Update test after debug message bug fix.
[exim.git] / doc / doc-docbook / spec.xfpt
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1. $Cambridge: exim/doc/doc-docbook/spec.xfpt,v 1.1 2006/02/01 11:01:02 ph10 Exp $
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.
8. /////////////////////////////////////////////////////////////////////////////
9
10.include stdflags
11.include stdmacs
12.docbook
13.book
14
15. /////////////////////////////////////////////////////////////////////////////
16. These definitions set some parameters and save some typing. Remember that
17. the <bookinfo> element must also be updated for each new edition.
18. /////////////////////////////////////////////////////////////////////////////
19
20.set ACL "access control lists (ACLs)"
21.set previousversion "4.50"
22.set version "4.60"
23
24
25. /////////////////////////////////////////////////////////////////////////////
26. Additional xfpt markup used by this document, over and above the default
27. provided in the xfpt library.
28. /////////////////////////////////////////////////////////////////////////////
29
30. --- Override the &$ flag to automatically insert a $ with the variable name
31
32.flag &$ $& "<varname>$" "</varname>"
33
34. --- Short flags for daggers in option headings. They will always be inside
35. --- an italic string, but we want the daggers to be roman.
36
37.flag &!! "</emphasis>&dagger;<emphasis>"
38.flag &!? "</emphasis>&Dagger;<emphasis>"
39
40. --- A macro for an Exim option definition heading, generating a one-line
41. --- table with four columns.
42
43.macro option
44.oindex "$1"
45.itable all 0 0 4 8* left 5* center 5* center 6* right
46.row "&%$1%&" "Use: &'$2'&" "Type: &'$3'&" "Default: &'$4'&"
47.endtable
48.endmacro
49
50. --- A macro for the common 2-column tables. The width of the first column
51. --- is suitable for the many tables at the start of the main options chapter;
52. --- the small number of other 2-column tables override it.
53
54.macro table2 190pt 300pt
55.itable none 0 0 2 $1 left $2 left
56.endmacro
57
58. --- Macros for the concept and option index entries
59
60.macro cindex
61&<indexterm role="concept">&
62&<primary>&$1&</primary>&
63.arg 2
64&<secondary>&$2&</secondary>&
65.endarg
66&</indexterm>&
67.endmacro
68
69.macro oindex
70&<indexterm role="option">&
71&<primary>&$1&</primary>&
72.arg 2
73&<secondary>&$2&</secondary>&
74.endarg
75&</indexterm>&
76.endmacro
77
78.macro index
79.echo "** Don't use .index; use .cindex or .oindex"
80.endmacro
81. ////////////////////////////////////////////////////////////////////////////
82
83
84. ////////////////////////////////////////////////////////////////////////////
85. The <bookinfo> element is removed from the XML before processing for Ascii
86. output formats.
87. ////////////////////////////////////////////////////////////////////////////
88
89.literal xml
90<bookinfo>
91<title>Specification of the Exim Mail Transfer Agent</title>
92<titleabbrev>The Exim MTA</titleabbrev>
93<date>05 January 2006</date>
94<author><firstname>Philip</firstname><surname>Hazel</surname></author>
95<authorinitials>PH</authorinitials>
96<affiliation><orgname>University of Cambridge Computing Service</orgname></affiliation>
97<address>New Museums Site, Pembroke Street, Cambridge CB2 3QH, England</address>
98<revhistory><revision>
99 <revnumber>4.60-1</revnumber>
100 <date>30 January 2006</date>
101 <authorinitials>PH</authorinitials>
102</revision></revhistory>
103<copyright><year>2006</year><holder>University of Cambridge</holder></copyright>
104</bookinfo>
105.literal off
106
107
108. /////////////////////////////////////////////////////////////////////////////
109. This chunk of literal XML implements index entries of the form "x, see y" and
110. "x, see also y". However, the DocBook DTD doesn't allow <indexterm> entries
111. at the top level, so we have to put the .chapter directive first.
112. /////////////////////////////////////////////////////////////////////////////
113
114.chapter "Introduction"
115.literal xml
116
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117<indexterm role="concept">
118 <primary>$1, $2, etc.</primary>
119 <see><emphasis>numerical variables</emphasis></see>
120</indexterm>
121<indexterm role="concept">
122 <primary>address</primary>
123 <secondary>rewriting</secondary>
124 <see><emphasis>rewriting</emphasis></see>
125</indexterm>
126<indexterm role="concept">
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127 <primary>Bounce Address Tag Validation</primary>
128 <see><emphasis>BATV</emphasis></see>
129</indexterm>
130<indexterm role="concept">
131 <primary>Client SMTP Authorization</primary>
132 <see><emphasis>CSA</emphasis></see>
133</indexterm>
134<indexterm role="concept">
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135 <primary>CR character</primary>
136 <see><emphasis>carriage return</emphasis></see>
137</indexterm>
138<indexterm role="concept">
139 <primary>CRL</primary>
140 <see><emphasis>certificate revocation list</emphasis></see>
141</indexterm>
142<indexterm role="concept">
143 <primary>delivery</primary>
144 <secondary>failure report</secondary>
145 <see><emphasis>bounce message</emphasis></see>
146</indexterm>
147<indexterm role="concept">
148 <primary>dialup</primary>
149 <see><emphasis>intermittently connected hosts</emphasis></see>
150</indexterm>
151<indexterm role="concept">
152 <primary>exiscan</primary>
153 <see><emphasis>content scanning</emphasis></see>
154</indexterm>
155<indexterm role="concept">
156 <primary>failover</primary>
157 <see><emphasis>fallback</emphasis></see>
158</indexterm>
159<indexterm role="concept">
160 <primary>fallover</primary>
161 <see><emphasis>fallback</emphasis></see>
162</indexterm>
163<indexterm role="concept">
164 <primary>filter</primary>
165 <secondary>Sieve</secondary>
166 <see><emphasis>Sieve filter</emphasis></see>
167</indexterm>
168<indexterm role="concept">
169 <primary>ident</primary>
170 <see><emphasis>RFC 1413</emphasis></see>
171</indexterm>
172<indexterm role="concept">
173 <primary>LF character</primary>
174 <see><emphasis>linefeed</emphasis></see>
175</indexterm>
176<indexterm role="concept">
177 <primary>maximum</primary>
178 <see><emphasis>limit</emphasis></see>
179</indexterm>
180<indexterm role="concept">
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181 <primary>monitor</primary>
182 <see><emphasis>Exim monitor</emphasis></see>
183</indexterm>
184<indexterm role="concept">
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185 <primary>no_<emphasis>xxx</emphasis></primary>
186 <see>entry for xxx</see>
187</indexterm>
188<indexterm role="concept">
189 <primary>NUL</primary>
190 <see><emphasis>binary zero</emphasis></see>
191</indexterm>
192<indexterm role="concept">
193 <primary>passwd file</primary>
194 <see><emphasis>/etc/passwd</emphasis></see>
195</indexterm>
196<indexterm role="concept">
197 <primary>process id</primary>
198 <see><emphasis>pid</emphasis></see>
199</indexterm>
200<indexterm role="concept">
201 <primary>RBL</primary>
202 <see><emphasis>DNS list</emphasis></see>
203</indexterm>
204<indexterm role="concept">
205 <primary>redirection</primary>
206 <see><emphasis>address redirection</emphasis></see>
207</indexterm>
208<indexterm role="concept">
209 <primary>return path</primary>
210 <seealso><emphasis>envelope sender</emphasis></seealso>
211</indexterm>
212<indexterm role="concept">
213 <primary>scanning</primary>
214 <see><emphasis>content scanning</emphasis></see>
215</indexterm>
216<indexterm role="concept">
217 <primary>SSL</primary>
218 <see><emphasis>TLS</emphasis></see>
219</indexterm>
220<indexterm role="concept">
221 <primary>string</primary>
222 <secondary>expansion</secondary>
223 <see><emphasis>expansion</emphasis></see>
224</indexterm>
225<indexterm role="concept">
226 <primary>top bit</primary>
227 <see><emphasis>8-bit characters</emphasis></see>
228</indexterm>
229<indexterm role="concept">
230 <primary>variables</primary>
231 <see><emphasis>expansion, variables</emphasis></see>
232</indexterm>
233<indexterm role="concept">
234 <primary>zero, binary</primary>
235 <see><emphasis>binary zero</emphasis></see>
236</indexterm>
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237
238.literal off
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239
240
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241. /////////////////////////////////////////////////////////////////////////////
242. This is the real start of the first chapter. See the comment above as to why
243. we can't have the .chapter line here.
244. chapter "Introduction"
245. /////////////////////////////////////////////////////////////////////////////
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246
247Exim is a mail transfer agent (MTA) for hosts that are running Unix or
248Unix-like operating systems. It was designed on the assumption that it would be
249run on hosts that are permanently connected to the Internet. However, it can be
250used on intermittently connected hosts with suitable configuration adjustments.
251
252Configuration files currently exist for the following operating systems: AIX,
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253BSD/OS (aka BSDI), Darwin (Mac OS X), DGUX, Dragonfly, FreeBSD, GNU/Hurd,
254GNU/Linux, HI-OSF (Hitachi), HI-UX, HP-UX, IRIX, MIPS RISCOS, NetBSD, OpenBSD,
255OpenUNIX, QNX, SCO, SCO SVR4.2 (aka UNIX-SV), Solaris (aka SunOS5), SunOS4,
256Tru64-Unix (formerly Digital UNIX, formerly DEC-OSF1), Ultrix, and Unixware.
257Some of these operating systems are no longer current and cannot easily be
258tested, so the configuration files may no longer work in practice.
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259
260There are also configuration files for compiling Exim in the Cygwin environment
261that can be installed on systems running Windows. However, this document does
262not contain any information about running Exim in the Cygwin environment.
263
264The terms and conditions for the use and distribution of Exim are contained in
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265the file &_NOTICE_&. Exim is distributed under the terms of the GNU General
266Public Licence, a copy of which may be found in the file &_LICENCE_&.
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267
268The use, supply or promotion of Exim for the purpose of sending bulk,
269unsolicited electronic mail is incompatible with the basic aims of the program,
270which revolve around the free provision of a service that enhances the quality
271of personal communications. The author of Exim regards indiscriminate
272mass-mailing as an antisocial, irresponsible abuse of the Internet.
273
274Exim owes a great deal to Smail 3 and its author, Ron Karr. Without the
275experience of running and working on the Smail 3 code, I could never have
276contemplated starting to write a new MTA. Many of the ideas and user interfaces
277were originally taken from Smail 3, though the actual code of Exim is entirely
278new, and has developed far beyond the initial concept.
279
280Many people, both in Cambridge and around the world, have contributed to the
281development and the testing of Exim, and to porting it to various operating
282systems. I am grateful to them all. The distribution now contains a file called
9b371988 283&_ACKNOWLEDGMENTS_&, in which I have started recording the names of
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284contributors.
285
286
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287.section "Exim documentation"
288.new
289.cindex "documentation"
290This edition of the Exim specification applies to version &version; of Exim.
291Substantive changes from the &previousversion; edition are marked in some
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292renditions of the document; this paragraph is so marked if the rendition is
293capable of showing a change indicator.
9b371988 294.wen
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295
296This document is very much a reference manual; it is not a tutorial. The reader
297is expected to have some familiarity with the SMTP mail transfer protocol and
298with general Unix system administration. Although there are some discussions
299and examples in places, the information is mostly organized in a way that makes
300it easy to look up, rather than in a natural order for sequential reading.
301Furthermore, the manual aims to cover every aspect of Exim in detail, including
302a number of rarely-used, special-purpose features that are unlikely to be of
303very wide interest.
304
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305.cindex "books about Exim"
306An &"easier"& discussion of Exim which provides more in-depth explanatory,
307introductory, and tutorial material can be found in a book entitled &'The Exim
308SMTP Mail Server'&, published by UIT Cambridge
309(&url(http://www.uit.co.uk/exim-book/)).
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310
311This book also contains a chapter that gives a general introduction to SMTP and
312Internet mail. Inevitably, however, the book is unlikely to be fully up-to-date
313with the latest release of Exim. (Note that the earlier book about Exim,
314published by O'Reilly, covers Exim 3, and many things have changed in Exim 4.)
315
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316.new
317.cindex "Debian" "information sources"
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318If you are using a Debian distribution of Exim, you will find information about
319Debian-specific features in the file
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320.display
321&_/usr/share/doc/exim4-base/README.Debian_&
322.endd
323The command &(man update-exim.conf)& is another source of Debian-specific
068aaea8 324information.
9b371988 325.wen
068aaea8 326
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327.cindex "&_doc/NewStuff_&"
328.cindex "&_doc/ChangeLog_&"
329.cindex "change log"
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330As the program develops, there may be features in newer versions that have not
331yet made it into this document, which is updated only when the most significant
332digit of the fractional part of the version number changes. Specifications of
333new features that are not yet in this manual are placed in the file
9b371988 334&_doc/NewStuff_& in the Exim distribution.
168e428f 335
9b371988 336Some features may be classified as &"experimental"&. These may change
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337incompatibly while they are developing, or even be withdrawn. For this reason,
338they are not documented in this manual. Information about experimental features
9b371988 339can be found in the file &_doc/experimental.txt_&.
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340
341All changes to the program (whether new features, bug fixes, or other kinds of
9b371988 342change) are noted briefly in the file called &_doc/ChangeLog_&.
168e428f 343
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344.cindex "&_doc/spec.txt_&"
345This specification itself is available as an ASCII file in &_doc/spec.txt_& so
346that it can easily be searched with a text editor. Other files in the &_doc_&
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347directory are:
348
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349.table2 100pt
350.row &_OptionLists.txt_& "list of all options in alphabetical order"
351.row &_dbm.discuss.txt_& "discussion about DBM libraries"
352.row &_exim.8_& "a man page of Exim's command line options"
353.row &_experimental.txt_& "documentation of experimental features"
354.row &_filter.txt_& "specification of the filter language"
355.row &_pcrepattern.txt_& "specification of PCRE regular expressions"
356.row &_pcretest.txt_& "specification of the PCRE testing program"
357.row &_Exim3.upgrade_& "upgrade notes from release 2 to release 3"
358.row &_Exim4.upgrade_& "upgrade notes from release 3 to release 4"
359.endtable
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360
361The main specification and the specification of the filtering language are also
362available in other formats (HTML, PostScript, PDF, and Texinfo). Section
9b371988 363&<<SECTavail>>& below tells you how to get hold of these.
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364
365
366
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367.section "FTP and web sites"
368.cindex "web site"
369.cindex "FTP site"
068aaea8 370The primary site for Exim source distributions is currently the University of
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371Cambridge's FTP site, whose contents are described in &'Where to find the Exim
372distribution'& below. In addition, there is a web site and an FTP site at
373&%exim.org%&. These are now also hosted at the University of Cambridge. The
374&%exim.org%& site was previously hosted for a number of years by Energis
375Squared, formerly Planet Online Ltd, whose support I gratefully acknowledge.
376
377.cindex "wiki"
378.cindex "FAQ"
168e428f 379As well as Exim distribution tar files, the Exim web site contains a number of
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380differently formatted versions of the documentation, including the FAQ in both
381text and HTML formats. The HTML version comes with a keyword-in-context index.
382A recent addition to the online information is the Exim wiki
383(&url(http://www.exim.org/eximwiki/)). We hope that this will make it easier
384for Exim users to contribute examples, tips, and know-how for the benefit of
385others.
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386
387
388
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389.section "Mailing lists"
390.cindex "mailing lists" "for Exim users"
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391The following are the three main Exim mailing lists:
392
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393.table2 140pt
394.row &'exim-users@exim.org'& "general discussion list"
395.row &'exim-dev@exim.org'& "discussion of bugs, enhancements, etc."
396.row &'exim-announce@exim.org'& "moderated, low volume announcements list"
397.endtable
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398
399You can subscribe to these lists, change your existing subscriptions, and view
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400or search the archives via the mailing lists link on the Exim home page.
401.cindex "Debian" "mailing list for"
402&new("If you are using a Debian distribution of Exim, you may wish to subscribe
403to the Debian-specific mailing list
404&'pkg-exim4-users@lists.alioth.debian.org'&.")
405.wen
406
407.section "Exim training"
408.cindex "training courses"
068aaea8 409From time to time (approximately annually at the time of writing), training
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410courses are run by the author of Exim in Cambridge, UK. Details of any
411forthcoming courses can be found on the web site
412&url(http://www-tus.csx.cam.ac.uk/courses/exim/).
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413
414
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415.section "Bug reports"
416.cindex "bug reports"
417.cindex "reporting bugs"
418Reports of obvious bugs should be emailed to &'bugs@exim.org'&. However, if you
419are unsure whether some behaviour is a bug or not, the best thing to do is to
420post a message to the &'exim-dev'& mailing list and have it discussed.
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421
422
423
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424.section "Where to find the Exim distribution" "SECTavail"
425.cindex "FTP site"
426.cindex "distribution" "ftp site"
168e428f 427The master ftp site for the Exim distribution is
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428.display
429&*ftp://ftp.csx.cam.ac.uk/pub/software/email/exim*&
430.endd
168e428f 431This is mirrored by
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432.display
433&*ftp://ftp.exim.org/pub/exim*&
434.endd
435The file references that follow are relative to the &_exim_& directories at
436these sites. There are now quite a number of independent mirror sites around
437the world. Those that I know about are listed in the file called &_Mirrors_&.
438
439Within the &_exim_& directory there are subdirectories called &_exim3_& (for
440previous Exim 3 distributions), &_exim4_& (for the latest Exim 4
441distributions), and &_Testing_& for testing versions. In the &_exim4_&
168e428f 442subdirectory, the current release can always be found in files called
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443.display
444&_exim-n.nn.tar.gz_&
445&_exim-n.nn.tar.bz2_&
446.endd
447where &'n.nn'& is the highest such version number in the directory. The two
168e428f 448files contain identical data; the only difference is the type of compression.
