DKIM: document proper Ed25519 key-generation methods; remove helper program
[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
3721c554 48.set previousversion "4.90"
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
c45e9ca1 552018
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
54fda09b 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.
54fda09b 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.
168e428f 417
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"
2eec84ca 439.row &_openssl.txt_& "installing a current OpenSSL release"
9b371988 440.endtable
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441
442The main specification and the specification of the filtering language are also
443available in other formats (HTML, PostScript, PDF, and Texinfo). Section
9b371988 444&<<SECTavail>>& below tells you how to get hold of these.
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445
446
447
f89d2485 448.section "FTP and web sites" "SECID2"
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449.cindex "web site"
450.cindex "FTP site"
068aaea8 451The primary site for Exim source distributions is currently the University of
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452Cambridge's FTP site, whose contents are described in &'Where to find the Exim
453distribution'& below. In addition, there is a web site and an FTP site at
454&%exim.org%&. These are now also hosted at the University of Cambridge. The
455&%exim.org%& site was previously hosted for a number of years by Energis
456Squared, formerly Planet Online Ltd, whose support I gratefully acknowledge.
457
458.cindex "wiki"
459.cindex "FAQ"
168e428f 460As well as Exim distribution tar files, the Exim web site contains a number of
f89d2485 461differently formatted versions of the documentation. A recent addition to the
7d0ab55c 462online information is the Exim wiki (&url(http://wiki.exim.org)),
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463which contains what used to be a separate FAQ, as well as various other
464examples, tips, and know-how that have been contributed by Exim users.
465
466.cindex Bugzilla
77c27011 467An Exim Bugzilla exists at &url(https://bugs.exim.org). You can use
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468this to report bugs, and also to add items to the wish list. Please search
469first to check that you are not duplicating a previous entry.
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470
471
472
f89d2485 473.section "Mailing lists" "SECID3"
9b371988 474.cindex "mailing lists" "for Exim users"
f89d2485 475The following Exim mailing lists exist:
168e428f 476
9b371988 477.table2 140pt
d854d3a9 478.row &'exim-announce@exim.org'& "Moderated, low volume announcements list"
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479.row &'exim-users@exim.org'& "General discussion list"
480.row &'exim-dev@exim.org'& "Discussion of bugs, enhancements, etc."
d854d3a9 481.row &'exim-cvs@exim.org'& "Automated commit messages from the VCS"
9b371988 482.endtable
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483
484You can subscribe to these lists, change your existing subscriptions, and view
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485or search the archives via the mailing lists link on the Exim home page.
486.cindex "Debian" "mailing list for"
4f578862 487If you are using a Debian distribution of Exim, you may wish to subscribe to
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488the Debian-specific mailing list &'pkg-exim4-users@lists.alioth.debian.org'&
489via this web page:
490.display
491&url(http://lists.alioth.debian.org/mailman/listinfo/pkg-exim4-users)
492.endd
493Please ask Debian-specific questions on this list and not on the general Exim
494lists.
9b371988 495
f89d2485 496.section "Bug reports" "SECID5"
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497.cindex "bug reports"
498.cindex "reporting bugs"
7d0ab55c 499Reports of obvious bugs can be emailed to &'bugs@exim.org'& or reported
77c27011 500via the Bugzilla (&url(https://bugs.exim.org)). However, if you are unsure
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501whether some behaviour is a bug or not, the best thing to do is to post a
502message to the &'exim-dev'& mailing list and have it discussed.
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503
504
505
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506.section "Where to find the Exim distribution" "SECTavail"
507.cindex "FTP site"
508.cindex "distribution" "ftp site"
168e428f 509The master ftp site for the Exim distribution is
9b371988 510.display
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511&*ftp://ftp.exim.org/pub/exim*&
512.endd
513The file references that follow are relative to the &_exim_& directories at
514these sites. There are now quite a number of independent mirror sites around
515the world. Those that I know about are listed in the file called &_Mirrors_&.
516
517Within the &_exim_& directory there are subdirectories called &_exim3_& (for
518previous Exim 3 distributions), &_exim4_& (for the latest Exim 4
519distributions), and &_Testing_& for testing versions. In the &_exim4_&
168e428f 520subdirectory, the current release can always be found in files called
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521.display
522&_exim-n.nn.tar.gz_&
523&_exim-n.nn.tar.bz2_&
524.endd
525where &'n.nn'& is the highest such version number in the directory. The two
168e428f 526files contain identical data; the only difference is the type of compression.
9b371988 527The &_.bz2_& file is usually a lot smaller than the &_.gz_& file.
168e428f 528
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529.cindex "distribution" "signing details"
530.cindex "distribution" "public key"
531.cindex "public key for signed distribution"
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532The distributions will be PGP signed by an individual key of the Release
533Coordinator. This key will have a uid containing an email address in the
534&'exim.org'& domain and will have signatures from other people, including
535other Exim maintainers. We expect that the key will be in the "strong set" of
536PGP keys. There should be a trust path to that key from Nigel Metheringham's
537PGP key, a version of which can be found in the release directory in the file
538&_nigel-pubkey.asc_&. All keys used will be available in public keyserver pools,
539such as &'pool.sks-keyservers.net'&.
540
541At time of last update, releases were being made by Phil Pennock and signed with
542key &'0x403043153903637F'&, although that key is expected to be replaced in 2013.
543A trust path from Nigel's key to Phil's can be observed at
544&url(https://www.security.spodhuis.org/exim-trustpath).
85b2d6f3 545
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546Releases have also been authorized to be performed by Todd Lyons who signs with
547key &'0xC4F4F94804D29EBA'&. A direct trust path exists between previous RE Phil
548Pennock and Todd Lyons through a common associate.
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549
550The signatures for the tar bundles are in:
9b371988 551.display
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552&_exim-n.nn.tar.gz.asc_&
553&_exim-n.nn.tar.bz2.asc_&
9b371988 554.endd
168e428f 555For each released version, the log of changes is made separately available in a
9b371988 556separate file in the directory &_ChangeLogs_& so that it is possible to
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557find out what has changed without having to download the entire distribution.
558
9b371988 559.cindex "documentation" "available formats"
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560The main distribution contains ASCII versions of this specification and other
561documentation; other formats of the documents are available in separate files
9b371988
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562inside the &_exim4_& directory of the FTP site:
563.display
564&_exim-html-n.nn.tar.gz_&
565&_exim-pdf-n.nn.tar.gz_&
566&_exim-postscript-n.nn.tar.gz_&
567&_exim-texinfo-n.nn.tar.gz_&
568.endd
569These tar files contain only the &_doc_& directory, not the complete
570distribution, and are also available in &_.bz2_& as well as &_.gz_& forms.
168e428f 571
168e428f 572
f89d2485 573.section "Limitations" "SECID6"
9b371988
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574.ilist
575.cindex "limitations of Exim"
576.cindex "bang paths" "not handled by Exim"
577Exim is designed for use as an Internet MTA, and therefore handles addresses in
578RFC 2822 domain format only. It cannot handle UUCP &"bang paths"&, though
579simple two-component bang paths can be converted by a straightforward rewriting
580configuration. This restriction does not prevent Exim from being interfaced to
581UUCP as a transport mechanism, provided that domain addresses are used.
582.next
583.cindex "domainless addresses"
584.cindex "address" "without domain"
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585Exim insists that every address it handles has a domain attached. For incoming
586local messages, domainless addresses are automatically qualified with a
587configured domain value. Configuration options specify from which remote
588systems unqualified addresses are acceptable. These are then qualified on
589arrival.
9b371988
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590.next
591.cindex "transport" "external"
592.cindex "external transports"
593The only external transport mechanisms that are currently implemented are SMTP
594and LMTP over a TCP/IP network (including support for IPv6). However, a pipe
168e428f 595transport is available, and there are facilities for writing messages to files
9b371988
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596and pipes, optionally in &'batched SMTP'& format; these facilities can be used
597to send messages to other transport mechanisms such as UUCP, provided they can
598handle domain-style addresses. Batched SMTP input is also catered for.
599.next
600Exim is not designed for storing mail for dial-in hosts. When the volumes of
601such mail are large, it is better to get the messages &"delivered"& into files
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602(that is, off Exim's queue) and subsequently passed on to the dial-in hosts by
603other means.
9b371988
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604.next
605Although Exim does have basic facilities for scanning incoming messages, these
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606are not comprehensive enough to do full virus or spam scanning. Such operations
607are best carried out using additional specialized software packages. If you
608compile Exim with the content-scanning extension, straightforward interfaces to
609a number of common scanners are provided.
9b371988 610.endlist
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611
612
f89d2485 613.section "Run time configuration" "SECID7"
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614Exim's run time configuration is held in a single text file that is divided
615into a number of sections. The entries in this file consist of keywords and
616values, in the style of Smail 3 configuration files. A default configuration
617file which is suitable for simple online installations is provided in the
9b371988 618distribution, and is described in chapter &<<CHAPdefconfil>>& below.
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619
620
f89d2485 621.section "Calling interface" "SECID8"
9b371988 622.cindex "Sendmail compatibility" "command line interface"
168e428f 623Like many MTAs, Exim has adopted the Sendmail command line interface so that it
9b371988
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624can be a straight replacement for &_/usr/lib/sendmail_& or
625&_/usr/sbin/sendmail_& when sending mail, but you do not need to know anything
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626about Sendmail in order to run Exim. For actions other than sending messages,
627Sendmail-compatible options also exist, but those that produce output (for
9b371988 628example, &%-bp%&, which lists the messages on the queue) do so in Exim's own
168e428f 629format. There are also some additional options that are compatible with Smail
9b371988 6303, and some further options that are new to Exim. Chapter &<<CHAPcommandline>>&
168e428f
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631documents all Exim's command line options. This information is automatically
632made into the man page that forms part of the Exim distribution.
633
634Control of messages on the queue can be done via certain privileged command
9b371988
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635line options. There is also an optional monitor program called &'eximon'&,
636which displays current information in an X window, and which contains a menu
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637interface to Exim's command line administration options.
638
639
640
f89d2485 641.section "Terminology" "SECID9"
9b371988
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642.cindex "terminology definitions"
643.cindex "body of message" "definition of"
644The &'body'& of a message is the actual data that the sender wants to transmit.
645It is the last part of a message, and is separated from the &'header'& (see
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646below) by a blank line.
647
9b371988 648.cindex "bounce message" "definition of"
168e428f 649When a message cannot be delivered, it is normally returned to the sender in a
9b371988
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650delivery failure message or a &"non-delivery report"& (NDR). The term
651&'bounce'& is commonly used for this action, and the error reports are often
652called &'bounce messages'&. This is a convenient shorthand for &"delivery
653failure error report"&. Such messages have an empty sender address in the
654message's &'envelope'& (see below) to ensure that they cannot themselves give
655rise to further bounce messages.
656
657The term &'default'& appears frequently in this manual. It is used to qualify a
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658value which is used in the absence of any setting in the configuration. It may
659also qualify an action which is taken unless a configuration setting specifies
660otherwise.
661
9b371988 662The term &'defer'& is used when the delivery of a message to a specific
168e428f 663destination cannot immediately take place for some reason (a remote host may be
9b371988 664down, or a user's local mailbox may be full). Such deliveries are &'deferred'&
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665until a later time.
666
9b371988
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667The word &'domain'& is sometimes used to mean all but the first component of a
668host's name. It is &'not'& used in that sense here, where it normally refers to
669the part of an email address following the @ sign.
168e428f 670
f89d2485 671.cindex "envelope, definition of"
9b371988
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672.cindex "sender" "definition of"
673A message in transit has an associated &'envelope'&, as well as a header and a
168e428f
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674body. The envelope contains a sender address (to which bounce messages should
675be delivered), and any number of recipient addresses. References to the
676sender or the recipients of a message usually mean the addresses in the
677envelope. An MTA uses these addresses for delivery, and for returning bounce
678messages, not the addresses that appear in the header lines.
679
f89d2485 680.cindex "message" "header, definition of"
9b371988
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681.cindex "header section" "definition of"
682The &'header'& of a message is the first part of a message's text, consisting
683of a number of lines, each of which has a name such as &'From:'&, &'To:'&,
684&'Subject:'&, etc. Long header lines can be split over several text lines by
168e428f
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685indenting the continuations. The header is separated from the body by a blank
686line.
687
9b371988
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688.cindex "local part" "definition of"
689.cindex "domain" "definition of"
690The term &'local part'&, which is taken from RFC 2822, is used to refer to that
168e428f 691part of an email address that precedes the @ sign. The part that follows the
9b371988 692@ sign is called the &'domain'& or &'mail domain'&.
168e428f 693
9b371988 694.cindex "local delivery" "definition of"
f89d2485 695.cindex "remote delivery, definition of"
9b371988 696The terms &'local delivery'& and &'remote delivery'& are used to distinguish
168e428f 697delivery to a file or a pipe on the local host from delivery by SMTP over
068aaea8 698TCP/IP to another host. As far as Exim is concerned, all hosts other than the
9b371988 699host it is running on are &'remote'&.
168e428f 700
9b371988
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701.cindex "return path" "definition of"
702&'Return path'& is another name that is used for the sender address in a
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703message's envelope.
704
9b371988
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705.cindex "queue" "definition of"
706The term &'queue'& is used to refer to the set of messages awaiting delivery,
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707because this term is in widespread use in the context of MTAs. However, in
708Exim's case the reality is more like a pool than a queue, because there is
709normally no ordering of waiting messages.
710
9b371988
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711.cindex "queue runner" "definition of"
712The term &'queue runner'& is used to describe a process that scans the queue
168e428f 713and attempts to deliver those messages whose retry times have come. This term
9b371988 714is used by other MTAs, and also relates to the command &%runq%&, but in Exim
168e428f
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715the waiting messages are normally processed in an unpredictable order.
716
9b371988
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717.cindex "spool directory" "definition of"
718The term &'spool directory'& is used for a directory in which Exim keeps the
719messages on its queue &-- that is, those that it is in the process of
168e428f 720delivering. This should not be confused with the directory in which local
9b371988
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721mailboxes are stored, which is called a &"spool directory"& by some people. In
722the Exim documentation, &"spool"& is always used in the first sense.
168e428f
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723
724
725
726
727
728
9b371988
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729. ////////////////////////////////////////////////////////////////////////////
730. ////////////////////////////////////////////////////////////////////////////
168e428f 731
f89d2485 732.chapter "Incorporated code" "CHID2"
9b371988
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733.cindex "incorporated code"
734.cindex "regular expressions" "library"
735.cindex "PCRE"
1899bab2 736.cindex "OpenDMARC"
168e428f
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737A number of pieces of external code are included in the Exim distribution.
738
9b371988 739.ilist
210f147e
NM
740Regular expressions are supported in the main Exim program and in the
741Exim monitor using the freely-distributable PCRE library, copyright
40df1be3
TF
742&copy; University of Cambridge. The source to PCRE is no longer shipped with
743Exim, so you will need to use the version of PCRE shipped with your system,
744or obtain and install the full version of the library from
f89d2485 745&url(ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre).
9b371988 746.next
f89d2485 747.cindex "cdb" "acknowledgment"
168e428f
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748Support for the cdb (Constant DataBase) lookup method is provided by code
749contributed by Nigel Metheringham of (at the time he contributed it) Planet
9b371988
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750Online Ltd. The implementation is completely contained within the code of Exim.
751It does not link against an external cdb library. The code contains the
752following statements:
753
754.blockquote
755Copyright &copy; 1998 Nigel Metheringham, Planet Online Ltd
756
168e428f
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757This program is free software; you can redistribute it and/or modify it under
758the terms of the GNU General Public License as published by the Free Software
759Foundation; either version 2 of the License, or (at your option) any later
760version.
168e428f
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761This code implements Dan Bernstein's Constant DataBase (cdb) spec. Information,
762the spec and sample code for cdb can be obtained from
f89d2485
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763&url(http://www.pobox.com/~djb/cdb.html). This implementation borrows
764some code from Dan Bernstein's implementation (which has no license
765restrictions applied to it).
9b371988
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766.endblockquote
767.next
768.cindex "SPA authentication"
769.cindex "Samba project"
770.cindex "Microsoft Secure Password Authentication"
771Client support for Microsoft's &'Secure Password Authentication'& is provided
168e428f
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772by code contributed by Marc Prud'hommeaux. Server support was contributed by
773Tom Kistner. This includes code taken from the Samba project, which is released
774under the Gnu GPL.
