342when the relevant conditions are met. The &(redirect)& router has a &"fail"&
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1343facility for this purpose.
1344
1345
f89d2485 1346.section "Duplicate addresses" "SECID17"
9b371988 1347.cindex "case of local parts"
f89d2485 1348.cindex "address duplicate, discarding"
db9452a9 1349.cindex "duplicate addresses"
068aaea8
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1350Once routing is complete, Exim scans the addresses that are assigned to local
1351and remote transports, and discards any duplicates that it finds. During this
3cb1b51e 1352check, local parts are treated as case-sensitive. This happens only when
db9452a9 1353actually delivering a message; when testing routers with &%-bt%&, all the
3cb1b51e 1354routed addresses are shown.
db9452a9 1355
068aaea8 1356
168e428f 1357
9b371988 1358.section "Router preconditions" "SECTrouprecon"
f89d2485 1359.cindex "router" "preconditions, order of processing"
9b371988 1360.cindex "preconditions" "order of processing"
168e428f
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1361The preconditions that are tested for each router are listed below, in the
1362order in which they are tested. The individual configuration options are
9b371988 1363described in more detail in chapter &<<CHAProutergeneric>>&.
168e428f 1364
9b371988
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1365.ilist
1366The &%local_part_prefix%& and &%local_part_suffix%& options can specify that
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1367the local parts handled by the router may or must have certain prefixes and/or
1368suffixes. If a mandatory affix (prefix or suffix) is not present, the router is
1369skipped. These conditions are tested first. When an affix is present, it is
1370removed from the local part before further processing, including the evaluation
1371of any other conditions.
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1372.next
1373Routers can be designated for use only when not verifying an address, that is,
168e428f 1374only when routing it for delivery (or testing its delivery routing). If the
9b371988 1375&%verify%& option is set false, the router is skipped when Exim is verifying an
168e428f 1376address.
9b371988
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1377Setting the &%verify%& option actually sets two options, &%verify_sender%& and
1378&%verify_recipient%&, which independently control the use of the router for
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1379sender and recipient verification. You can set these options directly if
1380you want a router to be used for only one type of verification.
6ece2e77 1381Note that cutthrough delivery is classed as a recipient verification for this purpose.
9b371988
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1382.next
1383If the &%address_test%& option is set false, the router is skipped when Exim is
1384run with the &%-bt%& option to test an address routing. This can be helpful
1385when the first router sends all new messages to a scanner of some sort; it
1386makes it possible to use &%-bt%& to test subsequent delivery routing without
1387having to simulate the effect of the scanner.
1388.next
1389Routers can be designated for use only when verifying an address, as
1390opposed to routing it for delivery. The &%verify_only%& option controls this.
6ece2e77 1391Again, cutthrough delivery counts as a verification.
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1392.next
1393Individual routers can be explicitly skipped when running the routers to
1394check an address given in the SMTP EXPN command (see the &%expn%& option).
1395.next
1396If the &%domains%& option is set, the domain of the address must be in the set
068aaea8 1397of domains that it defines.
9b371988 1398.next
f89d2485
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1399.vindex "&$local_part_prefix$&"
1400.vindex "&$local_part$&"
1401.vindex "&$local_part_suffix$&"
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1402If the &%local_parts%& option is set, the local part of the address must be in
1403the set of local parts that it defines. If &%local_part_prefix%& or
1404&%local_part_suffix%& is in use, the prefix or suffix is removed from the local
168e428f 1405part before this check. If you want to do precondition tests on local parts
9b371988
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1406that include affixes, you can do so by using a &%condition%& option (see below)
1407that uses the variables &$local_part$&, &$local_part_prefix$&, and
1408&$local_part_suffix$& as necessary.
1409.next
f89d2485
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1410.vindex "&$local_user_uid$&"
1411.vindex "&$local_user_gid$&"
1412.vindex "&$home$&"
9b371988 1413If the &%check_local_user%& option is set, the local part must be the name of
068aaea8 1414an account on the local host. If this check succeeds, the uid and gid of the
9b371988
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1415local user are placed in &$local_user_uid$& and &$local_user_gid$& and the
1416user's home directory is placed in &$home$&; these values can be used in the
1417remaining preconditions.
1418.next
1419If the &%router_home_directory%& option is set, it is expanded at this point,
1420because it overrides the value of &$home$&. If this expansion were left till
1421later, the value of &$home$& as set by &%check_local_user%& would be used in
1422subsequent tests. Having two different values of &$home$& in the same router
168e428f 1423could lead to confusion.
9b371988
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1424.next
1425If the &%senders%& option is set, the envelope sender address must be in the
1426set of addresses that it defines.
1427.next
1428If the &%require_files%& option is set, the existence or non-existence of
168e428f 1429specified files is tested.
9b371988
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1430.next
1431.cindex "customizing" "precondition"
1432If the &%condition%& option is set, it is evaluated and tested. This option
1433uses an expanded string to allow you to set up your own custom preconditions.
1434Expanded strings are described in chapter &<<CHAPexpand>>&.
1435.endlist
168e428f 1436
168e428f 1437
9b371988
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1438Note that &%require_files%& comes near the end of the list, so you cannot use
1439it to check for the existence of a file in which to lookup up a domain, local
168e428f 1440part, or sender. However, as these options are all expanded, you can use the
9b371988
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1441&%exists%& expansion condition to make such tests within each condition. The
1442&%require_files%& option is intended for checking files that the router may be
168e428f 1443going to use internally, or which are needed by a specific transport (for
9b371988 1444example, &_.procmailrc_&).
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1445
1446
1447
f89d2485 1448.section "Delivery in detail" "SECID18"
9b371988 1449.cindex "delivery" "in detail"
168e428f
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1450When a message is to be delivered, the sequence of events is as follows:
1451
9b371988
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1452.ilist
1453If a system-wide filter file is specified, the message is passed to it. The
168e428f
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1454filter may add recipients to the message, replace the recipients, discard the
1455message, cause a new message to be generated, or cause the message delivery to
1456fail. The format of the system filter file is the same as for Exim user filter
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1457files, described in the separate document entitled &'Exim's interfaces to mail
1458filtering'&.
1459.cindex "Sieve filter" "not available for system filter"
1460(&*Note*&: Sieve cannot be used for system filter files.)
1461
1462Some additional features are available in system filters &-- see chapter
1463&<<CHAPsystemfilter>>& for details. Note that a message is passed to the system
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1464filter only once per delivery attempt, however many recipients it has. However,
1465if there are several delivery attempts because one or more addresses could not
1466be immediately delivered, the system filter is run each time. The filter
9b371988 1467condition &%first_delivery%& can be used to detect the first run of the system
168e428f 1468filter.
9b371988
PH
1469.next
1470Each recipient address is offered to each configured router in turn, subject to
1471its preconditions, until one is able to handle it. If no router can handle the
1472address, that is, if they all decline, the address is failed. Because routers
1473can be targeted at particular domains, several locally handled domains can be
1474processed entirely independently of each other.
1475.next
1476.cindex "routing" "loops in"
1477.cindex "loop" "while routing"
1478A router that accepts an address may assign it to a local or a remote
1479transport. However, the transport is not run at this time. Instead, the address
1480is placed on a list for the particular transport, which will be run later.
068aaea8
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1481Alternatively, the router may generate one or more new addresses (typically
1482from alias, forward, or filter files). New addresses are fed back into this
1483process from the top, but in order to avoid loops, a router ignores any address
1484which has an identically-named ancestor that was processed by itself.
9b371988
PH
1485.next
1486When all the routing has been done, addresses that have been successfully
168e428f
PH
1487handled are passed to their assigned transports. When local transports are
1488doing real local deliveries, they handle only one address at a time, but if a
1489local transport is being used as a pseudo-remote transport (for example, to
1490collect batched SMTP messages for transmission by some other means) multiple
1491addresses can be handled. Remote transports can always handle more than one
1492address at a time, but can be configured not to do so, or to restrict multiple
1493addresses to the same domain.
9b371988
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1494.next
1495Each local delivery to a file or a pipe runs in a separate process under a
168e428f
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1496non-privileged uid, and these deliveries are run one at a time. Remote
1497deliveries also run in separate processes, normally under a uid that is private
9b371988 1498to Exim (&"the Exim user"&), but in this case, several remote deliveries can be
168e428f 1499run in parallel. The maximum number of simultaneous remote deliveries for any
9b371988 1500one message is set by the &%remote_max_parallel%& option.
168e428f
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1501The order in which deliveries are done is not defined, except that all local
1502deliveries happen before any remote deliveries.
9b371988
PH
1503.next
1504.cindex "queue runner"
168e428f
PH
1505When it encounters a local delivery during a queue run, Exim checks its retry
1506database to see if there has been a previous temporary delivery failure for the
1507address before running the local transport. If there was a previous failure,
1508Exim does not attempt a new delivery until the retry time for the address is
1509reached. However, this happens only for delivery attempts that are part of a
1510queue run. Local deliveries are always attempted when delivery immediately
1511follows message reception, even if retry times are set for them. This makes for
1512better behaviour if one particular message is causing problems (for example,
1513causing quota overflow, or provoking an error in a filter file).
9b371988
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1514.next
1515.cindex "delivery" "retry in remote transports"
168e428f
PH
1516Remote transports do their own retry handling, since an address may be
1517deliverable to one of a number of hosts, each of which may have a different
1518retry time. If there have been previous temporary failures and no host has
1519reached its retry time, no delivery is attempted, whether in a queue run or
9b371988
PH
1520not. See chapter &<<CHAPretry>>& for details of retry strategies.
1521.next
1522If there were any permanent errors, a bounce message is returned to an
168e428f
PH
1523appropriate address (the sender in the common case), with details of the error
1524for each failing address. Exim can be configured to send copies of bounce
1525messages to other addresses.
9b371988
PH
1526.next
1527.cindex "delivery" "deferral"
168e428f
PH
1528If one or more addresses suffered a temporary failure, the message is left on
1529the queue, to be tried again later. Delivery of these addresses is said to be
9b371988
PH
1530&'deferred'&.
1531.next
1532When all the recipient addresses have either been delivered or bounced,
168e428f
PH
1533handling of the message is complete. The spool files and message log are
1534deleted, though the message log can optionally be preserved if required.
9b371988 1535.endlist
168e428f
PH
1536
1537
1538
1539
f89d2485 1540.section "Retry mechanism" "SECID19"
9b371988
PH
1541.cindex "delivery" "retry mechanism"
1542.cindex "retry" "description of mechanism"
1543.cindex "queue runner"
168e428f
PH
1544Exim's mechanism for retrying messages that fail to get delivered at the first
1545attempt is the queue runner process. You must either run an Exim daemon that
9b371988
PH
1546uses the &%-q%& option with a time interval to start queue runners at regular
1547intervals, or use some other means (such as &'cron'&) to start them. If you do
168e428f
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1548not arrange for queue runners to be run, messages that fail temporarily at the
1549first attempt will remain on your queue for ever. A queue runner process works
068aaea8 1550its way through the queue, one message at a time, trying each delivery that has
168e428f
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1551passed its retry time.
1552You can run several queue runners at once.