9b371988 449The &_.bz2_& file is usually a lot smaller than the &_.gz_& file.
168e428f 450
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451.cindex "distribution" "signing details"
452.cindex "distribution" "public key"
453.cindex "public key for signed distribution"
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454The distributions are currently signed with Philip Hazel's GPG key. The
455corresponding public key is available from a number of keyservers, and there is
9b371988 456also a copy in the file &_Public-Key_&. The signatures for the tar bundles are
168e428f 457in:
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458.display
459&_exim-n.nn.tar.gz.sig_&
460&_exim-n.nn.tar.bz2.sig_&
461.endd
168e428f 462For each released version, the log of changes is made separately available in a
9b371988 463separate file in the directory &_ChangeLogs_& so that it is possible to
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464find out what has changed without having to download the entire distribution.
465
9b371988 466.cindex "documentation" "available formats"
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467The main distribution contains ASCII versions of this specification and other
468documentation; other formats of the documents are available in separate files
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469inside the &_exim4_& directory of the FTP site:
470.display
471&_exim-html-n.nn.tar.gz_&
472&_exim-pdf-n.nn.tar.gz_&
473&_exim-postscript-n.nn.tar.gz_&
474&_exim-texinfo-n.nn.tar.gz_&
475.endd
476These tar files contain only the &_doc_& directory, not the complete
477distribution, and are also available in &_.bz2_& as well as &_.gz_& forms.
478.cindex "FAQ"
168e428f 479The FAQ is available for downloading in two different formats in these files:
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480.display
481&_exim4/FAQ.txt.gz_&
482&_exim4/FAQ.html.tar.gz_&
483.endd
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484The first of these is a single ASCII file that can be searched with a text
485editor. The second is a directory of HTML files, normally accessed by starting
9b371988 486at &_index.html_&. The HTML version of the FAQ (which is also included in the
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487HTML documentation tarbundle) includes a keyword-in-context index, which is
488often the most convenient way of finding your way around.
489
490
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491.section "Wish list"
492.cindex "wish list"
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493A wish list is maintained, containing ideas for new features that have been
494submitted. From time to time the file is exported to the ftp site into the file
9b371988 495&_exim4/WishList_&. Items are removed from the list if they get implemented.
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496
497
498
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499.section "Contributed material"
500.cindex "contributed material"
501At the ftp site, there is a directory called &_Contrib_& that contains
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502miscellaneous files contributed to the Exim community by Exim users. There is
503also a collection of contributed configuration examples in
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504&_exim4/config.samples.tar.gz_&. These samples are referenced from the FAQ.
505
506
507
508.section "Limitations"
509.ilist
510.cindex "limitations of Exim"
511.cindex "bang paths" "not handled by Exim"
512Exim is designed for use as an Internet MTA, and therefore handles addresses in
513RFC 2822 domain format only. It cannot handle UUCP &"bang paths"&, though
514simple two-component bang paths can be converted by a straightforward rewriting
515configuration. This restriction does not prevent Exim from being interfaced to
516UUCP as a transport mechanism, provided that domain addresses are used.
517.next
518.cindex "domainless addresses"
519.cindex "address" "without domain"
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520Exim insists that every address it handles has a domain attached. For incoming
521local messages, domainless addresses are automatically qualified with a
522configured domain value. Configuration options specify from which remote
523systems unqualified addresses are acceptable. These are then qualified on
524arrival.
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525.next
526.cindex "transport" "external"
527.cindex "external transports"
528The only external transport mechanisms that are currently implemented are SMTP
529and LMTP over a TCP/IP network (including support for IPv6). However, a pipe
168e428f 530transport is available, and there are facilities for writing messages to files
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531and pipes, optionally in &'batched SMTP'& format; these facilities can be used
532to send messages to other transport mechanisms such as UUCP, provided they can
533handle domain-style addresses. Batched SMTP input is also catered for.
534.next
535Exim is not designed for storing mail for dial-in hosts. When the volumes of
536such mail are large, it is better to get the messages &"delivered"& into files
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537(that is, off Exim's queue) and subsequently passed on to the dial-in hosts by
538other means.
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539.next
540Although Exim does have basic facilities for scanning incoming messages, these
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541are not comprehensive enough to do full virus or spam scanning. Such operations
542are best carried out using additional specialized software packages. If you
543compile Exim with the content-scanning extension, straightforward interfaces to
544a number of common scanners are provided.
9b371988 545.endlist
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546
547
9b371988 548.section "Run time configuration"
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549Exim's run time configuration is held in a single text file that is divided
550into a number of sections. The entries in this file consist of keywords and
551values, in the style of Smail 3 configuration files. A default configuration
552file which is suitable for simple online installations is provided in the
9b371988 553distribution, and is described in chapter &<<CHAPdefconfil>>& below.
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554
555
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556.section "Calling interface"
557.cindex "Sendmail compatibility" "command line interface"
168e428f 558Like many MTAs, Exim has adopted the Sendmail command line interface so that it
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559can be a straight replacement for &_/usr/lib/sendmail_& or
560&_/usr/sbin/sendmail_& when sending mail, but you do not need to know anything
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561about Sendmail in order to run Exim. For actions other than sending messages,
562Sendmail-compatible options also exist, but those that produce output (for
9b371988 563example, &%-bp%&, which lists the messages on the queue) do so in Exim's own
168e428f 564format. There are also some additional options that are compatible with Smail
9b371988 5653, and some further options that are new to Exim. Chapter &<<CHAPcommandline>>&
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566documents all Exim's command line options. This information is automatically
567made into the man page that forms part of the Exim distribution.
568
569Control of messages on the queue can be done via certain privileged command
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570line options. There is also an optional monitor program called &'eximon'&,
571which displays current information in an X window, and which contains a menu
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572interface to Exim's command line administration options.
573
574
575
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576.section "Terminology"
577.cindex "terminology definitions"
578.cindex "body of message" "definition of"
579The &'body'& of a message is the actual data that the sender wants to transmit.
580It is the last part of a message, and is separated from the &'header'& (see
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581below) by a blank line.
582
9b371988 583.cindex "bounce message" "definition of"
168e428f 584When a message cannot be delivered, it is normally returned to the sender in a
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585delivery failure message or a &"non-delivery report"& (NDR). The term
586&'bounce'& is commonly used for this action, and the error reports are often
587called &'bounce messages'&. This is a convenient shorthand for &"delivery
588failure error report"&. Such messages have an empty sender address in the
589message's &'envelope'& (see below) to ensure that they cannot themselves give
590rise to further bounce messages.
591
592The term &'default'& appears frequently in this manual. It is used to qualify a
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593value which is used in the absence of any setting in the configuration. It may
594also qualify an action which is taken unless a configuration setting specifies
595otherwise.
596
9b371988 597The term &'defer'& is used when the delivery of a message to a specific
168e428f 598destination cannot immediately take place for some reason (a remote host may be
9b371988 599down, or a user's local mailbox may be full). Such deliveries are &'deferred'&
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600until a later time.
601
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602The word &'domain'& is sometimes used to mean all but the first component of a
603host's name. It is &'not'& used in that sense here, where it normally refers to
604the part of an email address following the @ sign.
168e428f 605
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606.cindex "envelope" "definition of"
607.cindex "sender" "definition of"
608A message in transit has an associated &'envelope'&, as well as a header and a
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609body. The envelope contains a sender address (to which bounce messages should
610be delivered), and any number of recipient addresses. References to the
611sender or the recipients of a message usually mean the addresses in the
612envelope. An MTA uses these addresses for delivery, and for returning bounce
613messages, not the addresses that appear in the header lines.
614
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615.cindex "message header" "definition of"
616.cindex "header section" "definition of"
617The &'header'& of a message is the first part of a message's text, consisting
618of a number of lines, each of which has a name such as &'From:'&, &'To:'&,
619&'Subject:'&, etc. Long header lines can be split over several text lines by
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620indenting the continuations. The header is separated from the body by a blank
621line.
622
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623.cindex "local part" "definition of"
624.cindex "domain" "definition of"
625The term &'local part'&, which is taken from RFC 2822, is used to refer to that
168e428f 626part of an email address that precedes the @ sign. The part that follows the
9b371988 627@ sign is called the &'domain'& or &'mail domain'&.
168e428f 628
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629.cindex "local delivery" "definition of"
630.cindex "remote delivery" "definition of"
631The terms &'local delivery'& and &'remote delivery'& are used to distinguish
168e428f 632delivery to a file or a pipe on the local host from delivery by SMTP over
068aaea8 633TCP/IP to another host. As far as Exim is concerned, all hosts other than the
9b371988 634host it is running on are &'remote'&.
168e428f 635
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636.cindex "return path" "definition of"
637&'Return path'& is another name that is used for the sender address in a
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638message's envelope.
639
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640.cindex "queue" "definition of"
641The term &'queue'& is used to refer to the set of messages awaiting delivery,
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642because this term is in widespread use in the context of MTAs. However, in
643Exim's case the reality is more like a pool than a queue, because there is
644normally no ordering of waiting messages.
645
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646.cindex "queue runner" "definition of"
647The term &'queue runner'& is used to describe a process that scans the queue
168e428f 648and attempts to deliver those messages whose retry times have come. This term
9b371988 649is used by other MTAs, and also relates to the command &%runq%&, but in Exim
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650the waiting messages are normally processed in an unpredictable order.
651
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652.cindex "spool directory" "definition of"
653The term &'spool directory'& is used for a directory in which Exim keeps the
654messages on its queue &-- that is, those that it is in the process of
168e428f 655delivering. This should not be confused with the directory in which local
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656mailboxes are stored, which is called a &"spool directory"& by some people. In
657the Exim documentation, &"spool"& is always used in the first sense.
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658
659
660
661
662
663
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664. ////////////////////////////////////////////////////////////////////////////
665. ////////////////////////////////////////////////////////////////////////////
168e428f 666
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667.chapter "Incorporated code"
668.cindex "incorporated code"
669.cindex "regular expressions" "library"
670.cindex "PCRE"
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671A number of pieces of external code are included in the Exim distribution.
672
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673.ilist
674Regular expressions are supported in the main Exim program and in the Exim
675monitor using the freely-distributable PCRE library, copyright &copy;
676University of Cambridge. The source is distributed in the directory
677&_src/pcre_&. However, this is a cut-down version of PCRE. If you want to use
678the PCRE library in other programs, you should obtain and install the full
679version from &*ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre*&.
680.next
681.cindex "cdb" "acknowledgement"
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682Support for the cdb (Constant DataBase) lookup method is provided by code
683contributed by Nigel Metheringham of (at the time he contributed it) Planet
9b371988
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684Online Ltd. The implementation is completely contained within the code of Exim.
685It does not link against an external cdb library. The code contains the
686following statements:
687
688.blockquote
689Copyright &copy; 1998 Nigel Metheringham, Planet Online Ltd
690
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691This program is free software; you can redistribute it and/or modify it under
692the terms of the GNU General Public License as published by the Free Software
693Foundation; either version 2 of the License, or (at your option) any later
694version.
9b371988 695
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696This code implements Dan Bernstein's Constant DataBase (cdb) spec. Information,
697the spec and sample code for cdb can be obtained from
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698&url(http://www.pobox.com/~djb/cdb.html). This implementation borrows some
699code from Dan Bernstein's implementation (which has no license restrictions
700applied to it).
701.endblockquote
702.next
703.cindex "SPA authentication"
704.cindex "Samba project"
705.cindex "Microsoft Secure Password Authentication"
706Client support for Microsoft's &'Secure Password Authentication'& is provided
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707by code contributed by Marc Prud'hommeaux. Server support was contributed by
708Tom Kistner. This includes code taken from the Samba project, which is released
709under the Gnu GPL.
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710.next
711.cindex "Cyrus"
712.cindex "&'pwcheck'& daemon"
713.cindex "&'pwauthd'& daemon"
714Support for calling the Cyrus &'pwcheck'& and &'saslauthd'& daemons is provided
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715by code taken from the Cyrus-SASL library and adapted by Alexander S.
716Sabourenkov. The permission notice appears below, in accordance with the
717conditions expressed therein.
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718
719.blockquote
720Copyright &copy; 2001 Carnegie Mellon University. All rights reserved.
721
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722Redistribution and use in source and binary forms, with or without
723modification, are permitted provided that the following conditions
724are met:
168e428f 725
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726.olist
727Redistributions of source code must retain the above copyright
728notice, this list of conditions and the following disclaimer.
729.next
730Redistributions in binary form must reproduce the above copyright
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731notice, this list of conditions and the following disclaimer in
732the documentation and/or other materials provided with the
733distribution.
9b371988
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734.next
735The name &"Carnegie Mellon University"& must not be used to
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736endorse or promote products derived from this software without
737prior written permission. For permission or any other legal
738details, please contact
9b371988 739.display
068aaea8
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740 Office of Technology Transfer
741 Carnegie Mellon University
742 5000 Forbes Avenue
743 Pittsburgh, PA 15213-3890
744 (412) 268-4387, fax: (412) 268-7395
745 tech-transfer@andrew.cmu.edu
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746.endd
747.next
748Redistributions of any form whatsoever must retain the following
168e428f 749acknowledgment:
9b371988
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750
751&"This product includes software developed by Computing Services
752at Carnegie Mellon University (&url(http://www.cmu.edu/computing/)."&
753
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754CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO
755THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
756AND FITNESS, IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE
757FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
758WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
759AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
760OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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761.endlist
762.endblockquote
168e428f 763
9b371988
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764.next
765.cindex "Exim monitor" "acknowledgement"
766.cindex "X-windows"
767.cindex "Athena"
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768The Exim Monitor program, which is an X-Window application, includes
769modified versions of the Athena StripChart and TextPop widgets.
770This code is copyright by DEC and MIT, and their permission notice appears
771below, in accordance with the conditions expressed therein.
9b371988
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772
773.blockquote
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774Copyright 1987, 1988 by Digital Equipment Corporation, Maynard, Massachusetts,
775and the Massachusetts Institute of Technology, Cambridge, Massachusetts.
9b371988 776
168e428f 777All Rights Reserved
9b371988 778
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779Permission to use, copy, modify, and distribute this software and its
780documentation for any purpose and without fee is hereby granted,
781provided that the above copyright notice appear in all copies and that
782both that copyright notice and this permission notice appear in
783supporting documentation, and that the names of Digital or MIT not be
784used in advertising or publicity pertaining to distribution of the
785software without specific, written prior permission.
9b371988 786
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787DIGITAL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
788ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
789DIGITAL BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
790ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
791WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
792ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
793SOFTWARE.
9b371988 794.endblockquote
168e428f 795
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796.next
797Many people have contributed code fragments, some large, some small, that were
168e428f
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798not covered by any specific licence requirements. It is assumed that the
799contributors are happy to see their code incoporated into Exim under the GPL.
9b371988 800.endlist
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801
802
803
804
805
9b371988
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806. ////////////////////////////////////////////////////////////////////////////
807. ////////////////////////////////////////////////////////////////////////////
168e428f 808
9b371988
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809.chapter "How Exim receives and delivers mail" "" &&&
810 "Receiving and delivering mail"
168e428f
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811
812
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813.section "Overall philosophy"
814.cindex "design philosophy"
168e428f
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815Exim is designed to work efficiently on systems that are permanently connected
816to the Internet and are handling a general mix of mail. In such circumstances,
817most messages can be delivered immediately. Consequently, Exim does not
818maintain independent queues of messages for specific domains or hosts, though
819it does try to send several messages in a single SMTP connection after a host
820has been down, and it also maintains per-host retry information.
821
822
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823.section "Policy control"
824.cindex "policy control" "overview"
168e428f
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825Policy controls are now an important feature of MTAs that are connected to the
826Internet. Perhaps their most important job is to stop MTAs being abused as
9b371988
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827&"open relays"& by misguided individuals who send out vast amounts of
828unsolicited junk, and want to disguise its source. Exim provides flexible
829facilities for specifying policy controls on incoming mail:
168e428f 830
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831.ilist
832.cindex "&ACL;" "introduction"
168e428f 833Exim 4 (unlike previous versions of Exim) implements policy controls on
9b371988 834incoming mail by means of &'Access Control Lists'& (ACLs). Each list is a
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835series of statements that may either grant or deny access. ACLs can be used at
836several places in the SMTP dialogue while receiving a message from a remote
9b371988
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837host. However, the most common places are after each RCPT command, and at the
838very end of the message. The sysadmin can specify conditions for accepting or
839rejecting individual recipients or the entire message, respectively, at these
840two points (see chapter &<<CHAPACL>>&). Denial of access results in an SMTP
168e428f 841error code.
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842.next
843An ACL is also available for locally generated, non-SMTP messages. In this
168e428f 844case, the only available actions are to accept or deny the entire message.
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845.next
846When Exim is compiled with the content-scanning extension, facilities are
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847provided in the ACL mechanism for passing the message to external virus and/or
848spam scanning software. The result of such a scan is passed back to the ACL,
849which can then use it to decide what to do with the message.
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850.next
851When a message has been received, either from a remote host or from the local
168e428f 852host, but before the final acknowledgement has been sent, a locally supplied C
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853function called &[local_scan()]& can be run to inspect the message and decide
854whether to accept it or not (see chapter &<<CHAPlocalscan>>&). If the message
855is accepted, the list of recipients can be modified by the function.
856.next
857Using the &[local_scan()]& mechanism is another way of calling external scanner
858software. The &%SA-Exim%& add-on package works this way. It does not require
859Exim to be compiled with the content-scanning extension.
