I happen to be looking at this again, so while I am here I'll polish the wording...
[exim.git] / doc / doc-docbook / spec.xfpt
CommitLineData
c6ac190c 1. $Cambridge: exim/doc/doc-docbook/spec.xfpt,v 1.31 2008/01/29 17:08:54 fanf2 Exp $
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2.
3. /////////////////////////////////////////////////////////////////////////////
4. This is the primary source of the Exim Manual. It is an xfpt document that is
5. converted into DocBook XML for subsequent conversion into printing and online
6. formats. The markup used herein is "standard" xfpt markup, with some extras.
7. The markup is summarized in a file called Markup.txt.
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8.
9. WARNING: When you use the .new macro, make sure it appears *before* any
10. adjacent index items; otherwise you get an empty "paragraph" which causes
11. unwanted vertical space.
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12. /////////////////////////////////////////////////////////////////////////////
13
14.include stdflags
15.include stdmacs
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16
17. /////////////////////////////////////////////////////////////////////////////
33393583 18. This outputs the standard DocBook boilerplate.
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19. /////////////////////////////////////////////////////////////////////////////
20
33393583 21.docbook
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22
23. /////////////////////////////////////////////////////////////////////////////
24. These lines are processing instructions for the Simple DocBook Processor that
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25. Philip Hazel has developed as a less cumbersome way of making PostScript and
26. PDFs than using xmlto and fop. They will be ignored by all other XML
27. processors.
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28. /////////////////////////////////////////////////////////////////////////////
29
30.literal xml
31<?sdop
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32 foot_right_recto="&chaptertitle; (&chapternumber;)"
33 foot_right_verso="&chaptertitle; (&chapternumber;)"
3cb1b51e 34 toc_chapter_blanks="yes,yes"
595028e4 35 table_warn_overflow="overprint"
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36?>
37.literal off
9b371988 38
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39. /////////////////////////////////////////////////////////////////////////////
40. This generate the outermost <book> element that wraps then entire document.
41. /////////////////////////////////////////////////////////////////////////////
42
43.book
44
45. /////////////////////////////////////////////////////////////////////////////
46. These definitions set some parameters and save some typing. Remember that
47. the <bookinfo> element must also be updated for each new edition.
48. /////////////////////////////////////////////////////////////////////////////
49
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50.set previousversion "4.69"
51.set version "4.70"
f89d2485 52
33393583 53.set ACL "access control lists (ACLs)"
f89d2485 54.set I "&nbsp;&nbsp;&nbsp;&nbsp;"
33393583 55
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56
57. /////////////////////////////////////////////////////////////////////////////
58. Additional xfpt markup used by this document, over and above the default
59. provided in the xfpt library.
60. /////////////////////////////////////////////////////////////////////////////
61
62. --- Override the &$ flag to automatically insert a $ with the variable name
63
64.flag &$ $& "<varname>$" "</varname>"
65
66. --- Short flags for daggers in option headings. They will always be inside
67. --- an italic string, but we want the daggers to be roman.
68
69.flag &!! "</emphasis>&dagger;<emphasis>"
70.flag &!? "</emphasis>&Dagger;<emphasis>"
71
72. --- A macro for an Exim option definition heading, generating a one-line
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73. --- table with four columns. For cases when the option name is given with
74. --- a space, so that it can be split, a fifth argument is used for the
75. --- index entry.
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76
77.macro option
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78.arg 5
79.oindex "&%$5%&"
80.endarg
81.arg -5
3cb1b51e 82.oindex "&%$1%&"
0a4e3112 83.endarg
f89d2485 84.itable all 0 0 4 8* left 6* center 6* center 6* right
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85.row "&%$1%&" "Use: &'$2'&" "Type: &'$3'&" "Default: &'$4'&"
86.endtable
87.endmacro
88
89. --- A macro for the common 2-column tables. The width of the first column
90. --- is suitable for the many tables at the start of the main options chapter;
91. --- the small number of other 2-column tables override it.
92
db9452a9 93.macro table2 196pt 254pt
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94.itable none 0 0 2 $1 left $2 left
95.endmacro
96
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97. --- A macro that generates .row, but puts &I; at the start of the first
98. --- argument, thus indenting it. Assume a minimum of two arguments, and
99. --- allow up to four arguments, which is as many as we'll ever need.
100
101.macro irow
102.arg 4
103.row "&I;$1" "$2" "$3" "$4"
104.endarg
105.arg -4
106.arg 3
107.row "&I;$1" "$2" "$3"
108.endarg
109.arg -3
110.row "&I;$1" "$2"
111.endarg
112.endarg
113.endmacro
114
115. --- Macros for option, variable, and concept index entries. For a "range"
116. --- style of entry, use .scindex for the start and .ecindex for the end. The
117. --- first argument of .scindex and the only argument of .ecindex must be the
118. --- ID that ties them together.
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119
120.macro cindex
121&<indexterm role="concept">&
122&<primary>&$1&</primary>&
123.arg 2
124&<secondary>&$2&</secondary>&
125.endarg
126&</indexterm>&
127.endmacro
128
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129.macro scindex
130&<indexterm role="concept" id="$1" class="startofrange">&
131&<primary>&$2&</primary>&
132.arg 3
133&<secondary>&$3&</secondary>&
134.endarg
135&</indexterm>&
136.endmacro
137
138.macro ecindex
139&<indexterm role="concept" startref="$1" class="endofrange"/>&
140.endmacro
141
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142.macro oindex
143&<indexterm role="option">&
144&<primary>&$1&</primary>&
145.arg 2
146&<secondary>&$2&</secondary>&
147.endarg
148&</indexterm>&
149.endmacro
150
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151.macro vindex
152&<indexterm role="variable">&
153&<primary>&$1&</primary>&
154.arg 2
155&<secondary>&$2&</secondary>&
156.endarg
157&</indexterm>&
158.endmacro
159
9b371988 160.macro index
f89d2485 161.echo "** Don't use .index; use .cindex or .oindex or .vindex"
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162.endmacro
163. ////////////////////////////////////////////////////////////////////////////
164
165
166. ////////////////////////////////////////////////////////////////////////////
167. The <bookinfo> element is removed from the XML before processing for Ascii
168. output formats.
169. ////////////////////////////////////////////////////////////////////////////
170
171.literal xml
172<bookinfo>
173<title>Specification of the Exim Mail Transfer Agent</title>
174<titleabbrev>The Exim MTA</titleabbrev>
595028e4 175<date>23 August 2007</date>
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176<author><firstname>Philip</firstname><surname>Hazel</surname></author>
177<authorinitials>PH</authorinitials>
178<affiliation><orgname>University of Cambridge Computing Service</orgname></affiliation>
179<address>New Museums Site, Pembroke Street, Cambridge CB2 3QH, England</address>
180<revhistory><revision>
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181 <revnumber>4.68</revnumber>
182 <date>23 August 2007</date>
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183 <authorinitials>PH</authorinitials>
184</revision></revhistory>
ad268134 185<copyright><year>2007</year><holder>University of Cambridge</holder></copyright>
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186</bookinfo>
187.literal off
188
189
190. /////////////////////////////////////////////////////////////////////////////
191. This chunk of literal XML implements index entries of the form "x, see y" and
192. "x, see also y". However, the DocBook DTD doesn't allow <indexterm> entries
193. at the top level, so we have to put the .chapter directive first.
194. /////////////////////////////////////////////////////////////////////////////
195
f89d2485 196.chapter "Introduction" "CHID1"
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197.literal xml
198
f89d2485 199<indexterm role="variable">
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200 <primary>$1, $2, etc.</primary>
201 <see><emphasis>numerical variables</emphasis></see>
202</indexterm>
203<indexterm role="concept">
204 <primary>address</primary>
205 <secondary>rewriting</secondary>
206 <see><emphasis>rewriting</emphasis></see>
207</indexterm>
208<indexterm role="concept">
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209 <primary>Bounce Address Tag Validation</primary>
210 <see><emphasis>BATV</emphasis></see>
211</indexterm>
212<indexterm role="concept">
213 <primary>Client SMTP Authorization</primary>
214 <see><emphasis>CSA</emphasis></see>
215</indexterm>
216<indexterm role="concept">
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217 <primary>CR character</primary>
218 <see><emphasis>carriage return</emphasis></see>
219</indexterm>
220<indexterm role="concept">
221 <primary>CRL</primary>
222 <see><emphasis>certificate revocation list</emphasis></see>
223</indexterm>
224<indexterm role="concept">
225 <primary>delivery</primary>
226 <secondary>failure report</secondary>
227 <see><emphasis>bounce message</emphasis></see>
228</indexterm>
229<indexterm role="concept">
230 <primary>dialup</primary>
231 <see><emphasis>intermittently connected hosts</emphasis></see>
232</indexterm>
233<indexterm role="concept">
234 <primary>exiscan</primary>
235 <see><emphasis>content scanning</emphasis></see>
236</indexterm>
237<indexterm role="concept">
238 <primary>failover</primary>
239 <see><emphasis>fallback</emphasis></see>
240</indexterm>
241<indexterm role="concept">
242 <primary>fallover</primary>
243 <see><emphasis>fallback</emphasis></see>
244</indexterm>
245<indexterm role="concept">
246 <primary>filter</primary>
247 <secondary>Sieve</secondary>
248 <see><emphasis>Sieve filter</emphasis></see>
249</indexterm>
250<indexterm role="concept">
251 <primary>ident</primary>
252 <see><emphasis>RFC 1413</emphasis></see>
253</indexterm>
254<indexterm role="concept">
255 <primary>LF character</primary>
256 <see><emphasis>linefeed</emphasis></see>
257</indexterm>
258<indexterm role="concept">
259 <primary>maximum</primary>
595028e4 260 <seealso><emphasis>limit</emphasis></seealso>
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261</indexterm>
262<indexterm role="concept">
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263 <primary>monitor</primary>
264 <see><emphasis>Exim monitor</emphasis></see>
265</indexterm>
266<indexterm role="concept">
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267 <primary>no_<emphasis>xxx</emphasis></primary>
268 <see>entry for xxx</see>
269</indexterm>
270<indexterm role="concept">
271 <primary>NUL</primary>
272 <see><emphasis>binary zero</emphasis></see>
273</indexterm>
274<indexterm role="concept">
275 <primary>passwd file</primary>
276 <see><emphasis>/etc/passwd</emphasis></see>
277</indexterm>
278<indexterm role="concept">
279 <primary>process id</primary>
280 <see><emphasis>pid</emphasis></see>
281</indexterm>
282<indexterm role="concept">
283 <primary>RBL</primary>
284 <see><emphasis>DNS list</emphasis></see>
285</indexterm>
286<indexterm role="concept">
287 <primary>redirection</primary>
288 <see><emphasis>address redirection</emphasis></see>
289</indexterm>
290<indexterm role="concept">
291 <primary>return path</primary>
292 <seealso><emphasis>envelope sender</emphasis></seealso>
293</indexterm>
294<indexterm role="concept">
295 <primary>scanning</primary>
296 <see><emphasis>content scanning</emphasis></see>
297</indexterm>
298<indexterm role="concept">
299 <primary>SSL</primary>
300 <see><emphasis>TLS</emphasis></see>
301</indexterm>
302<indexterm role="concept">
303 <primary>string</primary>
304 <secondary>expansion</secondary>
305 <see><emphasis>expansion</emphasis></see>
306</indexterm>
307<indexterm role="concept">
308 <primary>top bit</primary>
309 <see><emphasis>8-bit characters</emphasis></see>
310</indexterm>
311<indexterm role="concept">
312 <primary>variables</primary>
313 <see><emphasis>expansion, variables</emphasis></see>
314</indexterm>
315<indexterm role="concept">
316 <primary>zero, binary</primary>
317 <see><emphasis>binary zero</emphasis></see>
318</indexterm>
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319
320.literal off
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321
322
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323. /////////////////////////////////////////////////////////////////////////////
324. This is the real start of the first chapter. See the comment above as to why
325. we can't have the .chapter line here.
326. chapter "Introduction"
327. /////////////////////////////////////////////////////////////////////////////
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328
329Exim is a mail transfer agent (MTA) for hosts that are running Unix or
330Unix-like operating systems. It was designed on the assumption that it would be
331run on hosts that are permanently connected to the Internet. However, it can be
332used on intermittently connected hosts with suitable configuration adjustments.
333
334Configuration files currently exist for the following operating systems: AIX,
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335BSD/OS (aka BSDI), Darwin (Mac OS X), DGUX, Dragonfly, FreeBSD, GNU/Hurd,
336GNU/Linux, HI-OSF (Hitachi), HI-UX, HP-UX, IRIX, MIPS RISCOS, NetBSD, OpenBSD,
337OpenUNIX, QNX, SCO, SCO SVR4.2 (aka UNIX-SV), Solaris (aka SunOS5), SunOS4,
338Tru64-Unix (formerly Digital UNIX, formerly DEC-OSF1), Ultrix, and Unixware.
339Some of these operating systems are no longer current and cannot easily be
340tested, so the configuration files may no longer work in practice.
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341
342There are also configuration files for compiling Exim in the Cygwin environment
343that can be installed on systems running Windows. However, this document does
344not contain any information about running Exim in the Cygwin environment.
345
346The terms and conditions for the use and distribution of Exim are contained in
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347the file &_NOTICE_&. Exim is distributed under the terms of the GNU General
348Public Licence, a copy of which may be found in the file &_LICENCE_&.
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349
350The use, supply or promotion of Exim for the purpose of sending bulk,
351unsolicited electronic mail is incompatible with the basic aims of the program,
352which revolve around the free provision of a service that enhances the quality
353of personal communications. The author of Exim regards indiscriminate
354mass-mailing as an antisocial, irresponsible abuse of the Internet.
355
356Exim owes a great deal to Smail 3 and its author, Ron Karr. Without the
357experience of running and working on the Smail 3 code, I could never have
358contemplated starting to write a new MTA. Many of the ideas and user interfaces
359were originally taken from Smail 3, though the actual code of Exim is entirely
360new, and has developed far beyond the initial concept.
361
362Many people, both in Cambridge and around the world, have contributed to the
363development and the testing of Exim, and to porting it to various operating
364systems. I am grateful to them all. The distribution now contains a file called
9b371988 365&_ACKNOWLEDGMENTS_&, in which I have started recording the names of
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366contributors.
367
368
f89d2485 369.section "Exim documentation" "SECID1"
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370.new
371.cindex "documentation"
372This edition of the Exim specification applies to version &version; of Exim.
373Substantive changes from the &previousversion; edition are marked in some
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374renditions of the document; this paragraph is so marked if the rendition is
375capable of showing a change indicator.
9b371988 376.wen
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377
378This document is very much a reference manual; it is not a tutorial. The reader
379is expected to have some familiarity with the SMTP mail transfer protocol and
380with general Unix system administration. Although there are some discussions
381and examples in places, the information is mostly organized in a way that makes
382it easy to look up, rather than in a natural order for sequential reading.
383Furthermore, the manual aims to cover every aspect of Exim in detail, including
384a number of rarely-used, special-purpose features that are unlikely to be of
385very wide interest.
386
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387.cindex "books about Exim"
388An &"easier"& discussion of Exim which provides more in-depth explanatory,
389introductory, and tutorial material can be found in a book entitled &'The Exim
595028e4 390SMTP Mail Server'& (second edition, 2007), published by UIT Cambridge
9b371988 391(&url(http://www.uit.co.uk/exim-book/)).
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392
393This book also contains a chapter that gives a general introduction to SMTP and
394Internet mail. Inevitably, however, the book is unlikely to be fully up-to-date
395with the latest release of Exim. (Note that the earlier book about Exim,
396published by O'Reilly, covers Exim 3, and many things have changed in Exim 4.)
397
9b371988 398.cindex "Debian" "information sources"
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399If you are using a Debian distribution of Exim, you will find information about
400Debian-specific features in the file
f89d2485 401&_/usr/share/doc/exim4-base/README.Debian_&.
9b371988 402The command &(man update-exim.conf)& is another source of Debian-specific
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403information.
404
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405.cindex "&_doc/NewStuff_&"
406.cindex "&_doc/ChangeLog_&"
407.cindex "change log"
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408As the program develops, there may be features in newer versions that have not
409yet made it into this document, which is updated only when the most significant
410digit of the fractional part of the version number changes. Specifications of
411new features that are not yet in this manual are placed in the file
9b371988 412&_doc/NewStuff_& in the Exim distribution.
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9b371988 414Some features may be classified as &"experimental"&. These may change
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415incompatibly while they are developing, or even be withdrawn. For this reason,
416they are not documented in this manual. Information about experimental features
9b371988 417can be found in the file &_doc/experimental.txt_&.
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418
419All changes to the program (whether new features, bug fixes, or other kinds of
9b371988 420change) are noted briefly in the file called &_doc/ChangeLog_&.
168e428f 421
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422.cindex "&_doc/spec.txt_&"
423This specification itself is available as an ASCII file in &_doc/spec.txt_& so
424that it can easily be searched with a text editor. Other files in the &_doc_&
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425directory are:
426
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427.table2 100pt
428.row &_OptionLists.txt_& "list of all options in alphabetical order"
429.row &_dbm.discuss.txt_& "discussion about DBM libraries"
430.row &_exim.8_& "a man page of Exim's command line options"
431.row &_experimental.txt_& "documentation of experimental features"
432.row &_filter.txt_& "specification of the filter language"
433.row &_pcrepattern.txt_& "specification of PCRE regular expressions"
434.row &_pcretest.txt_& "specification of the PCRE testing program"
435.row &_Exim3.upgrade_& "upgrade notes from release 2 to release 3"
436.row &_Exim4.upgrade_& "upgrade notes from release 3 to release 4"
437.endtable
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438
439The main specification and the specification of the filtering language are also
440available in other formats (HTML, PostScript, PDF, and Texinfo). Section
9b371988 441&<<SECTavail>>& below tells you how to get hold of these.
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442
443
444
f89d2485 445.section "FTP and web sites" "SECID2"
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446.cindex "web site"
447.cindex "FTP site"
068aaea8 448The primary site for Exim source distributions is currently the University of
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449Cambridge's FTP site, whose contents are described in &'Where to find the Exim
450distribution'& below. In addition, there is a web site and an FTP site at
451&%exim.org%&. These are now also hosted at the University of Cambridge. The
452&%exim.org%& site was previously hosted for a number of years by Energis
453Squared, formerly Planet Online Ltd, whose support I gratefully acknowledge.