9b371988
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775.next
776.cindex "Cyrus"
777.cindex "&'pwcheck'& daemon"
778.cindex "&'pwauthd'& daemon"
779Support for calling the Cyrus &'pwcheck'& and &'saslauthd'& daemons is provided
168e428f
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780by code taken from the Cyrus-SASL library and adapted by Alexander S.
781Sabourenkov. The permission notice appears below, in accordance with the
782conditions expressed therein.
9b371988
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783
784.blockquote
785Copyright &copy; 2001 Carnegie Mellon University. All rights reserved.
786
168e428f
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787Redistribution and use in source and binary forms, with or without
788modification, are permitted provided that the following conditions
789are met:
168e428f 790
9b371988
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791.olist
792Redistributions of source code must retain the above copyright
793notice, this list of conditions and the following disclaimer.
794.next
795Redistributions in binary form must reproduce the above copyright
168e428f
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796notice, this list of conditions and the following disclaimer in
797the documentation and/or other materials provided with the
798distribution.
9b371988
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799.next
800The name &"Carnegie Mellon University"& must not be used to
168e428f
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801endorse or promote products derived from this software without
802prior written permission. For permission or any other legal
803details, please contact
9b371988 804.display
068aaea8
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805 Office of Technology Transfer
806 Carnegie Mellon University
807 5000 Forbes Avenue
808 Pittsburgh, PA 15213-3890
809 (412) 268-4387, fax: (412) 268-7395
810 tech-transfer@andrew.cmu.edu
9b371988
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811.endd
812.next
813Redistributions of any form whatsoever must retain the following
168e428f 814acknowledgment:
9b371988
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815
816&"This product includes software developed by Computing Services
817at Carnegie Mellon University (&url(http://www.cmu.edu/computing/)."&
818
168e428f
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819CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO
820THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
821AND FITNESS, IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE
822FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
823WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
824AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
825OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
9b371988
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826.endlist
827.endblockquote
168e428f 828
9b371988 829.next
f89d2485 830.cindex "Exim monitor" "acknowledgment"
9b371988
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831.cindex "X-windows"
832.cindex "Athena"
168e428f
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833The Exim Monitor program, which is an X-Window application, includes
834modified versions of the Athena StripChart and TextPop widgets.
835This code is copyright by DEC and MIT, and their permission notice appears
836below, in accordance with the conditions expressed therein.
9b371988
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837
838.blockquote
168e428f
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839Copyright 1987, 1988 by Digital Equipment Corporation, Maynard, Massachusetts,
840and the Massachusetts Institute of Technology, Cambridge, Massachusetts.
9b371988 841
168e428f 842All Rights Reserved
9b371988 843
168e428f
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844Permission to use, copy, modify, and distribute this software and its
845documentation for any purpose and without fee is hereby granted,
846provided that the above copyright notice appear in all copies and that
847both that copyright notice and this permission notice appear in
848supporting documentation, and that the names of Digital or MIT not be
849used in advertising or publicity pertaining to distribution of the
850software without specific, written prior permission.
9b371988 851
168e428f
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852DIGITAL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
853ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
854DIGITAL BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
855ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
856WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
857ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
858SOFTWARE.
9b371988 859.endblockquote
168e428f 860
9b371988 861.next
1899bab2
TL
862.cindex "opendmarc" "acknowledgment"
863The DMARC implementation uses the OpenDMARC library which is Copyrighted by
864The Trusted Domain Project. Portions of Exim source which use OpenDMARC
865derived code are indicated in the respective source files. The full OpenDMARC
866license is provided in the LICENSE.opendmarc file contained in the distributed
867source code.
868
869.next
9b371988 870Many people have contributed code fragments, some large, some small, that were
168e428f 871not covered by any specific licence requirements. It is assumed that the
f89d2485 872contributors are happy to see their code incorporated into Exim under the GPL.
9b371988 873.endlist
168e428f
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874
875
876
877
878
9b371988
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879. ////////////////////////////////////////////////////////////////////////////
880. ////////////////////////////////////////////////////////////////////////////
168e428f 881
f89d2485 882.chapter "How Exim receives and delivers mail" "CHID11" &&&
9b371988 883 "Receiving and delivering mail"
168e428f
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884
885
f89d2485 886.section "Overall philosophy" "SECID10"
9b371988 887.cindex "design philosophy"
168e428f
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888Exim is designed to work efficiently on systems that are permanently connected
889to the Internet and are handling a general mix of mail. In such circumstances,
890most messages can be delivered immediately. Consequently, Exim does not
891maintain independent queues of messages for specific domains or hosts, though
892it does try to send several messages in a single SMTP connection after a host
893has been down, and it also maintains per-host retry information.
894
895
f89d2485 896.section "Policy control" "SECID11"
9b371988 897.cindex "policy control" "overview"
168e428f
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898Policy controls are now an important feature of MTAs that are connected to the
899Internet. Perhaps their most important job is to stop MTAs being abused as
9b371988
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900&"open relays"& by misguided individuals who send out vast amounts of
901unsolicited junk, and want to disguise its source. Exim provides flexible
902facilities for specifying policy controls on incoming mail:
168e428f 903
9b371988
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904.ilist
905.cindex "&ACL;" "introduction"
168e428f 906Exim 4 (unlike previous versions of Exim) implements policy controls on
9b371988 907incoming mail by means of &'Access Control Lists'& (ACLs). Each list is a
168e428f
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908series of statements that may either grant or deny access. ACLs can be used at
909several places in the SMTP dialogue while receiving a message from a remote
9b371988
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910host. However, the most common places are after each RCPT command, and at the
911very end of the message. The sysadmin can specify conditions for accepting or
912rejecting individual recipients or the entire message, respectively, at these
913two points (see chapter &<<CHAPACL>>&). Denial of access results in an SMTP
168e428f 914error code.
9b371988
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915.next
916An ACL is also available for locally generated, non-SMTP messages. In this
168e428f 917case, the only available actions are to accept or deny the entire message.
9b371988
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918.next
919When Exim is compiled with the content-scanning extension, facilities are
168e428f
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920provided in the ACL mechanism for passing the message to external virus and/or
921spam scanning software. The result of such a scan is passed back to the ACL,
922which can then use it to decide what to do with the message.
9b371988
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923.next
924When a message has been received, either from a remote host or from the local
f89d2485 925host, but before the final acknowledgment has been sent, a locally supplied C
9b371988
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926function called &[local_scan()]& can be run to inspect the message and decide
927whether to accept it or not (see chapter &<<CHAPlocalscan>>&). If the message
928is accepted, the list of recipients can be modified by the function.
929.next
930Using the &[local_scan()]& mechanism is another way of calling external scanner
931software. The &%SA-Exim%& add-on package works this way. It does not require
932Exim to be compiled with the content-scanning extension.
933.next
934After a message has been accepted, a further checking mechanism is available in
935the form of the &'system filter'& (see chapter &<<CHAPsystemfilter>>&). This
936runs at the start of every delivery process.
937.endlist
938
939
940
f89d2485 941.section "User filters" "SECID12"
9b371988
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942.cindex "filter" "introduction"
943.cindex "Sieve filter"
168e428f 944In a conventional Exim configuration, users are able to run private filters by
9b371988
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945setting up appropriate &_.forward_& files in their home directories. See
946chapter &<<CHAPredirect>>& (about the &(redirect)& router) for the
947configuration needed to support this, and the separate document entitled
948&'Exim's interfaces to mail filtering'& for user details. Two different kinds
949of filtering are available:
950
951.ilist
952Sieve filters are written in the standard filtering language that is defined
168e428f 953by RFC 3028.
9b371988
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954.next
955Exim filters are written in a syntax that is unique to Exim, but which is more
168e428f 956powerful than Sieve, which it pre-dates.
9b371988 957.endlist
168e428f
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958
959User filters are run as part of the routing process, described below.
960
961
962
9b371988
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963.section "Message identification" "SECTmessiden"
964.cindex "message ids" "details of format"
965.cindex "format" "of message id"
966.cindex "id of message"
967.cindex "base62"
968.cindex "base36"
969.cindex "Darwin"
970.cindex "Cygwin"
971Every message handled by Exim is given a &'message id'& which is sixteen
168e428f 972characters long. It is divided into three parts, separated by hyphens, for
9b371988 973example &`16VDhn-0001bo-D3`&. Each part is a sequence of letters and digits,
168e428f
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974normally encoding numbers in base 62. However, in the Darwin operating
975system (Mac OS X) and when Exim is compiled to run under Cygwin, base 36
976(avoiding the use of lower case letters) is used instead, because the message
977id is used to construct file names, and the names of files in those systems are
068aaea8 978not always case-sensitive.
168e428f 979
9b371988 980.cindex "pid (process id)" "re-use of"
168e428f
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981The detail of the contents of the message id have changed as Exim has evolved.
982Earlier versions relied on the operating system not re-using a process id (pid)
983within one second. On modern operating systems, this assumption can no longer
984be made, so the algorithm had to be changed. To retain backward compatibility,
985the format of the message id was retained, which is why the following rules are
986somewhat eccentric:
987
9b371988
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988.ilist
989The first six characters of the message id are the time at which the message
168e428f
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990started to be received, to a granularity of one second. That is, this field
991contains the number of seconds since the start of the epoch (the normal Unix
992way of representing the date and time of day).
9b371988
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993.next
994After the first hyphen, the next six characters are the id of the process that
168e428f 995received the message.
9b371988
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996.next
997There are two different possibilities for the final two characters:
998.olist
0a4e3112 999.oindex "&%localhost_number%&"
9b371988 1000If &%localhost_number%& is not set, this value is the fractional part of the
168e428f
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1001time of reception, normally in units of 1/2000 of a second, but for systems
1002that must use base 36 instead of base 62 (because of case-insensitive file
1003systems), the units are 1/1000 of a second.
9b371988
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1004.next
1005If &%localhost_number%& is set, it is multiplied by 200 (100) and added to
168e428f
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1006the fractional part of the time, which in this case is in units of 1/200
1007(1/100) of a second.
9b371988
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1008.endlist
1009.endlist
168e428f
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1010
1011After a message has been received, Exim waits for the clock to tick at the
1012appropriate resolution before proceeding, so that if another message is
1013received by the same process, or by another process with the same (re-used)
1014pid, it is guaranteed that the time will be different. In most cases, the clock
1015will already have ticked while the message was being received.
1016
1017
f89d2485 1018.section "Receiving mail" "SECID13"
9b371988
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1019.cindex "receiving mail"
1020.cindex "message" "reception"
068aaea8
PH
1021The only way Exim can receive mail from another host is using SMTP over
1022TCP/IP, in which case the sender and recipient addresses are transferred using
168e428f
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1023SMTP commands. However, from a locally running process (such as a user's MUA),
1024there are several possibilities:
1025
9b371988
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1026.ilist
1027If the process runs Exim with the &%-bm%& option, the message is read
168e428f 1028non-interactively (usually via a pipe), with the recipients taken from the
9b371988
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1029command line, or from the body of the message if &%-t%& is also used.
1030.next
1031If the process runs Exim with the &%-bS%& option, the message is also read
168e428f
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1032non-interactively, but in this case the recipients are listed at the start of
1033the message in a series of SMTP RCPT commands, terminated by a DATA
9b371988 1034command. This is so-called &"batch SMTP"& format,
168e428f
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1035but it isn't really SMTP. The SMTP commands are just another way of passing
1036envelope addresses in a non-interactive submission.
9b371988
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1037.next
1038If the process runs Exim with the &%-bs%& option, the message is read
168e428f
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1039interactively, using the SMTP protocol. A two-way pipe is normally used for
1040passing data between the local process and the Exim process.
9b371988 1041This is &"real"& SMTP and is handled in the same way as SMTP over TCP/IP. For
168e428f 1042example, the ACLs for SMTP commands are used for this form of submission.
9b371988
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1043.next
1044A local process may also make a TCP/IP call to the host's loopback address
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1045(127.0.0.1) or any other of its IP addresses. When receiving messages, Exim
1046does not treat the loopback address specially. It treats all such connections
1047in the same way as connections from other hosts.
9b371988 1048.endlist
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1049
1050
f89d2485 1051.cindex "message sender, constructed by Exim"
9b371988 1052.cindex "sender" "constructed by Exim"
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1053In the three cases that do not involve TCP/IP, the sender address is
1054constructed from the login name of the user that called Exim and a default
9b371988 1055qualification domain (which can be set by the &%qualify_domain%& configuration
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1056option). For local or batch SMTP, a sender address that is passed using the
1057SMTP MAIL command is ignored. However, the system administrator may allow
9b371988 1058certain users (&"trusted users"&) to specify a different sender address
168e428f 1059unconditionally, or all users to specify certain forms of different sender
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1060address. The &%-f%& option or the SMTP MAIL command is used to specify these
1061different addresses. See section &<<SECTtrustedadmin>>& for details of trusted
1062users, and the &%untrusted_set_sender%& option for a way of allowing untrusted
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1063users to change sender addresses.
1064
1065Messages received by either of the non-interactive mechanisms are subject to
1066checking by the non-SMTP ACL, if one is defined. Messages received using SMTP
1067(either over TCP/IP, or interacting with a local process) can be checked by a
1068number of ACLs that operate at different times during the SMTP session. Either
1069individual recipients, or the entire message, can be rejected if local policy
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1070requirements are not met. The &[local_scan()]& function (see chapter
1071&<<CHAPlocalscan>>&) is run for all incoming messages.
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1072
1073Exim can be configured not to start a delivery process when a message is
1074received; this can be unconditional, or depend on the number of incoming SMTP
1075connections or the system load. In these situations, new messages wait on the
1076queue until a queue runner process picks them up. However, in standard
1077configurations under normal conditions, delivery is started as soon as a
1078message is received.
1079
1080
1081
1082
1083
f89d2485 1084.section "Handling an incoming message" "SECID14"
9b371988
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1085.cindex "spool directory" "files that hold a message"
1086.cindex "file" "how a message is held"
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1087When Exim accepts a message, it writes two files in its spool directory. The
1088first contains the envelope information, the current status of the message, and
1089the header lines, and the second contains the body of the message. The names of
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1090the two spool files consist of the message id, followed by &`-H`& for the
1091file containing the envelope and header, and &`-D`& for the data file.
168e428f 1092
9b371988 1093.cindex "spool directory" "&_input_& sub-directory"
168e428f 1094By default all these message files are held in a single directory called
9b371988 1095&_input_& inside the general Exim spool directory. Some operating systems do
c0712871 1096not perform very well if the number of files in a directory gets large; to
9b371988 1097improve performance in such cases, the &%split_spool_directory%& option can be
168e428f 1098used. This causes Exim to split up the input files into 62 sub-directories
db9452a9 1099whose names are single letters or digits. When this is done, the queue is
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1100processed one sub-directory at a time instead of all at once, which can improve
1101overall performance even when there are not enough files in each directory to
db9452a9 1102affect file system performance.
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1103
1104The envelope information consists of the address of the message's sender and
1105the addresses of the recipients. This information is entirely separate from
1106any addresses contained in the header lines. The status of the message includes
1107a list of recipients who have already received the message. The format of the
9b371988 1108first spool file is described in chapter &<<CHAPspool>>&.
168e428f 1109
9b371988 1110.cindex "rewriting" "addresses"
168e428f 1111Address rewriting that is specified in the rewrite section of the configuration
9b371988 1112(see chapter &<<CHAPrewrite>>&) is done once and for all on incoming addresses,
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1113both in the header lines and the envelope, at the time the message is accepted.
1114If during the course of delivery additional addresses are generated (for
1115example, via aliasing), these new addresses are rewritten as soon as they are
1116generated. At the time a message is actually delivered (transported) further
1117rewriting can take place; because this is a transport option, it can be
1118different for different forms of delivery. It is also possible to specify the
1119addition or removal of certain header lines at the time the message is
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1120delivered (see chapters &<<CHAProutergeneric>>& and
1121&<<CHAPtransportgeneric>>&).
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1122
1123
1124
f89d2485 1125.section "Life of a message" "SECID15"
9b371988
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1126.cindex "message" "life of"
1127.cindex "message" "frozen"
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1128A message remains in the spool directory until it is completely delivered to
1129its recipients or to an error address, or until it is deleted by an
1130administrator or by the user who originally created it. In cases when delivery
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1131cannot proceed &-- for example, when a message can neither be delivered to its
1132recipients nor returned to its sender, the message is marked &"frozen"& on the
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1133spool, and no more deliveries are attempted.
1134
9b371988
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1135.cindex "frozen messages" "thawing"
1136.cindex "message" "thawing frozen"
1137An administrator can &"thaw"& such messages when the problem has been
1138corrected, and can also freeze individual messages by hand if necessary. In
1139addition, an administrator can force a delivery error, causing a bounce message
1140to be sent.