860.next
861After a message has been accepted, a further checking mechanism is available in
862the form of the &'system filter'& (see chapter &<<CHAPsystemfilter>>&). This
863runs at the start of every delivery process.
864.endlist
865
866
867
868.section "User filters"
869.cindex "filter" "introduction"
870.cindex "Sieve filter"
168e428f 871In a conventional Exim configuration, users are able to run private filters by
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872setting up appropriate &_.forward_& files in their home directories. See
873chapter &<<CHAPredirect>>& (about the &(redirect)& router) for the
874configuration needed to support this, and the separate document entitled
875&'Exim's interfaces to mail filtering'& for user details. Two different kinds
876of filtering are available:
877
878.ilist
879Sieve filters are written in the standard filtering language that is defined
168e428f 880by RFC 3028.
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881.next
882Exim filters are written in a syntax that is unique to Exim, but which is more
168e428f 883powerful than Sieve, which it pre-dates.
9b371988 884.endlist
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885
886User filters are run as part of the routing process, described below.
887
888
889
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890.section "Message identification" "SECTmessiden"
891.cindex "message ids" "details of format"
892.cindex "format" "of message id"
893.cindex "id of message"
894.cindex "base62"
895.cindex "base36"
896.cindex "Darwin"
897.cindex "Cygwin"
898Every message handled by Exim is given a &'message id'& which is sixteen
168e428f 899characters long. It is divided into three parts, separated by hyphens, for
9b371988 900example &`16VDhn-0001bo-D3`&. Each part is a sequence of letters and digits,
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901normally encoding numbers in base 62. However, in the Darwin operating
902system (Mac OS X) and when Exim is compiled to run under Cygwin, base 36
903(avoiding the use of lower case letters) is used instead, because the message
904id is used to construct file names, and the names of files in those systems are
068aaea8 905not always case-sensitive.
168e428f 906
9b371988 907.cindex "pid (process id)" "re-use of"
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908The detail of the contents of the message id have changed as Exim has evolved.
909Earlier versions relied on the operating system not re-using a process id (pid)
910within one second. On modern operating systems, this assumption can no longer
911be made, so the algorithm had to be changed. To retain backward compatibility,
912the format of the message id was retained, which is why the following rules are
913somewhat eccentric:
914
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915.ilist
916The first six characters of the message id are the time at which the message
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917started to be received, to a granularity of one second. That is, this field
918contains the number of seconds since the start of the epoch (the normal Unix
919way of representing the date and time of day).
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920.next
921After the first hyphen, the next six characters are the id of the process that
168e428f 922received the message.
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923.next
924There are two different possibilities for the final two characters:
925.olist
926.cindex "&%localhost_number%&"
927If &%localhost_number%& is not set, this value is the fractional part of the
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928time of reception, normally in units of 1/2000 of a second, but for systems
929that must use base 36 instead of base 62 (because of case-insensitive file
930systems), the units are 1/1000 of a second.
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931.next
932If &%localhost_number%& is set, it is multiplied by 200 (100) and added to
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933the fractional part of the time, which in this case is in units of 1/200
934(1/100) of a second.
9b371988
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935.endlist
936.endlist
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937
938After a message has been received, Exim waits for the clock to tick at the
939appropriate resolution before proceeding, so that if another message is
940received by the same process, or by another process with the same (re-used)
941pid, it is guaranteed that the time will be different. In most cases, the clock
942will already have ticked while the message was being received.
943
944
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945.section "Receiving mail"
946.cindex "receiving mail"
947.cindex "message" "reception"
068aaea8
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948The only way Exim can receive mail from another host is using SMTP over
949TCP/IP, in which case the sender and recipient addresses are transferred using
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950SMTP commands. However, from a locally running process (such as a user's MUA),
951there are several possibilities:
952
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953.ilist
954If the process runs Exim with the &%-bm%& option, the message is read
168e428f 955non-interactively (usually via a pipe), with the recipients taken from the
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956command line, or from the body of the message if &%-t%& is also used.
957.next
958If the process runs Exim with the &%-bS%& option, the message is also read
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959non-interactively, but in this case the recipients are listed at the start of
960the message in a series of SMTP RCPT commands, terminated by a DATA
9b371988 961command. This is so-called &"batch SMTP"& format,
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962but it isn't really SMTP. The SMTP commands are just another way of passing
963envelope addresses in a non-interactive submission.
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964.next
965If the process runs Exim with the &%-bs%& option, the message is read
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966interactively, using the SMTP protocol. A two-way pipe is normally used for
967passing data between the local process and the Exim process.
9b371988 968This is &"real"& SMTP and is handled in the same way as SMTP over TCP/IP. For
168e428f 969example, the ACLs for SMTP commands are used for this form of submission.
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970.next
971A local process may also make a TCP/IP call to the host's loopback address
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972(127.0.0.1) or any other of its IP addresses. When receiving messages, Exim
973does not treat the loopback address specially. It treats all such connections
974in the same way as connections from other hosts.
9b371988 975.endlist
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976
977
9b371988
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978.cindex "message sender" "constructed by Exim"
979.cindex "sender" "constructed by Exim"
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980In the three cases that do not involve TCP/IP, the sender address is
981constructed from the login name of the user that called Exim and a default
9b371988 982qualification domain (which can be set by the &%qualify_domain%& configuration
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983option). For local or batch SMTP, a sender address that is passed using the
984SMTP MAIL command is ignored. However, the system administrator may allow
9b371988 985certain users (&"trusted users"&) to specify a different sender address
168e428f 986unconditionally, or all users to specify certain forms of different sender
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987address. The &%-f%& option or the SMTP MAIL command is used to specify these
988different addresses. See section &<<SECTtrustedadmin>>& for details of trusted
989users, and the &%untrusted_set_sender%& option for a way of allowing untrusted
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990users to change sender addresses.
991
992Messages received by either of the non-interactive mechanisms are subject to
993checking by the non-SMTP ACL, if one is defined. Messages received using SMTP
994(either over TCP/IP, or interacting with a local process) can be checked by a
995number of ACLs that operate at different times during the SMTP session. Either
996individual recipients, or the entire message, can be rejected if local policy
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997requirements are not met. The &[local_scan()]& function (see chapter
998&<<CHAPlocalscan>>&) is run for all incoming messages.
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999
1000Exim can be configured not to start a delivery process when a message is
1001received; this can be unconditional, or depend on the number of incoming SMTP
1002connections or the system load. In these situations, new messages wait on the
1003queue until a queue runner process picks them up. However, in standard
1004configurations under normal conditions, delivery is started as soon as a
1005message is received.
1006
1007
1008
1009
1010
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1011.section "Handling an incoming message"
1012.cindex "spool directory" "files that hold a message"
1013.cindex "file" "how a message is held"
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1014When Exim accepts a message, it writes two files in its spool directory. The
1015first contains the envelope information, the current status of the message, and
1016the header lines, and the second contains the body of the message. The names of
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1017the two spool files consist of the message id, followed by &`-H`& for the
1018file containing the envelope and header, and &`-D`& for the data file.
168e428f 1019
9b371988 1020.cindex "spool directory" "&_input_& sub-directory"
168e428f 1021By default all these message files are held in a single directory called
9b371988 1022&_input_& inside the general Exim spool directory. Some operating systems do
168e428f 1023not perform very well if the number of files in a directory gets very large; to
9b371988 1024improve performance in such cases, the &%split_spool_directory%& option can be
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1025used. This causes Exim to split up the input files into 62 sub-directories
1026whose names are single letters or digits.
1027
1028The envelope information consists of the address of the message's sender and
1029the addresses of the recipients. This information is entirely separate from
1030any addresses contained in the header lines. The status of the message includes
1031a list of recipients who have already received the message. The format of the
9b371988 1032first spool file is described in chapter &<<CHAPspool>>&.
168e428f 1033
9b371988 1034.cindex "rewriting" "addresses"
168e428f 1035Address rewriting that is specified in the rewrite section of the configuration
9b371988 1036(see chapter &<<CHAPrewrite>>&) is done once and for all on incoming addresses,
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1037both in the header lines and the envelope, at the time the message is accepted.
1038If during the course of delivery additional addresses are generated (for
1039example, via aliasing), these new addresses are rewritten as soon as they are
1040generated. At the time a message is actually delivered (transported) further
1041rewriting can take place; because this is a transport option, it can be
1042different for different forms of delivery. It is also possible to specify the
1043addition or removal of certain header lines at the time the message is
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1044delivered (see chapters &<<CHAProutergeneric>>& and
1045&<<CHAPtransportgeneric>>&).
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1046
1047
1048
9b371988
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1049.section "Life of a message"
1050.cindex "message" "life of"
1051.cindex "message" "frozen"
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1052A message remains in the spool directory until it is completely delivered to
1053its recipients or to an error address, or until it is deleted by an
1054administrator or by the user who originally created it. In cases when delivery
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1055cannot proceed &-- for example, when a message can neither be delivered to its
1056recipients nor returned to its sender, the message is marked &"frozen"& on the
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1057spool, and no more deliveries are attempted.
1058
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1059.cindex "frozen messages" "thawing"
1060.cindex "message" "thawing frozen"
1061An administrator can &"thaw"& such messages when the problem has been
1062corrected, and can also freeze individual messages by hand if necessary. In
1063addition, an administrator can force a delivery error, causing a bounce message
1064to be sent.
1065
1066.new
1067.cindex "&%timeout_frozen_after%&"
1068.cindex "&%ignore_bounce_errors_after%&"
1069There are options called &%ignore_bounce_errors_after%& and
1070&%timeout_frozen_after%&, which discard frozen messages after a certain time.
068aaea8 1071The first applies only to frozen bounces, the second to any frozen messages.
9b371988 1072.wen
168e428f 1073
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1074.cindex "message" "log file for"
1075.cindex "log" "file for each message"
168e428f 1076While Exim is working on a message, it writes information about each delivery
068aaea8 1077attempt to its main log file. This includes successful, unsuccessful, and
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1078delayed deliveries for each recipient (see chapter &<<CHAPlog>>&). The log
1079lines are also written to a separate &'message log'& file for each message.
1080These logs are solely for the benefit of the administrator, and are normally
1081deleted along with the spool files when processing of a message is complete.
168e428f 1082The use of individual message logs can be disabled by setting
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1083&%no_message_logs%&; this might give an improvement in performance on very busy
1084systems.
168e428f 1085
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1086.cindex "journal file"
1087.cindex "file" "journal"
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1088All the information Exim itself needs to set up a delivery is kept in the first
1089spool file, along with the header lines. When a successful delivery occurs, the
1090address is immediately written at the end of a journal file, whose name is the
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1091message id followed by &`-J`&. At the end of a delivery run, if there are some
1092addresses left to be tried again later, the first spool file (the &`-H`& file)
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1093is updated to indicate which these are, and the journal file is then deleted.
1094Updating the spool file is done by writing a new file and renaming it, to
1095minimize the possibility of data loss.
1096
1097Should the system or the program crash after a successful delivery but before
1098the spool file has been updated, the journal is left lying around. The next
1099time Exim attempts to deliver the message, it reads the journal file and
1100updates the spool file before proceeding. This minimizes the chances of double
1101deliveries caused by crashes.
1102
1103
1104
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1105.section "Processing an address for delivery" "SECTprocaddress"
1106.cindex "drivers" "definition of"
1107.cindex "router" "definition of"
1108.cindex "transport" "definition of"
1109The main delivery processing elements of Exim are called &'routers'& and
1110&'transports'&, and collectively these are known as &'drivers'&. Code for a
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1111number of them is provided in the source distribution, and compile-time options
1112specify which ones are included in the binary. Run time options specify which
1113ones are actually used for delivering messages.
1114
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1115.cindex "drivers" "instance definition"
1116Each driver that is specified in the run time configuration is an &'instance'&
168e428f 1117of that particular driver type. Multiple instances are allowed; for example,
9b371988 1118you can set up several different &(smtp)& transports, each with different
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1119option values that might specify different ports or different timeouts. Each
1120instance has its own identifying name. In what follows we will normally use the
1121instance name when discussing one particular instance (that is, one specific
1122configuration of the driver), and the generic driver name when discussing
1123the driver's features in general.
1124
9b371988 1125A &'router'& is a driver that operates on an address, either determining how
068aaea8 1126its delivery should happen, by assigning it to a specific transport, or
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1127converting the address into one or more new addresses (for example, via an
1128alias file). A router may also explicitly choose to fail an address, causing it
1129to be bounced.
1130
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1131A &'transport'& is a driver that transmits a copy of the message from Exim's
1132spool to some destination. There are two kinds of transport: for a &'local'&
168e428f 1133transport, the destination is a file or a pipe on the local host, whereas for a
9b371988 1134&'remote'& transport the destination is some other host. A message is passed
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1135to a specific transport as a result of successful routing. If a message has
1136several recipients, it may be passed to a number of different transports.
1137
9b371988 1138.cindex "preconditions" "definition of"
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1139An address is processed by passing it to each configured router instance in
1140turn, subject to certain preconditions, until a router accepts the address or
1141specifies that it should be bounced. We will describe this process in more
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1142detail shortly. First, as a simple example, we consider how each recipient
1143address in a message is processed in a small configuration of three routers.
168e428f 1144
068aaea8 1145To make this a more concrete example, it is described in terms of some actual
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1146routers, but remember, this is only an example. You can configure Exim's
1147routers in many different ways, and there may be any number of routers in a
1148configuration.
1149
1150The first router that is specified in a configuration is often one that handles
1151addresses in domains that are not recognized specially by the local host. These
1152are typically addresses for arbitrary domains on the Internet. A precondition
1153is set up which looks for the special domains known to the host (for example,
9b371988 1154its own domain name), and the router is run for addresses that do &'not'&
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1155match. Typically, this is a router that looks up domains in the DNS in order to
1156find the hosts to which this address routes. If it succeeds, the address is
068aaea8 1157assigned to a suitable SMTP transport; if it does not succeed, the router is
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1158configured to fail the address.
1159
068aaea8 1160The second router is reached only when the domain is recognized as one that
9b371988 1161&"belongs"& to the local host. This router does redirection &-- also known as
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1162aliasing and forwarding. When it generates one or more new addresses from the
1163original, each of them is routed independently from the start. Otherwise, the
1164router may cause an address to fail, or it may simply decline to handle the
1165address, in which case the address is passed to the next router.
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1166
1167The final router in many configurations is one that checks to see if the
1168address belongs to a local mailbox. The precondition may involve a check to
1169see if the local part is the name of a login account, or it may look up the
1170local part in a file or a database. If its preconditions are not met, or if
1171the router declines, we have reached the end of the routers. When this happens,
1172the address is bounced.
1173
1174
1175
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1176.section "Processing an address for verification"
1177.cindex "router" "for verification"
1178.cindex "verifying address" "overview"
168e428f 1179As well as being used to decide how to deliver to an address, Exim's routers
9b371988 1180are also used for &'address verification'&. Verification can be requested as
168e428f 1181one of the checks to be performed in an ACL for incoming messages, on both
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1182sender and recipient addresses, and it can be tested using the &%-bv%& and
1183&%-bvs%& command line options.
168e428f 1184
9b371988 1185When an address is being verified, the routers are run in &"verify mode"&. This
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1186does not affect the way the routers work, but it is a state that can be
1187detected. By this means, a router can be skipped or made to behave differently
1188when verifying. A common example is a configuration in which the first router
1189sends all messages to a message-scanning program, unless they have been
1190previously scanned. Thus, the first router accepts all addresses without any
9b371988 1191checking, making it useless for verifying. Normally, the &%no_verify%& option
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1192would be set for such a router, causing it to be skipped in verify mode.
1193
1194
1195
1196
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1197.section "Running an individual router" "SECTrunindrou"
1198.cindex "router" "running details"
1199.cindex "preconditions" "checking"
1200.cindex "router" "result of running"
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1201As explained in the example above, a number of preconditions are checked before
1202running a router. If any are not met, the router is skipped, and the address is
9b371988 1203passed to the next router. When all the preconditions on a router &'are'& met,
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1204the router is run. What happens next depends on the outcome, which is one of
1205the following:
1206
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1207.ilist
1208&'accept'&: The router accepts the address, and either assigns it to a
1209transport, or generates one or more &"child"& addresses. Processing the
1210original address ceases,
1211.cindex "&%unseen%& option"
1212unless the &%unseen%& option is set on the router. This option
168e428f 1213can be used to set up multiple deliveries with different routing (for example,
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1214for keeping archive copies of messages). When &%unseen%& is set, the address is
1215passed to the next router. Normally, however, an &'accept'& return marks the
168e428f 1216end of routing.
9b371988 1217
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1218Any child addresses generated by the router are processed independently,
1219starting with the first router by default. It is possible to change this by
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1220setting the &%redirect_router%& option to specify which router to start at for
1221child addresses. Unlike &%pass_router%& (see below) the router specified by
1222&%redirect_router%& may be anywhere in the router configuration.
1223.next
1224&'pass'&: The router recognizes the address, but cannot handle it itself. It
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1225requests that the address be passed to another router. By default the address
1226is passed to the next router, but this can be changed by setting the
9b371988 1227&%pass_router%& option. However, (unlike &%redirect_router%&) the named router
168e428f 1228must be below the current router (to avoid loops).
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1229.next
1230&'decline'&: The router declines to accept the address because it does not
168e428f 1231recognize it at all. By default, the address is passed to the next router, but
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1232this can be prevented by setting the &%no_more%& option. When &%no_more%& is
1233set, all the remaining routers are skipped. In effect, &%no_more%& converts
1234&'decline'& into &'fail'&.