454
455.cindex "wiki"
456.cindex "FAQ"
168e428f 457As well as Exim distribution tar files, the Exim web site contains a number of
f89d2485 458differently formatted versions of the documentation. A recent addition to the
595028e4 459online information is the Exim wiki &new("(&url(http://wiki.exim.org))"),
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460which contains what used to be a separate FAQ, as well as various other
461examples, tips, and know-how that have been contributed by Exim users.
462
463.cindex Bugzilla
595028e4 464An Exim Bugzilla exists at &new("&url(http://bugs.exim.org)"). You can use
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465this to report bugs, and also to add items to the wish list. Please search
466first to check that you are not duplicating a previous entry.
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467
468
469
f89d2485 470.section "Mailing lists" "SECID3"
9b371988 471.cindex "mailing lists" "for Exim users"
f89d2485 472The following Exim mailing lists exist:
168e428f 473
9b371988 474.table2 140pt
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475.row &'exim-users@exim.org'& "General discussion list"
476.row &'exim-dev@exim.org'& "Discussion of bugs, enhancements, etc."
477.row &'exim-announce@exim.org'& "Moderated, low volume announcements list"
478.row &'exim-future@exim.org'& "Discussion of long-term development"
9b371988 479.endtable
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480
481You can subscribe to these lists, change your existing subscriptions, and view
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482or search the archives via the mailing lists link on the Exim home page.
483.cindex "Debian" "mailing list for"
4f578862 484If you are using a Debian distribution of Exim, you may wish to subscribe to
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485the Debian-specific mailing list &'pkg-exim4-users@lists.alioth.debian.org'&
486via this web page:
487.display
488&url(http://lists.alioth.debian.org/mailman/listinfo/pkg-exim4-users)
489.endd
490Please ask Debian-specific questions on this list and not on the general Exim
491lists.
9b371988 492
f89d2485 493.section "Exim training" "SECID4"
9b371988 494.cindex "training courses"
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495Training courses in Cambridge (UK) used to be run annually by the author of
496Exim, before he retired. At the time of writing, there are no plans to run
497further Exim courses in Cambridge. However, if that changes, relevant
498information will be posted at &url(http://www-tus.csx.cam.ac.uk/courses/exim/).
168e428f 499
f89d2485 500.section "Bug reports" "SECID5"
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501.cindex "bug reports"
502.cindex "reporting bugs"
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503Reports of obvious bugs &new("can be emailed to &'bugs@exim.org'& or reported
504via the Bugzilla (&url(http://bugs.exim.org)).") However, if you are unsure
505whether some behaviour is a bug or not, the best thing to do is to post a
506message to the &'exim-dev'& mailing list and have it discussed.
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507
508
509
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510.section "Where to find the Exim distribution" "SECTavail"
511.cindex "FTP site"
512.cindex "distribution" "ftp site"
168e428f 513The master ftp site for the Exim distribution is
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514.display
515&*ftp://ftp.csx.cam.ac.uk/pub/software/email/exim*&
516.endd
168e428f 517This is mirrored by
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518.display
519&*ftp://ftp.exim.org/pub/exim*&
520.endd
521The file references that follow are relative to the &_exim_& directories at
522these sites. There are now quite a number of independent mirror sites around
523the world. Those that I know about are listed in the file called &_Mirrors_&.
524
525Within the &_exim_& directory there are subdirectories called &_exim3_& (for
526previous Exim 3 distributions), &_exim4_& (for the latest Exim 4
527distributions), and &_Testing_& for testing versions. In the &_exim4_&
168e428f 528subdirectory, the current release can always be found in files called
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529.display
530&_exim-n.nn.tar.gz_&
531&_exim-n.nn.tar.bz2_&
532.endd
533where &'n.nn'& is the highest such version number in the directory. The two
168e428f 534files contain identical data; the only difference is the type of compression.
9b371988 535The &_.bz2_& file is usually a lot smaller than the &_.gz_& file.
168e428f 536
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537.cindex "distribution" "signing details"
538.cindex "distribution" "public key"
539.cindex "public key for signed distribution"
210f147e 540The distributions are currently signed with Nigel Metheringham's GPG key. The
168e428f 541corresponding public key is available from a number of keyservers, and there is
210f147e 542also a copy in the file &_nigel-pubkey.asc_&. The signatures for the tar bundles are
168e428f 543in:
9b371988 544.display
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545&_exim-n.nn.tar.gz.asc_&
546&_exim-n.nn.tar.bz2.asc_&
9b371988 547.endd
168e428f 548For each released version, the log of changes is made separately available in a
9b371988 549separate file in the directory &_ChangeLogs_& so that it is possible to
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550find out what has changed without having to download the entire distribution.
551
9b371988 552.cindex "documentation" "available formats"
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553The main distribution contains ASCII versions of this specification and other
554documentation; other formats of the documents are available in separate files
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555inside the &_exim4_& directory of the FTP site:
556.display
557&_exim-html-n.nn.tar.gz_&
558&_exim-pdf-n.nn.tar.gz_&
559&_exim-postscript-n.nn.tar.gz_&
560&_exim-texinfo-n.nn.tar.gz_&
561.endd
562These tar files contain only the &_doc_& directory, not the complete
563distribution, and are also available in &_.bz2_& as well as &_.gz_& forms.
168e428f 564
168e428f 565
f89d2485 566.section "Limitations" "SECID6"
9b371988
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567.ilist
568.cindex "limitations of Exim"
569.cindex "bang paths" "not handled by Exim"
570Exim is designed for use as an Internet MTA, and therefore handles addresses in
571RFC 2822 domain format only. It cannot handle UUCP &"bang paths"&, though
572simple two-component bang paths can be converted by a straightforward rewriting
573configuration. This restriction does not prevent Exim from being interfaced to
574UUCP as a transport mechanism, provided that domain addresses are used.
575.next
576.cindex "domainless addresses"
577.cindex "address" "without domain"
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578Exim insists that every address it handles has a domain attached. For incoming
579local messages, domainless addresses are automatically qualified with a
580configured domain value. Configuration options specify from which remote
581systems unqualified addresses are acceptable. These are then qualified on
582arrival.
9b371988
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583.next
584.cindex "transport" "external"
585.cindex "external transports"
586The only external transport mechanisms that are currently implemented are SMTP
587and LMTP over a TCP/IP network (including support for IPv6). However, a pipe
168e428f 588transport is available, and there are facilities for writing messages to files
9b371988
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589and pipes, optionally in &'batched SMTP'& format; these facilities can be used
590to send messages to other transport mechanisms such as UUCP, provided they can
591handle domain-style addresses. Batched SMTP input is also catered for.
592.next
593Exim is not designed for storing mail for dial-in hosts. When the volumes of
594such mail are large, it is better to get the messages &"delivered"& into files
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595(that is, off Exim's queue) and subsequently passed on to the dial-in hosts by
596other means.
9b371988
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597.next
598Although Exim does have basic facilities for scanning incoming messages, these
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599are not comprehensive enough to do full virus or spam scanning. Such operations
600are best carried out using additional specialized software packages. If you
601compile Exim with the content-scanning extension, straightforward interfaces to
602a number of common scanners are provided.
9b371988 603.endlist
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604
605
f89d2485 606.section "Run time configuration" "SECID7"
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607Exim's run time configuration is held in a single text file that is divided
608into a number of sections. The entries in this file consist of keywords and
609values, in the style of Smail 3 configuration files. A default configuration
610file which is suitable for simple online installations is provided in the
9b371988 611distribution, and is described in chapter &<<CHAPdefconfil>>& below.
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612
613
f89d2485 614.section "Calling interface" "SECID8"
9b371988 615.cindex "Sendmail compatibility" "command line interface"
168e428f 616Like many MTAs, Exim has adopted the Sendmail command line interface so that it
9b371988
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617can be a straight replacement for &_/usr/lib/sendmail_& or
618&_/usr/sbin/sendmail_& when sending mail, but you do not need to know anything
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619about Sendmail in order to run Exim. For actions other than sending messages,
620Sendmail-compatible options also exist, but those that produce output (for
9b371988 621example, &%-bp%&, which lists the messages on the queue) do so in Exim's own
168e428f 622format. There are also some additional options that are compatible with Smail
9b371988 6233, and some further options that are new to Exim. Chapter &<<CHAPcommandline>>&
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624documents all Exim's command line options. This information is automatically
625made into the man page that forms part of the Exim distribution.
626
627Control of messages on the queue can be done via certain privileged command
9b371988
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628line options. There is also an optional monitor program called &'eximon'&,
629which displays current information in an X window, and which contains a menu
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630interface to Exim's command line administration options.
631
632
633
f89d2485 634.section "Terminology" "SECID9"
9b371988
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635.cindex "terminology definitions"
636.cindex "body of message" "definition of"
637The &'body'& of a message is the actual data that the sender wants to transmit.
638It is the last part of a message, and is separated from the &'header'& (see
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639below) by a blank line.
640
9b371988 641.cindex "bounce message" "definition of"
168e428f 642When a message cannot be delivered, it is normally returned to the sender in a
9b371988
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643delivery failure message or a &"non-delivery report"& (NDR). The term
644&'bounce'& is commonly used for this action, and the error reports are often
645called &'bounce messages'&. This is a convenient shorthand for &"delivery
646failure error report"&. Such messages have an empty sender address in the
647message's &'envelope'& (see below) to ensure that they cannot themselves give
648rise to further bounce messages.
649
650The term &'default'& appears frequently in this manual. It is used to qualify a
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651value which is used in the absence of any setting in the configuration. It may
652also qualify an action which is taken unless a configuration setting specifies
653otherwise.
654
9b371988 655The term &'defer'& is used when the delivery of a message to a specific
168e428f 656destination cannot immediately take place for some reason (a remote host may be
9b371988 657down, or a user's local mailbox may be full). Such deliveries are &'deferred'&
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658until a later time.
659
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660The word &'domain'& is sometimes used to mean all but the first component of a
661host's name. It is &'not'& used in that sense here, where it normally refers to
662the part of an email address following the @ sign.
168e428f 663
f89d2485 664.cindex "envelope, definition of"
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665.cindex "sender" "definition of"
666A message in transit has an associated &'envelope'&, as well as a header and a
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667body. The envelope contains a sender address (to which bounce messages should
668be delivered), and any number of recipient addresses. References to the
669sender or the recipients of a message usually mean the addresses in the
670envelope. An MTA uses these addresses for delivery, and for returning bounce
671messages, not the addresses that appear in the header lines.
672
f89d2485 673.cindex "message" "header, definition of"
9b371988
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674.cindex "header section" "definition of"
675The &'header'& of a message is the first part of a message's text, consisting
676of a number of lines, each of which has a name such as &'From:'&, &'To:'&,
677&'Subject:'&, etc. Long header lines can be split over several text lines by
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678indenting the continuations. The header is separated from the body by a blank
679line.
680
9b371988
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681.cindex "local part" "definition of"
682.cindex "domain" "definition of"
683The term &'local part'&, which is taken from RFC 2822, is used to refer to that
168e428f 684part of an email address that precedes the @ sign. The part that follows the
9b371988 685@ sign is called the &'domain'& or &'mail domain'&.
168e428f 686
9b371988 687.cindex "local delivery" "definition of"
f89d2485 688.cindex "remote delivery, definition of"
9b371988 689The terms &'local delivery'& and &'remote delivery'& are used to distinguish
168e428f 690delivery to a file or a pipe on the local host from delivery by SMTP over
068aaea8 691TCP/IP to another host. As far as Exim is concerned, all hosts other than the
9b371988 692host it is running on are &'remote'&.
168e428f 693
9b371988
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694.cindex "return path" "definition of"
695&'Return path'& is another name that is used for the sender address in a
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696message's envelope.
697
9b371988
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698.cindex "queue" "definition of"
699The term &'queue'& is used to refer to the set of messages awaiting delivery,
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700because this term is in widespread use in the context of MTAs. However, in
701Exim's case the reality is more like a pool than a queue, because there is
702normally no ordering of waiting messages.
703
9b371988
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704.cindex "queue runner" "definition of"
705The term &'queue runner'& is used to describe a process that scans the queue
168e428f 706and attempts to deliver those messages whose retry times have come. This term
9b371988 707is used by other MTAs, and also relates to the command &%runq%&, but in Exim
168e428f
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708the waiting messages are normally processed in an unpredictable order.
709
9b371988
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710.cindex "spool directory" "definition of"
711The term &'spool directory'& is used for a directory in which Exim keeps the
712messages on its queue &-- that is, those that it is in the process of
168e428f 713delivering. This should not be confused with the directory in which local
9b371988
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714mailboxes are stored, which is called a &"spool directory"& by some people. In
715the Exim documentation, &"spool"& is always used in the first sense.
168e428f
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716
717
718
719
720
721
9b371988
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722. ////////////////////////////////////////////////////////////////////////////
723. ////////////////////////////////////////////////////////////////////////////
168e428f 724
f89d2485 725.chapter "Incorporated code" "CHID2"
9b371988
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726.cindex "incorporated code"
727.cindex "regular expressions" "library"
728.cindex "PCRE"
168e428f
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729A number of pieces of external code are included in the Exim distribution.
730
9b371988 731.ilist
210f147e
NM
732Regular expressions are supported in the main Exim program and in the
733Exim monitor using the freely-distributable PCRE library, copyright
734&copy; University of Cambridge. The source to a cut down version of PCRE
735used to be distributed in the directory &_src/pcre_&. However, this is
736no longer the case and you will need to use a system PCRE library or
737obtain and install the full version of the library from
f89d2485 738&url(ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre).
9b371988 739.next
f89d2485 740.cindex "cdb" "acknowledgment"
168e428f
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741Support for the cdb (Constant DataBase) lookup method is provided by code
742contributed by Nigel Metheringham of (at the time he contributed it) Planet
9b371988
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743Online Ltd. The implementation is completely contained within the code of Exim.
744It does not link against an external cdb library. The code contains the
745following statements:
746
747.blockquote
748Copyright &copy; 1998 Nigel Metheringham, Planet Online Ltd
749
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750This program is free software; you can redistribute it and/or modify it under
751the terms of the GNU General Public License as published by the Free Software
752Foundation; either version 2 of the License, or (at your option) any later
753version.
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754This code implements Dan Bernstein's Constant DataBase (cdb) spec. Information,
755the spec and sample code for cdb can be obtained from
f89d2485
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756&url(http://www.pobox.com/~djb/cdb.html). This implementation borrows
757some code from Dan Bernstein's implementation (which has no license
758restrictions applied to it).
9b371988
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759.endblockquote
760.next
761.cindex "SPA authentication"
762.cindex "Samba project"
763.cindex "Microsoft Secure Password Authentication"
764Client support for Microsoft's &'Secure Password Authentication'& is provided
168e428f
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765by code contributed by Marc Prud'hommeaux. Server support was contributed by
766Tom Kistner. This includes code taken from the Samba project, which is released
767under the Gnu GPL.
9b371988
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768.next
769.cindex "Cyrus"
770.cindex "&'pwcheck'& daemon"
771.cindex "&'pwauthd'& daemon"
772Support for calling the Cyrus &'pwcheck'& and &'saslauthd'& daemons is provided
168e428f
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773by code taken from the Cyrus-SASL library and adapted by Alexander S.
774Sabourenkov. The permission notice appears below, in accordance with the
775conditions expressed therein.
9b371988
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776
777.blockquote
778Copyright &copy; 2001 Carnegie Mellon University. All rights reserved.
779
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780Redistribution and use in source and binary forms, with or without
781modification, are permitted provided that the following conditions
782are met:
168e428f 783
9b371988
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784.olist
785Redistributions of source code must retain the above copyright
786notice, this list of conditions and the following disclaimer.
787.next
788Redistributions in binary form must reproduce the above copyright
168e428f
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789notice, this list of conditions and the following disclaimer in
790the documentation and/or other materials provided with the
791distribution.
9b371988
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792.next
793The name &"Carnegie Mellon University"& must not be used to
168e428f
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794endorse or promote products derived from this software without
795prior written permission. For permission or any other legal
796details, please contact
9b371988 797.display
068aaea8
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798 Office of Technology Transfer
799 Carnegie Mellon University
800 5000 Forbes Avenue
801 Pittsburgh, PA 15213-3890
802 (412) 268-4387, fax: (412) 268-7395
803 tech-transfer@andrew.cmu.edu
9b371988
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804.endd
805.next
806Redistributions of any form whatsoever must retain the following
168e428f 807acknowledgment:
9b371988
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808
809&"This product includes software developed by Computing Services
810at Carnegie Mellon University (&url(http://www.cmu.edu/computing/)."&
811
168e428f
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812CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO
813THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
814AND FITNESS, IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE
815FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
816WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
817AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
818OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
9b371988
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819.endlist
820.endblockquote
168e428f 821
9b371988 822.next
f89d2485 823.cindex "Exim monitor" "acknowledgment"
9b371988
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824.cindex "X-windows"
825.cindex "Athena"
168e428f
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826The Exim Monitor program, which is an X-Window application, includes
827modified versions of the Athena StripChart and TextPop widgets.
828This code is copyright by DEC and MIT, and their permission notice appears
829below, in accordance with the conditions expressed therein.
9b371988
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830
831.blockquote
168e428f
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832Copyright 1987, 1988 by Digital Equipment Corporation, Maynard, Massachusetts,
833and the Massachusetts Institute of Technology, Cambridge, Massachusetts.
9b371988 834
168e428f 835All Rights Reserved
9b371988 836
168e428f
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837Permission to use, copy, modify, and distribute this software and its
838documentation for any purpose and without fee is hereby granted,
839provided that the above copyright notice appear in all copies and that
840both that copyright notice and this permission notice appear in
841supporting documentation, and that the names of Digital or MIT not be
842used in advertising or publicity pertaining to distribution of the
843software without specific, written prior permission.
9b371988 844
168e428f
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845DIGITAL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
846ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
847DIGITAL BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
848ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
849WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
850ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
851SOFTWARE.
9b371988 852.endblockquote
168e428f 853
9b371988
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854.next
855Many people have contributed code fragments, some large, some small, that were
168e428f 856not covered by any specific licence requirements. It is assumed that the
f89d2485 857contributors are happy to see their code incorporated into Exim under the GPL.