1141
0a4e3112
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1142.oindex "&%timeout_frozen_after%&"
1143.oindex "&%ignore_bounce_errors_after%&"
9b371988
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1144There are options called &%ignore_bounce_errors_after%& and
1145&%timeout_frozen_after%&, which discard frozen messages after a certain time.
068aaea8 1146The first applies only to frozen bounces, the second to any frozen messages.
168e428f 1147
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1148.cindex "message" "log file for"
1149.cindex "log" "file for each message"
168e428f 1150While Exim is working on a message, it writes information about each delivery
068aaea8 1151attempt to its main log file. This includes successful, unsuccessful, and
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1152delayed deliveries for each recipient (see chapter &<<CHAPlog>>&). The log
1153lines are also written to a separate &'message log'& file for each message.
1154These logs are solely for the benefit of the administrator, and are normally
1155deleted along with the spool files when processing of a message is complete.
168e428f 1156The use of individual message logs can be disabled by setting
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1157&%no_message_logs%&; this might give an improvement in performance on very busy
1158systems.
168e428f 1159
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1160.cindex "journal file"
1161.cindex "file" "journal"
168e428f
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1162All the information Exim itself needs to set up a delivery is kept in the first
1163spool file, along with the header lines. When a successful delivery occurs, the
1164address is immediately written at the end of a journal file, whose name is the
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1165message id followed by &`-J`&. At the end of a delivery run, if there are some
1166addresses left to be tried again later, the first spool file (the &`-H`& file)
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1167is updated to indicate which these are, and the journal file is then deleted.
1168Updating the spool file is done by writing a new file and renaming it, to
1169minimize the possibility of data loss.
1170
1171Should the system or the program crash after a successful delivery but before
1172the spool file has been updated, the journal is left lying around. The next
1173time Exim attempts to deliver the message, it reads the journal file and
1174updates the spool file before proceeding. This minimizes the chances of double
1175deliveries caused by crashes.
1176
1177
1178
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1179.section "Processing an address for delivery" "SECTprocaddress"
1180.cindex "drivers" "definition of"
1181.cindex "router" "definition of"
1182.cindex "transport" "definition of"
1183The main delivery processing elements of Exim are called &'routers'& and
1184&'transports'&, and collectively these are known as &'drivers'&. Code for a
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1185number of them is provided in the source distribution, and compile-time options
1186specify which ones are included in the binary. Run time options specify which
1187ones are actually used for delivering messages.
1188
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1189.cindex "drivers" "instance definition"
1190Each driver that is specified in the run time configuration is an &'instance'&
168e428f 1191of that particular driver type. Multiple instances are allowed; for example,
9b371988 1192you can set up several different &(smtp)& transports, each with different
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1193option values that might specify different ports or different timeouts. Each
1194instance has its own identifying name. In what follows we will normally use the
1195instance name when discussing one particular instance (that is, one specific
1196configuration of the driver), and the generic driver name when discussing
1197the driver's features in general.
1198
9b371988 1199A &'router'& is a driver that operates on an address, either determining how
068aaea8 1200its delivery should happen, by assigning it to a specific transport, or
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1201converting the address into one or more new addresses (for example, via an
1202alias file). A router may also explicitly choose to fail an address, causing it
1203to be bounced.
1204
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1205A &'transport'& is a driver that transmits a copy of the message from Exim's
1206spool to some destination. There are two kinds of transport: for a &'local'&
168e428f 1207transport, the destination is a file or a pipe on the local host, whereas for a
9b371988 1208&'remote'& transport the destination is some other host. A message is passed
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1209to a specific transport as a result of successful routing. If a message has
1210several recipients, it may be passed to a number of different transports.
1211
9b371988 1212.cindex "preconditions" "definition of"
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1213An address is processed by passing it to each configured router instance in
1214turn, subject to certain preconditions, until a router accepts the address or
1215specifies that it should be bounced. We will describe this process in more
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1216detail shortly. First, as a simple example, we consider how each recipient
1217address in a message is processed in a small configuration of three routers.
168e428f 1218
068aaea8 1219To make this a more concrete example, it is described in terms of some actual
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1220routers, but remember, this is only an example. You can configure Exim's
1221routers in many different ways, and there may be any number of routers in a
1222configuration.
1223
1224The first router that is specified in a configuration is often one that handles
1225addresses in domains that are not recognized specially by the local host. These
1226are typically addresses for arbitrary domains on the Internet. A precondition
1227is set up which looks for the special domains known to the host (for example,
9b371988 1228its own domain name), and the router is run for addresses that do &'not'&
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1229match. Typically, this is a router that looks up domains in the DNS in order to
1230find the hosts to which this address routes. If it succeeds, the address is
068aaea8 1231assigned to a suitable SMTP transport; if it does not succeed, the router is
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1232configured to fail the address.
1233
068aaea8 1234The second router is reached only when the domain is recognized as one that
9b371988 1235&"belongs"& to the local host. This router does redirection &-- also known as
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1236aliasing and forwarding. When it generates one or more new addresses from the
1237original, each of them is routed independently from the start. Otherwise, the
1238router may cause an address to fail, or it may simply decline to handle the
1239address, in which case the address is passed to the next router.
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1240
1241The final router in many configurations is one that checks to see if the
1242address belongs to a local mailbox. The precondition may involve a check to
1243see if the local part is the name of a login account, or it may look up the
1244local part in a file or a database. If its preconditions are not met, or if
1245the router declines, we have reached the end of the routers. When this happens,
1246the address is bounced.
1247
1248
1249
f89d2485 1250.section "Processing an address for verification" "SECID16"
9b371988
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1251.cindex "router" "for verification"
1252.cindex "verifying address" "overview"
168e428f 1253As well as being used to decide how to deliver to an address, Exim's routers
9b371988 1254are also used for &'address verification'&. Verification can be requested as
168e428f 1255one of the checks to be performed in an ACL for incoming messages, on both
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1256sender and recipient addresses, and it can be tested using the &%-bv%& and
1257&%-bvs%& command line options.
168e428f 1258
9b371988 1259When an address is being verified, the routers are run in &"verify mode"&. This
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1260does not affect the way the routers work, but it is a state that can be
1261detected. By this means, a router can be skipped or made to behave differently
1262when verifying. A common example is a configuration in which the first router
1263sends all messages to a message-scanning program, unless they have been
1264previously scanned. Thus, the first router accepts all addresses without any
9b371988 1265checking, making it useless for verifying. Normally, the &%no_verify%& option
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1266would be set for such a router, causing it to be skipped in verify mode.
1267
1268
1269
1270
9b371988
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1271.section "Running an individual router" "SECTrunindrou"
1272.cindex "router" "running details"
1273.cindex "preconditions" "checking"
1274.cindex "router" "result of running"
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1275As explained in the example above, a number of preconditions are checked before
1276running a router. If any are not met, the router is skipped, and the address is
9b371988 1277passed to the next router. When all the preconditions on a router &'are'& met,
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1278the router is run. What happens next depends on the outcome, which is one of
1279the following:
1280
9b371988
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1281.ilist
1282&'accept'&: The router accepts the address, and either assigns it to a
1283transport, or generates one or more &"child"& addresses. Processing the
1284original address ceases,
0a4e3112 1285.oindex "&%unseen%&"
9b371988 1286unless the &%unseen%& option is set on the router. This option
168e428f 1287can be used to set up multiple deliveries with different routing (for example,
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1288for keeping archive copies of messages). When &%unseen%& is set, the address is
1289passed to the next router. Normally, however, an &'accept'& return marks the
168e428f 1290end of routing.
9b371988 1291
068aaea8
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1292Any child addresses generated by the router are processed independently,
1293starting with the first router by default. It is possible to change this by
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1294setting the &%redirect_router%& option to specify which router to start at for
1295child addresses. Unlike &%pass_router%& (see below) the router specified by
1296&%redirect_router%& may be anywhere in the router configuration.
1297.next
1298&'pass'&: The router recognizes the address, but cannot handle it itself. It
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1299requests that the address be passed to another router. By default the address
1300is passed to the next router, but this can be changed by setting the
9b371988 1301&%pass_router%& option. However, (unlike &%redirect_router%&) the named router
168e428f 1302must be below the current router (to avoid loops).
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1303.next
1304&'decline'&: The router declines to accept the address because it does not
168e428f 1305recognize it at all. By default, the address is passed to the next router, but
9b371988
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1306this can be prevented by setting the &%no_more%& option. When &%no_more%& is
1307set, all the remaining routers are skipped. In effect, &%no_more%& converts
1308&'decline'& into &'fail'&.
1309.next
1310&'fail'&: The router determines that the address should fail, and queues it for
168e428f 1311the generation of a bounce message. There is no further processing of the
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1312original address unless &%unseen%& is set on the router.
1313.next
1314&'defer'&: The router cannot handle the address at the present time. (A
068aaea8
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1315database may be offline, or a DNS lookup may have timed out.) No further
1316processing of the address happens in this delivery attempt. It is tried again
1317next time the message is considered for delivery.
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1318.next
1319&'error'&: There is some error in the router (for example, a syntax error in
168e428f 1320its configuration). The action is as for defer.
9b371988 1321.endlist
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1322
1323If an address reaches the end of the routers without having been accepted by
068aaea8 1324any of them, it is bounced as unrouteable. The default error message in this
9b371988
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1325situation is &"unrouteable address"&, but you can set your own message by
1326making use of the &%cannot_route_message%& option. This can be set for any
1327router; the value from the last router that &"saw"& the address is used.
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1328
1329Sometimes while routing you want to fail a delivery when some conditions are
1330met but others are not, instead of passing the address on for further routing.
1331You can do this by having a second router that explicitly fails the delivery
9b371988 1332when the relevant conditions are met. The &(redirect)& router has a &"fail"&
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1333facility for this purpose.
1334
1335
f89d2485 1336.section "Duplicate addresses" "SECID17"
9b371988 1337.cindex "case of local parts"
f89d2485 1338.cindex "address duplicate, discarding"
db9452a9 1339.cindex "duplicate addresses"
068aaea8
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1340Once routing is complete, Exim scans the addresses that are assigned to local
1341and remote transports, and discards any duplicates that it finds. During this
3cb1b51e 1342check, local parts are treated as case-sensitive. This happens only when
db9452a9 1343actually delivering a message; when testing routers with &%-bt%&, all the
3cb1b51e 1344routed addresses are shown.
db9452a9 1345
068aaea8 1346
168e428f 1347
9b371988 1348.section "Router preconditions" "SECTrouprecon"
f89d2485 1349.cindex "router" "preconditions, order of processing"
9b371988 1350.cindex "preconditions" "order of processing"
168e428f
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1351The preconditions that are tested for each router are listed below, in the
1352order in which they are tested. The individual configuration options are
9b371988 1353described in more detail in chapter &<<CHAProutergeneric>>&.
168e428f 1354
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1355.ilist
1356The &%local_part_prefix%& and &%local_part_suffix%& options can specify that
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1357the local parts handled by the router may or must have certain prefixes and/or
1358suffixes. If a mandatory affix (prefix or suffix) is not present, the router is
1359skipped. These conditions are tested first. When an affix is present, it is
1360removed from the local part before further processing, including the evaluation
1361of any other conditions.
9b371988
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1362.next
1363Routers can be designated for use only when not verifying an address, that is,
168e428f 1364only when routing it for delivery (or testing its delivery routing). If the
9b371988 1365&%verify%& option is set false, the router is skipped when Exim is verifying an
168e428f 1366address.
9b371988
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1367Setting the &%verify%& option actually sets two options, &%verify_sender%& and
1368&%verify_recipient%&, which independently control the use of the router for
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1369sender and recipient verification. You can set these options directly if
1370you want a router to be used for only one type of verification.
6ece2e77 1371Note that cutthrough delivery is classed as a recipient verification for this purpose.
9b371988
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1372.next
1373If the &%address_test%& option is set false, the router is skipped when Exim is
1374run with the &%-bt%& option to test an address routing. This can be helpful
1375when the first router sends all new messages to a scanner of some sort; it
1376makes it possible to use &%-bt%& to test subsequent delivery routing without
1377having to simulate the effect of the scanner.
1378.next
1379Routers can be designated for use only when verifying an address, as
1380opposed to routing it for delivery. The &%verify_only%& option controls this.
6ece2e77 1381Again, cutthrough delivery counts as a verification.
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1382.next
1383Individual routers can be explicitly skipped when running the routers to
1384check an address given in the SMTP EXPN command (see the &%expn%& option).
1385.next
1386If the &%domains%& option is set, the domain of the address must be in the set
068aaea8 1387of domains that it defines.
9b371988 1388.next
f89d2485
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1389.vindex "&$local_part_prefix$&"
1390.vindex "&$local_part$&"
1391.vindex "&$local_part_suffix$&"
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1392If the &%local_parts%& option is set, the local part of the address must be in
1393the set of local parts that it defines. If &%local_part_prefix%& or
1394&%local_part_suffix%& is in use, the prefix or suffix is removed from the local
168e428f 1395part before this check. If you want to do precondition tests on local parts
9b371988
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1396that include affixes, you can do so by using a &%condition%& option (see below)
1397that uses the variables &$local_part$&, &$local_part_prefix$&, and
1398&$local_part_suffix$& as necessary.
1399.next
f89d2485
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1400.vindex "&$local_user_uid$&"
1401.vindex "&$local_user_gid$&"
1402.vindex "&$home$&"
9b371988 1403If the &%check_local_user%& option is set, the local part must be the name of
068aaea8 1404an account on the local host. If this check succeeds, the uid and gid of the
9b371988
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1405local user are placed in &$local_user_uid$& and &$local_user_gid$& and the
1406user's home directory is placed in &$home$&; these values can be used in the
1407remaining preconditions.
1408.next
1409If the &%router_home_directory%& option is set, it is expanded at this point,
1410because it overrides the value of &$home$&. If this expansion were left till
1411later, the value of &$home$& as set by &%check_local_user%& would be used in
1412subsequent tests. Having two different values of &$home$& in the same router
168e428f 1413could lead to confusion.
9b371988
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1414.next
1415If the &%senders%& option is set, the envelope sender address must be in the
1416set of addresses that it defines.
1417.next
1418If the &%require_files%& option is set, the existence or non-existence of
168e428f 1419specified files is tested.
9b371988
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1420.next
1421.cindex "customizing" "precondition"
1422If the &%condition%& option is set, it is evaluated and tested. This option
1423uses an expanded string to allow you to set up your own custom preconditions.
1424Expanded strings are described in chapter &<<CHAPexpand>>&.
1425.endlist
168e428f 1426
168e428f 1427
9b371988
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1428Note that &%require_files%& comes near the end of the list, so you cannot use
1429it to check for the existence of a file in which to lookup up a domain, local
168e428f 1430part, or sender. However, as these options are all expanded, you can use the
9b371988
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1431&%exists%& expansion condition to make such tests within each condition. The
1432&%require_files%& option is intended for checking files that the router may be
168e428f 1433going to use internally, or which are needed by a specific transport (for
9b371988 1434example, &_.procmailrc_&).
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1435
1436
1437
f89d2485 1438.section "Delivery in detail" "SECID18"
9b371988 1439.cindex "delivery" "in detail"
168e428f
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1440When a message is to be delivered, the sequence of events is as follows:
1441
9b371988
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1442.ilist
1443If a system-wide filter file is specified, the message is passed to it. The
168e428f
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1444filter may add recipients to the message, replace the recipients, discard the
1445message, cause a new message to be generated, or cause the message delivery to
1446fail. The format of the system filter file is the same as for Exim user filter
9b371988
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1447files, described in the separate document entitled &'Exim's interfaces to mail
1448filtering'&.
1449.cindex "Sieve filter" "not available for system filter"
1450(&*Note*&: Sieve cannot be used for system filter files.)
1451
1452Some additional features are available in system filters &-- see chapter
1453&<<CHAPsystemfilter>>& for details. Note that a message is passed to the system
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1454filter only once per delivery attempt, however many recipients it has. However,
1455if there are several delivery attempts because one or more addresses could not
1456be immediately delivered, the system filter is run each time. The filter
9b371988 1457condition &%first_delivery%& can be used to detect the first run of the system
168e428f 1458filter.
9b371988
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1459.next
1460Each recipient address is offered to each configured router in turn, subject to
1461its preconditions, until one is able to handle it. If no router can handle the
1462address, that is, if they all decline, the address is failed. Because routers
1463can be targeted at particular domains, several locally handled domains can be
1464processed entirely independently of each other.