1235.next
1236&'fail'&: The router determines that the address should fail, and queues it for
168e428f 1237the generation of a bounce message. There is no further processing of the
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1238original address unless &%unseen%& is set on the router.
1239.next
1240&'defer'&: The router cannot handle the address at the present time. (A
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1241database may be offline, or a DNS lookup may have timed out.) No further
1242processing of the address happens in this delivery attempt. It is tried again
1243next time the message is considered for delivery.
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1244.next
1245&'error'&: There is some error in the router (for example, a syntax error in
168e428f 1246its configuration). The action is as for defer.
9b371988 1247.endlist
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1248
1249If an address reaches the end of the routers without having been accepted by
068aaea8 1250any of them, it is bounced as unrouteable. The default error message in this
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1251situation is &"unrouteable address"&, but you can set your own message by
1252making use of the &%cannot_route_message%& option. This can be set for any
1253router; the value from the last router that &"saw"& the address is used.
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1254
1255Sometimes while routing you want to fail a delivery when some conditions are
1256met but others are not, instead of passing the address on for further routing.
1257You can do this by having a second router that explicitly fails the delivery
9b371988 1258when the relevant conditions are met. The &(redirect)& router has a &"fail"&
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1259facility for this purpose.
1260
1261
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1262.section "Duplicate addresses"
1263.new
1264.cindex "case of local parts"
1265.cindex "address duplicate" "discarding"
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1266Once routing is complete, Exim scans the addresses that are assigned to local
1267and remote transports, and discards any duplicates that it finds. During this
1268check, local parts are treated as case-sensitive.
9b371988 1269.wen
068aaea8 1270
168e428f 1271
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1272.section "Router preconditions" "SECTrouprecon"
1273.cindex "router preconditions" "order of processing"
1274.cindex "preconditions" "order of processing"
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1275The preconditions that are tested for each router are listed below, in the
1276order in which they are tested. The individual configuration options are
9b371988 1277described in more detail in chapter &<<CHAProutergeneric>>&.
168e428f 1278
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1279.ilist
1280The &%local_part_prefix%& and &%local_part_suffix%& options can specify that
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1281the local parts handled by the router may or must have certain prefixes and/or
1282suffixes. If a mandatory affix (prefix or suffix) is not present, the router is
1283skipped. These conditions are tested first. When an affix is present, it is
1284removed from the local part before further processing, including the evaluation
1285of any other conditions.
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1286.next
1287Routers can be designated for use only when not verifying an address, that is,
168e428f 1288only when routing it for delivery (or testing its delivery routing). If the
9b371988 1289&%verify%& option is set false, the router is skipped when Exim is verifying an
168e428f 1290address.
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1291Setting the &%verify%& option actually sets two options, &%verify_sender%& and
1292&%verify_recipient%&, which independently control the use of the router for
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1293sender and recipient verification. You can set these options directly if
1294you want a router to be used for only one type of verification.
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1295.next
1296If the &%address_test%& option is set false, the router is skipped when Exim is
1297run with the &%-bt%& option to test an address routing. This can be helpful
1298when the first router sends all new messages to a scanner of some sort; it
1299makes it possible to use &%-bt%& to test subsequent delivery routing without
1300having to simulate the effect of the scanner.
1301.next
1302Routers can be designated for use only when verifying an address, as
1303opposed to routing it for delivery. The &%verify_only%& option controls this.
1304.next
1305Individual routers can be explicitly skipped when running the routers to
1306check an address given in the SMTP EXPN command (see the &%expn%& option).
1307.next
1308If the &%domains%& option is set, the domain of the address must be in the set
068aaea8 1309of domains that it defines.
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1310.next
1311.cindex "&$local_part_prefix$&"
1312.cindex "&$local_part$&"
1313.cindex "&$local_part_suffix$&"
1314If the &%local_parts%& option is set, the local part of the address must be in
1315the set of local parts that it defines. If &%local_part_prefix%& or
1316&%local_part_suffix%& is in use, the prefix or suffix is removed from the local
168e428f 1317part before this check. If you want to do precondition tests on local parts
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1318that include affixes, you can do so by using a &%condition%& option (see below)
1319that uses the variables &$local_part$&, &$local_part_prefix$&, and
1320&$local_part_suffix$& as necessary.
1321.next
1322.cindex "&$local_user_uid$&"
1323.cindex "&$local_user_gid$&"
1324.cindex "&$home$&"
1325If the &%check_local_user%& option is set, the local part must be the name of
068aaea8 1326an account on the local host. If this check succeeds, the uid and gid of the
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1327local user are placed in &$local_user_uid$& and &$local_user_gid$& and the
1328user's home directory is placed in &$home$&; these values can be used in the
1329remaining preconditions.
1330.next
1331If the &%router_home_directory%& option is set, it is expanded at this point,
1332because it overrides the value of &$home$&. If this expansion were left till
1333later, the value of &$home$& as set by &%check_local_user%& would be used in
1334subsequent tests. Having two different values of &$home$& in the same router
168e428f 1335could lead to confusion.
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1336.next
1337If the &%senders%& option is set, the envelope sender address must be in the
1338set of addresses that it defines.
1339.next
1340If the &%require_files%& option is set, the existence or non-existence of
168e428f 1341specified files is tested.
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1342.next
1343.cindex "customizing" "precondition"
1344If the &%condition%& option is set, it is evaluated and tested. This option
1345uses an expanded string to allow you to set up your own custom preconditions.
1346Expanded strings are described in chapter &<<CHAPexpand>>&.
1347.endlist
168e428f 1348
168e428f 1349
9b371988
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1350Note that &%require_files%& comes near the end of the list, so you cannot use
1351it to check for the existence of a file in which to lookup up a domain, local
168e428f 1352part, or sender. However, as these options are all expanded, you can use the
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1353&%exists%& expansion condition to make such tests within each condition. The
1354&%require_files%& option is intended for checking files that the router may be
168e428f 1355going to use internally, or which are needed by a specific transport (for
9b371988 1356example, &_.procmailrc_&).
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1357
1358
1359
9b371988
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1360.section "Delivery in detail"
1361.cindex "delivery" "in detail"
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1362When a message is to be delivered, the sequence of events is as follows:
1363
9b371988
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1364.ilist
1365If a system-wide filter file is specified, the message is passed to it. The
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1366filter may add recipients to the message, replace the recipients, discard the
1367message, cause a new message to be generated, or cause the message delivery to
1368fail. The format of the system filter file is the same as for Exim user filter
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1369files, described in the separate document entitled &'Exim's interfaces to mail
1370filtering'&.
1371.cindex "Sieve filter" "not available for system filter"
1372(&*Note*&: Sieve cannot be used for system filter files.)
1373
1374Some additional features are available in system filters &-- see chapter
1375&<<CHAPsystemfilter>>& for details. Note that a message is passed to the system
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1376filter only once per delivery attempt, however many recipients it has. However,
1377if there are several delivery attempts because one or more addresses could not
1378be immediately delivered, the system filter is run each time. The filter
9b371988 1379condition &%first_delivery%& can be used to detect the first run of the system
168e428f 1380filter.
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1381.next
1382Each recipient address is offered to each configured router in turn, subject to
1383its preconditions, until one is able to handle it. If no router can handle the
1384address, that is, if they all decline, the address is failed. Because routers
1385can be targeted at particular domains, several locally handled domains can be
1386processed entirely independently of each other.
1387.next
1388.cindex "routing" "loops in"
1389.cindex "loop" "while routing"
1390A router that accepts an address may assign it to a local or a remote
1391transport. However, the transport is not run at this time. Instead, the address
1392is placed on a list for the particular transport, which will be run later.
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1393Alternatively, the router may generate one or more new addresses (typically
1394from alias, forward, or filter files). New addresses are fed back into this
1395process from the top, but in order to avoid loops, a router ignores any address
1396which has an identically-named ancestor that was processed by itself.
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1397.next
1398When all the routing has been done, addresses that have been successfully
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1399handled are passed to their assigned transports. When local transports are
1400doing real local deliveries, they handle only one address at a time, but if a
1401local transport is being used as a pseudo-remote transport (for example, to
1402collect batched SMTP messages for transmission by some other means) multiple
1403addresses can be handled. Remote transports can always handle more than one
1404address at a time, but can be configured not to do so, or to restrict multiple
1405addresses to the same domain.
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1406.next
1407Each local delivery to a file or a pipe runs in a separate process under a
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1408non-privileged uid, and these deliveries are run one at a time. Remote
1409deliveries also run in separate processes, normally under a uid that is private
9b371988 1410to Exim (&"the Exim user"&), but in this case, several remote deliveries can be
168e428f 1411run in parallel. The maximum number of simultaneous remote deliveries for any
9b371988 1412one message is set by the &%remote_max_parallel%& option.
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1413The order in which deliveries are done is not defined, except that all local
1414deliveries happen before any remote deliveries.
9b371988
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1415.next
1416.cindex "queue runner"
168e428f
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1417When it encounters a local delivery during a queue run, Exim checks its retry
1418database to see if there has been a previous temporary delivery failure for the
1419address before running the local transport. If there was a previous failure,
1420Exim does not attempt a new delivery until the retry time for the address is
1421reached. However, this happens only for delivery attempts that are part of a
1422queue run. Local deliveries are always attempted when delivery immediately
1423follows message reception, even if retry times are set for them. This makes for
1424better behaviour if one particular message is causing problems (for example,
1425causing quota overflow, or provoking an error in a filter file).
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1426.next
1427.cindex "delivery" "retry in remote transports"
168e428f
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1428Remote transports do their own retry handling, since an address may be
1429deliverable to one of a number of hosts, each of which may have a different
1430retry time. If there have been previous temporary failures and no host has
1431reached its retry time, no delivery is attempted, whether in a queue run or
9b371988
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1432not. See chapter &<<CHAPretry>>& for details of retry strategies.
1433.next
1434If there were any permanent errors, a bounce message is returned to an
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1435appropriate address (the sender in the common case), with details of the error
1436for each failing address. Exim can be configured to send copies of bounce
1437messages to other addresses.
9b371988
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1438.next
1439.cindex "delivery" "deferral"
168e428f
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1440If one or more addresses suffered a temporary failure, the message is left on
1441the queue, to be tried again later. Delivery of these addresses is said to be
9b371988
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1442&'deferred'&.
1443.next
1444When all the recipient addresses have either been delivered or bounced,
168e428f
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1445handling of the message is complete. The spool files and message log are
1446deleted, though the message log can optionally be preserved if required.
9b371988 1447.endlist
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1448
1449
1450
1451
9b371988
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1452.section "Retry mechanism"
1453.cindex "delivery" "retry mechanism"
1454.cindex "retry" "description of mechanism"
1455.cindex "queue runner"
168e428f
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1456Exim's mechanism for retrying messages that fail to get delivered at the first
1457attempt is the queue runner process. You must either run an Exim daemon that
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1458uses the &%-q%& option with a time interval to start queue runners at regular
1459intervals, or use some other means (such as &'cron'&) to start them. If you do
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1460not arrange for queue runners to be run, messages that fail temporarily at the
1461first attempt will remain on your queue for ever. A queue runner process works
068aaea8 1462its way through the queue, one message at a time, trying each delivery that has
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1463passed its retry time.
1464You can run several queue runners at once.
1465
1466Exim uses a set of configured rules to determine when next to retry the failing
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1467address (see chapter &<<CHAPretry>>&). These rules also specify when Exim
1468should give up trying to deliver to the address, at which point it generates a
1469bounce message. If no retry rules are set for a particular host, address, and
1470error combination, no retries are attempted, and temporary errors are treated
1471as permanent.
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1472
1473
1474
9b371988
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1475.section "Temporary delivery failure"
1476.cindex "delivery" "temporary failure"
168e428f
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1477There are many reasons why a message may not be immediately deliverable to a
1478particular address. Failure to connect to a remote machine (because it, or the
1479connection to it, is down) is one of the most common. Temporary failures may be
1480detected during routing as well as during the transport stage of delivery.
1481Local deliveries may be delayed if NFS files are unavailable, or if a mailbox
1482is on a file system where the user is over quota. Exim can be configured to
1483impose its own quotas on local mailboxes; where system quotas are set they will
1484also apply.
1485
1486If a host is unreachable for a period of time, a number of messages may be
1487waiting for it by the time it recovers, and sending them in a single SMTP
1488connection is clearly beneficial. Whenever a delivery to a remote host is
1489deferred,
1490
9b371988 1491.cindex "hints database"
168e428f
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1492Exim makes a note in its hints database, and whenever a successful
1493SMTP delivery has happened, it looks to see if any other messages are waiting
1494for the same host. If any are found, they are sent over the same SMTP
1495connection, subject to a configuration limit as to the maximum number in any
1496one connection.
1497
1498
1499
1500
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1501.section "Permanent delivery failure"
1502.cindex "delivery" "permanent failure"
1503.cindex "bounce message" "when generated"
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1504When a message cannot be delivered to some or all of its intended recipients, a
1505bounce message is generated. Temporary delivery failures turn into permanent
1506errors when their timeout expires. All the addresses that fail in a given
1507delivery attempt are listed in a single message. If the original message has
1508many recipients, it is possible for some addresses to fail in one delivery
1509attempt and others to fail subsequently, giving rise to more than one bounce
1510message. The wording of bounce messages can be customized by the administrator.
9b371988 1511See chapter &<<CHAPemsgcust>>& for details.
168e428f 1512
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1513.cindex "&'X-Failed-Recipients:'& header line"
1514Bounce messages contain an &'X-Failed-Recipients:'& header line that lists the
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1515failed addresses, for the benefit of programs that try to analyse such messages
1516automatically.
1517
9b371988 1518.cindex "bounce message" "recipient of"
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1519A bounce message is normally sent to the sender of the original message, as
1520obtained from the message's envelope. For incoming SMTP messages, this is the
9b371988
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1521address given in the MAIL command. However, when an address is expanded via a
1522forward or alias file, an alternative address can be specified for delivery
1523failures of the generated addresses. For a mailing list expansion (see section
1524&<<SECTmailinglists>>&) it is common to direct bounce messages to the manager
1525of the list.
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1526
1527
1528
9b371988
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1529.section "Failures to deliver bounce messages"
1530.cindex "bounce message" "failure to deliver"
168e428f
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1531If a bounce message (either locally generated or received from a remote host)
1532itself suffers a permanent delivery failure, the message is left on the queue,
1533but it is frozen, awaiting the attention of an administrator. There are options
068aaea8 1534that can be used to make Exim discard such failed messages, or to keep them
9b371988
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1535for only a short time (see &%timeout_frozen_after%& and
1536&%ignore_bounce_errors_after%&).
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1537
1538
1539
1540
1541
9b371988
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1542. ////////////////////////////////////////////////////////////////////////////
1543. ////////////////////////////////////////////////////////////////////////////
168e428f 1544
9b371988
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1545.chapter "Building and installing Exim"
1546.cindex "building Exim"
168e428f 1547
9b371988 1548.section "Unpacking"
168e428f
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1549Exim is distributed as a gzipped or bzipped tar file which, when upacked,
1550creates a directory with the name of the current release (for example,
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1551&_exim-&version;_&) into which the following files are placed:
1552
1553.table2 140pt
1554.row &_ACKNOWLEDGMENTS_& "contains some acknowledgments"
1555.row &_CHANGES_& "contains a reference to where changes are documented"
1556.row &_LICENCE_& "the GNU General Public Licence"
1557.row &_Makefile_& "top-level make file"
1558.row &_NOTICE_& "conditions for the use of Exim"
1559.row &_README_& "list of files, directories and simple build &&&
1560 instructions"
1561.endtable
1562
1563Other files whose names begin with &_README_& may also be present. The
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1564following subdirectories are created:
1565
9b371988
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1566.table2 140pt
1567.row &_Local_& "an empty directory for local configuration files"
1568.row &_OS_& "OS-specific files"
1569.row &_doc_& "documentation files"
1570.row &_exim_monitor_& "source files for the Exim monitor"
1571.row &_scripts_& "scripts used in the build process"
1572.row &_src_& "remaining source files"
1573.row &_util_& "independent utilities"
1574.endtable
1575
1576The main utility programs are contained in the &_src_& directory, and are built
1577with the Exim binary. The &_util_& directory contains a few optional scripts
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1578that may be useful to some sites.
1579
1580
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1581.section "Multiple machine architectures and operating systems"
1582.cindex "building Exim" "multiple OS/architectures"
168e428f
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1583The building process for Exim is arranged to make it easy to build binaries for
1584a number of different architectures and operating systems from the same set of
9b371988
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1585source files. Compilation does not take place in the &_src_& directory.
1586Instead, a &'build directory'& is created for each architecture and operating
1587system.
1588.cindex "symbolic link" "to build directory"
168e428f 1589Symbolic links to the sources are installed in this directory, which is where
9b371988
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1590the actual building takes place. In most cases, Exim can discover the machine
1591architecture and operating system for itself, but the defaults can be
1592overridden if necessary.
168e428f 1593
168e428f 1594
9b371988
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1595.section "DBM libraries" "SECTdb"
1596.cindex "DBM libraries" "discussion of"
1597.cindex "hints database" "DBM files used for"
168e428f
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1598Even if you do not use any DBM files in your configuration, Exim still needs a
1599DBM library in order to operate, because it uses indexed files for its hints
1600databases. Unfortunately, there are a number of DBM libraries in existence, and
1601different operating systems often have different ones installed.
1602
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1603.cindex "Solaris" "DBM library for"
1604.cindex "IRIX" "DBM library for"
1605.cindex "BSD" "DBM library for"
1606.cindex "Linux" "DBM library for"
168e428f
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1607If you are using Solaris, IRIX, one of the modern BSD systems, or a modern
1608Linux distribution, the DBM configuration should happen automatically, and you
1609may be able to ignore this section. Otherwise, you may have to learn more than
1610you would like about DBM libraries from what follows.