9b371988 858.endlist
168e428f
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859
860
861
862
863
9b371988
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864. ////////////////////////////////////////////////////////////////////////////
865. ////////////////////////////////////////////////////////////////////////////
168e428f 866
f89d2485 867.chapter "How Exim receives and delivers mail" "CHID11" &&&
9b371988 868 "Receiving and delivering mail"
168e428f
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869
870
f89d2485 871.section "Overall philosophy" "SECID10"
9b371988 872.cindex "design philosophy"
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873Exim is designed to work efficiently on systems that are permanently connected
874to the Internet and are handling a general mix of mail. In such circumstances,
875most messages can be delivered immediately. Consequently, Exim does not
876maintain independent queues of messages for specific domains or hosts, though
877it does try to send several messages in a single SMTP connection after a host
878has been down, and it also maintains per-host retry information.
879
880
f89d2485 881.section "Policy control" "SECID11"
9b371988 882.cindex "policy control" "overview"
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883Policy controls are now an important feature of MTAs that are connected to the
884Internet. Perhaps their most important job is to stop MTAs being abused as
9b371988
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885&"open relays"& by misguided individuals who send out vast amounts of
886unsolicited junk, and want to disguise its source. Exim provides flexible
887facilities for specifying policy controls on incoming mail:
168e428f 888
9b371988
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889.ilist
890.cindex "&ACL;" "introduction"
168e428f 891Exim 4 (unlike previous versions of Exim) implements policy controls on
9b371988 892incoming mail by means of &'Access Control Lists'& (ACLs). Each list is a
168e428f
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893series of statements that may either grant or deny access. ACLs can be used at
894several places in the SMTP dialogue while receiving a message from a remote
9b371988
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895host. However, the most common places are after each RCPT command, and at the
896very end of the message. The sysadmin can specify conditions for accepting or
897rejecting individual recipients or the entire message, respectively, at these
898two points (see chapter &<<CHAPACL>>&). Denial of access results in an SMTP
168e428f 899error code.
9b371988
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900.next
901An ACL is also available for locally generated, non-SMTP messages. In this
168e428f 902case, the only available actions are to accept or deny the entire message.
9b371988
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903.next
904When Exim is compiled with the content-scanning extension, facilities are
168e428f
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905provided in the ACL mechanism for passing the message to external virus and/or
906spam scanning software. The result of such a scan is passed back to the ACL,
907which can then use it to decide what to do with the message.
9b371988
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908.next
909When a message has been received, either from a remote host or from the local
f89d2485 910host, but before the final acknowledgment has been sent, a locally supplied C
9b371988
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911function called &[local_scan()]& can be run to inspect the message and decide
912whether to accept it or not (see chapter &<<CHAPlocalscan>>&). If the message
913is accepted, the list of recipients can be modified by the function.
914.next
915Using the &[local_scan()]& mechanism is another way of calling external scanner
916software. The &%SA-Exim%& add-on package works this way. It does not require
917Exim to be compiled with the content-scanning extension.
918.next
919After a message has been accepted, a further checking mechanism is available in
920the form of the &'system filter'& (see chapter &<<CHAPsystemfilter>>&). This
921runs at the start of every delivery process.
922.endlist
923
924
925
f89d2485 926.section "User filters" "SECID12"
9b371988
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927.cindex "filter" "introduction"
928.cindex "Sieve filter"
168e428f 929In a conventional Exim configuration, users are able to run private filters by
9b371988
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930setting up appropriate &_.forward_& files in their home directories. See
931chapter &<<CHAPredirect>>& (about the &(redirect)& router) for the
932configuration needed to support this, and the separate document entitled
933&'Exim's interfaces to mail filtering'& for user details. Two different kinds
934of filtering are available:
935
936.ilist
937Sieve filters are written in the standard filtering language that is defined
168e428f 938by RFC 3028.
9b371988
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939.next
940Exim filters are written in a syntax that is unique to Exim, but which is more
168e428f 941powerful than Sieve, which it pre-dates.
9b371988 942.endlist
168e428f
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943
944User filters are run as part of the routing process, described below.
945
946
947
9b371988
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948.section "Message identification" "SECTmessiden"
949.cindex "message ids" "details of format"
950.cindex "format" "of message id"
951.cindex "id of message"
952.cindex "base62"
953.cindex "base36"
954.cindex "Darwin"
955.cindex "Cygwin"
956Every message handled by Exim is given a &'message id'& which is sixteen
168e428f 957characters long. It is divided into three parts, separated by hyphens, for
9b371988 958example &`16VDhn-0001bo-D3`&. Each part is a sequence of letters and digits,
168e428f
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959normally encoding numbers in base 62. However, in the Darwin operating
960system (Mac OS X) and when Exim is compiled to run under Cygwin, base 36
961(avoiding the use of lower case letters) is used instead, because the message
962id is used to construct file names, and the names of files in those systems are
068aaea8 963not always case-sensitive.
168e428f 964
9b371988 965.cindex "pid (process id)" "re-use of"
168e428f
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966The detail of the contents of the message id have changed as Exim has evolved.
967Earlier versions relied on the operating system not re-using a process id (pid)
968within one second. On modern operating systems, this assumption can no longer
969be made, so the algorithm had to be changed. To retain backward compatibility,
970the format of the message id was retained, which is why the following rules are
971somewhat eccentric:
972
9b371988
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973.ilist
974The first six characters of the message id are the time at which the message
168e428f
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975started to be received, to a granularity of one second. That is, this field
976contains the number of seconds since the start of the epoch (the normal Unix
977way of representing the date and time of day).
9b371988
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978.next
979After the first hyphen, the next six characters are the id of the process that
168e428f 980received the message.
9b371988
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981.next
982There are two different possibilities for the final two characters:
983.olist
0a4e3112 984.oindex "&%localhost_number%&"
9b371988 985If &%localhost_number%& is not set, this value is the fractional part of the
168e428f
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986time of reception, normally in units of 1/2000 of a second, but for systems
987that must use base 36 instead of base 62 (because of case-insensitive file
988systems), the units are 1/1000 of a second.
9b371988
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989.next
990If &%localhost_number%& is set, it is multiplied by 200 (100) and added to
168e428f
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991the fractional part of the time, which in this case is in units of 1/200
992(1/100) of a second.
9b371988
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993.endlist
994.endlist
168e428f
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995
996After a message has been received, Exim waits for the clock to tick at the
997appropriate resolution before proceeding, so that if another message is
998received by the same process, or by another process with the same (re-used)
999pid, it is guaranteed that the time will be different. In most cases, the clock
1000will already have ticked while the message was being received.
1001
1002
f89d2485 1003.section "Receiving mail" "SECID13"
9b371988
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1004.cindex "receiving mail"
1005.cindex "message" "reception"
068aaea8
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1006The only way Exim can receive mail from another host is using SMTP over
1007TCP/IP, in which case the sender and recipient addresses are transferred using
168e428f
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1008SMTP commands. However, from a locally running process (such as a user's MUA),
1009there are several possibilities:
1010
9b371988
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1011.ilist
1012If the process runs Exim with the &%-bm%& option, the message is read
168e428f 1013non-interactively (usually via a pipe), with the recipients taken from the
9b371988
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1014command line, or from the body of the message if &%-t%& is also used.
1015.next
1016If the process runs Exim with the &%-bS%& option, the message is also read
168e428f
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1017non-interactively, but in this case the recipients are listed at the start of
1018the message in a series of SMTP RCPT commands, terminated by a DATA
9b371988 1019command. This is so-called &"batch SMTP"& format,
168e428f
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1020but it isn't really SMTP. The SMTP commands are just another way of passing
1021envelope addresses in a non-interactive submission.
9b371988
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1022.next
1023If the process runs Exim with the &%-bs%& option, the message is read
168e428f
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1024interactively, using the SMTP protocol. A two-way pipe is normally used for
1025passing data between the local process and the Exim process.
9b371988 1026This is &"real"& SMTP and is handled in the same way as SMTP over TCP/IP. For
168e428f 1027example, the ACLs for SMTP commands are used for this form of submission.
9b371988
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1028.next
1029A local process may also make a TCP/IP call to the host's loopback address
168e428f
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1030(127.0.0.1) or any other of its IP addresses. When receiving messages, Exim
1031does not treat the loopback address specially. It treats all such connections
1032in the same way as connections from other hosts.
9b371988 1033.endlist
168e428f
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1034
1035
f89d2485 1036.cindex "message sender, constructed by Exim"
9b371988 1037.cindex "sender" "constructed by Exim"
168e428f
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1038In the three cases that do not involve TCP/IP, the sender address is
1039constructed from the login name of the user that called Exim and a default
9b371988 1040qualification domain (which can be set by the &%qualify_domain%& configuration
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1041option). For local or batch SMTP, a sender address that is passed using the
1042SMTP MAIL command is ignored. However, the system administrator may allow
9b371988 1043certain users (&"trusted users"&) to specify a different sender address
168e428f 1044unconditionally, or all users to specify certain forms of different sender
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1045address. The &%-f%& option or the SMTP MAIL command is used to specify these
1046different addresses. See section &<<SECTtrustedadmin>>& for details of trusted
1047users, and the &%untrusted_set_sender%& option for a way of allowing untrusted
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1048users to change sender addresses.
1049
1050Messages received by either of the non-interactive mechanisms are subject to
1051checking by the non-SMTP ACL, if one is defined. Messages received using SMTP
1052(either over TCP/IP, or interacting with a local process) can be checked by a
1053number of ACLs that operate at different times during the SMTP session. Either
1054individual recipients, or the entire message, can be rejected if local policy
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1055requirements are not met. The &[local_scan()]& function (see chapter
1056&<<CHAPlocalscan>>&) is run for all incoming messages.
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1057
1058Exim can be configured not to start a delivery process when a message is
1059received; this can be unconditional, or depend on the number of incoming SMTP
1060connections or the system load. In these situations, new messages wait on the
1061queue until a queue runner process picks them up. However, in standard
1062configurations under normal conditions, delivery is started as soon as a
1063message is received.
1064
1065
1066
1067
1068
f89d2485 1069.section "Handling an incoming message" "SECID14"
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1070.cindex "spool directory" "files that hold a message"
1071.cindex "file" "how a message is held"
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1072When Exim accepts a message, it writes two files in its spool directory. The
1073first contains the envelope information, the current status of the message, and
1074the header lines, and the second contains the body of the message. The names of
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1075the two spool files consist of the message id, followed by &`-H`& for the
1076file containing the envelope and header, and &`-D`& for the data file.
168e428f 1077
9b371988 1078.cindex "spool directory" "&_input_& sub-directory"
168e428f 1079By default all these message files are held in a single directory called
9b371988 1080&_input_& inside the general Exim spool directory. Some operating systems do
c0712871 1081not perform very well if the number of files in a directory gets large; to
9b371988 1082improve performance in such cases, the &%split_spool_directory%& option can be
168e428f 1083used. This causes Exim to split up the input files into 62 sub-directories
db9452a9 1084whose names are single letters or digits. When this is done, the queue is
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1085processed one sub-directory at a time instead of all at once, which can improve
1086overall performance even when there are not enough files in each directory to
db9452a9 1087affect file system performance.
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1088
1089The envelope information consists of the address of the message's sender and
1090the addresses of the recipients. This information is entirely separate from
1091any addresses contained in the header lines. The status of the message includes
1092a list of recipients who have already received the message. The format of the
9b371988 1093first spool file is described in chapter &<<CHAPspool>>&.
168e428f 1094
9b371988 1095.cindex "rewriting" "addresses"
168e428f 1096Address rewriting that is specified in the rewrite section of the configuration
9b371988 1097(see chapter &<<CHAPrewrite>>&) is done once and for all on incoming addresses,
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1098both in the header lines and the envelope, at the time the message is accepted.
1099If during the course of delivery additional addresses are generated (for
1100example, via aliasing), these new addresses are rewritten as soon as they are
1101generated. At the time a message is actually delivered (transported) further
1102rewriting can take place; because this is a transport option, it can be
1103different for different forms of delivery. It is also possible to specify the
1104addition or removal of certain header lines at the time the message is
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1105delivered (see chapters &<<CHAProutergeneric>>& and
1106&<<CHAPtransportgeneric>>&).
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1107
1108
1109
f89d2485 1110.section "Life of a message" "SECID15"
9b371988
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1111.cindex "message" "life of"
1112.cindex "message" "frozen"
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1113A message remains in the spool directory until it is completely delivered to
1114its recipients or to an error address, or until it is deleted by an
1115administrator or by the user who originally created it. In cases when delivery
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1116cannot proceed &-- for example, when a message can neither be delivered to its
1117recipients nor returned to its sender, the message is marked &"frozen"& on the
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1118spool, and no more deliveries are attempted.
1119
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1120.cindex "frozen messages" "thawing"
1121.cindex "message" "thawing frozen"
1122An administrator can &"thaw"& such messages when the problem has been
1123corrected, and can also freeze individual messages by hand if necessary. In
1124addition, an administrator can force a delivery error, causing a bounce message
1125to be sent.
1126
0a4e3112
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1127.oindex "&%timeout_frozen_after%&"
1128.oindex "&%ignore_bounce_errors_after%&"
9b371988
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1129There are options called &%ignore_bounce_errors_after%& and
1130&%timeout_frozen_after%&, which discard frozen messages after a certain time.
068aaea8 1131The first applies only to frozen bounces, the second to any frozen messages.
168e428f 1132
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1133.cindex "message" "log file for"
1134.cindex "log" "file for each message"
168e428f 1135While Exim is working on a message, it writes information about each delivery
068aaea8 1136attempt to its main log file. This includes successful, unsuccessful, and
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1137delayed deliveries for each recipient (see chapter &<<CHAPlog>>&). The log
1138lines are also written to a separate &'message log'& file for each message.
1139These logs are solely for the benefit of the administrator, and are normally
1140deleted along with the spool files when processing of a message is complete.
168e428f 1141The use of individual message logs can be disabled by setting
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1142&%no_message_logs%&; this might give an improvement in performance on very busy
1143systems.
168e428f 1144
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1145.cindex "journal file"
1146.cindex "file" "journal"
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1147All the information Exim itself needs to set up a delivery is kept in the first
1148spool file, along with the header lines. When a successful delivery occurs, the
1149address is immediately written at the end of a journal file, whose name is the
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1150message id followed by &`-J`&. At the end of a delivery run, if there are some
1151addresses left to be tried again later, the first spool file (the &`-H`& file)
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1152is updated to indicate which these are, and the journal file is then deleted.
1153Updating the spool file is done by writing a new file and renaming it, to
1154minimize the possibility of data loss.
1155
1156Should the system or the program crash after a successful delivery but before
1157the spool file has been updated, the journal is left lying around. The next
1158time Exim attempts to deliver the message, it reads the journal file and
1159updates the spool file before proceeding. This minimizes the chances of double
1160deliveries caused by crashes.
1161
1162
1163
9b371988
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1164.section "Processing an address for delivery" "SECTprocaddress"
1165.cindex "drivers" "definition of"
1166.cindex "router" "definition of"
1167.cindex "transport" "definition of"
1168The main delivery processing elements of Exim are called &'routers'& and
1169&'transports'&, and collectively these are known as &'drivers'&. Code for a
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1170number of them is provided in the source distribution, and compile-time options
1171specify which ones are included in the binary. Run time options specify which
1172ones are actually used for delivering messages.
1173
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1174.cindex "drivers" "instance definition"
1175Each driver that is specified in the run time configuration is an &'instance'&
168e428f 1176of that particular driver type. Multiple instances are allowed; for example,
9b371988 1177you can set up several different &(smtp)& transports, each with different
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1178option values that might specify different ports or different timeouts. Each
1179instance has its own identifying name. In what follows we will normally use the
1180instance name when discussing one particular instance (that is, one specific
1181configuration of the driver), and the generic driver name when discussing
1182the driver's features in general.
1183
9b371988 1184A &'router'& is a driver that operates on an address, either determining how
068aaea8 1185its delivery should happen, by assigning it to a specific transport, or
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1186converting the address into one or more new addresses (for example, via an
1187alias file). A router may also explicitly choose to fail an address, causing it
1188to be bounced.
1189
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1190A &'transport'& is a driver that transmits a copy of the message from Exim's
1191spool to some destination. There are two kinds of transport: for a &'local'&
168e428f 1192transport, the destination is a file or a pipe on the local host, whereas for a
9b371988 1193&'remote'& transport the destination is some other host. A message is passed
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1194to a specific transport as a result of successful routing. If a message has
1195several recipients, it may be passed to a number of different transports.
1196
9b371988 1197.cindex "preconditions" "definition of"
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1198An address is processed by passing it to each configured router instance in
1199turn, subject to certain preconditions, until a router accepts the address or
1200specifies that it should be bounced. We will describe this process in more
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1201detail shortly. First, as a simple example, we consider how each recipient
1202address in a message is processed in a small configuration of three routers.
168e428f 1203
068aaea8 1204To make this a more concrete example, it is described in terms of some actual
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1205routers, but remember, this is only an example. You can configure Exim's
1206routers in many different ways, and there may be any number of routers in a
1207configuration.
1208
1209The first router that is specified in a configuration is often one that handles
1210addresses in domains that are not recognized specially by the local host. These
1211are typically addresses for arbitrary domains on the Internet. A precondition
1212is set up which looks for the special domains known to the host (for example,
9b371988 1213its own domain name), and the router is run for addresses that do &'not'&
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1214match. Typically, this is a router that looks up domains in the DNS in order to
1215find the hosts to which this address routes. If it succeeds, the address is
068aaea8 1216assigned to a suitable SMTP transport; if it does not succeed, the router is
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1217configured to fail the address.
1218
068aaea8 1219The second router is reached only when the domain is recognized as one that
9b371988 1220&"belongs"& to the local host. This router does redirection &-- also known as
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1221aliasing and forwarding. When it generates one or more new addresses from the
1222original, each of them is routed independently from the start. Otherwise, the
1223router may cause an address to fail, or it may simply decline to handle the
1224address, in which case the address is passed to the next router.
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1225
1226The final router in many configurations is one that checks to see if the
1227address belongs to a local mailbox. The precondition may involve a check to
1228see if the local part is the name of a login account, or it may look up the
1229local part in a file or a database. If its preconditions are not met, or if
1230the router declines, we have reached the end of the routers. When this happens,
1231the address is bounced.
1232
1233
1234
f89d2485 1235.section "Processing an address for verification" "SECID16"
9b371988
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1236.cindex "router" "for verification"
1237.cindex "verifying address" "overview"
168e428f 1238As well as being used to decide how to deliver to an address, Exim's routers
9b371988 1239are also used for &'address verification'&. Verification can be requested as
168e428f 1240one of the checks to be performed in an ACL for incoming messages, on both
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1241sender and recipient addresses, and it can be tested using the &%-bv%& and
1242&%-bvs%& command line options.