1465.next
1466.cindex "routing" "loops in"
1467.cindex "loop" "while routing"
1468A router that accepts an address may assign it to a local or a remote
1469transport. However, the transport is not run at this time. Instead, the address
1470is placed on a list for the particular transport, which will be run later.
068aaea8
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1471Alternatively, the router may generate one or more new addresses (typically
1472from alias, forward, or filter files). New addresses are fed back into this
1473process from the top, but in order to avoid loops, a router ignores any address
1474which has an identically-named ancestor that was processed by itself.
9b371988
PH
1475.next
1476When all the routing has been done, addresses that have been successfully
168e428f
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1477handled are passed to their assigned transports. When local transports are
1478doing real local deliveries, they handle only one address at a time, but if a
1479local transport is being used as a pseudo-remote transport (for example, to
1480collect batched SMTP messages for transmission by some other means) multiple
1481addresses can be handled. Remote transports can always handle more than one
1482address at a time, but can be configured not to do so, or to restrict multiple
1483addresses to the same domain.
9b371988
PH
1484.next
1485Each local delivery to a file or a pipe runs in a separate process under a
168e428f
PH
1486non-privileged uid, and these deliveries are run one at a time. Remote
1487deliveries also run in separate processes, normally under a uid that is private
9b371988 1488to Exim (&"the Exim user"&), but in this case, several remote deliveries can be
168e428f 1489run in parallel. The maximum number of simultaneous remote deliveries for any
9b371988 1490one message is set by the &%remote_max_parallel%& option.
168e428f
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1491The order in which deliveries are done is not defined, except that all local
1492deliveries happen before any remote deliveries.
9b371988
PH
1493.next
1494.cindex "queue runner"
168e428f
PH
1495When it encounters a local delivery during a queue run, Exim checks its retry
1496database to see if there has been a previous temporary delivery failure for the
1497address before running the local transport. If there was a previous failure,
1498Exim does not attempt a new delivery until the retry time for the address is
1499reached. However, this happens only for delivery attempts that are part of a
1500queue run. Local deliveries are always attempted when delivery immediately
1501follows message reception, even if retry times are set for them. This makes for
1502better behaviour if one particular message is causing problems (for example,
1503causing quota overflow, or provoking an error in a filter file).
9b371988
PH
1504.next
1505.cindex "delivery" "retry in remote transports"
168e428f
PH
1506Remote transports do their own retry handling, since an address may be
1507deliverable to one of a number of hosts, each of which may have a different
1508retry time. If there have been previous temporary failures and no host has
1509reached its retry time, no delivery is attempted, whether in a queue run or
9b371988
PH
1510not. See chapter &<<CHAPretry>>& for details of retry strategies.
1511.next
1512If there were any permanent errors, a bounce message is returned to an
168e428f
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1513appropriate address (the sender in the common case), with details of the error
1514for each failing address. Exim can be configured to send copies of bounce
1515messages to other addresses.
9b371988
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1516.next
1517.cindex "delivery" "deferral"
168e428f
PH
1518If one or more addresses suffered a temporary failure, the message is left on
1519the queue, to be tried again later. Delivery of these addresses is said to be
9b371988
PH
1520&'deferred'&.
1521.next
1522When all the recipient addresses have either been delivered or bounced,
168e428f
PH
1523handling of the message is complete. The spool files and message log are
1524deleted, though the message log can optionally be preserved if required.
9b371988 1525.endlist
168e428f
PH
1526
1527
1528
1529
f89d2485 1530.section "Retry mechanism" "SECID19"
9b371988
PH
1531.cindex "delivery" "retry mechanism"
1532.cindex "retry" "description of mechanism"
1533.cindex "queue runner"
168e428f
PH
1534Exim's mechanism for retrying messages that fail to get delivered at the first
1535attempt is the queue runner process. You must either run an Exim daemon that
9b371988
PH
1536uses the &%-q%& option with a time interval to start queue runners at regular
1537intervals, or use some other means (such as &'cron'&) to start them. If you do
168e428f
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1538not arrange for queue runners to be run, messages that fail temporarily at the
1539first attempt will remain on your queue for ever. A queue runner process works
068aaea8 1540its way through the queue, one message at a time, trying each delivery that has
168e428f
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1541passed its retry time.
1542You can run several queue runners at once.
1543
1544Exim uses a set of configured rules to determine when next to retry the failing
9b371988
PH
1545address (see chapter &<<CHAPretry>>&). These rules also specify when Exim
1546should give up trying to deliver to the address, at which point it generates a
1547bounce message. If no retry rules are set for a particular host, address, and
1548error combination, no retries are attempted, and temporary errors are treated
1549as permanent.
168e428f
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1550
1551
1552
f89d2485 1553.section "Temporary delivery failure" "SECID20"
9b371988 1554.cindex "delivery" "temporary failure"
168e428f
PH
1555There are many reasons why a message may not be immediately deliverable to a
1556particular address. Failure to connect to a remote machine (because it, or the
1557connection to it, is down) is one of the most common. Temporary failures may be
1558detected during routing as well as during the transport stage of delivery.
1559Local deliveries may be delayed if NFS files are unavailable, or if a mailbox
1560is on a file system where the user is over quota. Exim can be configured to
1561impose its own quotas on local mailboxes; where system quotas are set they will
1562also apply.
1563
1564If a host is unreachable for a period of time, a number of messages may be
1565waiting for it by the time it recovers, and sending them in a single SMTP
1566connection is clearly beneficial. Whenever a delivery to a remote host is
1567deferred,
fa41615d 1568.cindex "hints database" "deferred deliveries"
168e428f
PH
1569Exim makes a note in its hints database, and whenever a successful
1570SMTP delivery has happened, it looks to see if any other messages are waiting
1571for the same host. If any are found, they are sent over the same SMTP
1572connection, subject to a configuration limit as to the maximum number in any
1573one connection.
168e428f
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1574
1575
1576
f89d2485 1577.section "Permanent delivery failure" "SECID21"
9b371988
PH
1578.cindex "delivery" "permanent failure"
1579.cindex "bounce message" "when generated"
168e428f
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1580When a message cannot be delivered to some or all of its intended recipients, a
1581bounce message is generated. Temporary delivery failures turn into permanent
1582errors when their timeout expires. All the addresses that fail in a given
1583delivery attempt are listed in a single message. If the original message has
1584many recipients, it is possible for some addresses to fail in one delivery
1585attempt and others to fail subsequently, giving rise to more than one bounce
1586message. The wording of bounce messages can be customized by the administrator.
9b371988 1587See chapter &<<CHAPemsgcust>>& for details.
168e428f 1588
9b371988
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1589.cindex "&'X-Failed-Recipients:'& header line"
1590Bounce messages contain an &'X-Failed-Recipients:'& header line that lists the
168e428f
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1591failed addresses, for the benefit of programs that try to analyse such messages
1592automatically.
1593
9b371988 1594.cindex "bounce message" "recipient of"
168e428f
PH
1595A bounce message is normally sent to the sender of the original message, as
1596obtained from the message's envelope. For incoming SMTP messages, this is the
9b371988
PH
1597address given in the MAIL command. However, when an address is expanded via a
1598forward or alias file, an alternative address can be specified for delivery
1599failures of the generated addresses. For a mailing list expansion (see section
1600&<<SECTmailinglists>>&) it is common to direct bounce messages to the manager
1601of the list.
168e428f
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1602
1603
1604
f89d2485 1605.section "Failures to deliver bounce messages" "SECID22"
9b371988 1606.cindex "bounce message" "failure to deliver"
168e428f
PH
1607If a bounce message (either locally generated or received from a remote host)
1608itself suffers a permanent delivery failure, the message is left on the queue,
1609but it is frozen, awaiting the attention of an administrator. There are options
068aaea8 1610that can be used to make Exim discard such failed messages, or to keep them
9b371988
PH
1611for only a short time (see &%timeout_frozen_after%& and
1612&%ignore_bounce_errors_after%&).
168e428f
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1613
1614
1615
1616
1617
9b371988
PH
1618. ////////////////////////////////////////////////////////////////////////////
1619. ////////////////////////////////////////////////////////////////////////////
168e428f 1620
f89d2485 1621.chapter "Building and installing Exim" "CHID3"
4f578862 1622.scindex IIDbuex "building Exim"
168e428f 1623
f89d2485
PH
1624.section "Unpacking" "SECID23"
1625Exim is distributed as a gzipped or bzipped tar file which, when unpacked,
168e428f 1626creates a directory with the name of the current release (for example,
2aee48d6 1627&_exim-&version()_&) into which the following files are placed:
9b371988
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1628
1629.table2 140pt
f89d2485
PH
1630.irow &_ACKNOWLEDGMENTS_& "contains some acknowledgments"
1631.irow &_CHANGES_& "contains a reference to where changes are &&&
1632 documented"
1633.irow &_LICENCE_& "the GNU General Public Licence"
1634.irow &_Makefile_& "top-level make file"
1635.irow &_NOTICE_& "conditions for the use of Exim"
1636.irow &_README_& "list of files, directories and simple build &&&
1637 instructions"
9b371988
PH
1638.endtable
1639
1640Other files whose names begin with &_README_& may also be present. The
168e428f
PH
1641following subdirectories are created:
1642
9b371988 1643.table2 140pt
f89d2485
PH
1644.irow &_Local_& "an empty directory for local configuration files"
1645.irow &_OS_& "OS-specific files"
1646.irow &_doc_& "documentation files"
1647.irow &_exim_monitor_& "source files for the Exim monitor"
1648.irow &_scripts_& "scripts used in the build process"
1649.irow &_src_& "remaining source files"
1650.irow &_util_& "independent utilities"
9b371988
PH
1651.endtable
1652
1653The main utility programs are contained in the &_src_& directory, and are built
1654with the Exim binary. The &_util_& directory contains a few optional scripts
168e428f
PH
1655that may be useful to some sites.
1656
1657
f89d2485 1658.section "Multiple machine architectures and operating systems" "SECID24"
9b371988 1659.cindex "building Exim" "multiple OS/architectures"
168e428f
PH
1660The building process for Exim is arranged to make it easy to build binaries for
1661a number of different architectures and operating systems from the same set of
9b371988
PH
1662source files. Compilation does not take place in the &_src_& directory.
1663Instead, a &'build directory'& is created for each architecture and operating
1664system.
1665.cindex "symbolic link" "to build directory"
168e428f 1666Symbolic links to the sources are installed in this directory, which is where
9b371988
PH
1667the actual building takes place. In most cases, Exim can discover the machine
1668architecture and operating system for itself, but the defaults can be
1669overridden if necessary.
f2ed27cf
JH
1670.cindex compiler requirements
1671.cindex compiler version
1672A C99-capable compiler will be required for the build.
168e428f 1673
168e428f 1674
8473d4ee 1675.section "PCRE library" "SECTpcre"
210f147e
NM
1676.cindex "PCRE library"
1677Exim no longer has an embedded PCRE library as the vast majority of
1678modern systems include PCRE as a system library, although you may need
1679to install the PCRE or PCRE development package for your operating
1680system. If your system has a normal PCRE installation the Exim build
1681process will need no further configuration. If the library or the
6a6084f8
PP
1682headers are in an unusual location you will need to either set the PCRE_LIBS
1683and INCLUDE directives appropriately,
1684or set PCRE_CONFIG=yes to use the installed &(pcre-config)& command.
1685If your operating system has no
210f147e
NM
1686PCRE support then you will need to obtain and build the current PCRE
1687from &url(ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/).
6a6084f8 1688More information on PCRE is available at &url(http://www.pcre.org/).
210f147e 1689
9b371988
PH
1690.section "DBM libraries" "SECTdb"
1691.cindex "DBM libraries" "discussion of"
1692.cindex "hints database" "DBM files used for"
168e428f
PH
1693Even if you do not use any DBM files in your configuration, Exim still needs a
1694DBM library in order to operate, because it uses indexed files for its hints
1695databases. Unfortunately, there are a number of DBM libraries in existence, and
1696different operating systems often have different ones installed.
1697
9b371988 1698.cindex "Solaris" "DBM library for"
f89d2485
PH
1699.cindex "IRIX, DBM library for"
1700.cindex "BSD, DBM library for"
1701.cindex "Linux, DBM library for"
168e428f
PH
1702If you are using Solaris, IRIX, one of the modern BSD systems, or a modern
1703Linux distribution, the DBM configuration should happen automatically, and you
1704may be able to ignore this section. Otherwise, you may have to learn more than
1705you would like about DBM libraries from what follows.
1706
9b371988 1707.cindex "&'ndbm'& DBM library"
168e428f 1708Licensed versions of Unix normally contain a library of DBM functions operating
9b371988 1709via the &'ndbm'& interface, and this is what Exim expects by default. Free
168e428f
PH
1710versions of Unix seem to vary in what they contain as standard. In particular,
1711some early versions of Linux have no default DBM library, and different
1712distributors have chosen to bundle different libraries with their packaged
f89d2485 1713versions. However, the more recent releases seem to have standardized on the
168e428f
PH
1714Berkeley DB library.
1715
1716Different DBM libraries have different conventions for naming the files they
9b371988 1717use. When a program opens a file called &_dbmfile_&, there are several
168e428f
PH
1718possibilities:
1719
9b371988
PH
1720.olist
1721A traditional &'ndbm'& implementation, such as that supplied as part of
1722Solaris, operates on two files called &_dbmfile.dir_& and &_dbmfile.pag_&.
1723.next
1724.cindex "&'gdbm'& DBM library"
1725The GNU library, &'gdbm'&, operates on a single file. If used via its &'ndbm'&
168e428f 1726compatibility interface it makes two different hard links to it with names
9b371988 1727&_dbmfile.dir_& and &_dbmfile.pag_&, but if used via its native interface, the
168e428f 1728file name is used unmodified.
9b371988
PH
1729.next
1730.cindex "Berkeley DB library"
1731The Berkeley DB package, if called via its &'ndbm'& compatibility interface,
1732operates on a single file called &_dbmfile.db_&, but otherwise looks to the
1733programmer exactly the same as the traditional &'ndbm'& implementation.
1734.next
1735If the Berkeley package is used in its native mode, it operates on a single
1736file called &_dbmfile_&; the programmer's interface is somewhat different to
1737the traditional &'ndbm'& interface.
1738.next
1739To complicate things further, there are several very different versions of the
168e428f 1740Berkeley DB package. Version 1.85 was stable for a very long time, releases
9b371988
PH
17412.&'x'& and 3.&'x'& were current for a while, but the latest versions are now
1742numbered 4.&'x'&. Maintenance of some of the earlier releases has ceased. All
168e428f 1743versions of Berkeley DB can be obtained from
9b371988
PH
1744&url(http://www.sleepycat.com/).
1745.next
1746.cindex "&'tdb'& DBM library"
1747Yet another DBM library, called &'tdb'&, is available from
1748&url(http://download.sourceforge.net/tdb). It has its own interface, and also
1749operates on a single file.
1750.endlist
1751
1752.cindex "USE_DB"
1753.cindex "DBM libraries" "configuration for building"
168e428f
PH
1754Exim and its utilities can be compiled to use any of these interfaces. In order
1755to use any version of the Berkeley DB package in native mode, you must set
1756USE_DB in an appropriate configuration file (typically
9b371988
PH
1757&_Local/Makefile_&). For example:
1758.code
1759USE_DB=yes
1760.endd
168e428f
PH
1761Similarly, for gdbm you set USE_GDBM, and for tdb you set USE_TDB. An
1762error is diagnosed if you set more than one of these.
1763
1764At the lowest level, the build-time configuration sets none of these options,
1765thereby assuming an interface of type (1). However, some operating system
1766configuration files (for example, those for the BSD operating systems and
1767Linux) assume type (4) by setting USE_DB as their default, and the
1768configuration files for Cygwin set USE_GDBM. Anything you set in
9b371988 1769&_Local/Makefile_&, however, overrides these system defaults.
168e428f
PH
1770
1771As well as setting USE_DB, USE_GDBM, or USE_TDB, it may also be
1772necessary to set DBMLIB, to cause inclusion of the appropriate library, as
1773in one of these lines:
9b371988
PH
1774.code
1775DBMLIB = -ldb
1776DBMLIB = -ltdb
1777.endd
168e428f
PH
1778Settings like that will work if the DBM library is installed in the standard
1779place. Sometimes it is not, and the library's header file may also not be in
1780the default path. You may need to set INCLUDE to specify where the header
1781file is, and to specify the path to the library more fully in DBMLIB, as in
1782this example:
9b371988
PH
1783.code
1784INCLUDE=-I/usr/local/include/db-4.1
1785DBMLIB=/usr/local/lib/db-4.1/libdb.a
1786.endd
168e428f 1787There is further detailed discussion about the various DBM libraries in the
9b371988 1788file &_doc/dbm.discuss.txt_& in the Exim distribution.