1611
9b371988 1612.cindex "&'ndbm'& DBM library"
168e428f 1613Licensed versions of Unix normally contain a library of DBM functions operating
9b371988 1614via the &'ndbm'& interface, and this is what Exim expects by default. Free
168e428f
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1615versions of Unix seem to vary in what they contain as standard. In particular,
1616some early versions of Linux have no default DBM library, and different
1617distributors have chosen to bundle different libraries with their packaged
1618versions. However, the more recent releases seem to have standardised on the
1619Berkeley DB library.
1620
1621Different DBM libraries have different conventions for naming the files they
9b371988 1622use. When a program opens a file called &_dbmfile_&, there are several
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1623possibilities:
1624
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1625.olist
1626A traditional &'ndbm'& implementation, such as that supplied as part of
1627Solaris, operates on two files called &_dbmfile.dir_& and &_dbmfile.pag_&.
1628.next
1629.cindex "&'gdbm'& DBM library"
1630The GNU library, &'gdbm'&, operates on a single file. If used via its &'ndbm'&
168e428f 1631compatibility interface it makes two different hard links to it with names
9b371988 1632&_dbmfile.dir_& and &_dbmfile.pag_&, but if used via its native interface, the
168e428f 1633file name is used unmodified.
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1634.next
1635.cindex "Berkeley DB library"
1636The Berkeley DB package, if called via its &'ndbm'& compatibility interface,
1637operates on a single file called &_dbmfile.db_&, but otherwise looks to the
1638programmer exactly the same as the traditional &'ndbm'& implementation.
1639.next
1640If the Berkeley package is used in its native mode, it operates on a single
1641file called &_dbmfile_&; the programmer's interface is somewhat different to
1642the traditional &'ndbm'& interface.
1643.next
1644To complicate things further, there are several very different versions of the
168e428f 1645Berkeley DB package. Version 1.85 was stable for a very long time, releases
9b371988
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16462.&'x'& and 3.&'x'& were current for a while, but the latest versions are now
1647numbered 4.&'x'&. Maintenance of some of the earlier releases has ceased. All
168e428f 1648versions of Berkeley DB can be obtained from
9b371988
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1649&url(http://www.sleepycat.com/).
1650.next
1651.cindex "&'tdb'& DBM library"
1652Yet another DBM library, called &'tdb'&, is available from
1653&url(http://download.sourceforge.net/tdb). It has its own interface, and also
1654operates on a single file.
1655.endlist
1656
1657.cindex "USE_DB"
1658.cindex "DBM libraries" "configuration for building"
168e428f
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1659Exim and its utilities can be compiled to use any of these interfaces. In order
1660to use any version of the Berkeley DB package in native mode, you must set
1661USE_DB in an appropriate configuration file (typically
9b371988
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1662&_Local/Makefile_&). For example:
1663.code
1664USE_DB=yes
1665.endd
168e428f
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1666Similarly, for gdbm you set USE_GDBM, and for tdb you set USE_TDB. An
1667error is diagnosed if you set more than one of these.
1668
1669At the lowest level, the build-time configuration sets none of these options,
1670thereby assuming an interface of type (1). However, some operating system
1671configuration files (for example, those for the BSD operating systems and
1672Linux) assume type (4) by setting USE_DB as their default, and the
1673configuration files for Cygwin set USE_GDBM. Anything you set in
9b371988 1674&_Local/Makefile_&, however, overrides these system defaults.
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1675
1676As well as setting USE_DB, USE_GDBM, or USE_TDB, it may also be
1677necessary to set DBMLIB, to cause inclusion of the appropriate library, as
1678in one of these lines:
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1679.code
1680DBMLIB = -ldb
1681DBMLIB = -ltdb
1682.endd
168e428f
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1683Settings like that will work if the DBM library is installed in the standard
1684place. Sometimes it is not, and the library's header file may also not be in
1685the default path. You may need to set INCLUDE to specify where the header
1686file is, and to specify the path to the library more fully in DBMLIB, as in
1687this example:
9b371988
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1688.code
1689INCLUDE=-I/usr/local/include/db-4.1
1690DBMLIB=/usr/local/lib/db-4.1/libdb.a
1691.endd
168e428f 1692There is further detailed discussion about the various DBM libraries in the
9b371988 1693file &_doc/dbm.discuss.txt_& in the Exim distribution.
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1694
1695
1696
9b371988
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1697.section "Pre-building configuration"
1698.cindex "building Exim" "pre-building configuration"
1699.cindex "configuration for building Exim"
1700.cindex "&_Local/Makefile_&"
1701.cindex "&_src/EDITME_&"
168e428f
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1702Before building Exim, a local configuration file that specifies options
1703independent of any operating system has to be created with the name
9b371988
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1704&_Local/Makefile_&. A template for this file is supplied as the file
1705&_src/EDITME_&, and it contains full descriptions of all the option settings
168e428f
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1706therein. These descriptions are therefore not repeated here. If you are
1707building Exim for the first time, the simplest thing to do is to copy
9b371988 1708&_src/EDITME_& to &_Local/Makefile_&, then read it and edit it appropriately.
168e428f
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1709
1710There are three settings that you must supply, because Exim will not build
1711without them. They are the location of the run time configuration file
1712(CONFIGURE_FILE), the directory in which Exim binaries will be installed
1713(BIN_DIRECTORY), and the identity of the Exim user (EXIM_USER and
1714maybe EXIM_GROUP as well). The value of CONFIGURE_FILE can in fact be
1715a colon-separated list of file names; Exim uses the first of them that exists.
1716
1717There are a few other parameters that can be specified either at build time or
1718at run time, to enable the same binary to be used on a number of different
1719machines. However, if the locations of Exim's spool directory and log file
1720directory (if not within the spool directory) are fixed, it is recommended that
9b371988 1721you specify them in &_Local/Makefile_& instead of at run time, so that errors
168e428f
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1722detected early in Exim's execution (such as a malformed configuration file) can
1723be logged.
1724
9b371988 1725.cindex "content scanning" "specifying at build time"
068aaea8 1726Exim's interfaces for calling virus and spam scanning software directly from
168e428f
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1727access control lists are not compiled by default. If you want to include these
1728facilities, you need to set
9b371988
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1729.code
1730WITH_CONTENT_SCAN=yes
1731.endd
1732in your &_Local/Makefile_&. For details of the facilities themselves, see
1733chapter &<<CHAPexiscan>>&.
168e428f
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1734
1735
9b371988
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1736.cindex "&_Local/eximon.conf_&"
1737.cindex "_exim_monitor/EDITME_"
168e428f 1738If you are going to build the Exim monitor, a similar configuration process is
9b371988
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1739required. The file &_exim_monitor/EDITME_& must be edited appropriately for
1740your installation and saved under the name &_Local/eximon.conf_&. If you are
1741happy with the default settings described in &_exim_monitor/EDITME_&,
1742&_Local/eximon.conf_& can be empty, but it must exist.
168e428f
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1743
1744This is all the configuration that is needed in straightforward cases for known
1745operating systems. However, the building process is set up so that it is easy
1746to override options that are set by default or by operating-system-specific
1747configuration files, for example to change the name of the C compiler, which
9b371988
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1748defaults to &%gcc%&. See section &<<SECToverride>>& below for details of how to
1749do this.
168e428f
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1750
1751
1752
9b371988
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1753.section "Support for iconv()"
1754.cindex "&[iconv()]& support"
1755.cindex "RFC 2047"
168e428f
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1756The contents of header lines in messages may be encoded according to the rules
1757described RFC 2047. This makes it possible to transmit characters that are not
1758in the ASCII character set, and to label them as being in a particular
9b371988 1759character set. When Exim is inspecting header lines by means of the &%$h_%&
168e428f
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1760mechanism, it decodes them, and translates them into a specified character set
1761(default ISO-8859-1). The translation is possible only if the operating system
9b371988
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1762supports the &[iconv()]& function.
1763
1764However, some of the operating systems that supply &[iconv()]& do not support
1765very many conversions. The GNU &%libiconv%& library (available from
1766&url(http://www.gnu.org/software/libiconv/)) can be installed on such
1767systems to remedy this deficiency, as well as on systems that do not supply
1768&[iconv()]& at all. After installing &%libiconv%&, you should add
1769.code
1770HAVE_ICONV=yes
1771.endd
1772to your &_Local/Makefile_& and rebuild Exim.
1773
1774
1775
1776.section "Including TLS/SSL encryption support" "SECTinctlsssl"
1777.cindex "TLS" "including support for TLS"
1778.cindex "encryption" "including support for"
1779.cindex "SUPPORT_TLS"
1780.cindex "OpenSSL" "building Exim with"
1781.cindex "GnuTLS" "building Exim with"
168e428f
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1782Exim can be built to support encrypted SMTP connections, using the STARTTLS
1783command as per RFC 2487. It can also support legacy clients that expect to
1784start a TLS session immediately on connection to a non-standard port (see the
9b371988 1785&%tls_on_connect_ports%& runtime option and the &%-tls-on-connect%& command
168e428f
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1786line option).
1787
1788If you want to build Exim with TLS support, you must first install either the
1789OpenSSL or GnuTLS library. There is no cryptographic code in Exim itself for
1790implementing SSL.
1791
1792If OpenSSL is installed, you should set
9b371988
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1793.code
1794SUPPORT_TLS=yes
1795TLS_LIBS=-lssl -lcrypto
1796.endd
1797in &_Local/Makefile_&. You may also need to specify the locations of the
168e428f 1798OpenSSL library and include files. For example:
9b371988
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1799.code
1800SUPPORT_TLS=yes
1801TLS_LIBS=-L/usr/local/openssl/lib -lssl -lcrypto
1802TLS_INCLUDE=-I/usr/local/openssl/include/
1803.endd
1804.cindex "USE_GNUTLS"
168e428f 1805If GnuTLS is installed, you should set
9b371988
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1806.code
1807SUPPORT_TLS=yes
1808USE_GNUTLS=yes
1809TLS_LIBS=-lgnutls -ltasn1 -lgcrypt
1810.endd
1811in &_Local/Makefile_&, and again you may need to specify the locations of the
168e428f 1812library and include files. For example:
9b371988
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1813.code
1814SUPPORT_TLS=yes
1815USE_GNUTLS=yes
1816TLS_LIBS=-L/usr/gnu/lib -lgnutls -ltasn1 -lgcrypt
1817TLS_INCLUDE=-I/usr/gnu/include
1818.endd
168e428f 1819You do not need to set TLS_INCLUDE if the relevant directory is already
9b371988
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1820specified in INCLUDE. Details of how to configure Exim to make use of TLS are
1821given in chapter &<<CHAPTLS>>&.
168e428f
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1822
1823
1824
1825
9b371988
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1826.section "Use of tcpwrappers"
1827.cindex "tcpwrappers" "building Exim to support"
1828.cindex "USE_TCP_WRAPPERS"
1829Exim can be linked with the &'tcpwrappers'& library in order to check incoming
1830SMTP calls using the &'tcpwrappers'& control files. This may be a convenient
168e428f 1831alternative to Exim's own checking facilities for installations that are
9b371988
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1832already making use of &'tcpwrappers'& for other purposes. To do this, you
1833should set USE_TCP_WRAPPERS in &_Local/Makefile_&, arrange for the file
1834&_tcpd.h_& to be available at compile time, and also ensure that the library
1835&_libwrap.a_& is available at link time, typically by including &%-lwrap%& in
1836EXTRALIBS_EXIM. For example, if &'tcpwrappers'& is installed in &_/usr/local_&,
1837you might have
1838.code
1839USE_TCP_WRAPPERS=yes
1840CFLAGS=-O -I/usr/local/include
1841EXTRALIBS_EXIM=-L/usr/local/lib -lwrap
1842.endd
1843in &_Local/Makefile_&. The name to use in the &'tcpwrappers'& control files is
1844&"exim"&. For example, the line
1845.code
1846exim : LOCAL 192.168.1. .friendly.domain.example
1847.endd
1848in your &_/etc/hosts.allow_& file allows connections from the local host, from
1849the subnet 192.168.1.0/24, and from all hosts in &'friendly.domain.example'&.
1850All other connections are denied. Consult the &'tcpwrappers'& documentation for
168e428f
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1851further details.
1852
1853
1854
9b371988
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1855.section "Including support for IPv6"
1856.cindex "IPv6" "including support for"
168e428f 1857Exim contains code for use on systems that have IPv6 support. Setting
9b371988 1858&`HAVE_IPV6=YES`& in &_Local/Makefile_& causes the IPv6 code to be included;
168e428f
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1859it may also be necessary to set IPV6_INCLUDE and IPV6_LIBS on systems
1860where the IPv6 support is not fully integrated into the normal include and
1861library files.
1862
1863Two different types of DNS record for handling IPv6 addresses have been
1864defined. AAAA records (analagous to A records for IPv4) are in use, and are
1865currently seen as the mainstream. Another record type called A6 was proposed
1866as better than AAAA because it had more flexibility. However, it was felt to be
9b371988 1867over-complex, and its status was reduced to &"experimental"&. It is not known
168e428f 1868if anyone is actually using A6 records. Exim has support for A6 records, but
9b371988 1869this is included only if you set &`SUPPORT_A6=YES`& in &_Local/Makefile_&. The
168e428f
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1870support has not been tested for some time.
1871
1872
1873
9b371988
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1874.section "The building process"
1875.cindex "build directory"
1876Once &_Local/Makefile_& (and &_Local/eximon.conf_&, if required) have been
1877created, run &'make'& at the top level. It determines the architecture and
168e428f
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1878operating system types, and creates a build directory if one does not exist.
1879For example, on a Sun system running Solaris 8, the directory
9b371988
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1880&_build-SunOS5-5.8-sparc_& is created.
1881.cindex "symbolic link" "to source files"
168e428f
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1882Symbolic links to relevant source files are installed in the build directory.
1883
9b371988 1884&*Warning*&: The &%-j%& (parallel) flag must not be used with &'make'&; the
168e428f
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1885building process fails if it is set.
1886
9b371988 1887If this is the first time &'make'& has been run, it calls a script that builds
168e428f 1888a make file inside the build directory, using the configuration files from the
9b371988
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1889&_Local_& directory. The new make file is then passed to another instance of
1890&'make'&. This does the real work, building a number of utility scripts, and
168e428f 1891then compiling and linking the binaries for the Exim monitor (if configured), a
9b371988
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1892number of utility programs, and finally Exim itself. The command &`make
1893makefile`& can be used to force a rebuild of the make file in the build
168e428f
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1894directory, should this ever be necessary.
1895
1896If you have problems building Exim, check for any comments there may be in the
9b371988 1897&_README_& file concerning your operating system, and also take a look at the
168e428f
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1898FAQ, where some common problems are covered.
1899
1900
1901
9b371988
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1902.section 'Output from &"make"&'
1903.new
1904The output produced by the &'make'& process for compile lines is often very
068aaea8
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1905unreadable, because these lines can be very long. For this reason, the normal
1906output is suppressed by default, and instead output similar to that which
1907appears when compiling the 2.6 Linux kernel is generated: just a short line for
1908each module that is being compiled or linked. However, it is still possible to
9b371988
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1909get the full output, by calling &'make'& like this:
1910.code
1911FULLECHO='' make -e
1912.endd
1913The value of FULLECHO defaults to &"@"&, the flag character that suppresses
1914command reflection in &'make'&. When you ask for the full output, it is
068aaea8 1915given in addition to the the short output.
9b371988 1916.wen
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1917
1918
1919
9b371988
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1920.section "Overriding build-time options for Exim" "SECToverride"
1921.cindex "build-time options" "overriding"
168e428f
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1922The main make file that is created at the beginning of the building process
1923consists of the concatenation of a number of files which set configuration
9b371988 1924values, followed by a fixed set of &'make'& instructions. If a value is set
168e428f
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1925more than once, the last setting overrides any previous ones. This provides a
1926convenient way of overriding defaults. The files that are concatenated are, in
1927order:
9b371988
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1928.display
1929&_OS/Makefile-Default_&
1930&_OS/Makefile-_&<&'ostype'&>
1931&_Local/Makefile_&
1932&_Local/Makefile-_&<&'ostype'&>
1933&_Local/Makefile-_&<&'archtype'&>
1934&_Local/Makefile-_&<&'ostype'&>-<&'archtype'&>
1935&_OS/Makefile-Base_&
1936.endd
1937.cindex "&_Local/Makefile_&"
1938.cindex "building Exim" "operating system type"
1939.cindex "building Exim" "architecture type"
1940where <&'ostype'&> is the operating system type and <&'archtype'&> is the
1941architecture type. &_Local/Makefile_& is required to exist, and the building
1942process fails if it is absent. The other three &_Local_& files are optional,
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1943and are often not needed.
1944
9b371988
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1945The values used for <&'ostype'&> and <&'archtype'&> are obtained from scripts
1946called &_scripts/os-type_& and &_scripts/arch-type_& respectively. If either of
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1947the environment variables EXIM_OSTYPE or EXIM_ARCHTYPE is set, their
1948values are used, thereby providing a means of forcing particular settings.
9b371988 1949Otherwise, the scripts try to get values from the &%uname%& command. If this
168e428f 1950fails, the shell variables OSTYPE and ARCHTYPE are inspected. A number
9b371988 1951of &'ad hoc'& transformations are then applied, to produce the standard names
168e428f
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1952that Exim expects. You can run these scripts directly from the shell in order
1953to find out what values are being used on your system.