1553
1554Exim uses a set of configured rules to determine when next to retry the failing
9b371988
PH
1555address (see chapter &<<CHAPretry>>&). These rules also specify when Exim
1556should give up trying to deliver to the address, at which point it generates a
1557bounce message. If no retry rules are set for a particular host, address, and
1558error combination, no retries are attempted, and temporary errors are treated
1559as permanent.
168e428f
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1560
1561
1562
f89d2485 1563.section "Temporary delivery failure" "SECID20"
9b371988 1564.cindex "delivery" "temporary failure"
168e428f
PH
1565There are many reasons why a message may not be immediately deliverable to a
1566particular address. Failure to connect to a remote machine (because it, or the
1567connection to it, is down) is one of the most common. Temporary failures may be
1568detected during routing as well as during the transport stage of delivery.
1569Local deliveries may be delayed if NFS files are unavailable, or if a mailbox
1570is on a file system where the user is over quota. Exim can be configured to
1571impose its own quotas on local mailboxes; where system quotas are set they will
1572also apply.
1573
1574If a host is unreachable for a period of time, a number of messages may be
1575waiting for it by the time it recovers, and sending them in a single SMTP
1576connection is clearly beneficial. Whenever a delivery to a remote host is
1577deferred,
fa41615d 1578.cindex "hints database" "deferred deliveries"
168e428f
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1579Exim makes a note in its hints database, and whenever a successful
1580SMTP delivery has happened, it looks to see if any other messages are waiting
1581for the same host. If any are found, they are sent over the same SMTP
1582connection, subject to a configuration limit as to the maximum number in any
1583one connection.
168e428f
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1584
1585
1586
f89d2485 1587.section "Permanent delivery failure" "SECID21"
9b371988
PH
1588.cindex "delivery" "permanent failure"
1589.cindex "bounce message" "when generated"
168e428f
PH
1590When a message cannot be delivered to some or all of its intended recipients, a
1591bounce message is generated. Temporary delivery failures turn into permanent
1592errors when their timeout expires. All the addresses that fail in a given
1593delivery attempt are listed in a single message. If the original message has
1594many recipients, it is possible for some addresses to fail in one delivery
1595attempt and others to fail subsequently, giving rise to more than one bounce
1596message. The wording of bounce messages can be customized by the administrator.
9b371988 1597See chapter &<<CHAPemsgcust>>& for details.
168e428f 1598
9b371988
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1599.cindex "&'X-Failed-Recipients:'& header line"
1600Bounce messages contain an &'X-Failed-Recipients:'& header line that lists the
168e428f
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1601failed addresses, for the benefit of programs that try to analyse such messages
1602automatically.
1603
9b371988 1604.cindex "bounce message" "recipient of"
168e428f
PH
1605A bounce message is normally sent to the sender of the original message, as
1606obtained from the message's envelope. For incoming SMTP messages, this is the
9b371988
PH
1607address given in the MAIL command. However, when an address is expanded via a
1608forward or alias file, an alternative address can be specified for delivery
1609failures of the generated addresses. For a mailing list expansion (see section
1610&<<SECTmailinglists>>&) it is common to direct bounce messages to the manager
1611of the list.
168e428f
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1612
1613
1614
f89d2485 1615.section "Failures to deliver bounce messages" "SECID22"
9b371988 1616.cindex "bounce message" "failure to deliver"
168e428f
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1617If a bounce message (either locally generated or received from a remote host)
1618itself suffers a permanent delivery failure, the message is left on the queue,
1619but it is frozen, awaiting the attention of an administrator. There are options
068aaea8 1620that can be used to make Exim discard such failed messages, or to keep them
9b371988
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1621for only a short time (see &%timeout_frozen_after%& and
1622&%ignore_bounce_errors_after%&).
168e428f
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1623
1624
1625
1626
1627
9b371988
PH
1628. ////////////////////////////////////////////////////////////////////////////
1629. ////////////////////////////////////////////////////////////////////////////
168e428f 1630
f89d2485 1631.chapter "Building and installing Exim" "CHID3"
4f578862 1632.scindex IIDbuex "building Exim"
168e428f 1633
f89d2485
PH
1634.section "Unpacking" "SECID23"
1635Exim is distributed as a gzipped or bzipped tar file which, when unpacked,
168e428f 1636creates a directory with the name of the current release (for example,
2aee48d6 1637&_exim-&version()_&) into which the following files are placed:
9b371988
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1638
1639.table2 140pt
f89d2485
PH
1640.irow &_ACKNOWLEDGMENTS_& "contains some acknowledgments"
1641.irow &_CHANGES_& "contains a reference to where changes are &&&
1642 documented"
1643.irow &_LICENCE_& "the GNU General Public Licence"
1644.irow &_Makefile_& "top-level make file"
1645.irow &_NOTICE_& "conditions for the use of Exim"
1646.irow &_README_& "list of files, directories and simple build &&&
1647 instructions"
9b371988
PH
1648.endtable
1649
1650Other files whose names begin with &_README_& may also be present. The
168e428f
PH
1651following subdirectories are created:
1652
9b371988 1653.table2 140pt
f89d2485
PH
1654.irow &_Local_& "an empty directory for local configuration files"
1655.irow &_OS_& "OS-specific files"
1656.irow &_doc_& "documentation files"
1657.irow &_exim_monitor_& "source files for the Exim monitor"
1658.irow &_scripts_& "scripts used in the build process"
1659.irow &_src_& "remaining source files"
1660.irow &_util_& "independent utilities"
9b371988
PH
1661.endtable
1662
1663The main utility programs are contained in the &_src_& directory, and are built
1664with the Exim binary. The &_util_& directory contains a few optional scripts
168e428f
PH
1665that may be useful to some sites.
1666
1667
f89d2485 1668.section "Multiple machine architectures and operating systems" "SECID24"
9b371988 1669.cindex "building Exim" "multiple OS/architectures"
168e428f
PH
1670The building process for Exim is arranged to make it easy to build binaries for
1671a number of different architectures and operating systems from the same set of
9b371988
PH
1672source files. Compilation does not take place in the &_src_& directory.
1673Instead, a &'build directory'& is created for each architecture and operating
1674system.
1675.cindex "symbolic link" "to build directory"
168e428f 1676Symbolic links to the sources are installed in this directory, which is where
9b371988
PH
1677the actual building takes place. In most cases, Exim can discover the machine
1678architecture and operating system for itself, but the defaults can be
1679overridden if necessary.
168e428f 1680
168e428f 1681
8473d4ee 1682.section "PCRE library" "SECTpcre"
210f147e
NM
1683.cindex "PCRE library"
1684Exim no longer has an embedded PCRE library as the vast majority of
1685modern systems include PCRE as a system library, although you may need
1686to install the PCRE or PCRE development package for your operating
1687system. If your system has a normal PCRE installation the Exim build
1688process will need no further configuration. If the library or the
6a6084f8
PP
1689headers are in an unusual location you will need to either set the PCRE_LIBS
1690and INCLUDE directives appropriately,
1691or set PCRE_CONFIG=yes to use the installed &(pcre-config)& command.
1692If your operating system has no
210f147e
NM
1693PCRE support then you will need to obtain and build the current PCRE
1694from &url(ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/).
6a6084f8 1695More information on PCRE is available at &url(http://www.pcre.org/).
210f147e 1696
9b371988
PH
1697.section "DBM libraries" "SECTdb"
1698.cindex "DBM libraries" "discussion of"
1699.cindex "hints database" "DBM files used for"
168e428f
PH
1700Even if you do not use any DBM files in your configuration, Exim still needs a
1701DBM library in order to operate, because it uses indexed files for its hints
1702databases. Unfortunately, there are a number of DBM libraries in existence, and
1703different operating systems often have different ones installed.
1704
9b371988 1705.cindex "Solaris" "DBM library for"
f89d2485
PH
1706.cindex "IRIX, DBM library for"
1707.cindex "BSD, DBM library for"
1708.cindex "Linux, DBM library for"
168e428f
PH
1709If you are using Solaris, IRIX, one of the modern BSD systems, or a modern
1710Linux distribution, the DBM configuration should happen automatically, and you
1711may be able to ignore this section. Otherwise, you may have to learn more than
1712you would like about DBM libraries from what follows.
1713
9b371988 1714.cindex "&'ndbm'& DBM library"
168e428f 1715Licensed versions of Unix normally contain a library of DBM functions operating
9b371988 1716via the &'ndbm'& interface, and this is what Exim expects by default. Free
168e428f
PH
1717versions of Unix seem to vary in what they contain as standard. In particular,
1718some early versions of Linux have no default DBM library, and different
1719distributors have chosen to bundle different libraries with their packaged
f89d2485 1720versions. However, the more recent releases seem to have standardized on the
168e428f
PH
1721Berkeley DB library.
1722
1723Different DBM libraries have different conventions for naming the files they
9b371988 1724use. When a program opens a file called &_dbmfile_&, there are several
168e428f
PH
1725possibilities:
1726
9b371988
PH
1727.olist
1728A traditional &'ndbm'& implementation, such as that supplied as part of
1729Solaris, operates on two files called &_dbmfile.dir_& and &_dbmfile.pag_&.
1730.next
1731.cindex "&'gdbm'& DBM library"
1732The GNU library, &'gdbm'&, operates on a single file. If used via its &'ndbm'&
168e428f 1733compatibility interface it makes two different hard links to it with names
9b371988 1734&_dbmfile.dir_& and &_dbmfile.pag_&, but if used via its native interface, the
168e428f 1735file name is used unmodified.
9b371988
PH
1736.next
1737.cindex "Berkeley DB library"
1738The Berkeley DB package, if called via its &'ndbm'& compatibility interface,
1739operates on a single file called &_dbmfile.db_&, but otherwise looks to the
1740programmer exactly the same as the traditional &'ndbm'& implementation.
1741.next
1742If the Berkeley package is used in its native mode, it operates on a single
1743file called &_dbmfile_&; the programmer's interface is somewhat different to
1744the traditional &'ndbm'& interface.
1745.next
1746To complicate things further, there are several very different versions of the
168e428f 1747Berkeley DB package. Version 1.85 was stable for a very long time, releases
9b371988
PH
17482.&'x'& and 3.&'x'& were current for a while, but the latest versions are now
1749numbered 4.&'x'&. Maintenance of some of the earlier releases has ceased. All
168e428f 1750versions of Berkeley DB can be obtained from
9b371988
PH
1751&url(http://www.sleepycat.com/).
1752.next
1753.cindex "&'tdb'& DBM library"
1754Yet another DBM library, called &'tdb'&, is available from
1755&url(http://download.sourceforge.net/tdb). It has its own interface, and also
1756operates on a single file.
1757.endlist
1758
1759.cindex "USE_DB"
1760.cindex "DBM libraries" "configuration for building"
168e428f
PH
1761Exim and its utilities can be compiled to use any of these interfaces. In order
1762to use any version of the Berkeley DB package in native mode, you must set
1763USE_DB in an appropriate configuration file (typically
9b371988
PH
1764&_Local/Makefile_&). For example:
1765.code
1766USE_DB=yes
1767.endd
168e428f
PH
1768Similarly, for gdbm you set USE_GDBM, and for tdb you set USE_TDB. An
1769error is diagnosed if you set more than one of these.