168e428f
PH
1789
1790
1791
f89d2485 1792.section "Pre-building configuration" "SECID25"
9b371988
PH
1793.cindex "building Exim" "pre-building configuration"
1794.cindex "configuration for building Exim"
1795.cindex "&_Local/Makefile_&"
1796.cindex "&_src/EDITME_&"
168e428f
PH
1797Before building Exim, a local configuration file that specifies options
1798independent of any operating system has to be created with the name
9b371988
PH
1799&_Local/Makefile_&. A template for this file is supplied as the file
1800&_src/EDITME_&, and it contains full descriptions of all the option settings
168e428f
PH
1801therein. These descriptions are therefore not repeated here. If you are
1802building Exim for the first time, the simplest thing to do is to copy
9b371988 1803&_src/EDITME_& to &_Local/Makefile_&, then read it and edit it appropriately.
168e428f
PH
1804
1805There are three settings that you must supply, because Exim will not build
1806without them. They are the location of the run time configuration file
1807(CONFIGURE_FILE), the directory in which Exim binaries will be installed
1808(BIN_DIRECTORY), and the identity of the Exim user (EXIM_USER and
1809maybe EXIM_GROUP as well). The value of CONFIGURE_FILE can in fact be
1810a colon-separated list of file names; Exim uses the first of them that exists.
1811
1812There are a few other parameters that can be specified either at build time or
1813at run time, to enable the same binary to be used on a number of different
1814machines. However, if the locations of Exim's spool directory and log file
1815directory (if not within the spool directory) are fixed, it is recommended that
9b371988 1816you specify them in &_Local/Makefile_& instead of at run time, so that errors
168e428f
PH
1817detected early in Exim's execution (such as a malformed configuration file) can
1818be logged.
1819
9b371988 1820.cindex "content scanning" "specifying at build time"
068aaea8 1821Exim's interfaces for calling virus and spam scanning software directly from
168e428f
PH
1822access control lists are not compiled by default. If you want to include these
1823facilities, you need to set
9b371988
PH
1824.code
1825WITH_CONTENT_SCAN=yes
1826.endd
1827in your &_Local/Makefile_&. For details of the facilities themselves, see
1828chapter &<<CHAPexiscan>>&.
168e428f
PH
1829
1830
9b371988 1831.cindex "&_Local/eximon.conf_&"
3cb1b51e 1832.cindex "&_exim_monitor/EDITME_&"
168e428f 1833If you are going to build the Exim monitor, a similar configuration process is
9b371988
PH
1834required. The file &_exim_monitor/EDITME_& must be edited appropriately for
1835your installation and saved under the name &_Local/eximon.conf_&. If you are
1836happy with the default settings described in &_exim_monitor/EDITME_&,
1837&_Local/eximon.conf_& can be empty, but it must exist.
168e428f
PH
1838
1839This is all the configuration that is needed in straightforward cases for known
1840operating systems. However, the building process is set up so that it is easy
1841to override options that are set by default or by operating-system-specific
1842configuration files, for example to change the name of the C compiler, which
9b371988
PH
1843defaults to &%gcc%&. See section &<<SECToverride>>& below for details of how to
1844do this.
168e428f
PH
1845
1846
1847
f89d2485 1848.section "Support for iconv()" "SECID26"
9b371988
PH
1849.cindex "&[iconv()]& support"
1850.cindex "RFC 2047"
168e428f
PH
1851The contents of header lines in messages may be encoded according to the rules
1852described RFC 2047. This makes it possible to transmit characters that are not
1853in the ASCII character set, and to label them as being in a particular
9b371988 1854character set. When Exim is inspecting header lines by means of the &%$h_%&
168e428f 1855mechanism, it decodes them, and translates them into a specified character set
1459a03d 1856(default is set at build time). The translation is possible only if the operating system
9b371988
PH
1857supports the &[iconv()]& function.
1858
1859However, some of the operating systems that supply &[iconv()]& do not support
1860very many conversions. The GNU &%libiconv%& library (available from
1861&url(http://www.gnu.org/software/libiconv/)) can be installed on such
1862systems to remedy this deficiency, as well as on systems that do not supply
1863&[iconv()]& at all. After installing &%libiconv%&, you should add
1864.code
1865HAVE_ICONV=yes
1866.endd
1867to your &_Local/Makefile_& and rebuild Exim.
1868
1869
1870
1871.section "Including TLS/SSL encryption support" "SECTinctlsssl"
1872.cindex "TLS" "including support for TLS"
1873.cindex "encryption" "including support for"
1874.cindex "SUPPORT_TLS"
1875.cindex "OpenSSL" "building Exim with"
1876.cindex "GnuTLS" "building Exim with"
168e428f
PH
1877Exim can be built to support encrypted SMTP connections, using the STARTTLS
1878command as per RFC 2487. It can also support legacy clients that expect to
1879start a TLS session immediately on connection to a non-standard port (see the
9b371988 1880&%tls_on_connect_ports%& runtime option and the &%-tls-on-connect%& command
168e428f
PH
1881line option).
1882
1883If you want to build Exim with TLS support, you must first install either the
1884OpenSSL or GnuTLS library. There is no cryptographic code in Exim itself for
1885implementing SSL.
1886
1887If OpenSSL is installed, you should set
9b371988
PH
1888.code
1889SUPPORT_TLS=yes
1890TLS_LIBS=-lssl -lcrypto
1891.endd
1892in &_Local/Makefile_&. You may also need to specify the locations of the
168e428f 1893OpenSSL library and include files. For example:
9b371988
PH
1894.code
1895SUPPORT_TLS=yes
1896TLS_LIBS=-L/usr/local/openssl/lib -lssl -lcrypto
1897TLS_INCLUDE=-I/usr/local/openssl/include/
1898.endd
7e6a8985
PP
1899.cindex "pkg-config" "OpenSSL"
1900If you have &'pkg-config'& available, then instead you can just use:
1901.code
1902SUPPORT_TLS=yes
1903USE_OPENSSL_PC=openssl
1904.endd
9b371988 1905.cindex "USE_GNUTLS"
168e428f 1906If GnuTLS is installed, you should set
9b371988
PH
1907.code
1908SUPPORT_TLS=yes
1909USE_GNUTLS=yes
1910TLS_LIBS=-lgnutls -ltasn1 -lgcrypt
1911.endd
1912in &_Local/Makefile_&, and again you may need to specify the locations of the
168e428f 1913library and include files. For example:
9b371988
PH
1914.code
1915SUPPORT_TLS=yes
1916USE_GNUTLS=yes
1917TLS_LIBS=-L/usr/gnu/lib -lgnutls -ltasn1 -lgcrypt
1918TLS_INCLUDE=-I/usr/gnu/include
1919.endd
7e6a8985
PP
1920.cindex "pkg-config" "GnuTLS"
1921If you have &'pkg-config'& available, then instead you can just use:
1922.code
1923SUPPORT_TLS=yes
1924USE_GNUTLS=yes
1925USE_GNUTLS_PC=gnutls
1926.endd
7e6a8985 1927
168e428f 1928You do not need to set TLS_INCLUDE if the relevant directory is already
9b371988
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1929specified in INCLUDE. Details of how to configure Exim to make use of TLS are
1930given in chapter &<<CHAPTLS>>&.
168e428f
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1931
1932
1933
1934
b52ed2b3
NM
1935.section "Use of tcpwrappers" "SECID27"
1936
f89d2485 1937.cindex "tcpwrappers, building Exim to support"
9b371988 1938.cindex "USE_TCP_WRAPPERS"
5dc43717
JJ
1939.cindex "TCP_WRAPPERS_DAEMON_NAME"
1940.cindex "tcp_wrappers_daemon_name"
9b371988
PH
1941Exim can be linked with the &'tcpwrappers'& library in order to check incoming
1942SMTP calls using the &'tcpwrappers'& control files. This may be a convenient
168e428f 1943alternative to Exim's own checking facilities for installations that are
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1944already making use of &'tcpwrappers'& for other purposes. To do this, you
1945should set USE_TCP_WRAPPERS in &_Local/Makefile_&, arrange for the file
1946&_tcpd.h_& to be available at compile time, and also ensure that the library
1947&_libwrap.a_& is available at link time, typically by including &%-lwrap%& in
1948EXTRALIBS_EXIM. For example, if &'tcpwrappers'& is installed in &_/usr/local_&,
1949you might have
1950.code
1951USE_TCP_WRAPPERS=yes
1952CFLAGS=-O -I/usr/local/include
1953EXTRALIBS_EXIM=-L/usr/local/lib -lwrap
1954.endd
5dc43717
JJ
1955in &_Local/Makefile_&. The daemon name to use in the &'tcpwrappers'& control
1956files is &"exim"&. For example, the line
9b371988
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1957.code
1958exim : LOCAL 192.168.1. .friendly.domain.example
1959.endd
1960in your &_/etc/hosts.allow_& file allows connections from the local host, from
1961the subnet 192.168.1.0/24, and from all hosts in &'friendly.domain.example'&.
5dc43717
JJ
1962All other connections are denied. The daemon name used by &'tcpwrappers'&
1963can be changed at build time by setting TCP_WRAPPERS_DAEMON_NAME in
a543079f 1964&_Local/Makefile_&, or by setting tcp_wrappers_daemon_name in the
5dc43717 1965configure file. Consult the &'tcpwrappers'& documentation for
168e428f 1966further details.
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1967
1968
f89d2485 1969.section "Including support for IPv6" "SECID28"
9b371988 1970.cindex "IPv6" "including support for"
168e428f 1971Exim contains code for use on systems that have IPv6 support. Setting
9b371988 1972&`HAVE_IPV6=YES`& in &_Local/Makefile_& causes the IPv6 code to be included;
168e428f
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1973it may also be necessary to set IPV6_INCLUDE and IPV6_LIBS on systems
1974where the IPv6 support is not fully integrated into the normal include and
1975library files.
1976
1977Two different types of DNS record for handling IPv6 addresses have been
f89d2485 1978defined. AAAA records (analogous to A records for IPv4) are in use, and are
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1979currently seen as the mainstream. Another record type called A6 was proposed
1980as better than AAAA because it had more flexibility. However, it was felt to be
badb25a9 1981over-complex, and its status was reduced to &"experimental"&.
badb25a9 1982Exim used to
cc00f4af
JH
1983have a compile option for including A6 record support but this has now been
1984withdrawn.
168e428f
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1985
1986
1987
0a349494
PP
1988.section "Dynamically loaded lookup module support" "SECTdynamicmodules"
1989.cindex "lookup modules"
1990.cindex "dynamic modules"
1991.cindex ".so building"
1992On some platforms, Exim supports not compiling all lookup types directly into
1993the main binary, instead putting some into external modules which can be loaded
1994on demand.
1995This permits packagers to build Exim with support for lookups with extensive
1996library dependencies without requiring all users to install all of those
1997dependencies.
1998Most, but not all, lookup types can be built this way.
1999
2000Set &`LOOKUP_MODULE_DIR`& to the directory into which the modules will be
2001installed; Exim will only load modules from that directory, as a security
2002measure. You will need to set &`CFLAGS_DYNAMIC`& if not already defined
2003for your OS; see &_OS/Makefile-Linux_& for an example.
2004Some other requirements for adjusting &`EXTRALIBS`& may also be necessary,
2005see &_src/EDITME_& for details.
2006
2007Then, for each module to be loaded dynamically, define the relevant
2008&`LOOKUP_`&<&'lookup_type'&> flags to have the value "2" instead of "yes".
2009For example, this will build in lsearch but load sqlite and mysql support
2010on demand:
2011.code
2012LOOKUP_LSEARCH=yes
2013LOOKUP_SQLITE=2
2014LOOKUP_MYSQL=2
2015.endd
5d758a46 2016
0a349494 2017
f89d2485 2018.section "The building process" "SECID29"
9b371988
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2019.cindex "build directory"
2020Once &_Local/Makefile_& (and &_Local/eximon.conf_&, if required) have been
2021created, run &'make'& at the top level. It determines the architecture and
168e428f
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2022operating system types, and creates a build directory if one does not exist.
2023For example, on a Sun system running Solaris 8, the directory
9b371988
PH
2024&_build-SunOS5-5.8-sparc_& is created.
2025.cindex "symbolic link" "to source files"
168e428f
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2026Symbolic links to relevant source files are installed in the build directory.
2027
9b371988 2028If this is the first time &'make'& has been run, it calls a script that builds
168e428f 2029a make file inside the build directory, using the configuration files from the
9b371988
PH
2030&_Local_& directory. The new make file is then passed to another instance of
2031&'make'&. This does the real work, building a number of utility scripts, and
168e428f 2032then compiling and linking the binaries for the Exim monitor (if configured), a
9b371988
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2033number of utility programs, and finally Exim itself. The command &`make
2034makefile`& can be used to force a rebuild of the make file in the build
168e428f
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2035directory, should this ever be necessary.
2036
2037If you have problems building Exim, check for any comments there may be in the
9b371988 2038&_README_& file concerning your operating system, and also take a look at the
168e428f
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2039FAQ, where some common problems are covered.
2040
2041
2042
f89d2485 2043.section 'Output from &"make"&' "SECID283"
9b371988 2044The output produced by the &'make'& process for compile lines is often very
068aaea8
PH
2045unreadable, because these lines can be very long. For this reason, the normal
2046output is suppressed by default, and instead output similar to that which
2047appears when compiling the 2.6 Linux kernel is generated: just a short line for
2048each module that is being compiled or linked. However, it is still possible to
9b371988
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2049get the full output, by calling &'make'& like this:
2050.code
2051FULLECHO='' make -e
2052.endd
2053The value of FULLECHO defaults to &"@"&, the flag character that suppresses
2054command reflection in &'make'&. When you ask for the full output, it is
3cb1b51e 2055given in addition to the short output.
068aaea8
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2056
2057
2058
9b371988 2059.section "Overriding build-time options for Exim" "SECToverride"
f89d2485 2060.cindex "build-time options, overriding"
168e428f
PH
2061The main make file that is created at the beginning of the building process
2062consists of the concatenation of a number of files which set configuration
9b371988 2063values, followed by a fixed set of &'make'& instructions. If a value is set
168e428f
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2064more than once, the last setting overrides any previous ones. This provides a
2065convenient way of overriding defaults. The files that are concatenated are, in
2066order:
9b371988
PH
2067.display
2068&_OS/Makefile-Default_&
2069&_OS/Makefile-_&<&'ostype'&>
2070&_Local/Makefile_&
2071&_Local/Makefile-_&<&'ostype'&>
2072&_Local/Makefile-_&<&'archtype'&>
2073&_Local/Makefile-_&<&'ostype'&>-<&'archtype'&>
2074&_OS/Makefile-Base_&
2075.endd
2076.cindex "&_Local/Makefile_&"
2077.cindex "building Exim" "operating system type"
2078.cindex "building Exim" "architecture type"
2079where <&'ostype'&> is the operating system type and <&'archtype'&> is the
2080architecture type. &_Local/Makefile_& is required to exist, and the building
2081process fails if it is absent. The other three &_Local_& files are optional,
168e428f
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2082and are often not needed.
2083
9b371988
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2084The values used for <&'ostype'&> and <&'archtype'&> are obtained from scripts
2085called &_scripts/os-type_& and &_scripts/arch-type_& respectively. If either of
168e428f
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2086the environment variables EXIM_OSTYPE or EXIM_ARCHTYPE is set, their
2087values are used, thereby providing a means of forcing particular settings.
9b371988 2088Otherwise, the scripts try to get values from the &%uname%& command. If this
168e428f 2089fails, the shell variables OSTYPE and ARCHTYPE are inspected. A number
9b371988 2090of &'ad hoc'& transformations are then applied, to produce the standard names
168e428f
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2091that Exim expects. You can run these scripts directly from the shell in order
2092to find out what values are being used on your system.
2093
2094
9b371988 2095&_OS/Makefile-Default_& contains comments about the variables that are set
168e428f
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2096therein. Some (but not all) are mentioned below. If there is something that
2097needs changing, review the contents of this file and the contents of the make
9b371988 2098file for your operating system (&_OS/Makefile-<ostype>_&) to see what the
168e428f
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2099default values are.