1954
1955
9b371988 1956&_OS/Makefile-Default_& contains comments about the variables that are set
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1957therein. Some (but not all) are mentioned below. If there is something that
1958needs changing, review the contents of this file and the contents of the make
9b371988 1959file for your operating system (&_OS/Makefile-<ostype>_&) to see what the
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1960default values are.
1961
1962
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1963.cindex "building Exim" "overriding default settings"
1964If you need to change any of the values that are set in &_OS/Makefile-Default_&
1965or in &_OS/Makefile-<ostype>_&, or to add any new definitions, you do not
168e428f 1966need to change the original files. Instead, you should make the changes by
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1967putting the new values in an appropriate &_Local_& file. For example,
1968.cindex "Tru64-Unix build-time settings"
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1969when building Exim in many releases of the Tru64-Unix (formerly Digital UNIX,
1970formerly DEC-OSF1) operating system, it is necessary to specify that the C
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1971compiler is called &'cc'& rather than &'gcc'&. Also, the compiler must be
1972called with the option &%-std1%&, to make it recognize some of the features of
168e428f 1973Standard C that Exim uses. (Most other compilers recognize Standard C by
9b371988 1974default.) To do this, you should create a file called &_Local/Makefile-OSF1_&
168e428f 1975containing the lines
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1976.code
1977CC=cc
1978CFLAGS=-std1
1979.endd
168e428f 1980If you are compiling for just one operating system, it may be easier to put
9b371988 1981these lines directly into &_Local/Makefile_&.
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1982
1983Keeping all your local configuration settings separate from the distributed
1984files makes it easy to transfer them to new versions of Exim simply by copying
9b371988 1985the contents of the &_Local_& directory.
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1986
1987
9b371988
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1988.cindex "NIS lookup type" "including support for"
1989.cindex "NIS+ lookup type" "including support for"
1990.cindex "LDAP" "including support for"
1991.cindex "lookup" "inclusion in binary"
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1992Exim contains support for doing LDAP, NIS, NIS+, and other kinds of file
1993lookup, but not all systems have these components installed, so the default is
1994not to include the relevant code in the binary. All the different kinds of file
1995and database lookup that Exim supports are implemented as separate code modules
1996which are included only if the relevant compile-time options are set. In the
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1997case of LDAP, NIS, and NIS+, the settings for &_Local/Makefile_& are:
1998.code
1999LOOKUP_LDAP=yes
2000LOOKUP_NIS=yes
2001LOOKUP_NISPLUS=yes
2002.endd
168e428f 2003and similar settings apply to the other lookup types. They are all listed in
9b371988 2004&_src/EDITME_&. In many cases the relevant include files and interface
168e428f 2005libraries need to be installed before compiling Exim.
9b371988 2006.cindex "cdb" "including support for"
068aaea8
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2007However, there are some optional lookup types (such as cdb) for which
2008the code is entirely contained within Exim, and no external include
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2009files or libraries are required. When a lookup type is not included in the
2010binary, attempts to configure Exim to use it cause run time configuration
2011errors.
2012
9b371988 2013.cindex "Perl" "including support for"
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2014Exim can be linked with an embedded Perl interpreter, allowing Perl
2015subroutines to be called during string expansion. To enable this facility,
9b371988
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2016.code
2017EXIM_PERL=perl.o
2018.endd
2019must be defined in &_Local/Makefile_&. Details of this facility are given in
2020chapter &<<CHAPperl>>&.
168e428f 2021
9b371988 2022.cindex "X11 libraries" "location of"
168e428f 2023The location of the X11 libraries is something that varies a lot between
068aaea8 2024operating systems, and there may be different versions of X11 to cope
168e428f
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2025with. Exim itself makes no use of X11, but if you are compiling the Exim
2026monitor, the X11 libraries must be available.
9b371988
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2027The following three variables are set in &_OS/Makefile-Default_&:
2028.code
2029X11=/usr/X11R6
2030XINCLUDE=-I$(X11)/include
2031XLFLAGS=-L$(X11)/lib
2032.endd
168e428f 2033These are overridden in some of the operating-system configuration files. For
9b371988
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2034example, in &_OS/Makefile-SunOS5_& there is
2035.code
2036X11=/usr/openwin
2037XINCLUDE=-I$(X11)/include
2038XLFLAGS=-L$(X11)/lib -R$(X11)/lib
2039.endd
168e428f
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2040If you need to override the default setting for your operating system, place a
2041definition of all three of these variables into your
9b371988 2042&_Local/Makefile-<ostype>_& file.
168e428f 2043
9b371988 2044.cindex "EXTRALIBS"
168e428f
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2045If you need to add any extra libraries to the link steps, these can be put in a
2046variable called EXTRALIBS, which appears in all the link commands, but by
2047default is not defined. In contrast, EXTRALIBS_EXIM is used only on the
2048command for linking the main Exim binary, and not for any associated utilities.
2049
9b371988 2050.cindex "DBM libraries" "configuration for building"
168e428f 2051There is also DBMLIB, which appears in the link commands for binaries that
9b371988 2052use DBM functions (see also section &<<SECTdb>>&). Finally, there is
168e428f
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2053EXTRALIBS_EXIMON, which appears only in the link step for the Exim monitor
2054binary, and which can be used, for example, to include additional X11
2055libraries.
2056
9b371988 2057.cindex "configuration file" "editing"
168e428f
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2058The make file copes with rebuilding Exim correctly if any of the configuration
2059files are edited. However, if an optional configuration file is deleted, it is
9b371988
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2060necessary to touch the associated non-optional file (that is,
2061&_Local/Makefile_& or &_Local/eximon.conf_&) before rebuilding.
168e428f
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2062
2063
9b371988
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2064.section "OS-specific header files"
2065.cindex "&_os.h_&"
2066.cindex "building Exim" "OS-specific C header files"
2067The &_OS_& directory contains a number of files with names of the form
2068&_os.h-<ostype>_&. These are system-specific C header files that should not
168e428f 2069normally need to be changed. There is a list of macro settings that are
9b371988 2070recognized in the file &_OS/os.configuring_&, which should be consulted if you
168e428f
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2071are porting Exim to a new operating system.
2072
2073
2074
9b371988
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2075.section "Overriding build-time options for the monitor"
2076.cindex "building Eximon" "overriding default options"
168e428f
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2077A similar process is used for overriding things when building the Exim monitor,
2078where the files that are involved are
9b371988
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2079.display
2080&_OS/eximon.conf-Default_&
2081&_OS/eximon.conf-_&<&'ostype'&>
2082&_Local/eximon.conf_&
2083&_Local/eximon.conf-_&<&'ostype'&>
2084&_Local/eximon.conf-_&<&'archtype'&>
2085&_Local/eximon.conf-_&<&'ostype'&>-<&'archtype'&>
2086.endd
2087.cindex "&_Local/eximon.conf_&"
168e428f 2088As with Exim itself, the final three files need not exist, and in this case the
9b371988
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2089&_OS/eximon.conf-<ostype>_& file is also optional. The default values in
2090&_OS/eximon.conf-Default_& can be overridden dynamically by setting environment
168e428f
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2091variables of the same name, preceded by EXIMON_. For example, setting
2092EXIMON_LOG_DEPTH in the environment overrides the value of
2093LOG_DEPTH at run time.
2094
2095
2096
2097
9b371988
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2098.section "Installing Exim binaries and scripts"
2099.cindex "installing Exim"
2100.cindex "BIN_DIRECTORY"
2101The command &`make install`& runs the &(exim_install)& script with no
2102arguments. The script copies binaries and utility scripts into the directory
2103whose name is specified by the BIN_DIRECTORY setting in &_Local/Makefile_&.
2104.cindex "setuid" "installing Exim with"
068aaea8
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2105The install script copies files only if they are newer than the files they are
2106going to replace. The Exim binary is required to be owned by root and have the
9b371988
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2107&'setuid'& bit set, for normal configurations. Therefore, you must run &`make
2108install`& as root so that it can set up the Exim binary in this way. However, in
068aaea8
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2109some special situations (for example, if a host is doing no local deliveries)
2110it may be possible to run Exim without making the binary setuid root (see
9b371988 2111chapter &<<CHAPsecurity>>& for details).
168e428f 2112
9b371988 2113.cindex "CONFIGURE_FILE"
168e428f 2114Exim's run time configuration file is named by the CONFIGURE_FILE setting
9b371988
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2115in &_Local/Makefile_&. If this names a single file, and the file does not
2116exist, the default configuration file &_src/configure.default_& is copied there
168e428f
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2117by the installation script. If a run time configuration file already exists, it
2118is left alone. If CONFIGURE_FILE is a colon-separated list, naming several
2119alternative files, no default is installed.
2120
9b371988
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2121.cindex "system aliases file"
2122.cindex "&_/etc/aliases_&"
168e428f
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2123One change is made to the default configuration file when it is installed: the
2124default configuration contains a router that references a system aliases file.
2125The path to this file is set to the value specified by
9b371988 2126SYSTEM_ALIASES_FILE in &_Local/Makefile_& (&_/etc/aliases_& by default).
168e428f
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2127If the system aliases file does not exist, the installation script creates it,
2128and outputs a comment to the user.
2129
2130The created file contains no aliases, but it does contain comments about the
2131aliases a site should normally have. Mail aliases have traditionally been
9b371988
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2132kept in &_/etc/aliases_&. However, some operating systems are now using
2133&_/etc/mail/aliases_&. You should check if yours is one of these, and change
168e428f
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2134Exim's configuration if necessary.
2135
2136The default configuration uses the local host's name as the only local domain,
9b371988
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2137and is set up to do local deliveries into the shared directory &_/var/mail_&,
2138running as the local user. System aliases and &_.forward_& files in users' home
168e428f
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2139directories are supported, but no NIS or NIS+ support is configured. Domains
2140other than the name of the local host are routed using the DNS, with delivery
2141over SMTP.
2142
168e428f
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2143It is possible to install Exim for special purposes (such as building a binary
2144distribution) in a private part of the file system. You can do this by a
2145command such as
9b371988
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2146.code
2147make DESTDIR=/some/directory/ install
2148.endd
168e428f
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2149This has the effect of pre-pending the specified directory to all the file
2150paths, except the name of the system aliases file that appears in the default
9b371988 2151configuration. (If a default alias file is created, its name &'is'& modified.)
168e428f
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2152For backwards compatibility, ROOT is used if DESTDIR is not set,
2153but this usage is deprecated.
2154
9b371988
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2155.cindex "installing Exim" "what is not installed"
2156Running &'make install'& does not copy the Exim 4 conversion script
2157&'convert4r4'&, or the &'pcretest'& test program. You will probably run the
168e428f 2158first of these only once (if you are upgrading from Exim 3), and the second
9b371988 2159isn't really part of Exim. None of the documentation files in the &_doc_&
168e428f 2160directory are copied, except for the info files when you have set
9b371988 2161INFO_DIRECTORY, as described in section &<<SECTinsinfdoc>>& below.
168e428f 2162
9b371988 2163For the utility programs, old versions are renamed by adding the suffix &_.O_&
168e428f
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2164to their names. The Exim binary itself, however, is handled differently. It is
2165installed under a name that includes the version number and the compile number,
9b371988
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2166for example &_exim-&version;-1_&. The script then arranges for a symbolic link
2167called &_exim_& to point to the binary. If you are updating a previous version
2168of Exim, the script takes care to ensure that the name &_exim_& is never absent
168e428f
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2169from the directory (as seen by other processes).
2170
9b371988
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2171.cindex "installing Exim" "testing the script"
2172If you want to see what the &'make install'& will do before running it for
2173real, you can pass the &%-n%& option to the installation script by this
2174command:
2175.code
2176make INSTALL_ARG=-n install
2177.endd
168e428f
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2178The contents of the variable INSTALL_ARG are passed to the installation
2179script. You do not need to be root to run this test. Alternatively, you can run
2180the installation script directly, but this must be from within the build
2181directory. For example, from the top-level Exim directory you could use this
2182command:
9b371988
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2183.code
2184(cd build-SunOS5-5.5.1-sparc; ../scripts/exim_install -n)
2185.endd
2186.cindex "installing Exim" "install script options"
168e428f
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2187There are two other options that can be supplied to the installation script.
2188
9b371988
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2189.ilist
2190&%-no_chown%& bypasses the call to change the owner of the installed binary
168e428f 2191to root, and the call to make it a setuid binary.
9b371988
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2192.next
2193&%-no_symlink%& bypasses the setting up of the symbolic link &_exim_& to the
168e428f 2194installed binary.
9b371988 2195.endlist
168e428f
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2196
2197INSTALL_ARG can be used to pass these options to the script. For example:
9b371988
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2198.code
2199make INSTALL_ARG=-no_symlink install
2200.endd
168e428f
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2201The installation script can also be given arguments specifying which files are
2202to be copied. For example, to install just the Exim binary, and nothing else,
2203without creating the symbolic link, you could use:
9b371988
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2204.code
2205make INSTALL_ARG='-no_symlink exim' install
2206.endd
168e428f
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2207
2208
2209
9b371988
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2210.section "Installing info documentation" "SECTinsinfdoc"
2211.cindex "installing Exim" "&'info'& documentation"
2212Not all systems use the GNU &'info'& system for documentation, and for this
168e428f
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2213reason, the Texinfo source of Exim's documentation is not included in the main
2214distribution. Instead it is available separately from the ftp site (see section
9b371988 2215&<<SECTavail>>&).
168e428f 2216
9b371988
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2217If you have defined INFO_DIRECTORY in &_Local/Makefile_& and the Texinfo
2218source of the documentation is found in the source tree, running &`make
2219install`& automatically builds the info files and installs them.
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2220
2221
2222
9b371988
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2223.section "Setting up the spool directory"
2224.cindex "spool directory" "creating"
168e428f
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2225When it starts up, Exim tries to create its spool directory if it does not
2226exist. The Exim uid and gid are used for the owner and group of the spool
2227directory. Sub-directories are automatically created in the spool directory as
2228necessary.
2229
2230
2231
2232
9b371988
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2233.section "Testing"
2234.cindex "testing" "installation"
168e428f
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2235Having installed Exim, you can check that the run time configuration file is
2236syntactically valid by running the following command, which assumes that the
2237Exim binary directory is within your PATH environment variable:
9b371988
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2238.code
2239exim -bV
2240.endd
168e428f
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2241If there are any errors in the configuration file, Exim outputs error messages.
2242Otherwise it outputs the version number and build date,
2243the DBM library that is being used, and information about which drivers and
2244other optional code modules are included in the binary.
2245Some simple routing tests can be done by using the address testing option. For
2246example,
9b371988
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2247.display
2248&`exim -bt`& <&'local username'&>
2249.endd
168e428f 2250should verify that it recognizes a local mailbox, and
9b371988
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2251.display
2252&`exim -bt`& <&'remote address'&>
2253.endd
168e428f
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2254a remote one. Then try getting it to deliver mail, both locally and remotely.
2255This can be done by passing messages directly to Exim, without going through a
2256user agent. For example:
9b371988 2257.code
068aaea8
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2258exim -v postmaster@your.domain.example
2259From: user@your.domain.example
2260To: postmaster@your.domain.example
2261Subject: Testing Exim
168e428f 2262
068aaea8
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2263This is a test message.
2264^D
9b371988
PH
2265.endd
2266The &%-v%& option causes Exim to output some verification of what it is doing.
168e428f 2267In this case you should see copies of three log lines, one for the message's
9b371988 2268arrival, one for its delivery, and one containing &"Completed"&.
168e428f 2269
9b371988
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2270.cindex "delivery" "problems with"
2271If you encounter problems, look at Exim's log files (&'mainlog'& and
2272&'paniclog'&) to see if there is any relevant information there. Another source
168e428f 2273of information is running Exim with debugging turned on, by specifying the
9b371988 2274&%-d%& option. If a message is stuck on Exim's spool, you can force a delivery
168e428f 2275with debugging turned on by a command of the form
9b371988
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2276.display
2277&`exim -d -M`& <&'exim-message-id'&>
2278.endd
2279You must be root or an &"admin user"& in order to do this. The &%-d%& option
168e428f 2280produces rather a lot of output, but you can cut this down to specific areas.
9b371988
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2281For example, if you use &%-d-all+route%& only the debugging information
2282relevant to routing is included. (See the &%-d%& option in chapter
2283&<<CHAPcommandline>>& for more details.)
168e428f 2284
9b371988
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2285.cindex '&"sticky"& bit'
2286.cindex "lock files"
168e428f
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2287One specific problem that has shown up on some sites is the inability to do
2288local deliveries into a shared mailbox directory, because it does not have the
9b371988 2289&"sticky bit"& set on it. By default, Exim tries to create a lock file before
168e428f 2290writing to a mailbox file, and if it cannot create the lock file, the delivery
9b371988 2291is deferred. You can get round this either by setting the &"sticky bit"& on the
168e428f
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2292directory, or by setting a specific group for local deliveries and allowing
2293that group to create files in the directory (see the comments above the
9b371988 2294&(local_delivery)& transport in the default configuration file). Another
168e428f 2295approach is to configure Exim not to use lock files, but just to rely on
9b371988
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2296&[fcntl()]& locking instead. However, you should do this only if all user
2297agents also use &[fcntl()]& locking. For further discussion of locking issues,
2298see chapter &<<CHAPappendfile>>&.
168e428f
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2299
2300One thing that cannot be tested on a system that is already running an MTA is
2301the receipt of incoming SMTP mail on the standard SMTP port. However, the
9b371988
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2302&%-oX%& option can be used to run an Exim daemon that listens on some other
2303port, or &'inetd'& can be used to do this. The &%-bh%& option and the
2304&'exim_checkaccess'& utility can be used to check out policy controls on
168e428f
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2305incoming SMTP mail.