1770
1771At the lowest level, the build-time configuration sets none of these options,
1772thereby assuming an interface of type (1). However, some operating system
1773configuration files (for example, those for the BSD operating systems and
1774Linux) assume type (4) by setting USE_DB as their default, and the
1775configuration files for Cygwin set USE_GDBM. Anything you set in
9b371988 1776&_Local/Makefile_&, however, overrides these system defaults.
168e428f
PH
1777
1778As well as setting USE_DB, USE_GDBM, or USE_TDB, it may also be
1779necessary to set DBMLIB, to cause inclusion of the appropriate library, as
1780in one of these lines:
9b371988
PH
1781.code
1782DBMLIB = -ldb
1783DBMLIB = -ltdb
1784.endd
168e428f
PH
1785Settings like that will work if the DBM library is installed in the standard
1786place. Sometimes it is not, and the library's header file may also not be in
1787the default path. You may need to set INCLUDE to specify where the header
1788file is, and to specify the path to the library more fully in DBMLIB, as in
1789this example:
9b371988
PH
1790.code
1791INCLUDE=-I/usr/local/include/db-4.1
1792DBMLIB=/usr/local/lib/db-4.1/libdb.a
1793.endd
168e428f 1794There is further detailed discussion about the various DBM libraries in the
9b371988 1795file &_doc/dbm.discuss.txt_& in the Exim distribution.
168e428f
PH
1796
1797
1798
f89d2485 1799.section "Pre-building configuration" "SECID25"
9b371988
PH
1800.cindex "building Exim" "pre-building configuration"
1801.cindex "configuration for building Exim"
1802.cindex "&_Local/Makefile_&"
1803.cindex "&_src/EDITME_&"
168e428f
PH
1804Before building Exim, a local configuration file that specifies options
1805independent of any operating system has to be created with the name
9b371988
PH
1806&_Local/Makefile_&. A template for this file is supplied as the file
1807&_src/EDITME_&, and it contains full descriptions of all the option settings
168e428f
PH
1808therein. These descriptions are therefore not repeated here. If you are
1809building Exim for the first time, the simplest thing to do is to copy
9b371988 1810&_src/EDITME_& to &_Local/Makefile_&, then read it and edit it appropriately.
168e428f
PH
1811
1812There are three settings that you must supply, because Exim will not build
1813without them. They are the location of the run time configuration file
1814(CONFIGURE_FILE), the directory in which Exim binaries will be installed
1815(BIN_DIRECTORY), and the identity of the Exim user (EXIM_USER and
1816maybe EXIM_GROUP as well). The value of CONFIGURE_FILE can in fact be
1817a colon-separated list of file names; Exim uses the first of them that exists.
1818
1819There are a few other parameters that can be specified either at build time or
1820at run time, to enable the same binary to be used on a number of different
1821machines. However, if the locations of Exim's spool directory and log file
1822directory (if not within the spool directory) are fixed, it is recommended that
9b371988 1823you specify them in &_Local/Makefile_& instead of at run time, so that errors
168e428f
PH
1824detected early in Exim's execution (such as a malformed configuration file) can
1825be logged.
1826
9b371988 1827.cindex "content scanning" "specifying at build time"
068aaea8 1828Exim's interfaces for calling virus and spam scanning software directly from
168e428f
PH
1829access control lists are not compiled by default. If you want to include these
1830facilities, you need to set
9b371988
PH
1831.code
1832WITH_CONTENT_SCAN=yes
1833.endd
1834in your &_Local/Makefile_&. For details of the facilities themselves, see
1835chapter &<<CHAPexiscan>>&.
168e428f
PH
1836
1837
9b371988 1838.cindex "&_Local/eximon.conf_&"
3cb1b51e 1839.cindex "&_exim_monitor/EDITME_&"
168e428f 1840If you are going to build the Exim monitor, a similar configuration process is
9b371988
PH
1841required. The file &_exim_monitor/EDITME_& must be edited appropriately for
1842your installation and saved under the name &_Local/eximon.conf_&. If you are
1843happy with the default settings described in &_exim_monitor/EDITME_&,
1844&_Local/eximon.conf_& can be empty, but it must exist.
168e428f
PH
1845
1846This is all the configuration that is needed in straightforward cases for known
1847operating systems. However, the building process is set up so that it is easy
1848to override options that are set by default or by operating-system-specific
1849configuration files, for example to change the name of the C compiler, which
9b371988
PH
1850defaults to &%gcc%&. See section &<<SECToverride>>& below for details of how to
1851do this.
168e428f
PH
1852
1853
1854
f89d2485 1855.section "Support for iconv()" "SECID26"
9b371988
PH
1856.cindex "&[iconv()]& support"
1857.cindex "RFC 2047"
168e428f
PH
1858The contents of header lines in messages may be encoded according to the rules
1859described RFC 2047. This makes it possible to transmit characters that are not
1860in the ASCII character set, and to label them as being in a particular
9b371988 1861character set. When Exim is inspecting header lines by means of the &%$h_%&
168e428f 1862mechanism, it decodes them, and translates them into a specified character set
1459a03d 1863(default is set at build time). The translation is possible only if the operating system
9b371988
PH
1864supports the &[iconv()]& function.
1865
1866However, some of the operating systems that supply &[iconv()]& do not support
1867very many conversions. The GNU &%libiconv%& library (available from
1868&url(http://www.gnu.org/software/libiconv/)) can be installed on such
1869systems to remedy this deficiency, as well as on systems that do not supply
1870&[iconv()]& at all. After installing &%libiconv%&, you should add
1871.code
1872HAVE_ICONV=yes
1873.endd
1874to your &_Local/Makefile_& and rebuild Exim.
1875
1876
1877
1878.section "Including TLS/SSL encryption support" "SECTinctlsssl"
1879.cindex "TLS" "including support for TLS"
1880.cindex "encryption" "including support for"
1881.cindex "SUPPORT_TLS"
1882.cindex "OpenSSL" "building Exim with"
1883.cindex "GnuTLS" "building Exim with"
168e428f
PH
1884Exim can be built to support encrypted SMTP connections, using the STARTTLS
1885command as per RFC 2487. It can also support legacy clients that expect to
1886start a TLS session immediately on connection to a non-standard port (see the
9b371988 1887&%tls_on_connect_ports%& runtime option and the &%-tls-on-connect%& command
168e428f
PH
1888line option).
1889
1890If you want to build Exim with TLS support, you must first install either the
1891OpenSSL or GnuTLS library. There is no cryptographic code in Exim itself for
1892implementing SSL.
1893
1894If OpenSSL is installed, you should set
9b371988
PH
1895.code
1896SUPPORT_TLS=yes
1897TLS_LIBS=-lssl -lcrypto
1898.endd
1899in &_Local/Makefile_&. You may also need to specify the locations of the
168e428f 1900OpenSSL library and include files. For example:
9b371988
PH
1901.code
1902SUPPORT_TLS=yes
1903TLS_LIBS=-L/usr/local/openssl/lib -lssl -lcrypto
1904TLS_INCLUDE=-I/usr/local/openssl/include/
1905.endd
7e6a8985
PP
1906.cindex "pkg-config" "OpenSSL"
1907If you have &'pkg-config'& available, then instead you can just use:
1908.code
1909SUPPORT_TLS=yes
1910USE_OPENSSL_PC=openssl
1911.endd
9b371988 1912.cindex "USE_GNUTLS"
168e428f 1913If GnuTLS is installed, you should set
9b371988
PH
1914.code
1915SUPPORT_TLS=yes
1916USE_GNUTLS=yes
1917TLS_LIBS=-lgnutls -ltasn1 -lgcrypt
1918.endd
1919in &_Local/Makefile_&, and again you may need to specify the locations of the
168e428f 1920library and include files. For example:
9b371988
PH
1921.code
1922SUPPORT_TLS=yes
1923USE_GNUTLS=yes
1924TLS_LIBS=-L/usr/gnu/lib -lgnutls -ltasn1 -lgcrypt
1925TLS_INCLUDE=-I/usr/gnu/include
1926.endd
7e6a8985
PP
1927.cindex "pkg-config" "GnuTLS"
1928If you have &'pkg-config'& available, then instead you can just use:
1929.code
1930SUPPORT_TLS=yes
1931USE_GNUTLS=yes
1932USE_GNUTLS_PC=gnutls
1933.endd
7e6a8985 1934
168e428f 1935You do not need to set TLS_INCLUDE if the relevant directory is already
9b371988
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1936specified in INCLUDE. Details of how to configure Exim to make use of TLS are
1937given in chapter &<<CHAPTLS>>&.
168e428f
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1938
1939
1940
1941
b52ed2b3
NM
1942.section "Use of tcpwrappers" "SECID27"
1943
f89d2485 1944.cindex "tcpwrappers, building Exim to support"
9b371988 1945.cindex "USE_TCP_WRAPPERS"
5dc43717
JJ
1946.cindex "TCP_WRAPPERS_DAEMON_NAME"
1947.cindex "tcp_wrappers_daemon_name"
9b371988
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1948Exim can be linked with the &'tcpwrappers'& library in order to check incoming
1949SMTP calls using the &'tcpwrappers'& control files. This may be a convenient
168e428f 1950alternative to Exim's own checking facilities for installations that are
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1951already making use of &'tcpwrappers'& for other purposes. To do this, you
1952should set USE_TCP_WRAPPERS in &_Local/Makefile_&, arrange for the file
1953&_tcpd.h_& to be available at compile time, and also ensure that the library
1954&_libwrap.a_& is available at link time, typically by including &%-lwrap%& in
1955EXTRALIBS_EXIM. For example, if &'tcpwrappers'& is installed in &_/usr/local_&,
1956you might have
1957.code
1958USE_TCP_WRAPPERS=yes
1959CFLAGS=-O -I/usr/local/include
1960EXTRALIBS_EXIM=-L/usr/local/lib -lwrap
1961.endd
5dc43717
JJ
1962in &_Local/Makefile_&. The daemon name to use in the &'tcpwrappers'& control
1963files is &"exim"&. For example, the line
9b371988
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1964.code
1965exim : LOCAL 192.168.1. .friendly.domain.example
1966.endd
1967in your &_/etc/hosts.allow_& file allows connections from the local host, from
1968the subnet 192.168.1.0/24, and from all hosts in &'friendly.domain.example'&.
5dc43717
JJ
1969All other connections are denied. The daemon name used by &'tcpwrappers'&
1970can be changed at build time by setting TCP_WRAPPERS_DAEMON_NAME in
a543079f 1971&_Local/Makefile_&, or by setting tcp_wrappers_daemon_name in the
5dc43717 1972configure file. Consult the &'tcpwrappers'& documentation for
168e428f 1973further details.
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1974
1975
f89d2485 1976.section "Including support for IPv6" "SECID28"
9b371988 1977.cindex "IPv6" "including support for"
168e428f 1978Exim contains code for use on systems that have IPv6 support. Setting
9b371988 1979&`HAVE_IPV6=YES`& in &_Local/Makefile_& causes the IPv6 code to be included;
168e428f
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1980it may also be necessary to set IPV6_INCLUDE and IPV6_LIBS on systems
1981where the IPv6 support is not fully integrated into the normal include and
1982library files.