2100
2101
9b371988
PH
2102.cindex "building Exim" "overriding default settings"
2103If you need to change any of the values that are set in &_OS/Makefile-Default_&
2104or in &_OS/Makefile-<ostype>_&, or to add any new definitions, you do not
168e428f 2105need to change the original files. Instead, you should make the changes by
9b371988
PH
2106putting the new values in an appropriate &_Local_& file. For example,
2107.cindex "Tru64-Unix build-time settings"
168e428f
PH
2108when building Exim in many releases of the Tru64-Unix (formerly Digital UNIX,
2109formerly DEC-OSF1) operating system, it is necessary to specify that the C
9b371988
PH
2110compiler is called &'cc'& rather than &'gcc'&. Also, the compiler must be
2111called with the option &%-std1%&, to make it recognize some of the features of
168e428f 2112Standard C that Exim uses. (Most other compilers recognize Standard C by
9b371988 2113default.) To do this, you should create a file called &_Local/Makefile-OSF1_&
168e428f 2114containing the lines
9b371988
PH
2115.code
2116CC=cc
2117CFLAGS=-std1
2118.endd
168e428f 2119If you are compiling for just one operating system, it may be easier to put
9b371988 2120these lines directly into &_Local/Makefile_&.
168e428f
PH
2121
2122Keeping all your local configuration settings separate from the distributed
2123files makes it easy to transfer them to new versions of Exim simply by copying
9b371988 2124the contents of the &_Local_& directory.
168e428f
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2125
2126
9b371988
PH
2127.cindex "NIS lookup type" "including support for"
2128.cindex "NIS+ lookup type" "including support for"
2129.cindex "LDAP" "including support for"
2130.cindex "lookup" "inclusion in binary"
168e428f
PH
2131Exim contains support for doing LDAP, NIS, NIS+, and other kinds of file
2132lookup, but not all systems have these components installed, so the default is
2133not to include the relevant code in the binary. All the different kinds of file
2134and database lookup that Exim supports are implemented as separate code modules
2135which are included only if the relevant compile-time options are set. In the
9b371988
PH
2136case of LDAP, NIS, and NIS+, the settings for &_Local/Makefile_& are:
2137.code
2138LOOKUP_LDAP=yes
2139LOOKUP_NIS=yes
2140LOOKUP_NISPLUS=yes
2141.endd
168e428f 2142and similar settings apply to the other lookup types. They are all listed in
9b371988 2143&_src/EDITME_&. In many cases the relevant include files and interface
168e428f 2144libraries need to be installed before compiling Exim.
9b371988 2145.cindex "cdb" "including support for"
068aaea8
PH
2146However, there are some optional lookup types (such as cdb) for which
2147the code is entirely contained within Exim, and no external include
168e428f
PH
2148files or libraries are required. When a lookup type is not included in the
2149binary, attempts to configure Exim to use it cause run time configuration
2150errors.
2151
7e6a8985
PP
2152.cindex "pkg-config" "lookups"
2153.cindex "pkg-config" "authenticators"
252e0c7b
PP
2154Many systems now use a tool called &'pkg-config'& to encapsulate information
2155about how to compile against a library; Exim has some initial support for
2156being able to use pkg-config for lookups and authenticators. For any given
2157makefile variable which starts &`LOOKUP_`& or &`AUTH_`&, you can add a new
2158variable with the &`_PC`& suffix in the name and assign as the value the
2159name of the package to be queried. The results of querying via the
2160&'pkg-config'& command will be added to the appropriate Makefile variables
2161with &`+=`& directives, so your version of &'make'& will need to support that
2162syntax. For instance:
2163.code
2164LOOKUP_SQLITE=yes
2165LOOKUP_SQLITE_PC=sqlite3
2166AUTH_GSASL=yes
2167AUTH_GSASL_PC=libgsasl
2168AUTH_HEIMDAL_GSSAPI=yes
2169AUTH_HEIMDAL_GSSAPI_PC=heimdal-gssapi
2170.endd
252e0c7b 2171
9b371988 2172.cindex "Perl" "including support for"
168e428f
PH
2173Exim can be linked with an embedded Perl interpreter, allowing Perl
2174subroutines to be called during string expansion. To enable this facility,
9b371988
PH
2175.code
2176EXIM_PERL=perl.o
2177.endd
2178must be defined in &_Local/Makefile_&. Details of this facility are given in
2179chapter &<<CHAPperl>>&.
168e428f 2180
f89d2485 2181.cindex "X11 libraries, location of"
168e428f 2182The location of the X11 libraries is something that varies a lot between
068aaea8 2183operating systems, and there may be different versions of X11 to cope
168e428f
PH
2184with. Exim itself makes no use of X11, but if you are compiling the Exim
2185monitor, the X11 libraries must be available.
9b371988
PH
2186The following three variables are set in &_OS/Makefile-Default_&:
2187.code
2188X11=/usr/X11R6
2189XINCLUDE=-I$(X11)/include
2190XLFLAGS=-L$(X11)/lib
2191.endd
168e428f 2192These are overridden in some of the operating-system configuration files. For
9b371988
PH
2193example, in &_OS/Makefile-SunOS5_& there is
2194.code
2195X11=/usr/openwin
2196XINCLUDE=-I$(X11)/include
2197XLFLAGS=-L$(X11)/lib -R$(X11)/lib
2198.endd
168e428f
PH
2199If you need to override the default setting for your operating system, place a
2200definition of all three of these variables into your
9b371988 2201&_Local/Makefile-<ostype>_& file.
168e428f 2202
9b371988 2203.cindex "EXTRALIBS"
168e428f
PH
2204If you need to add any extra libraries to the link steps, these can be put in a
2205variable called EXTRALIBS, which appears in all the link commands, but by
2206default is not defined. In contrast, EXTRALIBS_EXIM is used only on the
2207command for linking the main Exim binary, and not for any associated utilities.
2208
9b371988 2209.cindex "DBM libraries" "configuration for building"
168e428f 2210There is also DBMLIB, which appears in the link commands for binaries that
9b371988 2211use DBM functions (see also section &<<SECTdb>>&). Finally, there is
168e428f
PH
2212EXTRALIBS_EXIMON, which appears only in the link step for the Exim monitor
2213binary, and which can be used, for example, to include additional X11
2214libraries.
2215
9b371988 2216.cindex "configuration file" "editing"
168e428f
PH
2217The make file copes with rebuilding Exim correctly if any of the configuration
2218files are edited. However, if an optional configuration file is deleted, it is
9b371988
PH
2219necessary to touch the associated non-optional file (that is,
2220&_Local/Makefile_& or &_Local/eximon.conf_&) before rebuilding.
168e428f
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2221
2222
f89d2485 2223.section "OS-specific header files" "SECID30"
9b371988
PH
2224.cindex "&_os.h_&"
2225.cindex "building Exim" "OS-specific C header files"
2226The &_OS_& directory contains a number of files with names of the form
2227&_os.h-<ostype>_&. These are system-specific C header files that should not
168e428f 2228normally need to be changed. There is a list of macro settings that are
9b371988 2229recognized in the file &_OS/os.configuring_&, which should be consulted if you
168e428f
PH
2230are porting Exim to a new operating system.
2231
2232
2233
f89d2485
PH
2234.section "Overriding build-time options for the monitor" "SECID31"
2235.cindex "building Eximon"
168e428f
PH
2236A similar process is used for overriding things when building the Exim monitor,
2237where the files that are involved are
9b371988
PH
2238.display
2239&_OS/eximon.conf-Default_&
2240&_OS/eximon.conf-_&<&'ostype'&>
2241&_Local/eximon.conf_&
2242&_Local/eximon.conf-_&<&'ostype'&>
2243&_Local/eximon.conf-_&<&'archtype'&>
2244&_Local/eximon.conf-_&<&'ostype'&>-<&'archtype'&>
2245.endd
2246.cindex "&_Local/eximon.conf_&"
168e428f 2247As with Exim itself, the final three files need not exist, and in this case the
9b371988
PH
2248&_OS/eximon.conf-<ostype>_& file is also optional. The default values in
2249&_OS/eximon.conf-Default_& can be overridden dynamically by setting environment
168e428f
PH
2250variables of the same name, preceded by EXIMON_. For example, setting
2251EXIMON_LOG_DEPTH in the environment overrides the value of
2252LOG_DEPTH at run time.
4f578862 2253.ecindex IIDbuex
168e428f
PH
2254
2255
f89d2485 2256.section "Installing Exim binaries and scripts" "SECID32"
9b371988
PH
2257.cindex "installing Exim"
2258.cindex "BIN_DIRECTORY"
2259The command &`make install`& runs the &(exim_install)& script with no
2260arguments. The script copies binaries and utility scripts into the directory
2261whose name is specified by the BIN_DIRECTORY setting in &_Local/Makefile_&.
2262.cindex "setuid" "installing Exim with"
068aaea8
PH
2263The install script copies files only if they are newer than the files they are
2264going to replace. The Exim binary is required to be owned by root and have the
9b371988
PH
2265&'setuid'& bit set, for normal configurations. Therefore, you must run &`make
2266install`& as root so that it can set up the Exim binary in this way. However, in
068aaea8
PH
2267some special situations (for example, if a host is doing no local deliveries)
2268it may be possible to run Exim without making the binary setuid root (see
9b371988 2269chapter &<<CHAPsecurity>>& for details).
168e428f 2270
9b371988 2271.cindex "CONFIGURE_FILE"
168e428f 2272Exim's run time configuration file is named by the CONFIGURE_FILE setting
9b371988
PH
2273in &_Local/Makefile_&. If this names a single file, and the file does not
2274exist, the default configuration file &_src/configure.default_& is copied there
168e428f
PH
2275by the installation script. If a run time configuration file already exists, it
2276is left alone. If CONFIGURE_FILE is a colon-separated list, naming several
2277alternative files, no default is installed.
2278
9b371988
PH
2279.cindex "system aliases file"
2280.cindex "&_/etc/aliases_&"
168e428f
PH
2281One change is made to the default configuration file when it is installed: the
2282default configuration contains a router that references a system aliases file.
2283The path to this file is set to the value specified by
9b371988 2284SYSTEM_ALIASES_FILE in &_Local/Makefile_& (&_/etc/aliases_& by default).
168e428f
PH
2285If the system aliases file does not exist, the installation script creates it,
2286and outputs a comment to the user.
2287
2288The created file contains no aliases, but it does contain comments about the
2289aliases a site should normally have. Mail aliases have traditionally been
9b371988
PH
2290kept in &_/etc/aliases_&. However, some operating systems are now using
2291&_/etc/mail/aliases_&. You should check if yours is one of these, and change
168e428f
PH
2292Exim's configuration if necessary.
2293
2294The default configuration uses the local host's name as the only local domain,
9b371988
PH
2295and is set up to do local deliveries into the shared directory &_/var/mail_&,
2296running as the local user. System aliases and &_.forward_& files in users' home
168e428f
PH
2297directories are supported, but no NIS or NIS+ support is configured. Domains
2298other than the name of the local host are routed using the DNS, with delivery
2299over SMTP.
2300
168e428f
PH
2301It is possible to install Exim for special purposes (such as building a binary
2302distribution) in a private part of the file system. You can do this by a
2303command such as
9b371988
PH
2304.code
2305make DESTDIR=/some/directory/ install
2306.endd
168e428f
PH
2307This has the effect of pre-pending the specified directory to all the file
2308paths, except the name of the system aliases file that appears in the default
9b371988 2309configuration. (If a default alias file is created, its name &'is'& modified.)
168e428f
PH
2310For backwards compatibility, ROOT is used if DESTDIR is not set,
2311but this usage is deprecated.
2312
9b371988
PH
2313.cindex "installing Exim" "what is not installed"
2314Running &'make install'& does not copy the Exim 4 conversion script
40df1be3
TF
2315&'convert4r4'&. You will probably run this only once if you are
2316upgrading from Exim 3. None of the documentation files in the &_doc_&
168e428f 2317directory are copied, except for the info files when you have set
9b371988 2318INFO_DIRECTORY, as described in section &<<SECTinsinfdoc>>& below.
168e428f 2319
9b371988 2320For the utility programs, old versions are renamed by adding the suffix &_.O_&
168e428f
PH
2321to their names. The Exim binary itself, however, is handled differently. It is
2322installed under a name that includes the version number and the compile number,
2aee48d6 2323for example &_exim-&version()-1_&. The script then arranges for a symbolic link
9b371988
PH
2324called &_exim_& to point to the binary. If you are updating a previous version
2325of Exim, the script takes care to ensure that the name &_exim_& is never absent
168e428f
PH
2326from the directory (as seen by other processes).
2327
9b371988
PH
2328.cindex "installing Exim" "testing the script"
2329If you want to see what the &'make install'& will do before running it for
2330real, you can pass the &%-n%& option to the installation script by this
2331command:
2332.code
2333make INSTALL_ARG=-n install
2334.endd
168e428f
PH
2335The contents of the variable INSTALL_ARG are passed to the installation
2336script. You do not need to be root to run this test. Alternatively, you can run
2337the installation script directly, but this must be from within the build
2338directory. For example, from the top-level Exim directory you could use this
2339command:
9b371988
PH
2340.code
2341(cd build-SunOS5-5.5.1-sparc; ../scripts/exim_install -n)
2342.endd
2343.cindex "installing Exim" "install script options"
168e428f
PH
2344There are two other options that can be supplied to the installation script.
2345
9b371988
PH
2346.ilist
2347&%-no_chown%& bypasses the call to change the owner of the installed binary
168e428f 2348to root, and the call to make it a setuid binary.
9b371988
PH
2349.next
2350&%-no_symlink%& bypasses the setting up of the symbolic link &_exim_& to the
168e428f 2351installed binary.
9b371988 2352.endlist
168e428f
PH
2353
2354INSTALL_ARG can be used to pass these options to the script. For example:
9b371988
PH
2355.code
2356make INSTALL_ARG=-no_symlink install
2357.endd
168e428f
PH
2358The installation script can also be given arguments specifying which files are
2359to be copied. For example, to install just the Exim binary, and nothing else,
2360without creating the symbolic link, you could use:
9b371988
PH
2361.code
2362make INSTALL_ARG='-no_symlink exim' install
2363.endd
168e428f
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2364
2365
2366
9b371988
PH
2367.section "Installing info documentation" "SECTinsinfdoc"
2368.cindex "installing Exim" "&'info'& documentation"
2369Not all systems use the GNU &'info'& system for documentation, and for this
168e428f
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2370reason, the Texinfo source of Exim's documentation is not included in the main
2371distribution. Instead it is available separately from the ftp site (see section
9b371988 2372&<<SECTavail>>&).
168e428f 2373
9b371988
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2374If you have defined INFO_DIRECTORY in &_Local/Makefile_& and the Texinfo
2375source of the documentation is found in the source tree, running &`make
2376install`& automatically builds the info files and installs them.
168e428f
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2377
2378
2379
f89d2485 2380.section "Setting up the spool directory" "SECID33"
9b371988 2381.cindex "spool directory" "creating"
168e428f
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2382When it starts up, Exim tries to create its spool directory if it does not
2383exist. The Exim uid and gid are used for the owner and group of the spool
2384directory. Sub-directories are automatically created in the spool directory as
2385necessary.
2386
2387
2388
2389
f89d2485 2390.section "Testing" "SECID34"
9b371988 2391.cindex "testing" "installation"
168e428f
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2392Having installed Exim, you can check that the run time configuration file is
2393syntactically valid by running the following command, which assumes that the
2394Exim binary directory is within your PATH environment variable:
9b371988
PH
2395.code
2396exim -bV
2397.endd
168e428f
PH
2398If there are any errors in the configuration file, Exim outputs error messages.
2399Otherwise it outputs the version number and build date,
2400the DBM library that is being used, and information about which drivers and
2401other optional code modules are included in the binary.
2402Some simple routing tests can be done by using the address testing option. For
2403example,
9b371988
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2404.display
2405&`exim -bt`& <&'local username'&>
2406.endd
168e428f 2407should verify that it recognizes a local mailbox, and
9b371988
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2408.display
2409&`exim -bt`& <&'remote address'&>
2410.endd
168e428f
PH
2411a remote one. Then try getting it to deliver mail, both locally and remotely.
2412This can be done by passing messages directly to Exim, without going through a
2413user agent. For example:
9b371988 2414.code
068aaea8
PH
2415exim -v postmaster@your.domain.example
2416From: user@your.domain.example
2417To: postmaster@your.domain.example
2418Subject: Testing Exim
168e428f 2419
068aaea8
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2420This is a test message.
2421^D
9b371988
PH
2422.endd
2423The &%-v%& option causes Exim to output some verification of what it is doing.