2306
2307Testing a new version on a system that is already running Exim can most easily
2308be done by building a binary with a different CONFIGURE_FILE setting. From
2309within the run time configuration, all other file and directory names
2310that Exim uses can be altered, in order to keep it entirely clear of the
2311production version.
2312
2313
9b371988
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2314.section "Replacing another MTA with Exim"
2315.cindex "replacing another MTA"
168e428f
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2316Building and installing Exim for the first time does not of itself put it in
2317general use. The name by which the system's MTA is called by mail user agents
9b371988
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2318is either &_/usr/sbin/sendmail_&, or &_/usr/lib/sendmail_& (depending on the
2319operating system), and it is necessary to make this name point to the &'exim'&
168e428f 2320binary in order to get the user agents to pass messages to Exim. This is
9b371988
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2321normally done by renaming any existing file and making &_/usr/sbin/sendmail_&
2322or &_/usr/lib/sendmail_&
2323.cindex "symbolic link" "to &'exim'& binary"
2324a symbolic link to the &'exim'& binary. It is a good idea to remove any setuid
168e428f
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2325privilege and executable status from the old MTA. It is then necessary to stop
2326and restart the mailer daemon, if one is running.
2327
9b371988
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2328.cindex "FreeBSD" "MTA indirection"
2329.cindex "&_/etc/mail/mailer.conf_&"
168e428f
PH
2330Some operating systems have introduced alternative ways of switching MTAs. For
2331example, if you are running FreeBSD, you need to edit the file
9b371988 2332&_/etc/mail/mailer.conf_& instead of setting up a symbolic link as just
168e428f
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2333described. A typical example of the contents of this file for running Exim is
2334as follows:
9b371988
PH
2335.code
2336sendmail /usr/exim/bin/exim
2337send-mail /usr/exim/bin/exim
2338mailq /usr/exim/bin/exim -bp
2339newaliases /usr/bin/true
2340.endd
2341Once you have set up the symbolic link, or edited &_/etc/mail/mailer.conf_&,
2342your Exim installation is &"live"&. Check it by sending a message from your
168e428f
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2343favourite user agent.
2344
2345You should consider what to tell your users about the change of MTA. Exim may
2346have different capabilities to what was previously running, and there are
2347various operational differences such as the text of messages produced by
2348command line options and in bounce messages. If you allow your users to make
2349use of Exim's filtering capabilities, you should make the document entitled
9b371988 2350&'Exim's interface to mail filtering'& available to them.
168e428f
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2351
2352
2353
9b371988
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2354.section "Upgrading Exim"
2355.cindex "upgrading Exim"
168e428f
PH
2356If you are already running Exim on your host, building and installing a new
2357version automatically makes it available to MUAs, or any other programs that
2358call the MTA directly. However, if you are running an Exim daemon, you do need
9b371988
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2359to send it a HUP signal, to make it re-execute itself, and thereby pick up the
2360new binary. You do not need to stop processing mail in order to install a new
068aaea8
PH
2361version of Exim. The install script does not modify an existing runtime
2362configuration file.
2363
168e428f
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2364
2365
2366
9b371988
PH
2367.section "Stopping the Exim daemon on Solaris"
2368.cindex "Solaris" "stopping Exim on"
168e428f 2369The standard command for stopping the mailer daemon on Solaris is
9b371988
PH
2370.code
2371/etc/init.d/sendmail stop
2372.endd
2373If &_/usr/lib/sendmail_& has been turned into a symbolic link, this script
2374fails to stop Exim because it uses the command &'ps -e'& and greps the output
2375for the text &"sendmail"&; this is not present because the actual program name
2376(that is, &"exim"&) is given by the &'ps'& command with these options. A
2377solution is to replace the line that finds the process id with something like
2378.code
2379pid=`cat /var/spool/exim/exim-daemon.pid`
2380.endd
168e428f
PH
2381to obtain the daemon's pid directly from the file that Exim saves it in.
2382
9b371988 2383Note, however, that stopping the daemon does not &"stop Exim"&. Messages can
168e428f
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2384still be received from local processes, and if automatic delivery is configured
2385(the normal case), deliveries will still occur.
2386
2387
2388
2389
9b371988
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2390. ////////////////////////////////////////////////////////////////////////////
2391. ////////////////////////////////////////////////////////////////////////////
168e428f 2392
9b371988
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2393.chapter "The Exim command line" "CHAPcommandline"
2394.cindex "command line" "options"
2395.cindex "options" "command line"
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2396Exim's command line takes the standard Unix form of a sequence of options,
2397each starting with a hyphen character, followed by a number of arguments. The
2398options are compatible with the main options of Sendmail, and there are also
2399some additional options, some of which are compatible with Smail 3. Certain
2400combinations of options do not make sense, and provoke an error if used.
2401The form of the arguments depends on which options are set.
2402
2403
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2404.section "Setting options by program name"
2405.cindex "&'mailq'&"
2406If Exim is called under the name &'mailq'&, it behaves as if the option &%-bp%&
168e428f 2407were present before any other options.
9b371988 2408The &%-bp%& option requests a listing of the contents of the mail queue on the
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2409standard output.
2410This feature is for compatibility with some systems that contain a command of
2411that name in one of the standard libraries, symbolically linked to
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2412&_/usr/sbin/sendmail_& or &_/usr/lib/sendmail_&.
2413
2414.cindex "&'rsmtp'&"
2415If Exim is called under the name &'rsmtp'& it behaves as if the option &%-bS%&
2416were present before any other options, for compatibility with Smail. The
2417&%-bS%& option is used for reading in a number of messages in batched SMTP
2418format.
2419
2420.cindex "&'rmail'&"
2421If Exim is called under the name &'rmail'& it behaves as if the &%-i%& and
2422&%-oee%& options were present before any other options, for compatibility with
2423Smail. The name &'rmail'& is used as an interface by some UUCP systems.
2424
2425.cindex "&'runq'&"
2426.cindex "queue runner"
2427If Exim is called under the name &'runq'& it behaves as if the option &%-q%&
2428were present before any other options, for compatibility with Smail. The &%-q%&
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2429option causes a single queue runner process to be started.
2430
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2431.cindex "&'newaliases'&"
2432.cindex "alias file" "building"
2433.cindex "Sendmail compatibility" "calling Exim as &'newaliases'&"
2434If Exim is called under the name &'newaliases'& it behaves as if the option
2435&%-bi%& were present before any other options, for compatibility with Sendmail.
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2436This option is used for rebuilding Sendmail's alias file. Exim does not have
2437the concept of a single alias file, but can be configured to run a given
9b371988 2438command if called with the &%-bi%& option.
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2439
2440
9b371988
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2441.section "Trusted and admin users" "SECTtrustedadmin"
2442Some Exim options are available only to &'trusted users'& and others are
2443available only to &'admin users'&. In the description below, the phrases &"Exim
2444user"& and &"Exim group"& mean the user and group defined by EXIM_USER and
2445EXIM_GROUP in &_Local/Makefile_& or set by the &%exim_user%& and
2446&%exim_group%& options. These do not necessarily have to use the name &"exim"&.
168e428f 2447
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2448.ilist
2449.cindex "trusted user" "definition of"
2450.cindex "user" "trusted definition of"
168e428f 2451The trusted users are root, the Exim user, any user listed in the
9b371988
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2452&%trusted_users%& configuration option, and any user whose current group or any
2453supplementary group is one of those listed in the &%trusted_groups%&
168e428f 2454configuration option. Note that the Exim group is not automatically trusted.
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2455
2456.cindex '&"From"& line'
2457.cindex "envelope sender"
2458Trusted users are always permitted to use the &%-f%& option or a leading
2459&"From&~"& line to specify the envelope sender of a message that is passed to
2460Exim through the local interface (see the &%-bm%& and &%-f%& options below).
2461See the &%untrusted_set_sender%& option for a way of permitting non-trusted
2462users to set envelope senders.
2463
2464.cindex "&'From:'& header line"
2465.cindex "&'Sender:'& header line"
2466For a trusted user, there is never any check on the contents of the &'From:'&
2467header line, and a &'Sender:'& line is never added. Furthermore, any existing
2468&'Sender:'& line in incoming local (non-TCP/IP) messages is not removed.
2469
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2470Trusted users may also specify a host name, host address, interface address,
2471protocol name, ident value, and authentication data when submitting a message
2472locally. Thus, they are able to insert messages into Exim's queue locally that
2473have the characteristics of messages received from a remote host. Untrusted
9b371988 2474users may in some circumstances use &%-f%&, but can never set the other values
168e428f 2475that are available to trusted users.
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2476.next
2477.cindex "user" "admin definition of"
2478.cindex "admin user" "definition of"
168e428f 2479The admin users are root, the Exim user, and any user that is a member of the
9b371988 2480Exim group or of any group listed in the &%admin_groups%& configuration option.
168e428f 2481The current group does not have to be one of these groups.
9b371988 2482
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2483Admin users are permitted to list the queue, and to carry out certain
2484operations on messages, for example, to force delivery failures. It is also
2485necessary to be an admin user in order to see the full information provided by
2486the Exim monitor, and full debugging output.
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2487
2488By default, the use of the &%-M%&, &%-q%&, &%-R%&, and &%-S%& options to cause
2489Exim to attempt delivery of messages on its queue is restricted to admin users.
2490However, this restriction can be relaxed by setting the &%prod_requires_admin%&
2491option false (that is, specifying &%no_prod_requires_admin%&).
2492
2493Similarly, the use of the &%-bp%& option to list all the messages in the queue
2494is restricted to admin users unless &%queue_list_requires_admin%& is set
168e428f 2495false.
9b371988 2496.endlist
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2497
2498
9b371988 2499&*Warning*&: If you configure your system so that admin users are able to
168e428f
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2500edit Exim's configuration file, you are giving those users an easy way of
2501getting root. There is further discussion of this issue at the start of chapter
9b371988 2502&<<CHAPconf>>&.
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2503
2504
2505
2506
9b371988 2507.section "Command line options"
168e428f
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2508The command options are described in alphabetical order below.
2509
9b371988
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2510. ////////////////////////////////////////////////////////////////////////////
2511. Insert a stylized XML comment here, to identify the start of the command line
2512. options. This is for the benefit of the Perl script that automatically
2513. creates a man page for the options.
2514. ////////////////////////////////////////////////////////////////////////////
168e428f 2515
9b371988 2516.literal xml
168e428f 2517<!-- === Start of command line options === -->
9b371988 2518.literal off
168e428f
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2519
2520
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2521.vlist
2522.vitem &%--%&
2523.oindex "--"
2524.cindex "options" "command line; terminating"
168e428f
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2525This is a pseudo-option whose only purpose is to terminate the options and
2526therefore to cause subsequent command line items to be treated as arguments
2527rather than options, even if they begin with hyphens.
2528
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2529.vitem &%--help%&
2530.oindex "&%--help%&"
168e428f
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2531This option causes Exim to output a few sentences stating what it is.
2532The same output is generated if the Exim binary is called with no options and
2533no arguments.
2534
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2535.vitem &%-B%&<&'type'&>
2536.oindex "&%-B%&"
2537.cindex "8-bit characters"
2538.cindex "Sendmail compatibility" "8-bit characters"
168e428f
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2539This is a Sendmail option for selecting 7 or 8 bit processing. Exim is 8-bit
2540clean; it ignores this option.
2541
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2542.vitem &%-bd%&
2543.oindex "&%-bd%&"
2544.cindex "daemon"
2545.cindex "SMTP listener"
2546.cindex "queue runner"
168e428f 2547This option runs Exim as a daemon, awaiting incoming SMTP connections. Usually
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2548the &%-bd%& option is combined with the &%-q%&<&'time'&> option, to specify
2549that the daemon should also initiate periodic queue runs.
2550
2551The &%-bd%& option can be used only by an admin user. If either of the &%-d%&
2552(debugging) or &%-v%& (verifying) options are set, the daemon does not
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2553disconnect from the controlling terminal. When running this way, it can be
2554stopped by pressing ctrl-C.
9b371988 2555
168e428f
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2556By default, Exim listens for incoming connections to the standard SMTP port on
2557all the host's running interfaces. However, it is possible to listen on other
2558ports, on multiple ports, and only on specific interfaces. Chapter
9b371988
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2559&<<CHAPinterfaces>>& contains a description of the options that control this.
2560
168e428f 2561When a listening daemon
9b371988
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2562.cindex "daemon" "process id (pid)"
2563.cindex "pid (process id)" "of daemon"
2564is started without the use of &%-oX%& (that is, without overriding the normal
2565configuration), it writes its process id to a file called &_exim-daemon.pid_&
2566in Exim's spool directory. This location can be overridden by setting
2567PID_FILE_PATH in &_Local/Makefile_&. The file is written while Exim is still
168e428f 2568running as root.
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2569
2570When &%-oX%& is used on the command line to start a listening daemon, the
2571process id is not written to the normal pid file path. However, &%-oP%& can be
168e428f 2572used to specify a path on the command line if a pid file is required.
9b371988 2573
168e428f 2574The SIGHUP signal
9b371988 2575.cindex "SIGHUP"
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2576can be used to cause the daemon to re-exec itself. This should be done whenever
2577Exim's configuration file, or any file that is incorporated into it by means of
9b371988
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2578the &%.include%& facility, is changed, and also whenever a new version of Exim
2579is installed. It is not necessary to do this when other files that are
2580referenced from the configuration (for example, alias files) are changed,
2581because these are reread each time they are used.
2582
2583.vitem &%-bdf%&
2584.oindex "&%-bdf%&"
2585This option has the same effect as &%-bd%& except that it never disconnects
2586from the controlling terminal, even when no debugging is specified.
2587
2588.vitem &%-be%&
2589.oindex "&%-be%&"
2590.cindex "testing" "string expansion"
2591.cindex "expansion" "testing"
168e428f
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2592Run Exim in expansion testing mode. Exim discards its root privilege, to
2593prevent ordinary users from using this mode to read otherwise inaccessible
2594files. If no arguments are given, Exim runs interactively, prompting for lines
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2595of data. &new("Otherwise, it processes each argument in turn.")
2596
2597If Exim was built with USE_READLINE=yes in &_Local/Makefile_&, it tries
2598to load the &%libreadline%& library dynamically whenever the &%-be%& option is
2599used without command line arguments. If successful, it uses the &[readline()]&
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2600function, which provides extensive line-editing facilities, for reading the
2601test data. A line history is supported.
9b371988 2602
168e428f 2603Long expansion expressions can be split over several lines by using backslash
068aaea8 2604continuations. As in Exim's run time configuration, white space at the start of
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2605continuation lines is ignored. Each argument or data line is passed through the
2606string expansion mechanism, and the result is output. Variable values from the
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2607configuration file (for example, &$qualify_domain$&) are available, but no
2608message-specific values (such as &$domain$&) are set, because no message is
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2609being processed.
2610
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2611.new
2612&*Note*&: If you use this mechanism to test lookups, and you change the data
2613files or databases you are using, you must exit and restart Exim before trying
2614the same lookup again. Otherwise, because each Exim process caches the results
2615of lookups, you will just get the same result as before.
2616.wen
2617
2618.vitem &%-bF%&&~<&'filename'&>
2619.oindex "&%-bF%&"
2620.cindex "system filter" "testing"
2621.cindex "testing" "system filter"
2622This option is the same as &%-bf%& except that it assumes that the filter being
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2623tested is a system filter. The additional commands that are available only in
2624system filters are recognized.
2625
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2626.vitem &%-bf%&&~<&'filename'&>
2627.oindex "&%-bf%&"
2628.cindex "filter" "testing"
2629.cindex "testing" "filter file"
2630.cindex "forward file" "testing"
2631.cindex "testing" "forward file"
2632.cindex "Sieve filter" "testing"
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2633This option runs Exim in user filter testing mode; the file is the filter file
2634to be tested, and a test message must be supplied on the standard input. If
2635there are no message-dependent tests in the filter, an empty file can be
2636supplied.
168e428f 2637
9b371988
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2638If you want to test a system filter file, use &%-bF%& instead of &%-bf%&. You
2639can use both &%-bF%& and &%-bf%& on the same command, in order to test a system
2640filter and a user filter in the same run. For example:
2641.code
2642exim -bF /system/filter -bf /user/filter </test/message
2643.endd
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2644This is helpful when the system filter adds header lines or sets filter
2645variables that are used by the user filter.
168e428f 2646
9b371988
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2647If the test filter file does not begin with one of the special lines
2648.code
2649# Exim filter
2650# Sieve filter
2651.endd
2652it is taken to be a normal &_.forward_& file, and is tested for validity under
2653that interpretation. See sections &<<SECTitenonfilred>>& to
2654&<<SECTspecitredli>>& for a description of the possible contents of non-filter
2655redirection lists.
2656
2657The result of an Exim command that uses &%-bf%&, provided no errors are
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2658detected, is a list of the actions that Exim would try to take if presented
2659with the message for real. More details of filter testing are given in the
9b371988
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2660separate document entitled &'Exim's interfaces to mail filtering'&.
2661
168e428f 2662When testing a filter file,
9b371988
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2663.cindex "&""From""& line"
2664.cindex "envelope sender"
2665.cindex "&%-f%& option" "for filter testing"
2666the envelope sender can be set by the &%-f%& option,
2667or by a &"From&~"& line at the start of the test message. Various parameters
2668that would normally be taken from the envelope recipient address of the message
2669can be set by means of additional command line options (see the next four
2670options).
2671
2672.vitem &%-bfd%&&~<&'domain'&>
2673.oindex "&%-bfd%&"
2674.cindex "&$qualify_domain$&"
168e428f 2675This sets the domain of the recipient address when a filter file is being
9b371988
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2676tested by means of the &%-bf%& option. The default is the value of
2677&$qualify_domain$&.