1983
1984Two different types of DNS record for handling IPv6 addresses have been
f89d2485 1985defined. AAAA records (analogous to A records for IPv4) are in use, and are
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1986currently seen as the mainstream. Another record type called A6 was proposed
1987as better than AAAA because it had more flexibility. However, it was felt to be
badb25a9 1988over-complex, and its status was reduced to &"experimental"&.
badb25a9 1989Exim used to
cc00f4af
JH
1990have a compile option for including A6 record support but this has now been
1991withdrawn.
168e428f
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1992
1993
1994
0a349494
PP
1995.section "Dynamically loaded lookup module support" "SECTdynamicmodules"
1996.cindex "lookup modules"
1997.cindex "dynamic modules"
1998.cindex ".so building"
1999On some platforms, Exim supports not compiling all lookup types directly into
2000the main binary, instead putting some into external modules which can be loaded
2001on demand.
2002This permits packagers to build Exim with support for lookups with extensive
2003library dependencies without requiring all users to install all of those
2004dependencies.
2005Most, but not all, lookup types can be built this way.
2006
2007Set &`LOOKUP_MODULE_DIR`& to the directory into which the modules will be
2008installed; Exim will only load modules from that directory, as a security
2009measure. You will need to set &`CFLAGS_DYNAMIC`& if not already defined
2010for your OS; see &_OS/Makefile-Linux_& for an example.
2011Some other requirements for adjusting &`EXTRALIBS`& may also be necessary,
2012see &_src/EDITME_& for details.
2013
2014Then, for each module to be loaded dynamically, define the relevant
2015&`LOOKUP_`&<&'lookup_type'&> flags to have the value "2" instead of "yes".
2016For example, this will build in lsearch but load sqlite and mysql support
2017on demand:
2018.code
2019LOOKUP_LSEARCH=yes
2020LOOKUP_SQLITE=2
2021LOOKUP_MYSQL=2
2022.endd
5d758a46 2023
0a349494 2024
f89d2485 2025.section "The building process" "SECID29"
9b371988
PH
2026.cindex "build directory"
2027Once &_Local/Makefile_& (and &_Local/eximon.conf_&, if required) have been
2028created, run &'make'& at the top level. It determines the architecture and
168e428f
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2029operating system types, and creates a build directory if one does not exist.
2030For example, on a Sun system running Solaris 8, the directory
9b371988
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2031&_build-SunOS5-5.8-sparc_& is created.
2032.cindex "symbolic link" "to source files"
168e428f
PH
2033Symbolic links to relevant source files are installed in the build directory.
2034
9b371988 2035If this is the first time &'make'& has been run, it calls a script that builds
168e428f 2036a make file inside the build directory, using the configuration files from the
9b371988
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2037&_Local_& directory. The new make file is then passed to another instance of
2038&'make'&. This does the real work, building a number of utility scripts, and
168e428f 2039then compiling and linking the binaries for the Exim monitor (if configured), a
9b371988
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2040number of utility programs, and finally Exim itself. The command &`make
2041makefile`& can be used to force a rebuild of the make file in the build
168e428f
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2042directory, should this ever be necessary.
2043
2044If you have problems building Exim, check for any comments there may be in the
9b371988 2045&_README_& file concerning your operating system, and also take a look at the
168e428f
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2046FAQ, where some common problems are covered.
2047
2048
2049
f89d2485 2050.section 'Output from &"make"&' "SECID283"
9b371988 2051The output produced by the &'make'& process for compile lines is often very
068aaea8
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2052unreadable, because these lines can be very long. For this reason, the normal
2053output is suppressed by default, and instead output similar to that which
2054appears when compiling the 2.6 Linux kernel is generated: just a short line for
2055each module that is being compiled or linked. However, it is still possible to
9b371988
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2056get the full output, by calling &'make'& like this:
2057.code
2058FULLECHO='' make -e
2059.endd
2060The value of FULLECHO defaults to &"@"&, the flag character that suppresses
2061command reflection in &'make'&. When you ask for the full output, it is
3cb1b51e 2062given in addition to the short output.
068aaea8
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2063
2064
2065
9b371988 2066.section "Overriding build-time options for Exim" "SECToverride"
f89d2485 2067.cindex "build-time options, overriding"
168e428f
PH
2068The main make file that is created at the beginning of the building process
2069consists of the concatenation of a number of files which set configuration
9b371988 2070values, followed by a fixed set of &'make'& instructions. If a value is set
168e428f
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2071more than once, the last setting overrides any previous ones. This provides a
2072convenient way of overriding defaults. The files that are concatenated are, in
2073order:
9b371988
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2074.display
2075&_OS/Makefile-Default_&
2076&_OS/Makefile-_&<&'ostype'&>
2077&_Local/Makefile_&
2078&_Local/Makefile-_&<&'ostype'&>
2079&_Local/Makefile-_&<&'archtype'&>
2080&_Local/Makefile-_&<&'ostype'&>-<&'archtype'&>
2081&_OS/Makefile-Base_&
2082.endd
2083.cindex "&_Local/Makefile_&"
2084.cindex "building Exim" "operating system type"
2085.cindex "building Exim" "architecture type"
2086where <&'ostype'&> is the operating system type and <&'archtype'&> is the
2087architecture type. &_Local/Makefile_& is required to exist, and the building
2088process fails if it is absent. The other three &_Local_& files are optional,
168e428f
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2089and are often not needed.
2090
9b371988
PH
2091The values used for <&'ostype'&> and <&'archtype'&> are obtained from scripts
2092called &_scripts/os-type_& and &_scripts/arch-type_& respectively. If either of
168e428f
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2093the environment variables EXIM_OSTYPE or EXIM_ARCHTYPE is set, their
2094values are used, thereby providing a means of forcing particular settings.
9b371988 2095Otherwise, the scripts try to get values from the &%uname%& command. If this
168e428f 2096fails, the shell variables OSTYPE and ARCHTYPE are inspected. A number
9b371988 2097of &'ad hoc'& transformations are then applied, to produce the standard names
168e428f
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2098that Exim expects. You can run these scripts directly from the shell in order
2099to find out what values are being used on your system.
2100
2101
9b371988 2102&_OS/Makefile-Default_& contains comments about the variables that are set
168e428f
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2103therein. Some (but not all) are mentioned below. If there is something that
2104needs changing, review the contents of this file and the contents of the make
9b371988 2105file for your operating system (&_OS/Makefile-<ostype>_&) to see what the
168e428f
PH
2106default values are.
2107
2108
9b371988
PH
2109.cindex "building Exim" "overriding default settings"
2110If you need to change any of the values that are set in &_OS/Makefile-Default_&
2111or in &_OS/Makefile-<ostype>_&, or to add any new definitions, you do not
168e428f 2112need to change the original files. Instead, you should make the changes by
9b371988
PH
2113putting the new values in an appropriate &_Local_& file. For example,
2114.cindex "Tru64-Unix build-time settings"
168e428f
PH
2115when building Exim in many releases of the Tru64-Unix (formerly Digital UNIX,
2116formerly DEC-OSF1) operating system, it is necessary to specify that the C
9b371988
PH
2117compiler is called &'cc'& rather than &'gcc'&. Also, the compiler must be
2118called with the option &%-std1%&, to make it recognize some of the features of
168e428f 2119Standard C that Exim uses. (Most other compilers recognize Standard C by
9b371988 2120default.) To do this, you should create a file called &_Local/Makefile-OSF1_&
168e428f 2121containing the lines
9b371988
PH
2122.code
2123CC=cc
2124CFLAGS=-std1
2125.endd
168e428f 2126If you are compiling for just one operating system, it may be easier to put
9b371988 2127these lines directly into &_Local/Makefile_&.
168e428f
PH
2128
2129Keeping all your local configuration settings separate from the distributed
2130files makes it easy to transfer them to new versions of Exim simply by copying
9b371988 2131the contents of the &_Local_& directory.
168e428f
PH
2132
2133
9b371988
PH
2134.cindex "NIS lookup type" "including support for"
2135.cindex "NIS+ lookup type" "including support for"
2136.cindex "LDAP" "including support for"
2137.cindex "lookup" "inclusion in binary"
168e428f
PH
2138Exim contains support for doing LDAP, NIS, NIS+, and other kinds of file
2139lookup, but not all systems have these components installed, so the default is
2140not to include the relevant code in the binary. All the different kinds of file
2141and database lookup that Exim supports are implemented as separate code modules
2142which are included only if the relevant compile-time options are set. In the
9b371988
PH
2143case of LDAP, NIS, and NIS+, the settings for &_Local/Makefile_& are:
2144.code
2145LOOKUP_LDAP=yes
2146LOOKUP_NIS=yes
2147LOOKUP_NISPLUS=yes
2148.endd
168e428f 2149and similar settings apply to the other lookup types. They are all listed in
9b371988 2150&_src/EDITME_&. In many cases the relevant include files and interface
168e428f 2151libraries need to be installed before compiling Exim.
9b371988 2152.cindex "cdb" "including support for"
068aaea8
PH
2153However, there are some optional lookup types (such as cdb) for which
2154the code is entirely contained within Exim, and no external include
168e428f
PH
2155files or libraries are required. When a lookup type is not included in the
2156binary, attempts to configure Exim to use it cause run time configuration
2157errors.
2158
7e6a8985
PP
2159.cindex "pkg-config" "lookups"
2160.cindex "pkg-config" "authenticators"
252e0c7b
PP
2161Many systems now use a tool called &'pkg-config'& to encapsulate information
2162about how to compile against a library; Exim has some initial support for
2163being able to use pkg-config for lookups and authenticators. For any given
2164makefile variable which starts &`LOOKUP_`& or &`AUTH_`&, you can add a new
2165variable with the &`_PC`& suffix in the name and assign as the value the
2166name of the package to be queried. The results of querying via the
2167&'pkg-config'& command will be added to the appropriate Makefile variables
2168with &`+=`& directives, so your version of &'make'& will need to support that
2169syntax. For instance:
2170.code
2171LOOKUP_SQLITE=yes
2172LOOKUP_SQLITE_PC=sqlite3
2173AUTH_GSASL=yes
2174AUTH_GSASL_PC=libgsasl
2175AUTH_HEIMDAL_GSSAPI=yes
2176AUTH_HEIMDAL_GSSAPI_PC=heimdal-gssapi
2177.endd
252e0c7b 2178
9b371988 2179.cindex "Perl" "including support for"
168e428f
PH
2180Exim can be linked with an embedded Perl interpreter, allowing Perl
2181subroutines to be called during string expansion. To enable this facility,
9b371988
PH
2182.code
2183EXIM_PERL=perl.o
2184.endd
2185must be defined in &_Local/Makefile_&. Details of this facility are given in
2186chapter &<<CHAPperl>>&.
168e428f 2187
f89d2485 2188.cindex "X11 libraries, location of"
168e428f 2189The location of the X11 libraries is something that varies a lot between
068aaea8 2190operating systems, and there may be different versions of X11 to cope
168e428f
PH
2191with. Exim itself makes no use of X11, but if you are compiling the Exim
2192monitor, the X11 libraries must be available.