168e428f 1243
9b371988 1244When an address is being verified, the routers are run in &"verify mode"&. This
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1245does not affect the way the routers work, but it is a state that can be
1246detected. By this means, a router can be skipped or made to behave differently
1247when verifying. A common example is a configuration in which the first router
1248sends all messages to a message-scanning program, unless they have been
1249previously scanned. Thus, the first router accepts all addresses without any
9b371988 1250checking, making it useless for verifying. Normally, the &%no_verify%& option
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1251would be set for such a router, causing it to be skipped in verify mode.
1252
1253
1254
1255
9b371988
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1256.section "Running an individual router" "SECTrunindrou"
1257.cindex "router" "running details"
1258.cindex "preconditions" "checking"
1259.cindex "router" "result of running"
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1260As explained in the example above, a number of preconditions are checked before
1261running a router. If any are not met, the router is skipped, and the address is
9b371988 1262passed to the next router. When all the preconditions on a router &'are'& met,
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1263the router is run. What happens next depends on the outcome, which is one of
1264the following:
1265
9b371988
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1266.ilist
1267&'accept'&: The router accepts the address, and either assigns it to a
1268transport, or generates one or more &"child"& addresses. Processing the
1269original address ceases,
0a4e3112 1270.oindex "&%unseen%&"
9b371988 1271unless the &%unseen%& option is set on the router. This option
168e428f 1272can be used to set up multiple deliveries with different routing (for example,
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1273for keeping archive copies of messages). When &%unseen%& is set, the address is
1274passed to the next router. Normally, however, an &'accept'& return marks the
168e428f 1275end of routing.
9b371988 1276
068aaea8
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1277Any child addresses generated by the router are processed independently,
1278starting with the first router by default. It is possible to change this by
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1279setting the &%redirect_router%& option to specify which router to start at for
1280child addresses. Unlike &%pass_router%& (see below) the router specified by
1281&%redirect_router%& may be anywhere in the router configuration.
1282.next
1283&'pass'&: The router recognizes the address, but cannot handle it itself. It
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1284requests that the address be passed to another router. By default the address
1285is passed to the next router, but this can be changed by setting the
9b371988 1286&%pass_router%& option. However, (unlike &%redirect_router%&) the named router
168e428f 1287must be below the current router (to avoid loops).
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1288.next
1289&'decline'&: The router declines to accept the address because it does not
168e428f 1290recognize it at all. By default, the address is passed to the next router, but
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1291this can be prevented by setting the &%no_more%& option. When &%no_more%& is
1292set, all the remaining routers are skipped. In effect, &%no_more%& converts
1293&'decline'& into &'fail'&.
1294.next
1295&'fail'&: The router determines that the address should fail, and queues it for
168e428f 1296the generation of a bounce message. There is no further processing of the
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1297original address unless &%unseen%& is set on the router.
1298.next
1299&'defer'&: The router cannot handle the address at the present time. (A
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1300database may be offline, or a DNS lookup may have timed out.) No further
1301processing of the address happens in this delivery attempt. It is tried again
1302next time the message is considered for delivery.
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1303.next
1304&'error'&: There is some error in the router (for example, a syntax error in
168e428f 1305its configuration). The action is as for defer.
9b371988 1306.endlist
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1307
1308If an address reaches the end of the routers without having been accepted by
068aaea8 1309any of them, it is bounced as unrouteable. The default error message in this
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1310situation is &"unrouteable address"&, but you can set your own message by
1311making use of the &%cannot_route_message%& option. This can be set for any
1312router; the value from the last router that &"saw"& the address is used.
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1313
1314Sometimes while routing you want to fail a delivery when some conditions are
1315met but others are not, instead of passing the address on for further routing.
1316You can do this by having a second router that explicitly fails the delivery
9b371988 1317when the relevant conditions are met. The &(redirect)& router has a &"fail"&
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1318facility for this purpose.
1319
1320
f89d2485 1321.section "Duplicate addresses" "SECID17"
9b371988 1322.cindex "case of local parts"
f89d2485 1323.cindex "address duplicate, discarding"
db9452a9 1324.cindex "duplicate addresses"
068aaea8
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1325Once routing is complete, Exim scans the addresses that are assigned to local
1326and remote transports, and discards any duplicates that it finds. During this
3cb1b51e 1327check, local parts are treated as case-sensitive. This happens only when
db9452a9 1328actually delivering a message; when testing routers with &%-bt%&, all the
3cb1b51e 1329routed addresses are shown.
db9452a9 1330
068aaea8 1331
168e428f 1332
9b371988 1333.section "Router preconditions" "SECTrouprecon"
f89d2485 1334.cindex "router" "preconditions, order of processing"
9b371988 1335.cindex "preconditions" "order of processing"
168e428f
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1336The preconditions that are tested for each router are listed below, in the
1337order in which they are tested. The individual configuration options are
9b371988 1338described in more detail in chapter &<<CHAProutergeneric>>&.
168e428f 1339
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1340.ilist
1341The &%local_part_prefix%& and &%local_part_suffix%& options can specify that
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1342the local parts handled by the router may or must have certain prefixes and/or
1343suffixes. If a mandatory affix (prefix or suffix) is not present, the router is
1344skipped. These conditions are tested first. When an affix is present, it is
1345removed from the local part before further processing, including the evaluation
1346of any other conditions.
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1347.next
1348Routers can be designated for use only when not verifying an address, that is,
168e428f 1349only when routing it for delivery (or testing its delivery routing). If the
9b371988 1350&%verify%& option is set false, the router is skipped when Exim is verifying an
168e428f 1351address.
9b371988
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1352Setting the &%verify%& option actually sets two options, &%verify_sender%& and
1353&%verify_recipient%&, which independently control the use of the router for
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1354sender and recipient verification. You can set these options directly if
1355you want a router to be used for only one type of verification.
9b371988
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1356.next
1357If the &%address_test%& option is set false, the router is skipped when Exim is
1358run with the &%-bt%& option to test an address routing. This can be helpful
1359when the first router sends all new messages to a scanner of some sort; it
1360makes it possible to use &%-bt%& to test subsequent delivery routing without
1361having to simulate the effect of the scanner.
1362.next
1363Routers can be designated for use only when verifying an address, as
1364opposed to routing it for delivery. The &%verify_only%& option controls this.
1365.next
1366Individual routers can be explicitly skipped when running the routers to
1367check an address given in the SMTP EXPN command (see the &%expn%& option).
1368.next
1369If the &%domains%& option is set, the domain of the address must be in the set
068aaea8 1370of domains that it defines.
9b371988 1371.next
f89d2485
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1372.vindex "&$local_part_prefix$&"
1373.vindex "&$local_part$&"
1374.vindex "&$local_part_suffix$&"
9b371988
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1375If the &%local_parts%& option is set, the local part of the address must be in
1376the set of local parts that it defines. If &%local_part_prefix%& or
1377&%local_part_suffix%& is in use, the prefix or suffix is removed from the local
168e428f 1378part before this check. If you want to do precondition tests on local parts
9b371988
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1379that include affixes, you can do so by using a &%condition%& option (see below)
1380that uses the variables &$local_part$&, &$local_part_prefix$&, and
1381&$local_part_suffix$& as necessary.
1382.next
f89d2485
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1383.vindex "&$local_user_uid$&"
1384.vindex "&$local_user_gid$&"
1385.vindex "&$home$&"
9b371988 1386If the &%check_local_user%& option is set, the local part must be the name of
068aaea8 1387an account on the local host. If this check succeeds, the uid and gid of the
9b371988
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1388local user are placed in &$local_user_uid$& and &$local_user_gid$& and the
1389user's home directory is placed in &$home$&; these values can be used in the
1390remaining preconditions.
1391.next
1392If the &%router_home_directory%& option is set, it is expanded at this point,
1393because it overrides the value of &$home$&. If this expansion were left till
1394later, the value of &$home$& as set by &%check_local_user%& would be used in
1395subsequent tests. Having two different values of &$home$& in the same router
168e428f 1396could lead to confusion.
9b371988
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1397.next
1398If the &%senders%& option is set, the envelope sender address must be in the
1399set of addresses that it defines.
1400.next
1401If the &%require_files%& option is set, the existence or non-existence of
168e428f 1402specified files is tested.
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1403.next
1404.cindex "customizing" "precondition"
1405If the &%condition%& option is set, it is evaluated and tested. This option
1406uses an expanded string to allow you to set up your own custom preconditions.
1407Expanded strings are described in chapter &<<CHAPexpand>>&.
1408.endlist
168e428f 1409
168e428f 1410
9b371988
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1411Note that &%require_files%& comes near the end of the list, so you cannot use
1412it to check for the existence of a file in which to lookup up a domain, local
168e428f 1413part, or sender. However, as these options are all expanded, you can use the
9b371988
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1414&%exists%& expansion condition to make such tests within each condition. The
1415&%require_files%& option is intended for checking files that the router may be
168e428f 1416going to use internally, or which are needed by a specific transport (for
9b371988 1417example, &_.procmailrc_&).
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1418
1419
1420
f89d2485 1421.section "Delivery in detail" "SECID18"
9b371988 1422.cindex "delivery" "in detail"
168e428f
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1423When a message is to be delivered, the sequence of events is as follows:
1424
9b371988
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1425.ilist
1426If a system-wide filter file is specified, the message is passed to it. The
168e428f
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1427filter may add recipients to the message, replace the recipients, discard the
1428message, cause a new message to be generated, or cause the message delivery to
1429fail. The format of the system filter file is the same as for Exim user filter
9b371988
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1430files, described in the separate document entitled &'Exim's interfaces to mail
1431filtering'&.
1432.cindex "Sieve filter" "not available for system filter"
1433(&*Note*&: Sieve cannot be used for system filter files.)
1434
1435Some additional features are available in system filters &-- see chapter
1436&<<CHAPsystemfilter>>& for details. Note that a message is passed to the system
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1437filter only once per delivery attempt, however many recipients it has. However,
1438if there are several delivery attempts because one or more addresses could not
1439be immediately delivered, the system filter is run each time. The filter
9b371988 1440condition &%first_delivery%& can be used to detect the first run of the system
168e428f 1441filter.
9b371988
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1442.next
1443Each recipient address is offered to each configured router in turn, subject to
1444its preconditions, until one is able to handle it. If no router can handle the
1445address, that is, if they all decline, the address is failed. Because routers
1446can be targeted at particular domains, several locally handled domains can be
1447processed entirely independently of each other.
1448.next
1449.cindex "routing" "loops in"
1450.cindex "loop" "while routing"
1451A router that accepts an address may assign it to a local or a remote
1452transport. However, the transport is not run at this time. Instead, the address
1453is placed on a list for the particular transport, which will be run later.
068aaea8
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1454Alternatively, the router may generate one or more new addresses (typically
1455from alias, forward, or filter files). New addresses are fed back into this
1456process from the top, but in order to avoid loops, a router ignores any address
1457which has an identically-named ancestor that was processed by itself.
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1458.next
1459When all the routing has been done, addresses that have been successfully
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1460handled are passed to their assigned transports. When local transports are
1461doing real local deliveries, they handle only one address at a time, but if a
1462local transport is being used as a pseudo-remote transport (for example, to
1463collect batched SMTP messages for transmission by some other means) multiple
1464addresses can be handled. Remote transports can always handle more than one
1465address at a time, but can be configured not to do so, or to restrict multiple
1466addresses to the same domain.
9b371988
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1467.next
1468Each local delivery to a file or a pipe runs in a separate process under a
168e428f
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1469non-privileged uid, and these deliveries are run one at a time. Remote
1470deliveries also run in separate processes, normally under a uid that is private
9b371988 1471to Exim (&"the Exim user"&), but in this case, several remote deliveries can be
168e428f 1472run in parallel. The maximum number of simultaneous remote deliveries for any
9b371988 1473one message is set by the &%remote_max_parallel%& option.
168e428f
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1474The order in which deliveries are done is not defined, except that all local
1475deliveries happen before any remote deliveries.
9b371988
PH
1476.next
1477.cindex "queue runner"
168e428f
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1478When it encounters a local delivery during a queue run, Exim checks its retry
1479database to see if there has been a previous temporary delivery failure for the
1480address before running the local transport. If there was a previous failure,
1481Exim does not attempt a new delivery until the retry time for the address is
1482reached. However, this happens only for delivery attempts that are part of a
1483queue run. Local deliveries are always attempted when delivery immediately
1484follows message reception, even if retry times are set for them. This makes for
1485better behaviour if one particular message is causing problems (for example,
1486causing quota overflow, or provoking an error in a filter file).
9b371988
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1487.next
1488.cindex "delivery" "retry in remote transports"
168e428f
PH
1489Remote transports do their own retry handling, since an address may be
1490deliverable to one of a number of hosts, each of which may have a different
1491retry time. If there have been previous temporary failures and no host has
1492reached its retry time, no delivery is attempted, whether in a queue run or
9b371988
PH
1493not. See chapter &<<CHAPretry>>& for details of retry strategies.
1494.next
1495If there were any permanent errors, a bounce message is returned to an
168e428f
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1496appropriate address (the sender in the common case), with details of the error
1497for each failing address. Exim can be configured to send copies of bounce
1498messages to other addresses.
9b371988
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1499.next
1500.cindex "delivery" "deferral"
168e428f
PH
1501If one or more addresses suffered a temporary failure, the message is left on
1502the queue, to be tried again later. Delivery of these addresses is said to be
9b371988
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1503&'deferred'&.
1504.next
1505When all the recipient addresses have either been delivered or bounced,
168e428f
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1506handling of the message is complete. The spool files and message log are
1507deleted, though the message log can optionally be preserved if required.
9b371988 1508.endlist
168e428f
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1509
1510
1511
1512
f89d2485 1513.section "Retry mechanism" "SECID19"
9b371988
PH
1514.cindex "delivery" "retry mechanism"
1515.cindex "retry" "description of mechanism"
1516.cindex "queue runner"
168e428f
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1517Exim's mechanism for retrying messages that fail to get delivered at the first
1518attempt is the queue runner process. You must either run an Exim daemon that
9b371988
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1519uses the &%-q%& option with a time interval to start queue runners at regular
1520intervals, or use some other means (such as &'cron'&) to start them. If you do
168e428f
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1521not arrange for queue runners to be run, messages that fail temporarily at the
1522first attempt will remain on your queue for ever. A queue runner process works
068aaea8 1523its way through the queue, one message at a time, trying each delivery that has
168e428f
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1524passed its retry time.
1525You can run several queue runners at once.
1526
1527Exim uses a set of configured rules to determine when next to retry the failing
9b371988
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1528address (see chapter &<<CHAPretry>>&). These rules also specify when Exim
1529should give up trying to deliver to the address, at which point it generates a
1530bounce message. If no retry rules are set for a particular host, address, and
1531error combination, no retries are attempted, and temporary errors are treated
1532as permanent.
168e428f
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1533
1534
1535
f89d2485 1536.section "Temporary delivery failure" "SECID20"
9b371988 1537.cindex "delivery" "temporary failure"
168e428f
PH
1538There are many reasons why a message may not be immediately deliverable to a
1539particular address. Failure to connect to a remote machine (because it, or the
1540connection to it, is down) is one of the most common. Temporary failures may be
1541detected during routing as well as during the transport stage of delivery.
1542Local deliveries may be delayed if NFS files are unavailable, or if a mailbox
1543is on a file system where the user is over quota. Exim can be configured to
1544impose its own quotas on local mailboxes; where system quotas are set they will
1545also apply.
1546
1547If a host is unreachable for a period of time, a number of messages may be
1548waiting for it by the time it recovers, and sending them in a single SMTP
1549connection is clearly beneficial. Whenever a delivery to a remote host is
1550deferred,
1551
9b371988 1552.cindex "hints database"
168e428f
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1553Exim makes a note in its hints database, and whenever a successful
1554SMTP delivery has happened, it looks to see if any other messages are waiting
1555for the same host. If any are found, they are sent over the same SMTP
1556connection, subject to a configuration limit as to the maximum number in any
1557one connection.
1558
1559
1560
1561
f89d2485 1562.section "Permanent delivery failure" "SECID21"
9b371988
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1563.cindex "delivery" "permanent failure"
1564.cindex "bounce message" "when generated"
168e428f
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1565When a message cannot be delivered to some or all of its intended recipients, a
1566bounce message is generated. Temporary delivery failures turn into permanent
1567errors when their timeout expires. All the addresses that fail in a given
1568delivery attempt are listed in a single message. If the original message has
1569many recipients, it is possible for some addresses to fail in one delivery
1570attempt and others to fail subsequently, giving rise to more than one bounce
1571message. The wording of bounce messages can be customized by the administrator.
9b371988 1572See chapter &<<CHAPemsgcust>>& for details.
168e428f 1573
9b371988
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1574.cindex "&'X-Failed-Recipients:'& header line"
1575Bounce messages contain an &'X-Failed-Recipients:'& header line that lists the
168e428f
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1576failed addresses, for the benefit of programs that try to analyse such messages
1577automatically.
1578
9b371988 1579.cindex "bounce message" "recipient of"
168e428f
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1580A bounce message is normally sent to the sender of the original message, as
1581obtained from the message's envelope. For incoming SMTP messages, this is the
9b371988
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1582address given in the MAIL command. However, when an address is expanded via a
1583forward or alias file, an alternative address can be specified for delivery
1584failures of the generated addresses. For a mailing list expansion (see section
1585&<<SECTmailinglists>>&) it is common to direct bounce messages to the manager
1586of the list.
168e428f
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1587
1588
1589
f89d2485 1590.section "Failures to deliver bounce messages" "SECID22"
9b371988 1591.cindex "bounce message" "failure to deliver"
168e428f
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1592If a bounce message (either locally generated or received from a remote host)
1593itself suffers a permanent delivery failure, the message is left on the queue,
1594but it is frozen, awaiting the attention of an administrator. There are options
068aaea8 1595that can be used to make Exim discard such failed messages, or to keep them
9b371988
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1596for only a short time (see &%timeout_frozen_after%& and
1597&%ignore_bounce_errors_after%&).