168e428f 2424In this case you should see copies of three log lines, one for the message's
9b371988 2425arrival, one for its delivery, and one containing &"Completed"&.
168e428f 2426
9b371988
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2427.cindex "delivery" "problems with"
2428If you encounter problems, look at Exim's log files (&'mainlog'& and
2429&'paniclog'&) to see if there is any relevant information there. Another source
168e428f 2430of information is running Exim with debugging turned on, by specifying the
9b371988 2431&%-d%& option. If a message is stuck on Exim's spool, you can force a delivery
168e428f 2432with debugging turned on by a command of the form
9b371988
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2433.display
2434&`exim -d -M`& <&'exim-message-id'&>
2435.endd
2436You must be root or an &"admin user"& in order to do this. The &%-d%& option
168e428f 2437produces rather a lot of output, but you can cut this down to specific areas.
9b371988
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2438For example, if you use &%-d-all+route%& only the debugging information
2439relevant to routing is included. (See the &%-d%& option in chapter
2440&<<CHAPcommandline>>& for more details.)
168e428f 2441
9b371988
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2442.cindex '&"sticky"& bit'
2443.cindex "lock files"
168e428f
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2444One specific problem that has shown up on some sites is the inability to do
2445local deliveries into a shared mailbox directory, because it does not have the
9b371988 2446&"sticky bit"& set on it. By default, Exim tries to create a lock file before
168e428f 2447writing to a mailbox file, and if it cannot create the lock file, the delivery
9b371988 2448is deferred. You can get round this either by setting the &"sticky bit"& on the
168e428f
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2449directory, or by setting a specific group for local deliveries and allowing
2450that group to create files in the directory (see the comments above the
9b371988 2451&(local_delivery)& transport in the default configuration file). Another
168e428f 2452approach is to configure Exim not to use lock files, but just to rely on
9b371988
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2453&[fcntl()]& locking instead. However, you should do this only if all user
2454agents also use &[fcntl()]& locking. For further discussion of locking issues,
2455see chapter &<<CHAPappendfile>>&.
168e428f
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2456
2457One thing that cannot be tested on a system that is already running an MTA is
2458the receipt of incoming SMTP mail on the standard SMTP port. However, the
9b371988
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2459&%-oX%& option can be used to run an Exim daemon that listens on some other
2460port, or &'inetd'& can be used to do this. The &%-bh%& option and the
2461&'exim_checkaccess'& utility can be used to check out policy controls on
168e428f
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2462incoming SMTP mail.
2463
2464Testing a new version on a system that is already running Exim can most easily
2465be done by building a binary with a different CONFIGURE_FILE setting. From
2466within the run time configuration, all other file and directory names
2467that Exim uses can be altered, in order to keep it entirely clear of the
2468production version.
2469
2470
f89d2485 2471.section "Replacing another MTA with Exim" "SECID35"
9b371988 2472.cindex "replacing another MTA"
168e428f
PH
2473Building and installing Exim for the first time does not of itself put it in
2474general use. The name by which the system's MTA is called by mail user agents
9b371988
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2475is either &_/usr/sbin/sendmail_&, or &_/usr/lib/sendmail_& (depending on the
2476operating system), and it is necessary to make this name point to the &'exim'&
168e428f 2477binary in order to get the user agents to pass messages to Exim. This is
9b371988
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2478normally done by renaming any existing file and making &_/usr/sbin/sendmail_&
2479or &_/usr/lib/sendmail_&
2480.cindex "symbolic link" "to &'exim'& binary"
2481a symbolic link to the &'exim'& binary. It is a good idea to remove any setuid
168e428f
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2482privilege and executable status from the old MTA. It is then necessary to stop
2483and restart the mailer daemon, if one is running.
2484
f89d2485 2485.cindex "FreeBSD, MTA indirection"
9b371988 2486.cindex "&_/etc/mail/mailer.conf_&"
168e428f
PH
2487Some operating systems have introduced alternative ways of switching MTAs. For
2488example, if you are running FreeBSD, you need to edit the file
9b371988 2489&_/etc/mail/mailer.conf_& instead of setting up a symbolic link as just
168e428f
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2490described. A typical example of the contents of this file for running Exim is
2491as follows:
9b371988
PH
2492.code
2493sendmail /usr/exim/bin/exim
2494send-mail /usr/exim/bin/exim
2495mailq /usr/exim/bin/exim -bp
2496newaliases /usr/bin/true
2497.endd
2498Once you have set up the symbolic link, or edited &_/etc/mail/mailer.conf_&,
2499your Exim installation is &"live"&. Check it by sending a message from your
168e428f
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2500favourite user agent.
2501
2502You should consider what to tell your users about the change of MTA. Exim may
2503have different capabilities to what was previously running, and there are
2504various operational differences such as the text of messages produced by
2505command line options and in bounce messages. If you allow your users to make
2506use of Exim's filtering capabilities, you should make the document entitled
9b371988 2507&'Exim's interface to mail filtering'& available to them.
168e428f
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2508
2509
2510
f89d2485 2511.section "Upgrading Exim" "SECID36"
9b371988 2512.cindex "upgrading Exim"
168e428f
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2513If you are already running Exim on your host, building and installing a new
2514version automatically makes it available to MUAs, or any other programs that
2515call the MTA directly. However, if you are running an Exim daemon, you do need
9b371988
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2516to send it a HUP signal, to make it re-execute itself, and thereby pick up the
2517new binary. You do not need to stop processing mail in order to install a new
068aaea8
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2518version of Exim. The install script does not modify an existing runtime
2519configuration file.
2520
168e428f
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2521
2522
2523
f89d2485 2524.section "Stopping the Exim daemon on Solaris" "SECID37"
9b371988 2525.cindex "Solaris" "stopping Exim on"
168e428f 2526The standard command for stopping the mailer daemon on Solaris is
9b371988
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2527.code
2528/etc/init.d/sendmail stop
2529.endd
2530If &_/usr/lib/sendmail_& has been turned into a symbolic link, this script
2531fails to stop Exim because it uses the command &'ps -e'& and greps the output
2532for the text &"sendmail"&; this is not present because the actual program name
2533(that is, &"exim"&) is given by the &'ps'& command with these options. A
2534solution is to replace the line that finds the process id with something like
2535.code
2536pid=`cat /var/spool/exim/exim-daemon.pid`
2537.endd
168e428f
PH
2538to obtain the daemon's pid directly from the file that Exim saves it in.
2539
9b371988 2540Note, however, that stopping the daemon does not &"stop Exim"&. Messages can
168e428f
PH
2541still be received from local processes, and if automatic delivery is configured
2542(the normal case), deliveries will still occur.
2543
2544
2545
2546
9b371988
PH
2547. ////////////////////////////////////////////////////////////////////////////
2548. ////////////////////////////////////////////////////////////////////////////
168e428f 2549
9b371988 2550.chapter "The Exim command line" "CHAPcommandline"
4f578862
PH
2551.scindex IIDclo1 "command line" "options"
2552.scindex IIDclo2 "options" "command line"
168e428f
PH
2553Exim's command line takes the standard Unix form of a sequence of options,
2554each starting with a hyphen character, followed by a number of arguments. The
2555options are compatible with the main options of Sendmail, and there are also
2556some additional options, some of which are compatible with Smail 3. Certain
2557combinations of options do not make sense, and provoke an error if used.
2558The form of the arguments depends on which options are set.
2559
2560
f89d2485 2561.section "Setting options by program name" "SECID38"
9b371988
PH
2562.cindex "&'mailq'&"
2563If Exim is called under the name &'mailq'&, it behaves as if the option &%-bp%&
168e428f 2564were present before any other options.
9b371988 2565The &%-bp%& option requests a listing of the contents of the mail queue on the
168e428f
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2566standard output.
2567This feature is for compatibility with some systems that contain a command of
2568that name in one of the standard libraries, symbolically linked to
9b371988
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2569&_/usr/sbin/sendmail_& or &_/usr/lib/sendmail_&.
2570
2571.cindex "&'rsmtp'&"
2572If Exim is called under the name &'rsmtp'& it behaves as if the option &%-bS%&
2573were present before any other options, for compatibility with Smail. The
2574&%-bS%& option is used for reading in a number of messages in batched SMTP
2575format.
2576
2577.cindex "&'rmail'&"
2578If Exim is called under the name &'rmail'& it behaves as if the &%-i%& and
2579&%-oee%& options were present before any other options, for compatibility with
2580Smail. The name &'rmail'& is used as an interface by some UUCP systems.
2581
2582.cindex "&'runq'&"
2583.cindex "queue runner"
2584If Exim is called under the name &'runq'& it behaves as if the option &%-q%&
2585were present before any other options, for compatibility with Smail. The &%-q%&
168e428f
PH
2586option causes a single queue runner process to be started.
2587
9b371988
PH
2588.cindex "&'newaliases'&"
2589.cindex "alias file" "building"
2590.cindex "Sendmail compatibility" "calling Exim as &'newaliases'&"
2591If Exim is called under the name &'newaliases'& it behaves as if the option
2592&%-bi%& were present before any other options, for compatibility with Sendmail.
168e428f
PH
2593This option is used for rebuilding Sendmail's alias file. Exim does not have
2594the concept of a single alias file, but can be configured to run a given
9b371988 2595command if called with the &%-bi%& option.
168e428f
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2596
2597
9b371988
PH
2598.section "Trusted and admin users" "SECTtrustedadmin"
2599Some Exim options are available only to &'trusted users'& and others are
2600available only to &'admin users'&. In the description below, the phrases &"Exim
2601user"& and &"Exim group"& mean the user and group defined by EXIM_USER and
2602EXIM_GROUP in &_Local/Makefile_& or set by the &%exim_user%& and
2603&%exim_group%& options. These do not necessarily have to use the name &"exim"&.
168e428f 2604
9b371988 2605.ilist
f89d2485 2606.cindex "trusted users" "definition of"
9b371988 2607.cindex "user" "trusted definition of"
168e428f 2608The trusted users are root, the Exim user, any user listed in the
9b371988
PH
2609&%trusted_users%& configuration option, and any user whose current group or any
2610supplementary group is one of those listed in the &%trusted_groups%&
168e428f 2611configuration option. Note that the Exim group is not automatically trusted.
9b371988
PH
2612
2613.cindex '&"From"& line'
2614.cindex "envelope sender"
2615Trusted users are always permitted to use the &%-f%& option or a leading
2616&"From&~"& line to specify the envelope sender of a message that is passed to
2617Exim through the local interface (see the &%-bm%& and &%-f%& options below).
2618See the &%untrusted_set_sender%& option for a way of permitting non-trusted
2619users to set envelope senders.
2620
2621.cindex "&'From:'& header line"
2622.cindex "&'Sender:'& header line"
1e4519cc
JH
2623.cindex "header lines" "From:"
2624.cindex "header lines" "Sender:"
9b371988
PH
2625For a trusted user, there is never any check on the contents of the &'From:'&
2626header line, and a &'Sender:'& line is never added. Furthermore, any existing
2627&'Sender:'& line in incoming local (non-TCP/IP) messages is not removed.
2628
168e428f
PH
2629Trusted users may also specify a host name, host address, interface address,
2630protocol name, ident value, and authentication data when submitting a message
2631locally. Thus, they are able to insert messages into Exim's queue locally that
2632have the characteristics of messages received from a remote host. Untrusted
9b371988 2633users may in some circumstances use &%-f%&, but can never set the other values
168e428f 2634that are available to trusted users.
9b371988
PH
2635.next
2636.cindex "user" "admin definition of"
2637.cindex "admin user" "definition of"
168e428f 2638The admin users are root, the Exim user, and any user that is a member of the
9b371988 2639Exim group or of any group listed in the &%admin_groups%& configuration option.
168e428f 2640The current group does not have to be one of these groups.
9b371988 2641
168e428f
PH
2642Admin users are permitted to list the queue, and to carry out certain
2643operations on messages, for example, to force delivery failures. It is also
2644necessary to be an admin user in order to see the full information provided by
2645the Exim monitor, and full debugging output.
9b371988
PH
2646
2647By default, the use of the &%-M%&, &%-q%&, &%-R%&, and &%-S%& options to cause
2648Exim to attempt delivery of messages on its queue is restricted to admin users.
2649However, this restriction can be relaxed by setting the &%prod_requires_admin%&
2650option false (that is, specifying &%no_prod_requires_admin%&).
2651
2652Similarly, the use of the &%-bp%& option to list all the messages in the queue
2653is restricted to admin users unless &%queue_list_requires_admin%& is set
168e428f 2654false.
9b371988 2655.endlist
168e428f
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2656
2657
9b371988 2658&*Warning*&: If you configure your system so that admin users are able to
168e428f
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2659edit Exim's configuration file, you are giving those users an easy way of
2660getting root. There is further discussion of this issue at the start of chapter
9b371988 2661&<<CHAPconf>>&.
168e428f
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2662
2663
2664
2665
f89d2485 2666.section "Command line options" "SECID39"
db9452a9
PH
2667Exim's command line options are described in alphabetical order below. If none
2668of the options that specifies a specific action (such as starting the daemon or
2669a queue runner, or testing an address, or receiving a message in a specific
2670format, or listing the queue) are present, and there is at least one argument
2671on the command line, &%-bm%& (accept a local message on the standard input,
2672with the arguments specifying the recipients) is assumed. Otherwise, Exim
2673outputs a brief message about itself and exits.
168e428f 2674
9b371988
PH
2675. ////////////////////////////////////////////////////////////////////////////
2676. Insert a stylized XML comment here, to identify the start of the command line
2677. options. This is for the benefit of the Perl script that automatically
2678. creates a man page for the options.
2679. ////////////////////////////////////////////////////////////////////////////
168e428f 2680
9b371988 2681.literal xml
168e428f 2682<!-- === Start of command line options === -->
9b371988 2683.literal off
168e428f
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2684
2685
9b371988
PH
2686.vlist
2687.vitem &%--%&
2688.oindex "--"
2689.cindex "options" "command line; terminating"
168e428f
PH
2690This is a pseudo-option whose only purpose is to terminate the options and
2691therefore to cause subsequent command line items to be treated as arguments
2692rather than options, even if they begin with hyphens.
2693
9b371988
PH
2694.vitem &%--help%&
2695.oindex "&%--help%&"
168e428f
PH
2696This option causes Exim to output a few sentences stating what it is.
2697The same output is generated if the Exim binary is called with no options and
2698no arguments.
2699
4b2241d2
PP
2700.vitem &%--version%&
2701.oindex "&%--version%&"
2702This option is an alias for &%-bV%& and causes version information to be
2703displayed.
2704
a3fb9793
PP
2705.vitem &%-Ac%& &&&
2706 &%-Am%&
2707.oindex "&%-Ac%&"
2708.oindex "&%-Am%&"
2709These options are used by Sendmail for selecting configuration files and are
2710ignored by Exim.
a3fb9793 2711
9b371988
PH
2712.vitem &%-B%&<&'type'&>
2713.oindex "&%-B%&"
2714.cindex "8-bit characters"
2715.cindex "Sendmail compatibility" "8-bit characters"
168e428f
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2716This is a Sendmail option for selecting 7 or 8 bit processing. Exim is 8-bit
2717clean; it ignores this option.
2718
9b371988
PH
2719.vitem &%-bd%&
2720.oindex "&%-bd%&"
2721.cindex "daemon"
f89d2485 2722.cindex "SMTP" "listener"
9b371988 2723.cindex "queue runner"
168e428f 2724This option runs Exim as a daemon, awaiting incoming SMTP connections. Usually
9b371988
PH
2725the &%-bd%& option is combined with the &%-q%&<&'time'&> option, to specify
2726that the daemon should also initiate periodic queue runs.
2727
2728The &%-bd%& option can be used only by an admin user. If either of the &%-d%&
2729(debugging) or &%-v%& (verifying) options are set, the daemon does not
168e428f
PH
2730disconnect from the controlling terminal. When running this way, it can be
2731stopped by pressing ctrl-C.
9b371988 2732
168e428f
PH
2733By default, Exim listens for incoming connections to the standard SMTP port on
2734all the host's running interfaces. However, it is possible to listen on other
2735ports, on multiple ports, and only on specific interfaces. Chapter
9b371988
PH
2736&<<CHAPinterfaces>>& contains a description of the options that control this.
2737
168e428f 2738When a listening daemon
9b371988
PH
2739.cindex "daemon" "process id (pid)"
2740.cindex "pid (process id)" "of daemon"
2741is started without the use of &%-oX%& (that is, without overriding the normal
2742configuration), it writes its process id to a file called &_exim-daemon.pid_&
2743in Exim's spool directory. This location can be overridden by setting
2744PID_FILE_PATH in &_Local/Makefile_&. The file is written while Exim is still
168e428f 2745running as root.