9b371988
PH
2193The following three variables are set in &_OS/Makefile-Default_&:
2194.code
2195X11=/usr/X11R6
2196XINCLUDE=-I$(X11)/include
2197XLFLAGS=-L$(X11)/lib
2198.endd
168e428f 2199These are overridden in some of the operating-system configuration files. For
9b371988
PH
2200example, in &_OS/Makefile-SunOS5_& there is
2201.code
2202X11=/usr/openwin
2203XINCLUDE=-I$(X11)/include
2204XLFLAGS=-L$(X11)/lib -R$(X11)/lib
2205.endd
168e428f
PH
2206If you need to override the default setting for your operating system, place a
2207definition of all three of these variables into your
9b371988 2208&_Local/Makefile-<ostype>_& file.
168e428f 2209
9b371988 2210.cindex "EXTRALIBS"
168e428f
PH
2211If you need to add any extra libraries to the link steps, these can be put in a
2212variable called EXTRALIBS, which appears in all the link commands, but by
2213default is not defined. In contrast, EXTRALIBS_EXIM is used only on the
2214command for linking the main Exim binary, and not for any associated utilities.
2215
9b371988 2216.cindex "DBM libraries" "configuration for building"
168e428f 2217There is also DBMLIB, which appears in the link commands for binaries that
9b371988 2218use DBM functions (see also section &<<SECTdb>>&). Finally, there is
168e428f
PH
2219EXTRALIBS_EXIMON, which appears only in the link step for the Exim monitor
2220binary, and which can be used, for example, to include additional X11
2221libraries.
2222
9b371988 2223.cindex "configuration file" "editing"
168e428f
PH
2224The make file copes with rebuilding Exim correctly if any of the configuration
2225files are edited. However, if an optional configuration file is deleted, it is
9b371988
PH
2226necessary to touch the associated non-optional file (that is,
2227&_Local/Makefile_& or &_Local/eximon.conf_&) before rebuilding.
168e428f
PH
2228
2229
f89d2485 2230.section "OS-specific header files" "SECID30"
9b371988
PH
2231.cindex "&_os.h_&"
2232.cindex "building Exim" "OS-specific C header files"
2233The &_OS_& directory contains a number of files with names of the form
2234&_os.h-<ostype>_&. These are system-specific C header files that should not
168e428f 2235normally need to be changed. There is a list of macro settings that are
9b371988 2236recognized in the file &_OS/os.configuring_&, which should be consulted if you
168e428f
PH
2237are porting Exim to a new operating system.
2238
2239
2240
f89d2485
PH
2241.section "Overriding build-time options for the monitor" "SECID31"
2242.cindex "building Eximon"
168e428f
PH
2243A similar process is used for overriding things when building the Exim monitor,
2244where the files that are involved are
9b371988
PH
2245.display
2246&_OS/eximon.conf-Default_&
2247&_OS/eximon.conf-_&<&'ostype'&>
2248&_Local/eximon.conf_&
2249&_Local/eximon.conf-_&<&'ostype'&>
2250&_Local/eximon.conf-_&<&'archtype'&>
2251&_Local/eximon.conf-_&<&'ostype'&>-<&'archtype'&>
2252.endd
2253.cindex "&_Local/eximon.conf_&"
168e428f 2254As with Exim itself, the final three files need not exist, and in this case the
9b371988
PH
2255&_OS/eximon.conf-<ostype>_& file is also optional. The default values in
2256&_OS/eximon.conf-Default_& can be overridden dynamically by setting environment
168e428f
PH
2257variables of the same name, preceded by EXIMON_. For example, setting
2258EXIMON_LOG_DEPTH in the environment overrides the value of
2259LOG_DEPTH at run time.
4f578862 2260.ecindex IIDbuex
168e428f
PH
2261
2262
f89d2485 2263.section "Installing Exim binaries and scripts" "SECID32"
9b371988
PH
2264.cindex "installing Exim"
2265.cindex "BIN_DIRECTORY"
2266The command &`make install`& runs the &(exim_install)& script with no
2267arguments. The script copies binaries and utility scripts into the directory
2268whose name is specified by the BIN_DIRECTORY setting in &_Local/Makefile_&.
2269.cindex "setuid" "installing Exim with"
068aaea8
PH
2270The install script copies files only if they are newer than the files they are
2271going to replace. The Exim binary is required to be owned by root and have the
9b371988
PH
2272&'setuid'& bit set, for normal configurations. Therefore, you must run &`make
2273install`& as root so that it can set up the Exim binary in this way. However, in
068aaea8
PH
2274some special situations (for example, if a host is doing no local deliveries)
2275it may be possible to run Exim without making the binary setuid root (see
9b371988 2276chapter &<<CHAPsecurity>>& for details).
168e428f 2277
9b371988 2278.cindex "CONFIGURE_FILE"
168e428f 2279Exim's run time configuration file is named by the CONFIGURE_FILE setting
9b371988
PH
2280in &_Local/Makefile_&. If this names a single file, and the file does not
2281exist, the default configuration file &_src/configure.default_& is copied there
168e428f
PH
2282by the installation script. If a run time configuration file already exists, it
2283is left alone. If CONFIGURE_FILE is a colon-separated list, naming several
2284alternative files, no default is installed.
2285
9b371988
PH
2286.cindex "system aliases file"
2287.cindex "&_/etc/aliases_&"
168e428f
PH
2288One change is made to the default configuration file when it is installed: the
2289default configuration contains a router that references a system aliases file.
2290The path to this file is set to the value specified by
9b371988 2291SYSTEM_ALIASES_FILE in &_Local/Makefile_& (&_/etc/aliases_& by default).
168e428f
PH
2292If the system aliases file does not exist, the installation script creates it,
2293and outputs a comment to the user.
2294
2295The created file contains no aliases, but it does contain comments about the
2296aliases a site should normally have. Mail aliases have traditionally been
9b371988
PH
2297kept in &_/etc/aliases_&. However, some operating systems are now using
2298&_/etc/mail/aliases_&. You should check if yours is one of these, and change
168e428f
PH
2299Exim's configuration if necessary.
2300
2301The default configuration uses the local host's name as the only local domain,
9b371988
PH
2302and is set up to do local deliveries into the shared directory &_/var/mail_&,
2303running as the local user. System aliases and &_.forward_& files in users' home
168e428f
PH
2304directories are supported, but no NIS or NIS+ support is configured. Domains
2305other than the name of the local host are routed using the DNS, with delivery
2306over SMTP.
2307
168e428f
PH
2308It is possible to install Exim for special purposes (such as building a binary
2309distribution) in a private part of the file system. You can do this by a
2310command such as
9b371988
PH
2311.code
2312make DESTDIR=/some/directory/ install
2313.endd
168e428f
PH
2314This has the effect of pre-pending the specified directory to all the file
2315paths, except the name of the system aliases file that appears in the default
9b371988 2316configuration. (If a default alias file is created, its name &'is'& modified.)
168e428f
PH
2317For backwards compatibility, ROOT is used if DESTDIR is not set,
2318but this usage is deprecated.
2319
9b371988
PH
2320.cindex "installing Exim" "what is not installed"
2321Running &'make install'& does not copy the Exim 4 conversion script
40df1be3
TF
2322&'convert4r4'&. You will probably run this only once if you are
2323upgrading from Exim 3. None of the documentation files in the &_doc_&
168e428f 2324directory are copied, except for the info files when you have set
9b371988 2325INFO_DIRECTORY, as described in section &<<SECTinsinfdoc>>& below.
168e428f 2326
9b371988 2327For the utility programs, old versions are renamed by adding the suffix &_.O_&
168e428f
PH
2328to their names. The Exim binary itself, however, is handled differently. It is
2329installed under a name that includes the version number and the compile number,
2aee48d6 2330for example &_exim-&version()-1_&. The script then arranges for a symbolic link
9b371988
PH
2331called &_exim_& to point to the binary. If you are updating a previous version
2332of Exim, the script takes care to ensure that the name &_exim_& is never absent
168e428f
PH
2333from the directory (as seen by other processes).
2334
9b371988
PH
2335.cindex "installing Exim" "testing the script"
2336If you want to see what the &'make install'& will do before running it for
2337real, you can pass the &%-n%& option to the installation script by this
2338command:
2339.code
2340make INSTALL_ARG=-n install
2341.endd
168e428f
PH
2342The contents of the variable INSTALL_ARG are passed to the installation
2343script. You do not need to be root to run this test. Alternatively, you can run
2344the installation script directly, but this must be from within the build
2345directory. For example, from the top-level Exim directory you could use this
2346command:
9b371988
PH
2347.code
2348(cd build-SunOS5-5.5.1-sparc; ../scripts/exim_install -n)
2349.endd
2350.cindex "installing Exim" "install script options"
168e428f
PH
2351There are two other options that can be supplied to the installation script.
2352
9b371988
PH
2353.ilist
2354&%-no_chown%& bypasses the call to change the owner of the installed binary
168e428f 2355to root, and the call to make it a setuid binary.
9b371988
PH
2356.next
2357&%-no_symlink%& bypasses the setting up of the symbolic link &_exim_& to the
168e428f 2358installed binary.
9b371988 2359.endlist
168e428f
PH
2360
2361INSTALL_ARG can be used to pass these options to the script. For example:
9b371988
PH
2362.code
2363make INSTALL_ARG=-no_symlink install
2364.endd
168e428f
PH
2365The installation script can also be given arguments specifying which files are
2366to be copied. For example, to install just the Exim binary, and nothing else,
2367without creating the symbolic link, you could use:
9b371988
PH
2368.code
2369make INSTALL_ARG='-no_symlink exim' install
2370.endd
168e428f
PH
2371
2372
2373
9b371988
PH
2374.section "Installing info documentation" "SECTinsinfdoc"
2375.cindex "installing Exim" "&'info'& documentation"
2376Not all systems use the GNU &'info'& system for documentation, and for this
168e428f
PH
2377reason, the Texinfo source of Exim's documentation is not included in the main
2378distribution. Instead it is available separately from the ftp site (see section
9b371988 2379&<<SECTavail>>&).
168e428f 2380
9b371988
PH
2381If you have defined INFO_DIRECTORY in &_Local/Makefile_& and the Texinfo
2382source of the documentation is found in the source tree, running &`make
2383install`& automatically builds the info files and installs them.
168e428f
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2384
2385
2386
f89d2485 2387.section "Setting up the spool directory" "SECID33"
9b371988 2388.cindex "spool directory" "creating"
168e428f
PH
2389When it starts up, Exim tries to create its spool directory if it does not
2390exist. The Exim uid and gid are used for the owner and group of the spool
2391directory. Sub-directories are automatically created in the spool directory as
2392necessary.
2393
2394
2395
2396
f89d2485 2397.section "Testing" "SECID34"
9b371988 2398.cindex "testing" "installation"
168e428f
PH
2399Having installed Exim, you can check that the run time configuration file is
2400syntactically valid by running the following command, which assumes that the
2401Exim binary directory is within your PATH environment variable:
9b371988
PH
2402.code
2403exim -bV
2404.endd
168e428f
PH
2405If there are any errors in the configuration file, Exim outputs error messages.
2406Otherwise it outputs the version number and build date,
2407the DBM library that is being used, and information about which drivers and
2408other optional code modules are included in the binary.
2409Some simple routing tests can be done by using the address testing option. For
2410example,
9b371988
PH
2411.display
2412&`exim -bt`& <&'local username'&>
2413.endd
168e428f 2414should verify that it recognizes a local mailbox, and
9b371988
PH
2415.display
2416&`exim -bt`& <&'remote address'&>
2417.endd
168e428f
PH
2418a remote one. Then try getting it to deliver mail, both locally and remotely.