168e428f
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1598
1599
1600
1601
1602
9b371988
PH
1603. ////////////////////////////////////////////////////////////////////////////
1604. ////////////////////////////////////////////////////////////////////////////
168e428f 1605
f89d2485 1606.chapter "Building and installing Exim" "CHID3"
4f578862 1607.scindex IIDbuex "building Exim"
168e428f 1608
f89d2485
PH
1609.section "Unpacking" "SECID23"
1610Exim is distributed as a gzipped or bzipped tar file which, when unpacked,
168e428f 1611creates a directory with the name of the current release (for example,
9b371988
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1612&_exim-&version;_&) into which the following files are placed:
1613
1614.table2 140pt
f89d2485
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1615.irow &_ACKNOWLEDGMENTS_& "contains some acknowledgments"
1616.irow &_CHANGES_& "contains a reference to where changes are &&&
1617 documented"
1618.irow &_LICENCE_& "the GNU General Public Licence"
1619.irow &_Makefile_& "top-level make file"
1620.irow &_NOTICE_& "conditions for the use of Exim"
1621.irow &_README_& "list of files, directories and simple build &&&
1622 instructions"
9b371988
PH
1623.endtable
1624
1625Other files whose names begin with &_README_& may also be present. The
168e428f
PH
1626following subdirectories are created:
1627
9b371988 1628.table2 140pt
f89d2485
PH
1629.irow &_Local_& "an empty directory for local configuration files"
1630.irow &_OS_& "OS-specific files"
1631.irow &_doc_& "documentation files"
1632.irow &_exim_monitor_& "source files for the Exim monitor"
1633.irow &_scripts_& "scripts used in the build process"
1634.irow &_src_& "remaining source files"
1635.irow &_util_& "independent utilities"
9b371988
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1636.endtable
1637
1638The main utility programs are contained in the &_src_& directory, and are built
1639with the Exim binary. The &_util_& directory contains a few optional scripts
168e428f
PH
1640that may be useful to some sites.
1641
1642
f89d2485 1643.section "Multiple machine architectures and operating systems" "SECID24"
9b371988 1644.cindex "building Exim" "multiple OS/architectures"
168e428f
PH
1645The building process for Exim is arranged to make it easy to build binaries for
1646a number of different architectures and operating systems from the same set of
9b371988
PH
1647source files. Compilation does not take place in the &_src_& directory.
1648Instead, a &'build directory'& is created for each architecture and operating
1649system.
1650.cindex "symbolic link" "to build directory"
168e428f 1651Symbolic links to the sources are installed in this directory, which is where
9b371988
PH
1652the actual building takes place. In most cases, Exim can discover the machine
1653architecture and operating system for itself, but the defaults can be
1654overridden if necessary.
168e428f 1655
168e428f 1656
210f147e
NM
1657.section "PCRE library" "SECTdb"
1658.cindex "PCRE library"
1659Exim no longer has an embedded PCRE library as the vast majority of
1660modern systems include PCRE as a system library, although you may need
1661to install the PCRE or PCRE development package for your operating
1662system. If your system has a normal PCRE installation the Exim build
1663process will need no further configuration. If the library or the
1664headers are in an unusual location you will need to set the PCRE_LIBS
1665and INCLUDE directives appropriately. If your operating system has no
1666PCRE support then you will need to obtain and build the current PCRE
1667from &url(ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/).
1668
9b371988
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1669.section "DBM libraries" "SECTdb"
1670.cindex "DBM libraries" "discussion of"
1671.cindex "hints database" "DBM files used for"
168e428f
PH
1672Even if you do not use any DBM files in your configuration, Exim still needs a
1673DBM library in order to operate, because it uses indexed files for its hints
1674databases. Unfortunately, there are a number of DBM libraries in existence, and
1675different operating systems often have different ones installed.
1676
9b371988 1677.cindex "Solaris" "DBM library for"
f89d2485
PH
1678.cindex "IRIX, DBM library for"
1679.cindex "BSD, DBM library for"
1680.cindex "Linux, DBM library for"
168e428f
PH
1681If you are using Solaris, IRIX, one of the modern BSD systems, or a modern
1682Linux distribution, the DBM configuration should happen automatically, and you
1683may be able to ignore this section. Otherwise, you may have to learn more than
1684you would like about DBM libraries from what follows.
1685
9b371988 1686.cindex "&'ndbm'& DBM library"
168e428f 1687Licensed versions of Unix normally contain a library of DBM functions operating
9b371988 1688via the &'ndbm'& interface, and this is what Exim expects by default. Free
168e428f
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1689versions of Unix seem to vary in what they contain as standard. In particular,
1690some early versions of Linux have no default DBM library, and different
1691distributors have chosen to bundle different libraries with their packaged
f89d2485 1692versions. However, the more recent releases seem to have standardized on the
168e428f
PH
1693Berkeley DB library.
1694
1695Different DBM libraries have different conventions for naming the files they
9b371988 1696use. When a program opens a file called &_dbmfile_&, there are several
168e428f
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1697possibilities:
1698
9b371988
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1699.olist
1700A traditional &'ndbm'& implementation, such as that supplied as part of
1701Solaris, operates on two files called &_dbmfile.dir_& and &_dbmfile.pag_&.
1702.next
1703.cindex "&'gdbm'& DBM library"
1704The GNU library, &'gdbm'&, operates on a single file. If used via its &'ndbm'&
168e428f 1705compatibility interface it makes two different hard links to it with names
9b371988 1706&_dbmfile.dir_& and &_dbmfile.pag_&, but if used via its native interface, the
168e428f 1707file name is used unmodified.
9b371988
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1708.next
1709.cindex "Berkeley DB library"
1710The Berkeley DB package, if called via its &'ndbm'& compatibility interface,
1711operates on a single file called &_dbmfile.db_&, but otherwise looks to the
1712programmer exactly the same as the traditional &'ndbm'& implementation.
1713.next
1714If the Berkeley package is used in its native mode, it operates on a single
1715file called &_dbmfile_&; the programmer's interface is somewhat different to
1716the traditional &'ndbm'& interface.
1717.next
1718To complicate things further, there are several very different versions of the
168e428f 1719Berkeley DB package. Version 1.85 was stable for a very long time, releases
9b371988
PH
17202.&'x'& and 3.&'x'& were current for a while, but the latest versions are now
1721numbered 4.&'x'&. Maintenance of some of the earlier releases has ceased. All
168e428f 1722versions of Berkeley DB can be obtained from
9b371988
PH
1723&url(http://www.sleepycat.com/).
1724.next
1725.cindex "&'tdb'& DBM library"
1726Yet another DBM library, called &'tdb'&, is available from
1727&url(http://download.sourceforge.net/tdb). It has its own interface, and also
1728operates on a single file.
1729.endlist
1730
1731.cindex "USE_DB"
1732.cindex "DBM libraries" "configuration for building"
168e428f
PH
1733Exim and its utilities can be compiled to use any of these interfaces. In order
1734to use any version of the Berkeley DB package in native mode, you must set
1735USE_DB in an appropriate configuration file (typically
9b371988
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1736&_Local/Makefile_&). For example:
1737.code
1738USE_DB=yes
1739.endd
168e428f
PH
1740Similarly, for gdbm you set USE_GDBM, and for tdb you set USE_TDB. An
1741error is diagnosed if you set more than one of these.
1742
1743At the lowest level, the build-time configuration sets none of these options,
1744thereby assuming an interface of type (1). However, some operating system
1745configuration files (for example, those for the BSD operating systems and
1746Linux) assume type (4) by setting USE_DB as their default, and the
1747configuration files for Cygwin set USE_GDBM. Anything you set in
9b371988 1748&_Local/Makefile_&, however, overrides these system defaults.
168e428f
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1749
1750As well as setting USE_DB, USE_GDBM, or USE_TDB, it may also be
1751necessary to set DBMLIB, to cause inclusion of the appropriate library, as
1752in one of these lines:
9b371988
PH
1753.code
1754DBMLIB = -ldb
1755DBMLIB = -ltdb
1756.endd
168e428f
PH
1757Settings like that will work if the DBM library is installed in the standard
1758place. Sometimes it is not, and the library's header file may also not be in
1759the default path. You may need to set INCLUDE to specify where the header
1760file is, and to specify the path to the library more fully in DBMLIB, as in
1761this example:
9b371988
PH
1762.code
1763INCLUDE=-I/usr/local/include/db-4.1
1764DBMLIB=/usr/local/lib/db-4.1/libdb.a
1765.endd
168e428f 1766There is further detailed discussion about the various DBM libraries in the
9b371988 1767file &_doc/dbm.discuss.txt_& in the Exim distribution.
168e428f
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1768
1769
1770
f89d2485 1771.section "Pre-building configuration" "SECID25"
9b371988
PH
1772.cindex "building Exim" "pre-building configuration"
1773.cindex "configuration for building Exim"
1774.cindex "&_Local/Makefile_&"
1775.cindex "&_src/EDITME_&"
168e428f
PH
1776Before building Exim, a local configuration file that specifies options
1777independent of any operating system has to be created with the name
9b371988
PH
1778&_Local/Makefile_&. A template for this file is supplied as the file
1779&_src/EDITME_&, and it contains full descriptions of all the option settings
168e428f
PH
1780therein. These descriptions are therefore not repeated here. If you are
1781building Exim for the first time, the simplest thing to do is to copy
9b371988 1782&_src/EDITME_& to &_Local/Makefile_&, then read it and edit it appropriately.
168e428f
PH
1783
1784There are three settings that you must supply, because Exim will not build
1785without them. They are the location of the run time configuration file
1786(CONFIGURE_FILE), the directory in which Exim binaries will be installed
1787(BIN_DIRECTORY), and the identity of the Exim user (EXIM_USER and
1788maybe EXIM_GROUP as well). The value of CONFIGURE_FILE can in fact be
1789a colon-separated list of file names; Exim uses the first of them that exists.
1790
1791There are a few other parameters that can be specified either at build time or
1792at run time, to enable the same binary to be used on a number of different
1793machines. However, if the locations of Exim's spool directory and log file
1794directory (if not within the spool directory) are fixed, it is recommended that
9b371988 1795you specify them in &_Local/Makefile_& instead of at run time, so that errors
168e428f
PH
1796detected early in Exim's execution (such as a malformed configuration file) can
1797be logged.
1798
9b371988 1799.cindex "content scanning" "specifying at build time"
068aaea8 1800Exim's interfaces for calling virus and spam scanning software directly from
168e428f
PH
1801access control lists are not compiled by default. If you want to include these
1802facilities, you need to set
9b371988
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1803.code
1804WITH_CONTENT_SCAN=yes
1805.endd
1806in your &_Local/Makefile_&. For details of the facilities themselves, see
1807chapter &<<CHAPexiscan>>&.
168e428f
PH
1808
1809
9b371988 1810.cindex "&_Local/eximon.conf_&"
3cb1b51e 1811.cindex "&_exim_monitor/EDITME_&"
168e428f 1812If you are going to build the Exim monitor, a similar configuration process is
9b371988
PH
1813required. The file &_exim_monitor/EDITME_& must be edited appropriately for
1814your installation and saved under the name &_Local/eximon.conf_&. If you are
1815happy with the default settings described in &_exim_monitor/EDITME_&,
1816&_Local/eximon.conf_& can be empty, but it must exist.
168e428f
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1817
1818This is all the configuration that is needed in straightforward cases for known
1819operating systems. However, the building process is set up so that it is easy
1820to override options that are set by default or by operating-system-specific
1821configuration files, for example to change the name of the C compiler, which
9b371988
PH
1822defaults to &%gcc%&. See section &<<SECToverride>>& below for details of how to
1823do this.
168e428f
PH
1824
1825
1826
f89d2485 1827.section "Support for iconv()" "SECID26"
9b371988
PH
1828.cindex "&[iconv()]& support"
1829.cindex "RFC 2047"
168e428f
PH
1830The contents of header lines in messages may be encoded according to the rules
1831described RFC 2047. This makes it possible to transmit characters that are not
1832in the ASCII character set, and to label them as being in a particular
9b371988 1833character set. When Exim is inspecting header lines by means of the &%$h_%&
168e428f
PH
1834mechanism, it decodes them, and translates them into a specified character set
1835(default ISO-8859-1). The translation is possible only if the operating system
9b371988
PH
1836supports the &[iconv()]& function.
1837
1838However, some of the operating systems that supply &[iconv()]& do not support
1839very many conversions. The GNU &%libiconv%& library (available from
1840&url(http://www.gnu.org/software/libiconv/)) can be installed on such
1841systems to remedy this deficiency, as well as on systems that do not supply
1842&[iconv()]& at all. After installing &%libiconv%&, you should add
1843.code
1844HAVE_ICONV=yes
1845.endd
1846to your &_Local/Makefile_& and rebuild Exim.
1847
1848
1849
1850.section "Including TLS/SSL encryption support" "SECTinctlsssl"
1851.cindex "TLS" "including support for TLS"
1852.cindex "encryption" "including support for"
1853.cindex "SUPPORT_TLS"
1854.cindex "OpenSSL" "building Exim with"
1855.cindex "GnuTLS" "building Exim with"
168e428f
PH
1856Exim can be built to support encrypted SMTP connections, using the STARTTLS
1857command as per RFC 2487. It can also support legacy clients that expect to
1858start a TLS session immediately on connection to a non-standard port (see the
9b371988 1859&%tls_on_connect_ports%& runtime option and the &%-tls-on-connect%& command
168e428f
PH
1860line option).
1861
1862If you want to build Exim with TLS support, you must first install either the
1863OpenSSL or GnuTLS library. There is no cryptographic code in Exim itself for
1864implementing SSL.
1865
1866If OpenSSL is installed, you should set
9b371988
PH
1867.code
1868SUPPORT_TLS=yes
1869TLS_LIBS=-lssl -lcrypto
1870.endd
1871in &_Local/Makefile_&. You may also need to specify the locations of the
168e428f 1872OpenSSL library and include files. For example:
9b371988
PH
1873.code
1874SUPPORT_TLS=yes
1875TLS_LIBS=-L/usr/local/openssl/lib -lssl -lcrypto
1876TLS_INCLUDE=-I/usr/local/openssl/include/
1877.endd
1878.cindex "USE_GNUTLS"
168e428f 1879If GnuTLS is installed, you should set
9b371988
PH
1880.code
1881SUPPORT_TLS=yes
1882USE_GNUTLS=yes
1883TLS_LIBS=-lgnutls -ltasn1 -lgcrypt
1884.endd
1885in &_Local/Makefile_&, and again you may need to specify the locations of the
168e428f 1886library and include files. For example:
9b371988
PH
1887.code
1888SUPPORT_TLS=yes
1889USE_GNUTLS=yes
1890TLS_LIBS=-L/usr/gnu/lib -lgnutls -ltasn1 -lgcrypt
1891TLS_INCLUDE=-I/usr/gnu/include
1892.endd
168e428f 1893You do not need to set TLS_INCLUDE if the relevant directory is already
9b371988
PH
1894specified in INCLUDE. Details of how to configure Exim to make use of TLS are
1895given in chapter &<<CHAPTLS>>&.
168e428f
PH
1896
1897
1898
1899
f89d2485
PH
1900.section "Use of tcpwrappers" "SECID27"
1901.cindex "tcpwrappers, building Exim to support"
9b371988
PH
1902.cindex "USE_TCP_WRAPPERS"
1903Exim can be linked with the &'tcpwrappers'& library in order to check incoming
1904SMTP calls using the &'tcpwrappers'& control files. This may be a convenient
168e428f 1905alternative to Exim's own checking facilities for installations that are
9b371988
PH
1906already making use of &'tcpwrappers'& for other purposes. To do this, you
1907should set USE_TCP_WRAPPERS in &_Local/Makefile_&, arrange for the file
1908&_tcpd.h_& to be available at compile time, and also ensure that the library
1909&_libwrap.a_& is available at link time, typically by including &%-lwrap%& in
1910EXTRALIBS_EXIM. For example, if &'tcpwrappers'& is installed in &_/usr/local_&,
1911you might have
1912.code
1913USE_TCP_WRAPPERS=yes
1914CFLAGS=-O -I/usr/local/include
1915EXTRALIBS_EXIM=-L/usr/local/lib -lwrap
1916.endd
1917in &_Local/Makefile_&. The name to use in the &'tcpwrappers'& control files is
1918&"exim"&. For example, the line
1919.code
1920exim : LOCAL 192.168.1. .friendly.domain.example
1921.endd
1922in your &_/etc/hosts.allow_& file allows connections from the local host, from
1923the subnet 192.168.1.0/24, and from all hosts in &'friendly.domain.example'&.
1924All other connections are denied. Consult the &'tcpwrappers'& documentation for
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1925further details.
1926
1927
1928
f89d2485 1929.section "Including support for IPv6" "SECID28"
9b371988 1930.cindex "IPv6" "including support for"
168e428f 1931Exim contains code for use on systems that have IPv6 support. Setting
9b371988 1932&`HAVE_IPV6=YES`& in &_Local/Makefile_& causes the IPv6 code to be included;
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1933it may also be necessary to set IPV6_INCLUDE and IPV6_LIBS on systems
1934where the IPv6 support is not fully integrated into the normal include and
1935library files.
1936
1937Two different types of DNS record for handling IPv6 addresses have been
f89d2485 1938defined. AAAA records (analogous to A records for IPv4) are in use, and are
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1939currently seen as the mainstream. Another record type called A6 was proposed
1940as better than AAAA because it had more flexibility. However, it was felt to be
9b371988 1941over-complex, and its status was reduced to &"experimental"&. It is not known
168e428f 1942if anyone is actually using A6 records. Exim has support for A6 records, but
9b371988 1943this is included only if you set &`SUPPORT_A6=YES`& in &_Local/Makefile_&. The
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1944support has not been tested for some time.
1945
1946
1947
f89d2485 1948.section "The building process" "SECID29"
9b371988
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1949.cindex "build directory"
1950Once &_Local/Makefile_& (and &_Local/eximon.conf_&, if required) have been
1951created, run &'make'& at the top level. It determines the architecture and
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1952operating system types, and creates a build directory if one does not exist.
1953For example, on a Sun system running Solaris 8, the directory
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1954&_build-SunOS5-5.8-sparc_& is created.
1955.cindex "symbolic link" "to source files"
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1956Symbolic links to relevant source files are installed in the build directory.
1957
9b371988 1958&*Warning*&: The &%-j%& (parallel) flag must not be used with &'make'&; the
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1959building process fails if it is set.