9b371988
PH
2746
2747When &%-oX%& is used on the command line to start a listening daemon, the
2748process id is not written to the normal pid file path. However, &%-oP%& can be
168e428f 2749used to specify a path on the command line if a pid file is required.
9b371988 2750
168e428f 2751The SIGHUP signal
9b371988 2752.cindex "SIGHUP"
3cb1b51e
PH
2753.cindex "daemon" "restarting"
2754can be used to cause the daemon to re-execute itself. This should be done
2755whenever Exim's configuration file, or any file that is incorporated into it by
2756means of the &%.include%& facility, is changed, and also whenever a new version
2757of Exim is installed. It is not necessary to do this when other files that are
9b371988
PH
2758referenced from the configuration (for example, alias files) are changed,
2759because these are reread each time they are used.
2760
2761.vitem &%-bdf%&
2762.oindex "&%-bdf%&"
2763This option has the same effect as &%-bd%& except that it never disconnects
2764from the controlling terminal, even when no debugging is specified.
2765
2766.vitem &%-be%&
2767.oindex "&%-be%&"
2768.cindex "testing" "string expansion"
2769.cindex "expansion" "testing"
168e428f
PH
2770Run Exim in expansion testing mode. Exim discards its root privilege, to
2771prevent ordinary users from using this mode to read otherwise inaccessible
2772files. If no arguments are given, Exim runs interactively, prompting for lines
4f578862 2773of data. Otherwise, it processes each argument in turn.
9b371988
PH
2774
2775If Exim was built with USE_READLINE=yes in &_Local/Makefile_&, it tries
2776to load the &%libreadline%& library dynamically whenever the &%-be%& option is
2777used without command line arguments. If successful, it uses the &[readline()]&
168e428f
PH
2778function, which provides extensive line-editing facilities, for reading the
2779test data. A line history is supported.
9b371988 2780
168e428f 2781Long expansion expressions can be split over several lines by using backslash
068aaea8 2782continuations. As in Exim's run time configuration, white space at the start of
168e428f
PH
2783continuation lines is ignored. Each argument or data line is passed through the
2784string expansion mechanism, and the result is output. Variable values from the
9b371988 2785configuration file (for example, &$qualify_domain$&) are available, but no
374dc194 2786message-specific values (such as &$message_exim_id$&) are set, because no message
f89d2485 2787is being processed (but see &%-bem%& and &%-Mset%&).
168e428f 2788
9b371988
PH
2789&*Note*&: If you use this mechanism to test lookups, and you change the data
2790files or databases you are using, you must exit and restart Exim before trying
2791the same lookup again. Otherwise, because each Exim process caches the results
2792of lookups, you will just get the same result as before.
9b371988 2793
9650d98a
JH
2794Macro processing is done on lines before string-expansion: new macros can be
2795defined and macros will be expanded.
2796Because macros in the config file are often used for secrets, those are only
2797available to admin users.
9650d98a 2798
3cb1b51e
PH
2799.vitem &%-bem%&&~<&'filename'&>
2800.oindex "&%-bem%&"
2801.cindex "testing" "string expansion"
2802.cindex "expansion" "testing"
2803This option operates like &%-be%& except that it must be followed by the name
2804of a file. For example:
2805.code
2806exim -bem /tmp/testmessage
2807.endd
2808The file is read as a message (as if receiving a locally-submitted non-SMTP
2809message) before any of the test expansions are done. Thus, message-specific
2810variables such as &$message_size$& and &$header_from:$& are available. However,
2811no &'Received:'& header is added to the message. If the &%-t%& option is set,
2812recipients are read from the headers in the normal way, and are shown in the
2813&$recipients$& variable. Note that recipients cannot be given on the command
2814line, because further arguments are taken as strings to expand (just like
2815&%-be%&).
3cb1b51e 2816
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PH
2817.vitem &%-bF%&&~<&'filename'&>
2818.oindex "&%-bF%&"
2819.cindex "system filter" "testing"
2820.cindex "testing" "system filter"
2821This option is the same as &%-bf%& except that it assumes that the filter being
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PH
2822tested is a system filter. The additional commands that are available only in
2823system filters are recognized.
2824
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PH
2825.vitem &%-bf%&&~<&'filename'&>
2826.oindex "&%-bf%&"
2827.cindex "filter" "testing"
2828.cindex "testing" "filter file"
2829.cindex "forward file" "testing"
2830.cindex "testing" "forward file"
2831.cindex "Sieve filter" "testing"
168e428f
PH
2832This option runs Exim in user filter testing mode; the file is the filter file
2833to be tested, and a test message must be supplied on the standard input. If
2834there are no message-dependent tests in the filter, an empty file can be
2835supplied.
168e428f 2836
9b371988
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2837If you want to test a system filter file, use &%-bF%& instead of &%-bf%&. You
2838can use both &%-bF%& and &%-bf%& on the same command, in order to test a system
2839filter and a user filter in the same run. For example:
2840.code
2841exim -bF /system/filter -bf /user/filter </test/message
2842.endd
168e428f
PH
2843This is helpful when the system filter adds header lines or sets filter
2844variables that are used by the user filter.
168e428f 2845
9b371988
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2846If the test filter file does not begin with one of the special lines
2847.code
2848# Exim filter
2849# Sieve filter
2850.endd
2851it is taken to be a normal &_.forward_& file, and is tested for validity under
2852that interpretation. See sections &<<SECTitenonfilred>>& to
2853&<<SECTspecitredli>>& for a description of the possible contents of non-filter
2854redirection lists.
2855
2856The result of an Exim command that uses &%-bf%&, provided no errors are
168e428f
PH
2857detected, is a list of the actions that Exim would try to take if presented
2858with the message for real. More details of filter testing are given in the
9b371988
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2859separate document entitled &'Exim's interfaces to mail filtering'&.
2860
168e428f 2861When testing a filter file,
9b371988
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2862.cindex "&""From""& line"
2863.cindex "envelope sender"
f89d2485 2864.oindex "&%-f%&" "for filter testing"
9b371988
PH
2865the envelope sender can be set by the &%-f%& option,
2866or by a &"From&~"& line at the start of the test message. Various parameters
2867that would normally be taken from the envelope recipient address of the message
2868can be set by means of additional command line options (see the next four
2869options).
2870
2871.vitem &%-bfd%&&~<&'domain'&>
2872.oindex "&%-bfd%&"
f89d2485 2873.vindex "&$qualify_domain$&"
168e428f 2874This sets the domain of the recipient address when a filter file is being
9b371988
PH
2875tested by means of the &%-bf%& option. The default is the value of
2876&$qualify_domain$&.
168e428f 2877
9b371988
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2878.vitem &%-bfl%&&~<&'local&~part'&>
2879.oindex "&%-bfl%&"
168e428f 2880This sets the local part of the recipient address when a filter file is being
9b371988 2881tested by means of the &%-bf%& option. The default is the username of the
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PH
2882process that calls Exim. A local part should be specified with any prefix or
2883suffix stripped, because that is how it appears to the filter when a message is
2884actually being delivered.
2885
9b371988
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2886.vitem &%-bfp%&&~<&'prefix'&>
2887.oindex "&%-bfp%&"
168e428f 2888This sets the prefix of the local part of the recipient address when a filter
9b371988 2889file is being tested by means of the &%-bf%& option. The default is an empty
168e428f
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2890prefix.
2891
9b371988
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2892.vitem &%-bfs%&&~<&'suffix'&>
2893.oindex "&%-bfs%&"
168e428f 2894This sets the suffix of the local part of the recipient address when a filter
9b371988 2895file is being tested by means of the &%-bf%& option. The default is an empty
168e428f
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2896suffix.
2897
9b371988
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2898.vitem &%-bh%&&~<&'IP&~address'&>
2899.oindex "&%-bh%&"
2900.cindex "testing" "incoming SMTP"
2901.cindex "SMTP" "testing incoming"
2902.cindex "testing" "relay control"
2903.cindex "relaying" "testing configuration"
2904.cindex "policy control" "testing"
2905.cindex "debugging" "&%-bh%& option"
168e428f
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2906This option runs a fake SMTP session as if from the given IP address, using the
2907standard input and output. The IP address may include a port number at the end,
2908after a full stop. For example:
9b371988
PH
2909.code
2910exim -bh 10.9.8.7.1234
2911exim -bh fe80::a00:20ff:fe86:a061.5678
2912.endd
168e428f 2913When an IPv6 address is given, it is converted into canonical form. In the case
9b371988
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2914of the second example above, the value of &$sender_host_address$& after
2915conversion to the canonical form is
2916&`fe80:0000:0000:0a00:20ff:fe86:a061.5678`&.
2917
168e428f 2918Comments as to what is going on are written to the standard error file. These
9b371988 2919include lines beginning with &"LOG"& for anything that would have been logged.
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2920This facility is provided for testing configuration options for incoming
2921messages, to make sure they implement the required policy. For example, you can
9b371988
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2922test your relay controls using &%-bh%&.
2923
2924&*Warning 1*&:
2925.cindex "RFC 1413"
db9452a9
PH
2926You can test features of the configuration that rely on ident (RFC 1413)
2927information by using the &%-oMt%& option. However, Exim cannot actually perform
2928an ident callout when testing using &%-bh%& because there is no incoming SMTP
2929connection.
9b371988
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2930
2931&*Warning 2*&: Address verification callouts (see section &<<SECTcallver>>&)
2932are also skipped when testing using &%-bh%&. If you want these callouts to
2933occur, use &%-bhc%& instead.
2934
168e428f
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2935Messages supplied during the testing session are discarded, and nothing is
2936written to any of the real log files. There may be pauses when DNS (and other)
9b371988 2937lookups are taking place, and of course these may time out. The &%-oMi%& option
db9452a9
PH
2938can be used to specify a specific IP interface and port if this is important,
2939and &%-oMaa%& and &%-oMai%& can be used to set parameters as if the SMTP
2940session were authenticated.
9b371988
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2941
2942The &'exim_checkaccess'& utility is a &"packaged"& version of &%-bh%& whose
168e428f 2943output just states whether a given recipient address from a given host is
9b371988 2944acceptable or not. See section &<<SECTcheckaccess>>&.
168e428f 2945
3cb1b51e 2946Features such as authentication and encryption, where the client input is not
f89d2485
PH
2947plain text, cannot easily be tested with &%-bh%&. Instead, you should use a
2948specialized SMTP test program such as
3cb1b51e 2949&url(http://jetmore.org/john/code/#swaks,swaks).
3cb1b51e 2950
9b371988
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2951.vitem &%-bhc%&&~<&'IP&~address'&>
2952.oindex "&%-bhc%&"
2953This option operates in the same way as &%-bh%&, except that address
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PH
2954verification callouts are performed if required. This includes consulting and
2955updating the callout cache database.
2956
9b371988
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2957.vitem &%-bi%&
2958.oindex "&%-bi%&"
2959.cindex "alias file" "building"
2960.cindex "building alias file"
2961.cindex "Sendmail compatibility" "&%-bi%& option"
2962Sendmail interprets the &%-bi%& option as a request to rebuild its alias file.
168e428f 2963Exim does not have the concept of a single alias file, and so it cannot mimic
9b371988 2964this behaviour. However, calls to &_/usr/lib/sendmail_& with the &%-bi%& option
168e428f
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2965tend to appear in various scripts such as NIS make files, so the option must be
2966recognized.
9b371988
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2967
2968If &%-bi%& is encountered, the command specified by the &%bi_command%&
168e428f 2969configuration option is run, under the uid and gid of the caller of Exim. If
9b371988
PH
2970the &%-oA%& option is used, its value is passed to the command as an argument.
2971The command set by &%bi_command%& may not contain arguments. The command can
2972use the &'exim_dbmbuild'& utility, or some other means, to rebuild alias files
2973if this is required. If the &%bi_command%& option is not set, calling Exim with
2974&%-bi%& is a no-op.
2975
36a3ae5f 2976. // Keep :help first, then the rest in alphabetical order
98a90c36
PP
2977.vitem &%-bI:help%&
2978.oindex "&%-bI:help%&"
2979.cindex "querying exim information"
2980We shall provide various options starting &`-bI:`& for querying Exim for
2981information. The output of many of these will be intended for machine
2982consumption. This one is not. The &%-bI:help%& option asks Exim for a
2983synopsis of supported options beginning &`-bI:`&. Use of any of these
2984options shall cause Exim to exit after producing the requested output.
2985
36a3ae5f
PP
2986.vitem &%-bI:dscp%&
2987.oindex "&%-bI:dscp%&"
2988.cindex "DSCP" "values"
2989This option causes Exim to emit an alphabetically sorted list of all
2990recognised DSCP names.
2991
98a90c36
PP
2992.vitem &%-bI:sieve%&
2993.oindex "&%-bI:sieve%&"
2994.cindex "Sieve filter" "capabilities"
2995This option causes Exim to emit an alphabetically sorted list of all supported
2996Sieve protocol extensions on stdout, one per line. This is anticipated to be
2997useful for ManageSieve (RFC 5804) implementations, in providing that protocol's
2998&`SIEVE`& capability response line. As the precise list may depend upon
2999compile-time build options, which this option will adapt to, this is the only
3000way to guarantee a correct response.
3001
9b371988
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3002.vitem &%-bm%&
3003.oindex "&%-bm%&"
3004.cindex "local message reception"
168e428f 3005This option runs an Exim receiving process that accepts an incoming,
a543079f 3006locally-generated message on the standard input. The recipients are given as the
9b371988 3007command arguments (except when &%-t%& is also present &-- see below). Each
168e428f
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3008argument can be a comma-separated list of RFC 2822 addresses. This is the
3009default option for selecting the overall action of an Exim call; it is assumed
3010if no other conflicting option is present.
9b371988 3011
168e428f 3012If any addresses in the message are unqualified (have no domain), they are
9b371988
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3013qualified by the values of the &%qualify_domain%& or &%qualify_recipient%&
3014options, as appropriate. The &%-bnq%& option (see below) provides a way of
168e428f 3015suppressing this for special cases.
9b371988 3016
168e428f 3017Policy checks on the contents of local messages can be enforced by means of
9b371988
PH
3018the non-SMTP ACL. See chapter &<<CHAPACL>>& for details.
3019
3020.cindex "return code" "for &%-bm%&"
3021The return code is zero if the message is successfully accepted. Otherwise, the
3022action is controlled by the &%-oe%&&'x'& option setting &-- see below.
3023
168e428f 3024The format
9b371988
PH
3025.cindex "message" "format"
3026.cindex "format" "message"
3027.cindex "&""From""& line"
3028.cindex "UUCP" "&""From""& line"
3029.cindex "Sendmail compatibility" "&""From""& line"
168e428f
PH
3030of the message must be as defined in RFC 2822, except that, for
3031compatibility with Sendmail and Smail, a line in one of the forms
9b371988
PH
3032.code
3033From sender Fri Jan 5 12:55 GMT 1997
3034From sender Fri, 5 Jan 97 12:55:01
3035.endd
168e428f
PH
3036(with the weekday optional, and possibly with additional text after the date)
3037is permitted to appear at the start of the message. There appears to be no
3038authoritative specification of the format of this line. Exim recognizes it by
9b371988 3039matching against the regular expression defined by the &%uucp_from_pattern%&
168e428f 3040option, which can be changed if necessary.
9b371988 3041
f89d2485
PH
3042.oindex "&%-f%&" "overriding &""From""& line"
3043The specified sender is treated as if it were given as the argument to the
9b371988 3044&%-f%& option, but if a &%-f%& option is also present, its argument is used in
168e428f
PH
3045preference to the address taken from the message. The caller of Exim must be a
3046trusted user for the sender of a message to be set in this way.
3047
5b257915
PP
3048.vitem &%-bmalware%&&~<&'filename'&>
3049.oindex "&%-bmalware%&"
3050.cindex "testing", "malware"
3051.cindex "malware scan test"
60f914bc
HSHR
3052This debugging option causes Exim to scan the given file or directory
3053(depending on the used scanner interface),
5b257915
PP
3054using the malware scanning framework. The option of &%av_scanner%& influences
3055this option, so if &%av_scanner%&'s value is dependent upon an expansion then
3056the expansion should have defaults which apply to this invocation. ACLs are
3057not invoked, so if &%av_scanner%& references an ACL variable then that variable
3058will never be populated and &%-bmalware%& will fail.
3059
3060Exim will have changed working directory before resolvin