2419This can be done by passing messages directly to Exim, without going through a
2420user agent. For example:
9b371988 2421.code
068aaea8
PH
2422exim -v postmaster@your.domain.example
2423From: user@your.domain.example
2424To: postmaster@your.domain.example
2425Subject: Testing Exim
168e428f 2426
068aaea8
PH
2427This is a test message.
2428^D
9b371988
PH
2429.endd
2430The &%-v%& option causes Exim to output some verification of what it is doing.
168e428f 2431In this case you should see copies of three log lines, one for the message's
9b371988 2432arrival, one for its delivery, and one containing &"Completed"&.
168e428f 2433
9b371988
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2434.cindex "delivery" "problems with"
2435If you encounter problems, look at Exim's log files (&'mainlog'& and
2436&'paniclog'&) to see if there is any relevant information there. Another source
168e428f 2437of information is running Exim with debugging turned on, by specifying the
9b371988 2438&%-d%& option. If a message is stuck on Exim's spool, you can force a delivery
168e428f 2439with debugging turned on by a command of the form
9b371988
PH
2440.display
2441&`exim -d -M`& <&'exim-message-id'&>
2442.endd
2443You must be root or an &"admin user"& in order to do this. The &%-d%& option
168e428f 2444produces rather a lot of output, but you can cut this down to specific areas.
9b371988
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2445For example, if you use &%-d-all+route%& only the debugging information
2446relevant to routing is included. (See the &%-d%& option in chapter
2447&<<CHAPcommandline>>& for more details.)
168e428f 2448
9b371988
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2449.cindex '&"sticky"& bit'
2450.cindex "lock files"
168e428f
PH
2451One specific problem that has shown up on some sites is the inability to do
2452local deliveries into a shared mailbox directory, because it does not have the
9b371988 2453&"sticky bit"& set on it. By default, Exim tries to create a lock file before
168e428f 2454writing to a mailbox file, and if it cannot create the lock file, the delivery
9b371988 2455is deferred. You can get round this either by setting the &"sticky bit"& on the
168e428f
PH
2456directory, or by setting a specific group for local deliveries and allowing
2457that group to create files in the directory (see the comments above the
9b371988 2458&(local_delivery)& transport in the default configuration file). Another
168e428f 2459approach is to configure Exim not to use lock files, but just to rely on
9b371988
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2460&[fcntl()]& locking instead. However, you should do this only if all user
2461agents also use &[fcntl()]& locking. For further discussion of locking issues,
2462see chapter &<<CHAPappendfile>>&.
168e428f
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2463
2464One thing that cannot be tested on a system that is already running an MTA is
2465the receipt of incoming SMTP mail on the standard SMTP port. However, the
9b371988
PH
2466&%-oX%& option can be used to run an Exim daemon that listens on some other
2467port, or &'inetd'& can be used to do this. The &%-bh%& option and the
2468&'exim_checkaccess'& utility can be used to check out policy controls on
168e428f
PH
2469incoming SMTP mail.
2470
2471Testing a new version on a system that is already running Exim can most easily
2472be done by building a binary with a different CONFIGURE_FILE setting. From
2473within the run time configuration, all other file and directory names
2474that Exim uses can be altered, in order to keep it entirely clear of the
2475production version.
2476
2477
f89d2485 2478.section "Replacing another MTA with Exim" "SECID35"
9b371988 2479.cindex "replacing another MTA"
168e428f
PH
2480Building and installing Exim for the first time does not of itself put it in
2481general use. The name by which the system's MTA is called by mail user agents
9b371988
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2482is either &_/usr/sbin/sendmail_&, or &_/usr/lib/sendmail_& (depending on the
2483operating system), and it is necessary to make this name point to the &'exim'&
168e428f 2484binary in order to get the user agents to pass messages to Exim. This is
9b371988
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2485normally done by renaming any existing file and making &_/usr/sbin/sendmail_&
2486or &_/usr/lib/sendmail_&
2487.cindex "symbolic link" "to &'exim'& binary"
2488a symbolic link to the &'exim'& binary. It is a good idea to remove any setuid
168e428f
PH
2489privilege and executable status from the old MTA. It is then necessary to stop
2490and restart the mailer daemon, if one is running.
2491
f89d2485 2492.cindex "FreeBSD, MTA indirection"
9b371988 2493.cindex "&_/etc/mail/mailer.conf_&"
168e428f
PH
2494Some operating systems have introduced alternative ways of switching MTAs. For
2495example, if you are running FreeBSD, you need to edit the file
9b371988 2496&_/etc/mail/mailer.conf_& instead of setting up a symbolic link as just
168e428f
PH
2497described. A typical example of the contents of this file for running Exim is
2498as follows:
9b371988
PH
2499.code
2500sendmail /usr/exim/bin/exim
2501send-mail /usr/exim/bin/exim
2502mailq /usr/exim/bin/exim -bp
2503newaliases /usr/bin/true
2504.endd
2505Once you have set up the symbolic link, or edited &_/etc/mail/mailer.conf_&,
2506your Exim installation is &"live"&. Check it by sending a message from your
168e428f
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2507favourite user agent.
2508
2509You should consider what to tell your users about the change of MTA. Exim may
2510have different capabilities to what was previously running, and there are
2511various operational differences such as the text of messages produced by
2512command line options and in bounce messages. If you allow your users to make
2513use of Exim's filtering capabilities, you should make the document entitled
9b371988 2514&'Exim's interface to mail filtering'& available to them.
168e428f
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2515
2516
2517
f89d2485 2518.section "Upgrading Exim" "SECID36"
9b371988 2519.cindex "upgrading Exim"
168e428f
PH
2520If you are already running Exim on your host, building and installing a new
2521version automatically makes it available to MUAs, or any other programs that
2522call the MTA directly. However, if you are running an Exim daemon, you do need
9b371988
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2523to send it a HUP signal, to make it re-execute itself, and thereby pick up the
2524new binary. You do not need to stop processing mail in order to install a new
068aaea8
PH
2525version of Exim. The install script does not modify an existing runtime
2526configuration file.
2527
168e428f
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2528
2529
2530
f89d2485 2531.section "Stopping the Exim daemon on Solaris" "SECID37"
9b371988 2532.cindex "Solaris" "stopping Exim on"
168e428f 2533The standard command for stopping the mailer daemon on Solaris is
9b371988
PH
2534.code
2535/etc/init.d/sendmail stop
2536.endd
2537If &_/usr/lib/sendmail_& has been turned into a symbolic link, this script
2538fails to stop Exim because it uses the command &'ps -e'& and greps the output
2539for the text &"sendmail"&; this is not present because the actual program name
2540(that is, &"exim"&) is given by the &'ps'& command with these options. A
2541solution is to replace the line that finds the process id with something like
2542.code
2543pid=`cat /var/spool/exim/exim-daemon.pid`
2544.endd
168e428f
PH
2545to obtain the daemon's pid directly from the file that Exim saves it in.
2546
9b371988 2547Note, however, that stopping the daemon does not &"stop Exim"&. Messages can
168e428f
PH
2548still be received from local processes, and if automatic delivery is configured
2549(the normal case), deliveries will still occur.
2550
2551
2552
2553
9b371988
PH
2554. ////////////////////////////////////////////////////////////////////////////
2555. ////////////////////////////////////////////////////////////////////////////
168e428f 2556
9b371988 2557.chapter "The Exim command line" "CHAPcommandline"
4f578862
PH
2558.scindex IIDclo1 "command line" "options"
2559.scindex IIDclo2 "options" "command line"
168e428f
PH
2560Exim's command line takes the standard Unix form of a sequence of options,
2561each starting with a hyphen character, followed by a number of arguments. The
2562options are compatible with the main options of Sendmail, and there are also
2563some additional options, some of which are compatible with Smail 3. Certain
2564combinations of options do not make sense, and provoke an error if used.
2565The form of the arguments depends on which options are set.
2566
2567
f89d2485 2568.section "Setting options by program name" "SECID38"
9b371988
PH
2569.cindex "&'mailq'&"
2570If Exim is called under the name &'mailq'&, it behaves as if the option &%-bp%&
168e428f 2571were present before any other options.
9b371988 2572The &%-bp%& option requests a listing of the contents of the mail queue on the
168e428f
PH
2573standard output.
2574This feature is for compatibility with some systems that contain a command of
2575that name in one of the standard libraries, symbolically linked to
9b371988
PH
2576&_/usr/sbin/sendmail_& or &_/usr/lib/sendmail_&.
2577
2578.cindex "&'rsmtp'&"
2579If Exim is called under the name &'rsmtp'& it behaves as if the option &%-bS%&
2580were present before any other options, for compatibility with Smail. The
2581&%-bS%& option is used for reading in a number of messages in batched SMTP
2582format.
2583
2584.cindex "&'rmail'&"
2585If Exim is called under the name &'rmail'& it behaves as if the &%-i%& and
2586&%-oee%& options were present before any other options, for compatibility with
2587Smail. The name &'rmail'& is used as an interface by some UUCP systems.
2588
2589.cindex "&'runq'&"
2590.cindex "queue runner"
2591If Exim is called under the name &'runq'& it behaves as if the option &%-q%&
2592were present before any other options, for compatibility with Smail. The &%-q%&
168e428f
PH
2593option causes a single queue runner process to be started.
2594
9b371988
PH
2595.cindex "&'newaliases'&"
2596.cindex "alias file" "building"
2597.cindex "Sendmail compatibility" "calling Exim as &'newaliases'&"
2598If Exim is called under the name &'newaliases'& it behaves as if the option
2599&%-bi%& were present before any other options, for compatibility with Sendmail.
168e428f
PH
2600This option is used for rebuilding Sendmail's alias file. Exim does not have
2601the concept of a single alias file, but can be configured to run a given
9b371988 2602command if called with the &%-bi%& option.
168e428f
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2603
2604
9b371988
PH
2605.section "Trusted and admin users" "SECTtrustedadmin"
2606Some Exim options are available only to &'trusted users'& and others are
2607available only to &'admin users'&. In the description below, the phrases &"Exim
2608user"& and &"Exim group"& mean the user and group defined by EXIM_USER and
2609EXIM_GROUP in &_Local/Makefile_& or set by the &%exim_user%& and
2610&%exim_group%& options. These do not necessarily have to use the name &"exim"&.
168e428f 2611
9b371988 2612.ilist
f89d2485 2613.cindex "trusted users" "definition of"
9b371988 2614.cindex "user" "trusted definition of"
168e428f 2615The trusted users are root, the Exim user, any user listed in the
9b371988
PH
2616&%trusted_users%& configuration option, and any user whose current group or any
2617supplementary group is one of those listed in the &%trusted_groups%&
168e428f 2618configuration option. Note that the Exim group is not automatically trusted.
9b371988
PH
2619
2620.cindex '&"From"& line'
2621.cindex "envelope sender"
2622Trusted users are always permitted to use the &%-f%& option or a leading
2623&"From&~"& line to specify the envelope sender of a message that is passed to
2624Exim through the local interface (see the &%-bm%& and &%-f%& options below).