1960
9b371988 1961If this is the first time &'make'& has been run, it calls a script that builds
168e428f 1962a make file inside the build directory, using the configuration files from the
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1963&_Local_& directory. The new make file is then passed to another instance of
1964&'make'&. This does the real work, building a number of utility scripts, and
168e428f 1965then compiling and linking the binaries for the Exim monitor (if configured), a
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1966number of utility programs, and finally Exim itself. The command &`make
1967makefile`& can be used to force a rebuild of the make file in the build
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1968directory, should this ever be necessary.
1969
1970If you have problems building Exim, check for any comments there may be in the
9b371988 1971&_README_& file concerning your operating system, and also take a look at the
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1972FAQ, where some common problems are covered.
1973
1974
1975
f89d2485 1976.section 'Output from &"make"&' "SECID283"
9b371988 1977The output produced by the &'make'& process for compile lines is often very
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1978unreadable, because these lines can be very long. For this reason, the normal
1979output is suppressed by default, and instead output similar to that which
1980appears when compiling the 2.6 Linux kernel is generated: just a short line for
1981each module that is being compiled or linked. However, it is still possible to
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1982get the full output, by calling &'make'& like this:
1983.code
1984FULLECHO='' make -e
1985.endd
1986The value of FULLECHO defaults to &"@"&, the flag character that suppresses
1987command reflection in &'make'&. When you ask for the full output, it is
3cb1b51e 1988given in addition to the short output.
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1989
1990
1991
9b371988 1992.section "Overriding build-time options for Exim" "SECToverride"
f89d2485 1993.cindex "build-time options, overriding"
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1994The main make file that is created at the beginning of the building process
1995consists of the concatenation of a number of files which set configuration
9b371988 1996values, followed by a fixed set of &'make'& instructions. If a value is set
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1997more than once, the last setting overrides any previous ones. This provides a
1998convenient way of overriding defaults. The files that are concatenated are, in
1999order:
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2000.display
2001&_OS/Makefile-Default_&
2002&_OS/Makefile-_&<&'ostype'&>
2003&_Local/Makefile_&
2004&_Local/Makefile-_&<&'ostype'&>
2005&_Local/Makefile-_&<&'archtype'&>
2006&_Local/Makefile-_&<&'ostype'&>-<&'archtype'&>
2007&_OS/Makefile-Base_&
2008.endd
2009.cindex "&_Local/Makefile_&"
2010.cindex "building Exim" "operating system type"
2011.cindex "building Exim" "architecture type"
2012where <&'ostype'&> is the operating system type and <&'archtype'&> is the
2013architecture type. &_Local/Makefile_& is required to exist, and the building
2014process fails if it is absent. The other three &_Local_& files are optional,
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2015and are often not needed.
2016
9b371988
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2017The values used for <&'ostype'&> and <&'archtype'&> are obtained from scripts
2018called &_scripts/os-type_& and &_scripts/arch-type_& respectively. If either of
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2019the environment variables EXIM_OSTYPE or EXIM_ARCHTYPE is set, their
2020values are used, thereby providing a means of forcing particular settings.
9b371988 2021Otherwise, the scripts try to get values from the &%uname%& command. If this
168e428f 2022fails, the shell variables OSTYPE and ARCHTYPE are inspected. A number
9b371988 2023of &'ad hoc'& transformations are then applied, to produce the standard names
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2024that Exim expects. You can run these scripts directly from the shell in order
2025to find out what values are being used on your system.
2026
2027
9b371988 2028&_OS/Makefile-Default_& contains comments about the variables that are set
168e428f
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2029therein. Some (but not all) are mentioned below. If there is something that
2030needs changing, review the contents of this file and the contents of the make
9b371988 2031file for your operating system (&_OS/Makefile-<ostype>_&) to see what the
168e428f
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2032default values are.
2033
2034
9b371988
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2035.cindex "building Exim" "overriding default settings"
2036If you need to change any of the values that are set in &_OS/Makefile-Default_&
2037or in &_OS/Makefile-<ostype>_&, or to add any new definitions, you do not
168e428f 2038need to change the original files. Instead, you should make the changes by
9b371988
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2039putting the new values in an appropriate &_Local_& file. For example,
2040.cindex "Tru64-Unix build-time settings"
168e428f
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2041when building Exim in many releases of the Tru64-Unix (formerly Digital UNIX,
2042formerly DEC-OSF1) operating system, it is necessary to specify that the C
9b371988
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2043compiler is called &'cc'& rather than &'gcc'&. Also, the compiler must be
2044called with the option &%-std1%&, to make it recognize some of the features of
168e428f 2045Standard C that Exim uses. (Most other compilers recognize Standard C by
9b371988 2046default.) To do this, you should create a file called &_Local/Makefile-OSF1_&
168e428f 2047containing the lines
9b371988
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2048.code
2049CC=cc
2050CFLAGS=-std1
2051.endd
168e428f 2052If you are compiling for just one operating system, it may be easier to put
9b371988 2053these lines directly into &_Local/Makefile_&.
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2054
2055Keeping all your local configuration settings separate from the distributed
2056files makes it easy to transfer them to new versions of Exim simply by copying
9b371988 2057the contents of the &_Local_& directory.
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2058
2059
9b371988
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2060.cindex "NIS lookup type" "including support for"
2061.cindex "NIS+ lookup type" "including support for"
2062.cindex "LDAP" "including support for"
2063.cindex "lookup" "inclusion in binary"
168e428f
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2064Exim contains support for doing LDAP, NIS, NIS+, and other kinds of file
2065lookup, but not all systems have these components installed, so the default is
2066not to include the relevant code in the binary. All the different kinds of file
2067and database lookup that Exim supports are implemented as separate code modules
2068which are included only if the relevant compile-time options are set. In the
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2069case of LDAP, NIS, and NIS+, the settings for &_Local/Makefile_& are:
2070.code
2071LOOKUP_LDAP=yes
2072LOOKUP_NIS=yes
2073LOOKUP_NISPLUS=yes
2074.endd
168e428f 2075and similar settings apply to the other lookup types. They are all listed in
9b371988 2076&_src/EDITME_&. In many cases the relevant include files and interface
168e428f 2077libraries need to be installed before compiling Exim.
9b371988 2078.cindex "cdb" "including support for"
068aaea8
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2079However, there are some optional lookup types (such as cdb) for which
2080the code is entirely contained within Exim, and no external include
168e428f
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2081files or libraries are required. When a lookup type is not included in the
2082binary, attempts to configure Exim to use it cause run time configuration
2083errors.
2084
9b371988 2085.cindex "Perl" "including support for"
168e428f
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2086Exim can be linked with an embedded Perl interpreter, allowing Perl
2087subroutines to be called during string expansion. To enable this facility,
9b371988
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2088.code
2089EXIM_PERL=perl.o
2090.endd
2091must be defined in &_Local/Makefile_&. Details of this facility are given in
2092chapter &<<CHAPperl>>&.
168e428f 2093
f89d2485 2094.cindex "X11 libraries, location of"
168e428f 2095The location of the X11 libraries is something that varies a lot between
068aaea8 2096operating systems, and there may be different versions of X11 to cope
168e428f
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2097with. Exim itself makes no use of X11, but if you are compiling the Exim
2098monitor, the X11 libraries must be available.
9b371988
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2099The following three variables are set in &_OS/Makefile-Default_&:
2100.code
2101X11=/usr/X11R6
2102XINCLUDE=-I$(X11)/include
2103XLFLAGS=-L$(X11)/lib
2104.endd
168e428f 2105These are overridden in some of the operating-system configuration files. For
9b371988
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2106example, in &_OS/Makefile-SunOS5_& there is
2107.code
2108X11=/usr/openwin
2109XINCLUDE=-I$(X11)/include
2110XLFLAGS=-L$(X11)/lib -R$(X11)/lib
2111.endd
168e428f
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2112If you need to override the default setting for your operating system, place a
2113definition of all three of these variables into your
9b371988 2114&_Local/Makefile-<ostype>_& file.
168e428f 2115
9b371988 2116.cindex "EXTRALIBS"
168e428f
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2117If you need to add any extra libraries to the link steps, these can be put in a
2118variable called EXTRALIBS, which appears in all the link commands, but by
2119default is not defined. In contrast, EXTRALIBS_EXIM is used only on the
2120command for linking the main Exim binary, and not for any associated utilities.
2121
9b371988 2122.cindex "DBM libraries" "configuration for building"
168e428f 2123There is also DBMLIB, which appears in the link commands for binaries that
9b371988 2124use DBM functions (see also section &<<SECTdb>>&). Finally, there is
168e428f
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2125EXTRALIBS_EXIMON, which appears only in the link step for the Exim monitor
2126binary, and which can be used, for example, to include additional X11
2127libraries.
2128
9b371988 2129.cindex "configuration file" "editing"
168e428f
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2130The make file copes with rebuilding Exim correctly if any of the configuration
2131files are edited. However, if an optional configuration file is deleted, it is
9b371988
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2132necessary to touch the associated non-optional file (that is,
2133&_Local/Makefile_& or &_Local/eximon.conf_&) before rebuilding.
168e428f
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2134
2135
f89d2485 2136.section "OS-specific header files" "SECID30"
9b371988
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2137.cindex "&_os.h_&"
2138.cindex "building Exim" "OS-specific C header files"
2139The &_OS_& directory contains a number of files with names of the form
2140&_os.h-<ostype>_&. These are system-specific C header files that should not
168e428f 2141normally need to be changed. There is a list of macro settings that are
9b371988 2142recognized in the file &_OS/os.configuring_&, which should be consulted if you
168e428f
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2143are porting Exim to a new operating system.
2144
2145
2146
f89d2485
PH
2147.section "Overriding build-time options for the monitor" "SECID31"
2148.cindex "building Eximon"
168e428f
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2149A similar process is used for overriding things when building the Exim monitor,
2150where the files that are involved are
9b371988
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2151.display
2152&_OS/eximon.conf-Default_&
2153&_OS/eximon.conf-_&<&'ostype'&>
2154&_Local/eximon.conf_&
2155&_Local/eximon.conf-_&<&'ostype'&>
2156&_Local/eximon.conf-_&<&'archtype'&>
2157&_Local/eximon.conf-_&<&'ostype'&>-<&'archtype'&>
2158.endd
2159.cindex "&_Local/eximon.conf_&"
168e428f 2160As with Exim itself, the final three files need not exist, and in this case the
9b371988
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2161&_OS/eximon.conf-<ostype>_& file is also optional. The default values in
2162&_OS/eximon.conf-Default_& can be overridden dynamically by setting environment
168e428f
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2163variables of the same name, preceded by EXIMON_. For example, setting
2164EXIMON_LOG_DEPTH in the environment overrides the value of
2165LOG_DEPTH at run time.
4f578862 2166.ecindex IIDbuex
168e428f
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2167
2168
f89d2485 2169.section "Installing Exim binaries and scripts" "SECID32"
9b371988
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2170.cindex "installing Exim"
2171.cindex "BIN_DIRECTORY"
2172The command &`make install`& runs the &(exim_install)& script with no
2173arguments. The script copies binaries and utility scripts into the directory
2174whose name is specified by the BIN_DIRECTORY setting in &_Local/Makefile_&.
2175.cindex "setuid" "installing Exim with"
068aaea8
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2176The install script copies files only if they are newer than the files they are
2177going to replace. The Exim binary is required to be owned by root and have the
9b371988
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2178&'setuid'& bit set, for normal configurations. Therefore, you must run &`make
2179install`& as root so that it can set up the Exim binary in this way. However, in
068aaea8
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2180some special situations (for example, if a host is doing no local deliveries)
2181it may be possible to run Exim without making the binary setuid root (see
9b371988 2182chapter &<<CHAPsecurity>>& for details).
168e428f 2183
9b371988 2184.cindex "CONFIGURE_FILE"
168e428f 2185Exim's run time configuration file is named by the CONFIGURE_FILE setting
9b371988
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2186in &_Local/Makefile_&. If this names a single file, and the file does not
2187exist, the default configuration file &_src/configure.default_& is copied there
168e428f
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2188by the installation script. If a run time configuration file already exists, it
2189is left alone. If CONFIGURE_FILE is a colon-separated list, naming several
2190alternative files, no default is installed.
2191
9b371988
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2192.cindex "system aliases file"
2193.cindex "&_/etc/aliases_&"
168e428f
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2194One change is made to the default configuration file when it is installed: the
2195default configuration contains a router that references a system aliases file.
2196The path to this file is set to the value specified by
9b371988 2197SYSTEM_ALIASES_FILE in &_Local/Makefile_& (&_/etc/aliases_& by default).
168e428f
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2198If the system aliases file does not exist, the installation script creates it,
2199and outputs a comment to the user.
2200
2201The created file contains no aliases, but it does contain comments about the
2202aliases a site should normally have. Mail aliases have traditionally been
9b371988
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2203kept in &_/etc/aliases_&. However, some operating systems are now using
2204&_/etc/mail/aliases_&. You should check if yours is one of these, and change
168e428f
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2205Exim's configuration if necessary.
2206
2207The default configuration uses the local host's name as the only local domain,
9b371988
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2208and is set up to do local deliveries into the shared directory &_/var/mail_&,
2209running as the local user. System aliases and &_.forward_& files in users' home
168e428f
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2210directories are supported, but no NIS or NIS+ support is configured. Domains
2211other than the name of the local host are routed using the DNS, with delivery
2212over SMTP.
2213
168e428f
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2214It is possible to install Exim for special purposes (such as building a binary
2215distribution) in a private part of the file system. You can do this by a
2216command such as
9b371988
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2217.code
2218make DESTDIR=/some/directory/ install
2219.endd
168e428f
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2220This has the effect of pre-pending the specified directory to all the file
2221paths, except the name of the system aliases file that appears in the default
9b371988 2222configuration. (If a default alias file is created, its name &'is'& modified.)
168e428f
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2223For backwards compatibility, ROOT is used if DESTDIR is not set,
2224but this usage is deprecated.
2225
9b371988
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2226.cindex "installing Exim" "what is not installed"
2227Running &'make install'& does not copy the Exim 4 conversion script
2228&'convert4r4'&, or the &'pcretest'& test program. You will probably run the
168e428f 2229first of these only once (if you are upgrading from Exim 3), and the second
9b371988 2230isn't really part of Exim. None of the documentation files in the &_doc_&
168e428f 2231directory are copied, except for the info files when you have set
9b371988 2232INFO_DIRECTORY, as described in section &<<SECTinsinfdoc>>& below.
168e428f 2233
9b371988 2234For the utility programs, old versions are renamed by adding the suffix &_.O_&
168e428f
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2235to their names. The Exim binary itself, however, is handled differently. It is
2236installed under a name that includes the version number and the compile number,
9b371988
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2237for example &_exim-&version;-1_&. The script then arranges for a symbolic link
2238called &_exim_& to point to the binary. If you are updating a previous version
2239of Exim, the script takes care to ensure that the name &_exim_& is never absent
168e428f
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2240from the directory (as seen by other processes).
2241
9b371988
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2242.cindex "installing Exim" "testing the script"
2243If you want to see what the &'make install'& will do before running it for
2244real, you can pass the &%-n%& option to the installation script by this
2245command:
2246.code
2247make INSTALL_ARG=-n install
2248.endd
168e428f
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2249The contents of the variable INSTALL_ARG are passed to the installation
2250script. You do not need to be root to run this test. Alternatively, you can run
2251the installation script directly, but this must be from within the build
2252directory. For example, from the top-level Exim directory you could use this
2253command:
9b371988
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2254.code
2255(cd build-SunOS5-5.5.1-sparc; ../scripts/exim_install -n)
2256.endd
2257.cindex "installing Exim" "install script options"
168e428f
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2258There are two other options that can be supplied to the installation script.
2259
9b371988
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2260.ilist
2261&%-no_chown%& bypasses the call to change the owner of the installed binary
168e428f 2262to root, and the call to make it a setuid binary.
9b371988
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2263.next
2264&%-no_symlink%& bypasses the setting up of the symbolic link &_exim_& to the
168e428f 2265installed binary.
9b371988 2266.endlist
168e428f
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2267
2268INSTALL_ARG can be used to pass these options to the script. For example:
9b371988
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2269.code
2270make INSTALL_ARG=-no_symlink install
2271.endd
168e428f
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2272The installation script can also be given arguments specifying which files are
2273to be copied. For example, to install just the Exim binary, and nothing else,
2274without creating the symbolic link, you could use:
9b371988
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2275.code
2276make INSTALL_ARG='-no_symlink exim' install
2277.endd
168e428f
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2278
2279
2280
9b371988
PH
2281.section "Installing info documentation" "SECTinsinfdoc"
2282.cindex "installing Exim" "&'info'& documentation"
2283Not all systems use the GNU &'info'& system for documentation, and for this
168e428f
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2284reason, the Texinfo source of Exim's documentation is not included in the main
2285distribution. Instead it is available separately from the ftp site (see section
9b371988 2286&<<SECTavail>>&).
168e428f 2287
9b371988
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2288If you have defined INFO_DIRECTORY in &_Local/Makefile_& and the Texinfo
2289source of the documentation is found in the source tree, running &`make
2290install`& automatically builds the info files and installs them.
168e428f
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2291
2292
2293
f89d2485 2294.section "Setting up the spool directory" "SECID33"
9b371988 2295.cindex "spool directory" "creating"
168e428f
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2296When it starts up, Exim tries to create its spool directory if it does not
2297exist. The Exim uid and gid are used for the owner and group of the spool
2298directory. Sub-directories are automatically created in the spool directory as
2299necessary.
2300
2301
2302
2303
f89d2485 2304.section "Testing" "SECID34"
9b371988 2305.cindex "testing" "installation"
168e428f
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2306Having installed Exim, you can check that the run time configuration file is
2307syntactically valid by running the following command, which assumes that the
2308Exim binary directory is within your PATH environment variable:
9b371988
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2309.code
2310exim -bV
2311.endd
168e428f
PH
2312If there are any errors in the configuration file, Exim outputs error messages.
2313Otherwise it outputs the version number and build date,
2314the DBM library that is being used, and information about which drivers and
2315other optional code modules are included in the binary.
2316Some simple routing tests can be done by using the address testing option. For
2317example,
9b371988
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2318.display
2319&`exim -bt`& <&'local username'&>
2320.endd
168e428f 2321should verify that it recognizes a local mailbox, and
9b371988
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2322.display
2323&`exim -bt`& <&'remote address'&>
2324.endd
168e428f
PH
2325a remote one. Then try getting it to deliver mail, both locally and remotely.