2625See the &%untrusted_set_sender%& option for a way of permitting non-trusted
2626users to set envelope senders.
2627
2628.cindex "&'From:'& header line"
2629.cindex "&'Sender:'& header line"
1e4519cc
JH
2630.cindex "header lines" "From:"
2631.cindex "header lines" "Sender:"
9b371988
PH
2632For a trusted user, there is never any check on the contents of the &'From:'&
2633header line, and a &'Sender:'& line is never added. Furthermore, any existing
2634&'Sender:'& line in incoming local (non-TCP/IP) messages is not removed.
2635
168e428f
PH
2636Trusted users may also specify a host name, host address, interface address,
2637protocol name, ident value, and authentication data when submitting a message
2638locally. Thus, they are able to insert messages into Exim's queue locally that
2639have the characteristics of messages received from a remote host. Untrusted
9b371988 2640users may in some circumstances use &%-f%&, but can never set the other values
168e428f 2641that are available to trusted users.
9b371988
PH
2642.next
2643.cindex "user" "admin definition of"
2644.cindex "admin user" "definition of"
168e428f 2645The admin users are root, the Exim user, and any user that is a member of the
9b371988 2646Exim group or of any group listed in the &%admin_groups%& configuration option.
168e428f 2647The current group does not have to be one of these groups.
9b371988 2648
168e428f
PH
2649Admin users are permitted to list the queue, and to carry out certain
2650operations on messages, for example, to force delivery failures. It is also
2651necessary to be an admin user in order to see the full information provided by
2652the Exim monitor, and full debugging output.
9b371988
PH
2653
2654By default, the use of the &%-M%&, &%-q%&, &%-R%&, and &%-S%& options to cause
2655Exim to attempt delivery of messages on its queue is restricted to admin users.
2656However, this restriction can be relaxed by setting the &%prod_requires_admin%&
2657option false (that is, specifying &%no_prod_requires_admin%&).
2658
2659Similarly, the use of the &%-bp%& option to list all the messages in the queue
2660is restricted to admin users unless &%queue_list_requires_admin%& is set
168e428f 2661false.
9b371988 2662.endlist
168e428f
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2663
2664
9b371988 2665&*Warning*&: If you configure your system so that admin users are able to
168e428f
PH
2666edit Exim's configuration file, you are giving those users an easy way of
2667getting root. There is further discussion of this issue at the start of chapter
9b371988 2668&<<CHAPconf>>&.
168e428f
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2669
2670
2671
2672
f89d2485 2673.section "Command line options" "SECID39"
db9452a9
PH
2674Exim's command line options are described in alphabetical order below. If none
2675of the options that specifies a specific action (such as starting the daemon or
2676a queue runner, or testing an address, or receiving a message in a specific
2677format, or listing the queue) are present, and there is at least one argument
2678on the command line, &%-bm%& (accept a local message on the standard input,
2679with the arguments specifying the recipients) is assumed. Otherwise, Exim
2680outputs a brief message about itself and exits.
168e428f 2681
9b371988
PH
2682. ////////////////////////////////////////////////////////////////////////////
2683. Insert a stylized XML comment here, to identify the start of the command line
2684. options. This is for the benefit of the Perl script that automatically
2685. creates a man page for the options.
2686. ////////////////////////////////////////////////////////////////////////////
168e428f 2687
9b371988 2688.literal xml
168e428f 2689<!-- === Start of command line options === -->
9b371988 2690.literal off
168e428f
PH
2691
2692
9b371988
PH
2693.vlist
2694.vitem &%--%&
2695.oindex "--"
2696.cindex "options" "command line; terminating"
168e428f
PH
2697This is a pseudo-option whose only purpose is to terminate the options and
2698therefore to cause subsequent command line items to be treated as arguments
2699rather than options, even if they begin with hyphens.
2700
9b371988
PH
2701.vitem &%--help%&
2702.oindex "&%--help%&"
168e428f
PH
2703This option causes Exim to output a few sentences stating what it is.
2704The same output is generated if the Exim binary is called with no options and
2705no arguments.
2706
4b2241d2
PP
2707.vitem &%--version%&
2708.oindex "&%--version%&"
2709This option is an alias for &%-bV%& and causes version information to be
2710displayed.
2711
a3fb9793
PP
2712.vitem &%-Ac%& &&&
2713 &%-Am%&
2714.oindex "&%-Ac%&"
2715.oindex "&%-Am%&"
2716These options are used by Sendmail for selecting configuration files and are
2717ignored by Exim.
a3fb9793 2718
9b371988
PH
2719.vitem &%-B%&<&'type'&>
2720.oindex "&%-B%&"
2721.cindex "8-bit characters"
2722.cindex "Sendmail compatibility" "8-bit characters"
168e428f
PH
2723This is a Sendmail option for selecting 7 or 8 bit processing. Exim is 8-bit
2724clean; it ignores this option.
2725
9b371988
PH
2726.vitem &%-bd%&
2727.oindex "&%-bd%&"
2728.cindex "daemon"
f89d2485 2729.cindex "SMTP" "listener"
9b371988 2730.cindex "queue runner"
168e428f 2731This option runs Exim as a daemon, awaiting incoming SMTP connections. Usually
9b371988
PH
2732the &%-bd%& option is combined with the &%-q%&<&'time'&> option, to specify
2733that the daemon should also initiate periodic queue runs.
2734
2735The &%-bd%& option can be used only by an admin user. If either of the &%-d%&
2736(debugging) or &%-v%& (verifying) options are set, the daemon does not
168e428f
PH
2737disconnect from the controlling terminal. When running this way, it can be
2738stopped by pressing ctrl-C.
9b371988 2739
168e428f
PH
2740By default, Exim listens for incoming connections to the standard SMTP port on
2741all the host's running interfaces. However, it is possible to listen on other
2742ports, on multiple ports, and only on specific interfaces. Chapter
9b371988
PH
2743&<<CHAPinterfaces>>& contains a description of the options that control this.
2744
168e428f 2745When a listening daemon
9b371988
PH
2746.cindex "daemon" "process id (pid)"
2747.cindex "pid (process id)" "of daemon"
2748is started without the use of &%-oX%& (that is, without overriding the normal
2749configuration), it writes its process id to a file called &_exim-daemon.pid_&
2750in Exim's spool directory. This location can be overridden by setting
2751PID_FILE_PATH in &_Local/Makefile_&. The file is written while Exim is still
168e428f 2752running as root.
9b371988
PH
2753
2754When &%-oX%& is used on the command line to start a listening daemon, the
2755process id is not written to the normal pid file path. However, &%-oP%& can be
168e428f 2756used to specify a path on the command line if a pid file is required.
9b371988 2757
168e428f 2758The SIGHUP signal
9b371988 2759.cindex "SIGHUP"
3cb1b51e
PH
2760.cindex "daemon" "restarting"
2761can be used to cause the daemon to re-execute itself. This should be done
2762whenever Exim's configuration file, or any file that is incorporated into it by
2763means of the &%.include%& facility, is changed, and also whenever a new version
2764of Exim is installed. It is not necessary to do this when other files that are
9b371988
PH
2765referenced from the configuration (for example, alias files) are changed,
2766because these are reread each time they are used.
2767
2768.vitem &%-bdf%&
2769.oindex "&%-bdf%&"
2770This option has the same effect as &%-bd%& except that it never disconnects
2771from the controlling terminal, even when no debugging is specified.
2772
2773.vitem &%-be%&
2774.oindex "&%-be%&"
2775.cindex "testing" "string expansion"
2776.cindex "expansion" "testing"
168e428f
PH
2777Run Exim in expansion testing mode. Exim discards its root privilege, to
2778prevent ordinary users from using this mode to read otherwise inaccessible
2779files. If no arguments are given, Exim runs interactively, prompting for lines
4f578862 2780of data. Otherwise, it processes each argument in turn.
9b371988
PH
2781
2782If Exim was built with USE_READLINE=yes in &_Local/Makefile_&, it tries
2783to load the &%libreadline%& library dynamically whenever the &%-be%& option is
2784used without command line arguments. If successful, it uses the &[readline()]&
168e428f
PH
2785function, which provides extensive line-editing facilities, for reading the
2786test data. A line history is supported.
9b371988 2787
168e428f 2788Long expansion expressions can be split over several lines by using backslash
068aaea8 2789continuations. As in Exim's run time configuration, white space at the start of
168e428f
PH
2790continuation lines is ignored. Each argument or data line is passed through the
2791string expansion mechanism, and the result is output. Variable values from the
9b371988 2792configuration file (for example, &$qualify_domain$&) are available, but no
374dc194 2793message-specific values (such as &$message_exim_id$&) are set, because no message
f89d2485 2794is being processed (but see &%-bem%& and &%-Mset%&).
168e428f 2795
9b371988
PH
2796&*Note*&: If you use this mechanism to test lookups, and you change the data
2797files or databases you are using, you must exit and restart Exim before trying
2798the same lookup again. Otherwise, because each Exim process caches the results
2799of lookups, you will just get the same result as before.
9b371988 2800
3cb1b51e
PH
2801.vitem &%-bem%&&~<&'filename'&>
2802.oindex "&%-bem%&"
2803.cindex "testing" "string expansion"
2804.cindex "expansion" "testing"
2805This option operates like &%-be%& except that it must be followed by the name
2806of a file. For example:
2807.code
2808exim -bem /tmp/testmessage
2809.endd
2810The file is read as a message (as if receiving a locally-submitted non-SMTP
2811message) before any of the test expansions are done. Thus, message-specific
2812variables such as &$message_size$& and &$header_from:$& are available. However,
2813no &'Received:'& header is added to the message. If the &%-t%& option is set,
2814recipients are read from the headers in the normal way, and are shown in the
2815&$recipients$& variable. Note that recipients cannot be given on the command
2816line, because further arguments are taken as strings to expand (just like
2817&%-be%&).
3cb1b51e 2818
9b371988
PH
2819.vitem &%-bF%&&~<&'filename'&>
2820.oindex "&%-bF%&"
2821.cindex "system filter" "testing"
2822.cindex "testing" "system filter"
2823This option is the same as &%-bf%& except that it assumes that the filter being
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PH
2824tested is a system filter. The additional commands that are available only in
2825system filters are recognized.
2826
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2827.vitem &%-bf%&&~<&'filename'&>
2828.oindex "&%-bf%&"
2829.cindex "filter" "testing"
2830.cindex "testing" "filter file"
2831.cindex "forward file" "testing"
2832.cindex "testing" "forward file"
2833.cindex "Sieve filter" "testing"
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PH
2834This option runs Exim in user filter testing mode; the file is the filter file
2835to be tested, and a test message must be supplied on the standard input. If
2836there are no message-dependent tests in the filter, an empty file can be
2837supplied.
168e428f 2838
9b371988
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2839If you want to test a system filter file, use &%-bF%& instead of &%-bf%&. You
2840can use both &%-bF%& and &%-bf%& on the same command, in order to test a system
2841filter and a user filter in the same run. For example:
2842.code
2843exim -bF /system/filter -bf /user/filter </test/message
2844.endd
168e428f
PH
2845This is helpful when the system filter adds header lines or sets filter
2846variables that are used by the user filter.