2326This can be done by passing messages directly to Exim, without going through a
2327user agent. For example:
9b371988 2328.code
068aaea8
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2329exim -v postmaster@your.domain.example
2330From: user@your.domain.example
2331To: postmaster@your.domain.example
2332Subject: Testing Exim
168e428f 2333
068aaea8
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2334This is a test message.
2335^D
9b371988
PH
2336.endd
2337The &%-v%& option causes Exim to output some verification of what it is doing.
168e428f 2338In this case you should see copies of three log lines, one for the message's
9b371988 2339arrival, one for its delivery, and one containing &"Completed"&.
168e428f 2340
9b371988
PH
2341.cindex "delivery" "problems with"
2342If you encounter problems, look at Exim's log files (&'mainlog'& and
2343&'paniclog'&) to see if there is any relevant information there. Another source
168e428f 2344of information is running Exim with debugging turned on, by specifying the
9b371988 2345&%-d%& option. If a message is stuck on Exim's spool, you can force a delivery
168e428f 2346with debugging turned on by a command of the form
9b371988
PH
2347.display
2348&`exim -d -M`& <&'exim-message-id'&>
2349.endd
2350You must be root or an &"admin user"& in order to do this. The &%-d%& option
168e428f 2351produces rather a lot of output, but you can cut this down to specific areas.
9b371988
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2352For example, if you use &%-d-all+route%& only the debugging information
2353relevant to routing is included. (See the &%-d%& option in chapter
2354&<<CHAPcommandline>>& for more details.)
168e428f 2355
9b371988
PH
2356.cindex '&"sticky"& bit'
2357.cindex "lock files"
168e428f
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2358One specific problem that has shown up on some sites is the inability to do
2359local deliveries into a shared mailbox directory, because it does not have the
9b371988 2360&"sticky bit"& set on it. By default, Exim tries to create a lock file before
168e428f 2361writing to a mailbox file, and if it cannot create the lock file, the delivery
9b371988 2362is deferred. You can get round this either by setting the &"sticky bit"& on the
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2363directory, or by setting a specific group for local deliveries and allowing
2364that group to create files in the directory (see the comments above the
9b371988 2365&(local_delivery)& transport in the default configuration file). Another
168e428f 2366approach is to configure Exim not to use lock files, but just to rely on
9b371988
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2367&[fcntl()]& locking instead. However, you should do this only if all user
2368agents also use &[fcntl()]& locking. For further discussion of locking issues,
2369see chapter &<<CHAPappendfile>>&.
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2370
2371One thing that cannot be tested on a system that is already running an MTA is
2372the receipt of incoming SMTP mail on the standard SMTP port. However, the
9b371988
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2373&%-oX%& option can be used to run an Exim daemon that listens on some other
2374port, or &'inetd'& can be used to do this. The &%-bh%& option and the
2375&'exim_checkaccess'& utility can be used to check out policy controls on
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2376incoming SMTP mail.
2377
2378Testing a new version on a system that is already running Exim can most easily
2379be done by building a binary with a different CONFIGURE_FILE setting. From
2380within the run time configuration, all other file and directory names
2381that Exim uses can be altered, in order to keep it entirely clear of the
2382production version.
2383
2384
f89d2485 2385.section "Replacing another MTA with Exim" "SECID35"
9b371988 2386.cindex "replacing another MTA"
168e428f
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2387Building and installing Exim for the first time does not of itself put it in
2388general use. The name by which the system's MTA is called by mail user agents
9b371988
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2389is either &_/usr/sbin/sendmail_&, or &_/usr/lib/sendmail_& (depending on the
2390operating system), and it is necessary to make this name point to the &'exim'&
168e428f 2391binary in order to get the user agents to pass messages to Exim. This is
9b371988
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2392normally done by renaming any existing file and making &_/usr/sbin/sendmail_&
2393or &_/usr/lib/sendmail_&
2394.cindex "symbolic link" "to &'exim'& binary"
2395a symbolic link to the &'exim'& binary. It is a good idea to remove any setuid
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2396privilege and executable status from the old MTA. It is then necessary to stop
2397and restart the mailer daemon, if one is running.
2398
f89d2485 2399.cindex "FreeBSD, MTA indirection"
9b371988 2400.cindex "&_/etc/mail/mailer.conf_&"
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2401Some operating systems have introduced alternative ways of switching MTAs. For
2402example, if you are running FreeBSD, you need to edit the file
9b371988 2403&_/etc/mail/mailer.conf_& instead of setting up a symbolic link as just
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2404described. A typical example of the contents of this file for running Exim is
2405as follows:
9b371988
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2406.code
2407sendmail /usr/exim/bin/exim
2408send-mail /usr/exim/bin/exim
2409mailq /usr/exim/bin/exim -bp
2410newaliases /usr/bin/true
2411.endd
2412Once you have set up the symbolic link, or edited &_/etc/mail/mailer.conf_&,
2413your Exim installation is &"live"&. Check it by sending a message from your
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2414favourite user agent.
2415
2416You should consider what to tell your users about the change of MTA. Exim may
2417have different capabilities to what was previously running, and there are
2418various operational differences such as the text of messages produced by
2419command line options and in bounce messages. If you allow your users to make
2420use of Exim's filtering capabilities, you should make the document entitled
9b371988 2421&'Exim's interface to mail filtering'& available to them.
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2422
2423
2424
f89d2485 2425.section "Upgrading Exim" "SECID36"
9b371988 2426.cindex "upgrading Exim"
168e428f
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2427If you are already running Exim on your host, building and installing a new
2428version automatically makes it available to MUAs, or any other programs that
2429call the MTA directly. However, if you are running an Exim daemon, you do need
9b371988
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2430to send it a HUP signal, to make it re-execute itself, and thereby pick up the
2431new binary. You do not need to stop processing mail in order to install a new
068aaea8
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2432version of Exim. The install script does not modify an existing runtime
2433configuration file.
2434
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2435
2436
2437
f89d2485 2438.section "Stopping the Exim daemon on Solaris" "SECID37"
9b371988 2439.cindex "Solaris" "stopping Exim on"
168e428f 2440The standard command for stopping the mailer daemon on Solaris is
9b371988
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2441.code
2442/etc/init.d/sendmail stop
2443.endd
2444If &_/usr/lib/sendmail_& has been turned into a symbolic link, this script
2445fails to stop Exim because it uses the command &'ps -e'& and greps the output
2446for the text &"sendmail"&; this is not present because the actual program name
2447(that is, &"exim"&) is given by the &'ps'& command with these options. A
2448solution is to replace the line that finds the process id with something like
2449.code
2450pid=`cat /var/spool/exim/exim-daemon.pid`
2451.endd
168e428f
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2452to obtain the daemon's pid directly from the file that Exim saves it in.
2453
9b371988 2454Note, however, that stopping the daemon does not &"stop Exim"&. Messages can
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2455still be received from local processes, and if automatic delivery is configured
2456(the normal case), deliveries will still occur.
2457
2458
2459
2460
9b371988
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2461. ////////////////////////////////////////////////////////////////////////////
2462. ////////////////////////////////////////////////////////////////////////////
168e428f 2463
9b371988 2464.chapter "The Exim command line" "CHAPcommandline"
4f578862
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2465.scindex IIDclo1 "command line" "options"
2466.scindex IIDclo2 "options" "command line"
168e428f
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2467Exim's command line takes the standard Unix form of a sequence of options,
2468each starting with a hyphen character, followed by a number of arguments. The
2469options are compatible with the main options of Sendmail, and there are also
2470some additional options, some of which are compatible with Smail 3. Certain
2471combinations of options do not make sense, and provoke an error if used.
2472The form of the arguments depends on which options are set.
2473
2474
f89d2485 2475.section "Setting options by program name" "SECID38"
9b371988
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2476.cindex "&'mailq'&"
2477If Exim is called under the name &'mailq'&, it behaves as if the option &%-bp%&
168e428f 2478were present before any other options.
9b371988 2479The &%-bp%& option requests a listing of the contents of the mail queue on the
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2480standard output.
2481This feature is for compatibility with some systems that contain a command of
2482that name in one of the standard libraries, symbolically linked to
9b371988
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2483&_/usr/sbin/sendmail_& or &_/usr/lib/sendmail_&.
2484
2485.cindex "&'rsmtp'&"
2486If Exim is called under the name &'rsmtp'& it behaves as if the option &%-bS%&
2487were present before any other options, for compatibility with Smail. The
2488&%-bS%& option is used for reading in a number of messages in batched SMTP
2489format.
2490
2491.cindex "&'rmail'&"
2492If Exim is called under the name &'rmail'& it behaves as if the &%-i%& and
2493&%-oee%& options were present before any other options, for compatibility with
2494Smail. The name &'rmail'& is used as an interface by some UUCP systems.
2495
2496.cindex "&'runq'&"
2497.cindex "queue runner"
2498If Exim is called under the name &'runq'& it behaves as if the option &%-q%&
2499were present before any other options, for compatibility with Smail. The &%-q%&
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2500option causes a single queue runner process to be started.
2501
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2502.cindex "&'newaliases'&"
2503.cindex "alias file" "building"
2504.cindex "Sendmail compatibility" "calling Exim as &'newaliases'&"
2505If Exim is called under the name &'newaliases'& it behaves as if the option
2506&%-bi%& were present before any other options, for compatibility with Sendmail.
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2507This option is used for rebuilding Sendmail's alias file. Exim does not have
2508the concept of a single alias file, but can be configured to run a given
9b371988 2509command if called with the &%-bi%& option.
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2510
2511
9b371988
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2512.section "Trusted and admin users" "SECTtrustedadmin"
2513Some Exim options are available only to &'trusted users'& and others are
2514available only to &'admin users'&. In the description below, the phrases &"Exim
2515user"& and &"Exim group"& mean the user and group defined by EXIM_USER and
2516EXIM_GROUP in &_Local/Makefile_& or set by the &%exim_user%& and
2517&%exim_group%& options. These do not necessarily have to use the name &"exim"&.
168e428f 2518
9b371988 2519.ilist
f89d2485 2520.cindex "trusted users" "definition of"
9b371988 2521.cindex "user" "trusted definition of"
168e428f 2522The trusted users are root, the Exim user, any user listed in the
9b371988
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2523&%trusted_users%& configuration option, and any user whose current group or any
2524supplementary group is one of those listed in the &%trusted_groups%&
168e428f 2525configuration option. Note that the Exim group is not automatically trusted.
9b371988
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2526
2527.cindex '&"From"& line'
2528.cindex "envelope sender"
2529Trusted users are always permitted to use the &%-f%& option or a leading
2530&"From&~"& line to specify the envelope sender of a message that is passed to
2531Exim through the local interface (see the &%-bm%& and &%-f%& options below).
2532See the &%untrusted_set_sender%& option for a way of permitting non-trusted
2533users to set envelope senders.
2534
2535.cindex "&'From:'& header line"
2536.cindex "&'Sender:'& header line"
2537For a trusted user, there is never any check on the contents of the &'From:'&
2538header line, and a &'Sender:'& line is never added. Furthermore, any existing
2539&'Sender:'& line in incoming local (non-TCP/IP) messages is not removed.
2540
168e428f
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2541Trusted users may also specify a host name, host address, interface address,
2542protocol name, ident value, and authentication data when submitting a message
2543locally. Thus, they are able to insert messages into Exim's queue locally that
2544have the characteristics of messages received from a remote host. Untrusted
9b371988 2545users may in some circumstances use &%-f%&, but can never set the other values
168e428f 2546that are available to trusted users.
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2547.next
2548.cindex "user" "admin definition of"
2549.cindex "admin user" "definition of"
168e428f 2550The admin users are root, the Exim user, and any user that is a member of the
9b371988 2551Exim group or of any group listed in the &%admin_groups%& configuration option.
168e428f 2552The current group does not have to be one of these groups.
9b371988 2553
168e428f
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2554Admin users are permitted to list the queue, and to carry out certain
2555operations on messages, for example, to force delivery failures. It is also
2556necessary to be an admin user in order to see the full information provided by
2557the Exim monitor, and full debugging output.
9b371988
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2558
2559By default, the use of the &%-M%&, &%-q%&, &%-R%&, and &%-S%& options to cause
2560Exim to attempt delivery of messages on its queue is restricted to admin users.
2561However, this restriction can be relaxed by setting the &%prod_requires_admin%&
2562option false (that is, specifying &%no_prod_requires_admin%&).
2563
2564Similarly, the use of the &%-bp%& option to list all the messages in the queue
2565is restricted to admin users unless &%queue_list_requires_admin%& is set
168e428f 2566false.
9b371988 2567.endlist
168e428f
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2568
2569
9b371988 2570&*Warning*&: If you configure your system so that admin users are able to
168e428f
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2571edit Exim's configuration file, you are giving those users an easy way of
2572getting root. There is further discussion of this issue at the start of chapter
9b371988 2573&<<CHAPconf>>&.
168e428f
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2574
2575
2576
2577
f89d2485 2578.section "Command line options" "SECID39"
db9452a9
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2579Exim's command line options are described in alphabetical order below. If none
2580of the options that specifies a specific action (such as starting the daemon or
2581a queue runner, or testing an address, or receiving a message in a specific
2582format, or listing the queue) are present, and there is at least one argument
2583on the command line, &%-bm%& (accept a local message on the standard input,
2584with the arguments specifying the recipients) is assumed. Otherwise, Exim
2585outputs a brief message about itself and exits.
168e428f 2586
9b371988
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2587. ////////////////////////////////////////////////////////////////////////////
2588. Insert a stylized XML comment here, to identify the start of the command line
2589. options. This is for the benefit of the Perl script that automatically
2590. creates a man page for the options.
2591. ////////////////////////////////////////////////////////////////////////////
168e428f 2592
9b371988 2593.literal xml
168e428f 2594<!-- === Start of command line options === -->
9b371988 2595.literal off
168e428f
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2596
2597
9b371988
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2598.vlist
2599.vitem &%--%&
2600.oindex "--"
2601.cindex "options" "command line; terminating"
168e428f
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2602This is a pseudo-option whose only purpose is to terminate the options and
2603therefore to cause subsequent command line items to be treated as arguments
2604rather than options, even if they begin with hyphens.
2605
9b371988
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2606.vitem &%--help%&
2607.oindex "&%--help%&"
168e428f
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2608This option causes Exim to output a few sentences stating what it is.
2609The same output is generated if the Exim binary is called with no options and
2610no arguments.
2611
9b371988
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2612.vitem &%-B%&<&'type'&>
2613.oindex "&%-B%&"
2614.cindex "8-bit characters"
2615.cindex "Sendmail compatibility" "8-bit characters"
168e428f
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2616This is a Sendmail option for selecting 7 or 8 bit processing. Exim is 8-bit
2617clean; it ignores this option.
2618
9b371988
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2619.vitem &%-bd%&
2620.oindex "&%-bd%&"
2621.cindex "daemon"
f89d2485 2622.cindex "SMTP" "listener"
9b371988 2623.cindex "queue runner"
168e428f 2624This option runs Exim as a daemon, awaiting incoming SMTP connections. Usually
9b371988
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2625the &%-bd%& option is combined with the &%-q%&<&'time'&> option, to specify
2626that the daemon should also initiate periodic queue runs.
2627
2628The &%-bd%& option can be used only by an admin user. If either of the &%-d%&
2629(debugging) or &%-v%& (verifying) options are set, the daemon does not
168e428f
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2630disconnect from the controlling terminal. When running this way, it can be
2631stopped by pressing ctrl-C.
9b371988 2632
168e428f
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2633By default, Exim listens for incoming connections to the standard SMTP port on
2634all the host's running interfaces. However, it is possible to listen on other
2635ports, on multiple ports, and only on specific interfaces. Chapter
9b371988
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2636&<<CHAPinterfaces>>& contains a description of the options that control this.
2637
168e428f 2638When a listening daemon
9b371988
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2639.cindex "daemon" "process id (pid)"
2640.cindex "pid (process id)" "of daemon"
2641is started without the use of &%-oX%& (that is, without overriding the normal
2642configuration), it writes its process id to a file called &_exim-daemon.pid_&
2643in Exim's spool directory. This location can be overridden by setting
2644PID_FILE_PATH in &_Local/Makefile_&. The file is written while Exim is still
168e428f 2645running as root.
9b371988
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2646
2647When &%-oX%& is used on the command line to start a listening daemon, the
2648process id is not written to the normal pid file path. However, &%-oP%& can be
168e428f 2649used to specify a path on the command line if a pid file is required.
9b371988 2650
168e428f 2651The SIGHUP signal
9b371988 2652.cindex "SIGHUP"
3cb1b51e
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2653.cindex "daemon" "restarting"
2654can be used to cause the daemon to re-execute itself. This should be done
2655whenever Exim's configuration file, or any file that is incorporated into it by
2656means of the &%.include%& facility, is changed, and also whenever a new version
2657of Exim is installed. It is not necessary to do this when other files that are
9b371988
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2658referenced from the configuration (for example, alias files) are changed,
2659because these are reread each time they are used.
2660
2661.vitem &%-bdf%&
2662.oindex "&%-bdf%&"
2663This option has the same effect as &%-bd%& except that it never disconnects
2664from the controlling terminal, even when no debugging is specified.
2665
2666.vitem &%-be%&
2667.oindex "&%-be%&"
2668.cindex "testing" "string expansion"
2669.cindex "expansion" "testing"
168e428f
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2670Run Exim in expansion testing mode. Exim discards its root privilege, to
2671prevent ordinary users from using this mode to read otherwise inaccessible
2672files. If no arguments are given, Exim runs interactively, prompting for lines
4f578862 2673of data. Otherwise, it processes each argument in turn.
9b371988
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2674
2675If Exim was built with USE_READLINE=yes in &_Local/Makefile_&, it tries
2676to load the &%libreadline%& library dynamically whenever the &%-be%& option is
2677used without command line arguments. If successful, it uses the &[readline()]&
168e428f
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2678function, which provides extensive line-editing facilities, for reading the
2679test data. A line history is supported.
9b371988 2680
168e428f 2681Long expansion expressions can be split over several lines by using backslash
068aaea8 2682continuations. As in Exim's run time configuration, white space at the start of
168e428f
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2683continuation lines is ignored. Each argument or data line is passed through the
2684string expansion mechanism, and the result is output. Variable values from the
9b371988 2685configuration file (for example, &$qualify_domain$&) are available, but no
3cb1b51e 2686message-specific values (such as &$sender_domain$&) are set, because no message
f89d2485 2687is being processed (but see &%-bem%& and &%-Mset%&).