168e428f 2847
9b371988
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2848If the test filter file does not begin with one of the special lines
2849.code
2850# Exim filter
2851# Sieve filter
2852.endd
2853it is taken to be a normal &_.forward_& file, and is tested for validity under
2854that interpretation. See sections &<<SECTitenonfilred>>& to
2855&<<SECTspecitredli>>& for a description of the possible contents of non-filter
2856redirection lists.
2857
2858The result of an Exim command that uses &%-bf%&, provided no errors are
168e428f
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2859detected, is a list of the actions that Exim would try to take if presented
2860with the message for real. More details of filter testing are given in the
9b371988
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2861separate document entitled &'Exim's interfaces to mail filtering'&.
2862
168e428f 2863When testing a filter file,
9b371988
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2864.cindex "&""From""& line"
2865.cindex "envelope sender"
f89d2485 2866.oindex "&%-f%&" "for filter testing"
9b371988
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2867the envelope sender can be set by the &%-f%& option,
2868or by a &"From&~"& line at the start of the test message. Various parameters
2869that would normally be taken from the envelope recipient address of the message
2870can be set by means of additional command line options (see the next four
2871options).
2872
2873.vitem &%-bfd%&&~<&'domain'&>
2874.oindex "&%-bfd%&"
f89d2485 2875.vindex "&$qualify_domain$&"
168e428f 2876This sets the domain of the recipient address when a filter file is being
9b371988
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2877tested by means of the &%-bf%& option. The default is the value of
2878&$qualify_domain$&.
168e428f 2879
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2880.vitem &%-bfl%&&~<&'local&~part'&>
2881.oindex "&%-bfl%&"
168e428f 2882This sets the local part of the recipient address when a filter file is being
9b371988 2883tested by means of the &%-bf%& option. The default is the username of the
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2884process that calls Exim. A local part should be specified with any prefix or
2885suffix stripped, because that is how it appears to the filter when a message is
2886actually being delivered.
2887
9b371988
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2888.vitem &%-bfp%&&~<&'prefix'&>
2889.oindex "&%-bfp%&"
168e428f 2890This sets the prefix of the local part of the recipient address when a filter
9b371988 2891file is being tested by means of the &%-bf%& option. The default is an empty
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2892prefix.
2893
9b371988
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2894.vitem &%-bfs%&&~<&'suffix'&>
2895.oindex "&%-bfs%&"
168e428f 2896This sets the suffix of the local part of the recipient address when a filter
9b371988 2897file is being tested by means of the &%-bf%& option. The default is an empty
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2898suffix.
2899
9b371988
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2900.vitem &%-bh%&&~<&'IP&~address'&>
2901.oindex "&%-bh%&"
2902.cindex "testing" "incoming SMTP"
2903.cindex "SMTP" "testing incoming"
2904.cindex "testing" "relay control"
2905.cindex "relaying" "testing configuration"
2906.cindex "policy control" "testing"
2907.cindex "debugging" "&%-bh%& option"
168e428f
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2908This option runs a fake SMTP session as if from the given IP address, using the
2909standard input and output. The IP address may include a port number at the end,
2910after a full stop. For example:
9b371988
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2911.code
2912exim -bh 10.9.8.7.1234
2913exim -bh fe80::a00:20ff:fe86:a061.5678
2914.endd
168e428f 2915When an IPv6 address is given, it is converted into canonical form. In the case
9b371988
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2916of the second example above, the value of &$sender_host_address$& after
2917conversion to the canonical form is
2918&`fe80:0000:0000:0a00:20ff:fe86:a061.5678`&.
2919
168e428f 2920Comments as to what is going on are written to the standard error file. These
9b371988 2921include lines beginning with &"LOG"& for anything that would have been logged.
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2922This facility is provided for testing configuration options for incoming
2923messages, to make sure they implement the required policy. For example, you can
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2924test your relay controls using &%-bh%&.
2925
2926&*Warning 1*&:
2927.cindex "RFC 1413"
db9452a9
PH
2928You can test features of the configuration that rely on ident (RFC 1413)
2929information by using the &%-oMt%& option. However, Exim cannot actually perform
2930an ident callout when testing using &%-bh%& because there is no incoming SMTP
2931connection.
9b371988
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2932
2933&*Warning 2*&: Address verification callouts (see section &<<SECTcallver>>&)
2934are also skipped when testing using &%-bh%&. If you want these callouts to
2935occur, use &%-bhc%& instead.
2936
168e428f
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2937Messages supplied during the testing session are discarded, and nothing is
2938written to any of the real log files. There may be pauses when DNS (and other)
9b371988 2939lookups are taking place, and of course these may time out. The &%-oMi%& option
db9452a9
PH
2940can be used to specify a specific IP interface and port if this is important,
2941and &%-oMaa%& and &%-oMai%& can be used to set parameters as if the SMTP
2942session were authenticated.
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2943
2944The &'exim_checkaccess'& utility is a &"packaged"& version of &%-bh%& whose
168e428f 2945output just states whether a given recipient address from a given host is
9b371988 2946acceptable or not. See section &<<SECTcheckaccess>>&.
168e428f 2947
3cb1b51e 2948Features such as authentication and encryption, where the client input is not
f89d2485
PH
2949plain text, cannot easily be tested with &%-bh%&. Instead, you should use a
2950specialized SMTP test program such as
3cb1b51e 2951&url(http://jetmore.org/john/code/#swaks,swaks).
3cb1b51e 2952
9b371988
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2953.vitem &%-bhc%&&~<&'IP&~address'&>
2954.oindex "&%-bhc%&"
2955This option operates in the same way as &%-bh%&, except that address
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2956verification callouts are performed if required. This includes consulting and
2957updating the callout cache database.
2958
9b371988
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2959.vitem &%-bi%&
2960.oindex "&%-bi%&"
2961.cindex "alias file" "building"
2962.cindex "building alias file"
2963.cindex "Sendmail compatibility" "&%-bi%& option"
2964Sendmail interprets the &%-bi%& option as a request to rebuild its alias file.
168e428f 2965Exim does not have the concept of a single alias file, and so it cannot mimic
9b371988 2966this behaviour. However, calls to &_/usr/lib/sendmail_& with the &%-bi%& option
168e428f
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2967tend to appear in various scripts such as NIS make files, so the option must be
2968recognized.
9b371988
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2969
2970If &%-bi%& is encountered, the command specified by the &%bi_command%&
168e428f 2971configuration option is run, under the uid and gid of the caller of Exim. If
9b371988
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2972the &%-oA%& option is used, its value is passed to the command as an argument.
2973The command set by &%bi_command%& may not contain arguments. The command can
2974use the &'exim_dbmbuild'& utility, or some other means, to rebuild alias files
2975if this is required. If the &%bi_command%& option is not set, calling Exim with
2976&%-bi%& is a no-op.
2977
36a3ae5f 2978. // Keep :help first, then the rest in alphabetical order
98a90c36
PP
2979.vitem &%-bI:help%&
2980.oindex "&%-bI:help%&"
2981.cindex "querying exim information"
2982We shall provide various options starting &`-bI:`& for querying Exim for
2983information. The output of many of these will be intended for machine
2984consumption. This one is not. The &%-bI:help%& option asks Exim for a
2985synopsis of supported options beginning &`-bI:`&. Use of any of these
2986options shall cause Exim to exit after producing the requested output.
2987
36a3ae5f
PP
2988.vitem &%-bI:dscp%&
2989.oindex "&%-bI:dscp%&"
2990.cindex "DSCP" "values"
2991This option causes Exim to emit an alphabetically sorted list of all
2992recognised DSCP names.
2993
98a90c36
PP
2994.vitem &%-bI:sieve%&
2995.oindex "&%-bI:sieve%&"
2996.cindex "Sieve filter" "capabilities"
2997This option causes Exim to emit an alphabetically sorted list of all supported
2998Sieve protocol extensions on stdout, one per line. This is anticipated to be
2999useful for ManageSieve (RFC 5804) implementations, in providing that protocol's
3000&`SIEVE`& capability response line. As the precise list may depend upon
3001compile-time build options, which this option will adapt to, this is the only
3002way to guarantee a correct response.
3003
9b371988
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3004.vitem &%-bm%&
3005.oindex "&%-bm%&"
3006.cindex "local message reception"
168e428f 3007This option runs an Exim receiving process that accepts an incoming,
a543079f 3008locally-generated message on the standard input. The recipients are given as the
9b371988 3009command arguments (except when &%-t%& is also present &-- see below). Each
168e428f
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3010argument can be a comma-separated list of RFC 2822 addresses. This is the
3011default option for selecting the overall action of an Exim call; it is assumed
3012if no other conflicting option is present.
9b371988 3013
168e428f 3014If any addresses in the message are unqualified (have no domain), they are
9b371988
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3015qualified by the values of the &%qualify_domain%& or &%qualify_recipient%&
3016options, as appropriate. The &%-bnq%& option (see below) provides a way of
168e428f 3017suppressing this for special cases.
9b371988 3018
168e428f 3019Policy checks on the contents of local messages can be enforced by means of
9b371988
PH
3020the non-SMTP ACL. See chapter &<<CHAPACL>>& for details.
3021
3022.cindex "return code" "for &%-bm%&"
3023The return code is zero if the message is successfully accepted. Otherwise, the
3024action is controlled by the &%-oe%&&'x'& option setting &-- see below.
3025
168e428f 3026The format
9b371988
PH
3027.cindex "message" "format"
3028.cindex "format" "message"
3029.cindex "&""From""& line"
3030.cindex "UUCP" "&""From""& line"
3031.cindex "Sendmail compatibility" "&""From""& line"
168e428f
PH
3032of the message must be as defined in RFC 2822, except that, for
3033compatibility with Sendmail and Smail, a line in one of the forms
9b371988
PH
3034.code
3035From sender Fri Jan 5 12:55 GMT 1997
3036From sender Fri, 5 Jan 97 12:55:01
3037.endd
168e428f
PH
3038(with the weekday optional, and possibly with additional text after the date)
3039is permitted to appear at the start of the message. There appears to be no
3040authoritative specification of the format of this line. Exim recognizes it by
9b371988 3041matching against the regular expression defined by the &%uucp_from_pattern%&
168e428f 3042option, which can be changed if necessary.
9b371988 3043
f89d2485
PH
3044.oindex "&%-f%&" "overriding &""From""& line"
3045The specified sender is treated as if it were given as the argument to the
9b371988 3046&%-f%& option, but if a &%-f%& option is also present, its argument is used in
168e428f
PH
3047preference to the address taken from the message. The caller of Exim must be a
3048trusted user for the sender of a message to be set in this way.
3049
5b257915
PP
3050.vitem &%-bmalware%&&~<&'filename'&>
3051.oindex "&%-bmalware%&"
3052.cindex "testing", "malware"
3053.cindex "malware scan test"
60f914bc
HSHR
3054This debugging option causes Exim to scan the given file or directory
3055(depending on the used scanner interface),
5b257915
PP
3056using the malware scanning framework. The option of &%av_scanner%& influences
3057this option, so if &%av_scanner%&'s value is dependent upon an expansion then
3058the expansion should have defaults which apply to this invocation. ACLs are
3059not invoked, so if &%av_scanner%& references an ACL variable then that variable
3060will never be populated and &%-bmalware%& will fail.
3061