168e428f 2688
9b371988
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2689&*Note*&: If you use this mechanism to test lookups, and you change the data
2690files or databases you are using, you must exit and restart Exim before trying
2691the same lookup again. Otherwise, because each Exim process caches the results
2692of lookups, you will just get the same result as before.
9b371988 2693
3cb1b51e
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2694.vitem &%-bem%&&~<&'filename'&>
2695.oindex "&%-bem%&"
2696.cindex "testing" "string expansion"
2697.cindex "expansion" "testing"
2698This option operates like &%-be%& except that it must be followed by the name
2699of a file. For example:
2700.code
2701exim -bem /tmp/testmessage
2702.endd
2703The file is read as a message (as if receiving a locally-submitted non-SMTP
2704message) before any of the test expansions are done. Thus, message-specific
2705variables such as &$message_size$& and &$header_from:$& are available. However,
2706no &'Received:'& header is added to the message. If the &%-t%& option is set,
2707recipients are read from the headers in the normal way, and are shown in the
2708&$recipients$& variable. Note that recipients cannot be given on the command
2709line, because further arguments are taken as strings to expand (just like
2710&%-be%&).
3cb1b51e 2711
9b371988
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2712.vitem &%-bF%&&~<&'filename'&>
2713.oindex "&%-bF%&"
2714.cindex "system filter" "testing"
2715.cindex "testing" "system filter"
2716This option is the same as &%-bf%& except that it assumes that the filter being
168e428f
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2717tested is a system filter. The additional commands that are available only in
2718system filters are recognized.
2719
9b371988
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2720.vitem &%-bf%&&~<&'filename'&>
2721.oindex "&%-bf%&"
2722.cindex "filter" "testing"
2723.cindex "testing" "filter file"
2724.cindex "forward file" "testing"
2725.cindex "testing" "forward file"
2726.cindex "Sieve filter" "testing"
168e428f
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2727This option runs Exim in user filter testing mode; the file is the filter file
2728to be tested, and a test message must be supplied on the standard input. If
2729there are no message-dependent tests in the filter, an empty file can be
2730supplied.
168e428f 2731
9b371988
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2732If you want to test a system filter file, use &%-bF%& instead of &%-bf%&. You
2733can use both &%-bF%& and &%-bf%& on the same command, in order to test a system
2734filter and a user filter in the same run. For example:
2735.code
2736exim -bF /system/filter -bf /user/filter </test/message
2737.endd
168e428f
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2738This is helpful when the system filter adds header lines or sets filter
2739variables that are used by the user filter.
168e428f 2740
9b371988
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2741If the test filter file does not begin with one of the special lines
2742.code
2743# Exim filter
2744# Sieve filter
2745.endd
2746it is taken to be a normal &_.forward_& file, and is tested for validity under
2747that interpretation. See sections &<<SECTitenonfilred>>& to
2748&<<SECTspecitredli>>& for a description of the possible contents of non-filter
2749redirection lists.
2750
2751The result of an Exim command that uses &%-bf%&, provided no errors are
168e428f
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2752detected, is a list of the actions that Exim would try to take if presented
2753with the message for real. More details of filter testing are given in the
9b371988
PH
2754separate document entitled &'Exim's interfaces to mail filtering'&.
2755
168e428f 2756When testing a filter file,
9b371988
PH
2757.cindex "&""From""& line"
2758.cindex "envelope sender"
f89d2485 2759.oindex "&%-f%&" "for filter testing"
9b371988
PH
2760the envelope sender can be set by the &%-f%& option,
2761or by a &"From&~"& line at the start of the test message. Various parameters
2762that would normally be taken from the envelope recipient address of the message
2763can be set by means of additional command line options (see the next four
2764options).
2765
2766.vitem &%-bfd%&&~<&'domain'&>
2767.oindex "&%-bfd%&"
f89d2485 2768.vindex "&$qualify_domain$&"
168e428f 2769This sets the domain of the recipient address when a filter file is being
9b371988
PH
2770tested by means of the &%-bf%& option. The default is the value of
2771&$qualify_domain$&.
168e428f 2772
9b371988
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2773.vitem &%-bfl%&&~<&'local&~part'&>
2774.oindex "&%-bfl%&"
168e428f 2775This sets the local part of the recipient address when a filter file is being
9b371988 2776tested by means of the &%-bf%& option. The default is the username of the
168e428f
PH
2777process that calls Exim. A local part should be specified with any prefix or
2778suffix stripped, because that is how it appears to the filter when a message is
2779actually being delivered.
2780
9b371988
PH
2781.vitem &%-bfp%&&~<&'prefix'&>
2782.oindex "&%-bfp%&"
168e428f 2783This sets the prefix of the local part of the recipient address when a filter
9b371988 2784file is being tested by means of the &%-bf%& option. The default is an empty
168e428f
PH
2785prefix.
2786
9b371988
PH
2787.vitem &%-bfs%&&~<&'suffix'&>
2788.oindex "&%-bfs%&"
168e428f 2789This sets the suffix of the local part of the recipient address when a filter
9b371988 2790file is being tested by means of the &%-bf%& option. The default is an empty
168e428f
PH
2791suffix.
2792
9b371988
PH
2793.vitem &%-bh%&&~<&'IP&~address'&>
2794.oindex "&%-bh%&"
2795.cindex "testing" "incoming SMTP"
2796.cindex "SMTP" "testing incoming"
2797.cindex "testing" "relay control"
2798.cindex "relaying" "testing configuration"
2799.cindex "policy control" "testing"
2800.cindex "debugging" "&%-bh%& option"
168e428f
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2801This option runs a fake SMTP session as if from the given IP address, using the
2802standard input and output. The IP address may include a port number at the end,
2803after a full stop. For example:
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2804.code
2805exim -bh 10.9.8.7.1234
2806exim -bh fe80::a00:20ff:fe86:a061.5678
2807.endd
168e428f 2808When an IPv6 address is given, it is converted into canonical form. In the case
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2809of the second example above, the value of &$sender_host_address$& after
2810conversion to the canonical form is
2811&`fe80:0000:0000:0a00:20ff:fe86:a061.5678`&.
2812
168e428f 2813Comments as to what is going on are written to the standard error file. These
9b371988 2814include lines beginning with &"LOG"& for anything that would have been logged.
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2815This facility is provided for testing configuration options for incoming
2816messages, to make sure they implement the required policy. For example, you can
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2817test your relay controls using &%-bh%&.
2818
2819&*Warning 1*&:
2820.cindex "RFC 1413"
db9452a9
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2821You can test features of the configuration that rely on ident (RFC 1413)
2822information by using the &%-oMt%& option. However, Exim cannot actually perform
2823an ident callout when testing using &%-bh%& because there is no incoming SMTP
2824connection.
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2825
2826&*Warning 2*&: Address verification callouts (see section &<<SECTcallver>>&)
2827are also skipped when testing using &%-bh%&. If you want these callouts to
2828occur, use &%-bhc%& instead.
2829
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2830Messages supplied during the testing session are discarded, and nothing is
2831written to any of the real log files. There may be pauses when DNS (and other)
9b371988 2832lookups are taking place, and of course these may time out. The &%-oMi%& option
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2833can be used to specify a specific IP interface and port if this is important,
2834and &%-oMaa%& and &%-oMai%& can be used to set parameters as if the SMTP
2835session were authenticated.
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2836
2837The &'exim_checkaccess'& utility is a &"packaged"& version of &%-bh%& whose
168e428f 2838output just states whether a given recipient address from a given host is
9b371988 2839acceptable or not. See section &<<SECTcheckaccess>>&.
168e428f 2840
3cb1b51e 2841Features such as authentication and encryption, where the client input is not
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2842plain text, cannot easily be tested with &%-bh%&. Instead, you should use a
2843specialized SMTP test program such as
3cb1b51e 2844&url(http://jetmore.org/john/code/#swaks,swaks).
3cb1b51e 2845
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2846.vitem &%-bhc%&&~<&'IP&~address'&>
2847.oindex "&%-bhc%&"
2848This option operates in the same way as &%-bh%&, except that address
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2849verification callouts are performed if required. This includes consulting and
2850updating the callout cache database.
2851
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2852.vitem &%-bi%&
2853.oindex "&%-bi%&"
2854.cindex "alias file" "building"
2855.cindex "building alias file"
2856.cindex "Sendmail compatibility" "&%-bi%& option"
2857Sendmail interprets the &%-bi%& option as a request to rebuild its alias file.
168e428f 2858Exim does not have the concept of a single alias file, and so it cannot mimic
9b371988 2859this behaviour. However, calls to &_/usr/lib/sendmail_& with the &%-bi%& option
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2860tend to appear in various scripts such as NIS make files, so the option must be
2861recognized.
9b371988
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2862
2863If &%-bi%& is encountered, the command specified by the &%bi_command%&
168e428f 2864configuration option is run, under the uid and gid of the caller of Exim. If
9b371988
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2865the &%-oA%& option is used, its value is passed to the command as an argument.
2866The command set by &%bi_command%& may not contain arguments. The command can
2867use the &'exim_dbmbuild'& utility, or some other means, to rebuild alias files
2868if this is required. If the &%bi_command%& option is not set, calling Exim with
2869&%-bi%& is a no-op.
2870
2871.vitem &%-bm%&
2872.oindex "&%-bm%&"
2873.cindex "local message reception"
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2874This option runs an Exim receiving process that accepts an incoming,
2875locally-generated message on the current input. The recipients are given as the
9b371988 2876command arguments (except when &%-t%& is also present &-- see below). Each
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2877argument can be a comma-separated list of RFC 2822 addresses. This is the
2878default option for selecting the overall action of an Exim call; it is assumed
2879if no other conflicting option is present.
9b371988 2880
168e428f 2881If any addresses in the message are unqualified (have no domain), they are
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2882qualified by the values of the &%qualify_domain%& or &%qualify_recipient%&
2883options, as appropriate. The &%-bnq%& option (see below) provides a way of
168e428f 2884suppressing this for special cases.
9b371988 2885
168e428f 2886Policy checks on the contents of local messages can be enforced by means of
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2887the non-SMTP ACL. See chapter &<<CHAPACL>>& for details.
2888
2889.cindex "return code" "for &%-bm%&"
2890The return code is zero if the message is successfully accepted. Otherwise, the
2891action is controlled by the &%-oe%&&'x'& option setting &-- see below.
2892
168e428f 2893The format
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2894.cindex "message" "format"
2895.cindex "format" "message"
2896.cindex "&""From""& line"
2897.cindex "UUCP" "&""From""& line"
2898.cindex "Sendmail compatibility" "&""From""& line"
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2899of the message must be as defined in RFC 2822, except that, for
2900compatibility with Sendmail and Smail, a line in one of the forms
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2901.code
2902From sender Fri Jan 5 12:55 GMT 1997
2903From sender Fri, 5 Jan 97 12:55:01
2904.endd
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2905(with the weekday optional, and possibly with additional text after the date)
2906is permitted to appear at the start of the message. There appears to be no
2907authoritative specification of the format of this line. Exim recognizes it by
9b371988 2908matching against the regular expression defined by the &%uucp_from_pattern%&
168e428f 2909option, which can be changed if necessary.
9b371988 2910
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2911.oindex "&%-f%&" "overriding &""From""& line"
2912The specified sender is treated as if it were given as the argument to the
9b371988 2913&%-f%& option, but if a &%-f%& option is also present, its argument is used in
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2914preference to the address taken from the message. The caller of Exim must be a
2915trusted user for the sender of a message to be set in this way.
2916
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2917.vitem &%-bnq%&
2918.oindex "&%-bnq%&"
f89d2485 2919.cindex "address qualification, suppressing"
168e428f
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2920By default, Exim automatically qualifies unqualified addresses (those
2921without domains) that appear in messages that are submitted locally (that
2922is, not over TCP/IP). This qualification applies both to addresses in
2923envelopes, and addresses in header lines. Sender addresses are qualified using
9b371988
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2924&%qualify_domain%&, and recipient addresses using &%qualify_recipient%& (which
2925defaults to the value of &%qualify_domain%&).
2926
2927Sometimes, qualification is not wanted. For example, if &%-bS%& (batch SMTP) is
168e428f
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2928being used to re-submit messages that originally came from remote hosts after
2929content scanning, you probably do not want to qualify unqualified addresses in
2930header lines. (Such lines will be present only if you have not enabled a header
2931syntax check in the appropriate ACL.)
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2932
2933The &%-bnq%& option suppresses all qualification of unqualified addresses in
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2934messages that originate on the local host. When this is used, unqualified
2935addresses in the envelope provoke errors (causing message rejection) and
2936unqualified addresses in header lines are left alone.
2937
2938
9b371988
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2939.vitem &%-bP%&
2940.oindex "&%-bP%&"
595028e4 2941.cindex "configuration options" "extracting"
9b371988 2942.cindex "options" "configuration &-- extracting"
168e428f
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2943If this option is given with no arguments, it causes the values of all Exim's
2944main configuration options to be written to the standard output. The values
2945of one or more specific options can be requested by giving their names as
2946arguments, for example:
9b371988
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2947.code
2948exim -bP qualify_domain hold_domains
2949.endd
595028e4
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2950.cindex "hiding configuration option values"
2951.cindex "configuration options" "hiding value of"
2952.cindex "options" "hiding value of"
9b371988 2953However, any option setting that is preceded by the word &"hide"& in the
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2954configuration file is not shown in full, except to an admin user. For other
2955users, the output is as in this example:
9b371988
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2956.code
2957mysql_servers = <value not displayable>
2958.endd
2959If &%configure_file%& is given as an argument, the name of the run time
168e428f
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2960configuration file is output.
2961If a list of configuration files was supplied, the value that is output here
2962is the name of the file that was actually used.
168e428f 2963
9b371988
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2964.cindex "daemon" "process id (pid)"
2965.cindex "pid (process id)" "of daemon"
2966If &%log_file_path%& or &%pid_file_path%& are given, the names of the
2967directories where log files and daemon pid files are written are output,
2968respectively. If these values are unset, log files are written in a
2969sub-directory of the spool directory called &%log%&, and the pid file is
2970written directly into the spool directory.
2971
2972If &%-bP%& is followed by a name preceded by &`+`&, for example,
2973.code
2974exim -bP +local_domains
2975.endd
168e428f
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2976it searches for a matching named list of any type (domain, host, address, or
2977local part) and outputs what it finds.
9b371988
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2978
2979.cindex "options" "router &-- extracting"
2980.cindex "options" "transport &-- extracting"
2981If one of the words &%router%&, &%transport%&, or &%authenticator%& is given,
168e428f
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2982followed by the name of an appropriate driver instance, the option settings for
2983that driver are output. For example:
9b371988
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2984.code
2985exim -bP transport local_delivery
2986.endd
168e428f
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2987The generic driver options are output first, followed by the driver's private
2988options. A list of the names of drivers of a particular type can be obtained by
9b371988
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2989using one of the words &%router_list%&, &%transport_list%&, or
2990&%authenticator_list%&, and a complete list of all drivers with their option
2991settings can be obtained by using &%routers%&, &%transports%&, or
2992&%authenticators%&.
168e428f
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2993
2994
9b371988
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2995.vitem &%-bp%&
2996.oindex "&%-bp%&"
2997.cindex "queue" "listing messages on"
2998.cindex "listing" "messages on the queue"
168e428f 2999This option requests a listing of the contents of the mail queue on the
9b371988 3000standard output. If the &%-bp%& option is followed by a list of message ids,
168e428f 3001just those messages are listed. By default, this option can be used only by an
9b371988 3002admin user. However, the &%queue_list_requires_admin%& option can be set false
168e428f 3003to allow any user to see the queue.
168e428f 3004
9b371988
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3005Each message on the queue is displayed as in the following example:
3006.code
300725m 2.9K 0t5C6f-0000c8-00 <alice@wonderland.fict.example>
3008 red.king@looking-glass.fict.example
3009 <other addresses>
3010.endd
3011.cindex "message" "size in queue listing"
3012.cindex "size" "of message"
3013The first line contains the length of time the message has been on the queue
168e428f
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3014(in this case 25 minutes), the size of the message (2.9K), the unique local
3015identifier for the message, and the message sender, as contained in the
3016envelope. For bounce messages, the sender address is empty, and appears as
9b371988 3017&"<>"&. If the message was submitted locally by an untrusted user who overrode
168e428f
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3018the default sender address, the user's login name is shown in parentheses
3019before the sender address.
9b371988
PH
3020
3021.cindex "frozen messages" "in queue listing"
3022If the message is frozen (attempts to deliver it are suspended) then the text
3023&"*** frozen ***"& is displayed at the end of this line.
3024
168e428f
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3025The recipients of the message (taken from the envelope, not the headers) are
3026displayed on subsequent lines. Those addresses to which the message has already
3027been delivered are marked with the letter D. If an original address gets
3028expanded into several addresses via an alias or forward file, the original is
3029displayed with a D only when deliveries for all of its child addresses are
3030complete.
3031
3032
9b371988
PH
3033.vitem &%-bpa%&
3034.oindex "&%-bpa%&"
3035This option operates like &%-bp%&, but in addition it shows delivered addresses
168e428f 3036that were generated from the original top level address(es) in each message by
9b371988
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3037alias or forwarding operations. These addresses are flagged with &"+D"& instead
3038of just &"D"&.
168e428f
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3039
3040
9b371988
PH
3041.vitem &%-bpc%&
3042.oindex "&%-bpc%&"
3043.cindex "queue" "count of messages on"
168e428f
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3044This option counts the number of messages on the queue, and writes the total
3045to the standard output. It is restricted to admin users, unless
9b371988 3046&%queue_list_requires_admin%& is set false.
168e428f
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3047
3048
9b371988
PH
3049.vitem &%-bpr%&
3050.oindex "&%-bpr%&"
3051This option operates like &%-bp%&, but the output is not sorted into
168e428f
PH
3052chronological order of message arrival. This can speed it up when there are
3053lots of messages on the queue, and is particularly useful if the output is
3054going to be post-processed in a way that doesn't need the sorting.
3055
9b371988
PH
3056.vitem &%-bpra%&
3057.oindex "&%-bpra%&"
3058This option is a combination of &%-bpr%& and &%-bpa%&.
168e428f 3059
9b371988
PH
3060.vitem &%-bpru%&
3061.oindex "&%-bpru%&"
3062This option is a combination of &%-bpr%& and &%-bpu%&.
168e428f