168e428f 2678
9b371988
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2679.vitem &%-bfl%&&~<&'local&~part'&>
2680.oindex "&%-bfl%&"
168e428f 2681This sets the local part of the recipient address when a filter file is being
9b371988 2682tested by means of the &%-bf%& option. The default is the username of the
168e428f
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2683process that calls Exim. A local part should be specified with any prefix or
2684suffix stripped, because that is how it appears to the filter when a message is
2685actually being delivered.
2686
9b371988
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2687.vitem &%-bfp%&&~<&'prefix'&>
2688.oindex "&%-bfp%&"
168e428f 2689This sets the prefix of the local part of the recipient address when a filter
9b371988 2690file is being tested by means of the &%-bf%& option. The default is an empty
168e428f
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2691prefix.
2692
9b371988
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2693.vitem &%-bfs%&&~<&'suffix'&>
2694.oindex "&%-bfs%&"
168e428f 2695This sets the suffix of the local part of the recipient address when a filter
9b371988 2696file is being tested by means of the &%-bf%& option. The default is an empty
168e428f
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2697suffix.
2698
9b371988
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2699.vitem &%-bh%&&~<&'IP&~address'&>
2700.oindex "&%-bh%&"
2701.cindex "testing" "incoming SMTP"
2702.cindex "SMTP" "testing incoming"
2703.cindex "testing" "relay control"
2704.cindex "relaying" "testing configuration"
2705.cindex "policy control" "testing"
2706.cindex "debugging" "&%-bh%& option"
168e428f
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2707This option runs a fake SMTP session as if from the given IP address, using the
2708standard input and output. The IP address may include a port number at the end,
2709after a full stop. For example:
9b371988
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2710.code
2711exim -bh 10.9.8.7.1234
2712exim -bh fe80::a00:20ff:fe86:a061.5678
2713.endd
168e428f 2714When an IPv6 address is given, it is converted into canonical form. In the case
9b371988
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2715of the second example above, the value of &$sender_host_address$& after
2716conversion to the canonical form is
2717&`fe80:0000:0000:0a00:20ff:fe86:a061.5678`&.
2718
168e428f 2719Comments as to what is going on are written to the standard error file. These
9b371988 2720include lines beginning with &"LOG"& for anything that would have been logged.
168e428f
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2721This facility is provided for testing configuration options for incoming
2722messages, to make sure they implement the required policy. For example, you can
9b371988
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2723test your relay controls using &%-bh%&.
2724
2725&*Warning 1*&:
2726.cindex "RFC 1413"
168e428f
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2727You cannot test features of the configuration that rely on
2728ident (RFC 1413) callouts. These cannot be done when testing using
9b371988
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2729&%-bh%& because there is no incoming SMTP connection.
2730
2731&*Warning 2*&: Address verification callouts (see section &<<SECTcallver>>&)
2732are also skipped when testing using &%-bh%&. If you want these callouts to
2733occur, use &%-bhc%& instead.
2734
168e428f
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2735Messages supplied during the testing session are discarded, and nothing is
2736written to any of the real log files. There may be pauses when DNS (and other)
9b371988 2737lookups are taking place, and of course these may time out. The &%-oMi%& option
168e428f 2738can be used to specify a specific IP interface and port if this is important.
9b371988
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2739
2740The &'exim_checkaccess'& utility is a &"packaged"& version of &%-bh%& whose
168e428f 2741output just states whether a given recipient address from a given host is
9b371988 2742acceptable or not. See section &<<SECTcheckaccess>>&.
168e428f 2743
9b371988
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2744.vitem &%-bhc%&&~<&'IP&~address'&>
2745.oindex "&%-bhc%&"
2746This option operates in the same way as &%-bh%&, except that address
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2747verification callouts are performed if required. This includes consulting and
2748updating the callout cache database.
2749
9b371988
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2750.vitem &%-bi%&
2751.oindex "&%-bi%&"
2752.cindex "alias file" "building"
2753.cindex "building alias file"
2754.cindex "Sendmail compatibility" "&%-bi%& option"
2755Sendmail interprets the &%-bi%& option as a request to rebuild its alias file.
168e428f 2756Exim does not have the concept of a single alias file, and so it cannot mimic
9b371988 2757this behaviour. However, calls to &_/usr/lib/sendmail_& with the &%-bi%& option
168e428f
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2758tend to appear in various scripts such as NIS make files, so the option must be
2759recognized.
9b371988
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2760
2761If &%-bi%& is encountered, the command specified by the &%bi_command%&
168e428f 2762configuration option is run, under the uid and gid of the caller of Exim. If
9b371988
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2763the &%-oA%& option is used, its value is passed to the command as an argument.
2764The command set by &%bi_command%& may not contain arguments. The command can
2765use the &'exim_dbmbuild'& utility, or some other means, to rebuild alias files
2766if this is required. If the &%bi_command%& option is not set, calling Exim with
2767&%-bi%& is a no-op.
2768
2769.vitem &%-bm%&
2770.oindex "&%-bm%&"
2771.cindex "local message reception"
168e428f
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2772This option runs an Exim receiving process that accepts an incoming,
2773locally-generated message on the current input. The recipients are given as the
9b371988 2774command arguments (except when &%-t%& is also present &-- see below). Each
168e428f
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2775argument can be a comma-separated list of RFC 2822 addresses. This is the
2776default option for selecting the overall action of an Exim call; it is assumed
2777if no other conflicting option is present.
9b371988 2778
168e428f 2779If any addresses in the message are unqualified (have no domain), they are
9b371988
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2780qualified by the values of the &%qualify_domain%& or &%qualify_recipient%&
2781options, as appropriate. The &%-bnq%& option (see below) provides a way of
168e428f 2782suppressing this for special cases.
9b371988 2783
168e428f 2784Policy checks on the contents of local messages can be enforced by means of
9b371988
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2785the non-SMTP ACL. See chapter &<<CHAPACL>>& for details.
2786
2787.cindex "return code" "for &%-bm%&"
2788The return code is zero if the message is successfully accepted. Otherwise, the
2789action is controlled by the &%-oe%&&'x'& option setting &-- see below.
2790
168e428f 2791The format
9b371988
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2792.cindex "message" "format"
2793.cindex "format" "message"
2794.cindex "&""From""& line"
2795.cindex "UUCP" "&""From""& line"
2796.cindex "Sendmail compatibility" "&""From""& line"
168e428f
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2797of the message must be as defined in RFC 2822, except that, for
2798compatibility with Sendmail and Smail, a line in one of the forms
9b371988
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2799.code
2800From sender Fri Jan 5 12:55 GMT 1997
2801From sender Fri, 5 Jan 97 12:55:01
2802.endd
168e428f
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2803(with the weekday optional, and possibly with additional text after the date)
2804is permitted to appear at the start of the message. There appears to be no
2805authoritative specification of the format of this line. Exim recognizes it by
9b371988 2806matching against the regular expression defined by the &%uucp_from_pattern%&
168e428f 2807option, which can be changed if necessary.
9b371988 2808
168e428f 2809The
9b371988 2810.cindex "&%-f%& option" "overriding &""From""& line"
168e428f 2811specified sender is treated as if it were given as the argument to the
9b371988 2812&%-f%& option, but if a &%-f%& option is also present, its argument is used in
168e428f
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2813preference to the address taken from the message. The caller of Exim must be a
2814trusted user for the sender of a message to be set in this way.
2815
9b371988
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2816.vitem &%-bnq%&
2817.oindex "&%-bnq%&"
2818.cindex "address qualification" "suppressing"
168e428f
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2819By default, Exim automatically qualifies unqualified addresses (those
2820without domains) that appear in messages that are submitted locally (that
2821is, not over TCP/IP). This qualification applies both to addresses in
2822envelopes, and addresses in header lines. Sender addresses are qualified using
9b371988
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2823&%qualify_domain%&, and recipient addresses using &%qualify_recipient%& (which
2824defaults to the value of &%qualify_domain%&).
2825
2826Sometimes, qualification is not wanted. For example, if &%-bS%& (batch SMTP) is
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2827being used to re-submit messages that originally came from remote hosts after
2828content scanning, you probably do not want to qualify unqualified addresses in
2829header lines. (Such lines will be present only if you have not enabled a header
2830syntax check in the appropriate ACL.)
9b371988
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2831
2832The &%-bnq%& option suppresses all qualification of unqualified addresses in
168e428f
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2833messages that originate on the local host. When this is used, unqualified
2834addresses in the envelope provoke errors (causing message rejection) and
2835unqualified addresses in header lines are left alone.
2836
2837
9b371988
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2838.vitem &%-bP%&
2839.oindex "&%-bP%&"
2840.cindex "configuration options" "extracting"
2841.cindex "options" "configuration &-- extracting"
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2842If this option is given with no arguments, it causes the values of all Exim's
2843main configuration options to be written to the standard output. The values
2844of one or more specific options can be requested by giving their names as
2845arguments, for example:
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2846.code
2847exim -bP qualify_domain hold_domains
2848.endd
2849However, any option setting that is preceded by the word &"hide"& in the
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2850configuration file is not shown in full, except to an admin user. For other
2851users, the output is as in this example:
9b371988
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2852.code
2853mysql_servers = <value not displayable>
2854.endd
2855If &%configure_file%& is given as an argument, the name of the run time
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2856configuration file is output.
2857If a list of configuration files was supplied, the value that is output here
2858is the name of the file that was actually used.
168e428f 2859
9b371988
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2860.cindex "daemon" "process id (pid)"
2861.cindex "pid (process id)" "of daemon"
2862If &%log_file_path%& or &%pid_file_path%& are given, the names of the
2863directories where log files and daemon pid files are written are output,
2864respectively. If these values are unset, log files are written in a
2865sub-directory of the spool directory called &%log%&, and the pid file is
2866written directly into the spool directory.
2867
2868If &%-bP%& is followed by a name preceded by &`+`&, for example,
2869.code
2870exim -bP +local_domains
2871.endd
168e428f
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2872it searches for a matching named list of any type (domain, host, address, or
2873local part) and outputs what it finds.
9b371988
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2874
2875.cindex "options" "router &-- extracting"
2876.cindex "options" "transport &-- extracting"
2877If one of the words &%router%&, &%transport%&, or &%authenticator%& is given,
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2878followed by the name of an appropriate driver instance, the option settings for
2879that driver are output. For example:
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2880.code
2881exim -bP transport local_delivery
2882.endd
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2883The generic driver options are output first, followed by the driver's private
2884options. A list of the names of drivers of a particular type can be obtained by
9b371988
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2885using one of the words &%router_list%&, &%transport_list%&, or
2886&%authenticator_list%&, and a complete list of all drivers with their option
2887settings can be obtained by using &%routers%&, &%transports%&, or
2888&%authenticators%&.
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2889
2890
9b371988
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2891.vitem &%-bp%&
2892.oindex "&%-bp%&"
2893.cindex "queue" "listing messages on"
2894.cindex "listing" "messages on the queue"
168e428f 2895This option requests a listing of the contents of the mail queue on the
9b371988 2896standard output. If the &%-bp%& option is followed by a list of message ids,
168e428f 2897just those messages are listed. By default, this option can be used only by an
9b371988 2898admin user. However, the &%queue_list_requires_admin%& option can be set false
168e428f 2899to allow any user to see the queue.
168e428f 2900
9b371988
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2901Each message on the queue is displayed as in the following example:
2902.code
290325m 2.9K 0t5C6f-0000c8-00 <alice@wonderland.fict.example>
2904 red.king@looking-glass.fict.example
2905 <other addresses>
2906.endd
2907.cindex "message" "size in queue listing"
2908.cindex "size" "of message"
2909The first line contains the length of time the message has been on the queue
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2910(in this case 25 minutes), the size of the message (2.9K), the unique local
2911identifier for the message, and the message sender, as contained in the
2912envelope. For bounce messages, the sender address is empty, and appears as
9b371988 2913&"<>"&. If the message was submitted locally by an untrusted user who overrode
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2914the default sender address, the user's login name is shown in parentheses
2915before the sender address.
9b371988
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2916
2917.cindex "frozen messages" "in queue listing"
2918If the message is frozen (attempts to deliver it are suspended) then the text
2919&"*** frozen ***"& is displayed at the end of this line.
2920
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2921The recipients of the message (taken from the envelope, not the headers) are
2922displayed on subsequent lines. Those addresses to which the message has already
2923been delivered are marked with the letter D. If an original address gets
2924expanded into several addresses via an alias or forward file, the original is
2925displayed with a D only when deliveries for all of its child addresses are
2926complete.
2927
2928
9b371988
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2929.vitem &%-bpa%&
2930.oindex "&%-bpa%&"
2931This option operates like &%-bp%&, but in addition it shows delivered addresses
168e428f 2932that were generated from the original top level address(es) in each message by
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2933alias or forwarding operations. These addresses are flagged with &"+D"& instead
2934of just &"D"&.
168e428f
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2935
2936
9b371988
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2937.vitem &%-bpc%&
2938.oindex "&%-bpc%&"
2939.cindex "queue" "count of messages on"
168e428f
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2940This option counts the number of messages on the queue, and writes the total
2941to the standard output. It is restricted to admin users, unless
9b371988 2942&%queue_list_requires_admin%& is set false.
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2943
2944
9b371988
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2945.vitem &%-bpr%&
2946.oindex "&%-bpr%&"
2947This option operates like &%-bp%&, but the output is not sorted into
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2948chronological order of message arrival. This can speed it up when there are
2949lots of messages on the queue, and is particularly useful if the output is
2950going to be post-processed in a way that doesn't need the sorting.
2951
9b371988
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2952.vitem &%-bpra%&
2953.oindex "&%-bpra%&"
2954This option is a combination of &%-bpr%& and &%-bpa%&.
168e428f 2955
9b371988
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2956.vitem &%-bpru%&
2957.oindex "&%-bpru%&"
2958This option is a combination of &%-bpr%& and &%-bpu%&.
168e428f
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2959
2960
9b371988
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2961.vitem &%-bpu%&
2962.oindex "&%-bpu%&"
2963This option operates like &%-bp%& but shows only undelivered top-level
2964addresses for each message displayed. Addresses generated by aliasing or
2965forwarding are not shown, unless the message was deferred after processing by a
2966router with the &%one_time%& option set.
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2967
2968
9b371988
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2969.vitem &%-brt%&
2970.oindex "&%-brt%&"
2971.cindex "testing" "retry configuration"
2972.cindex "retry" "configuration testing"
168e428f
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2973This option is for testing retry rules, and it must be followed by up to three
2974arguments. It causes Exim to look for a retry rule that matches the values
2975and to write it to the standard output. For example:
9b371988
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2976.code
2977exim -brt bach.comp.mus.example
2978Retry rule: *.comp.mus.example F,2h,15m; F,4d,30m;
2979.endd
2980See chapter &<<CHAPretry>>& for a description of Exim's retry rules. The first
168e428f 2981argument, which is required, can be a complete address in the form
9b371988 2982&'local_part@domain'&, or it can be just a domain name. The second argument is
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2983an optional second domain name; if no retry rule is found for the first
2984argument, the second is tried. This ties in with Exim's behaviour when looking
9b371988 2985for retry rules for remote hosts &-- if no rule is found that matches the host,
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2986one that matches the mail domain is sought. The final argument is the name of a
2987specific delivery error, as used in setting up retry rules, for example
9b371988 2988&"quota_3d"&.
168e428f 2989
9b371988
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2990.vitem &%-brw%&
2991.oindex "&%-brw%&"
2992.cindex "testing" "rewriting"
2993.cindex "rewriting" "testing"
168e428f
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2994This option is for testing address rewriting rules, and it must be followed by
2995a single argument, consisting of either a local part without a domain, or a
2996complete address with a fully qualified domain. Exim outputs how this address
2997would be rewritten for each possible place it might appear. See chapter
9b371988 2998&<<CHAPrewrite>>& for further details.
168e428f 2999
9b371988
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3000.vitem &%-bS%&
3001.oindex "&%-bS%&"
3002.cindex "SMTP" "batched incoming"
3003.cindex "batched SMTP input"
168e428f
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3004This option is used for batched SMTP input, which is an alternative interface
3005for non-interactive local message submission. A number of messages can be
3006submitted in a single run. However, despite its name, this is not really SMTP
3007input. Exim reads each message's envelope from SMTP commands on the standard
3008input, but generates no responses. If the caller is trusted, or
9b371988 3009&%untrusted_set_sender%& is set, the senders in the SMTP MAIL commands are
168e428f 3010believed; otherwise the sender is always the caller of Exim.
9b371988 3011
168e428f
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3012The message itself is read from the standard input, in SMTP format (leading
3013dots doubled), terminated by a line containing just a single dot. An error is
3014provoked if the terminating dot is missing. A further message may then follow.
9b371988 3015
168e428f 3016As for other local message submissions, the contents of incoming batch SMTP
9b371988
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3017messages can be checked using the non-SMTP ACL (see chapter &<<CHAPACL>>&).
3018Unqualified addresses are automatically qualified using &%qualify_domain%& and
3019&%qualify_recipient%&, as appropriate, unless the &%-bnq%& option is used.
3020
168e428f
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3021Some other SMTP commands are recognized in the input. HELO and EHLO act
3022as RSET; VRFY, EXPN, ETRN, and HELP act as NOOP;
3023QUIT quits, ignoring the rest of the standard input.
9b371988
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3024
3025.cindex "return code" "for &%-bS%&"
168e428f
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3026If any error is encountered, reports are written to the standard output and
3027error streams, and Exim gives up immediately. The return code is 0 if no error
3028was detected; it is 1 if one or more messages were accepted before the error
3029was detected; otherwise it is 2.
9b371988 3030
168e428f 3031More details of input using batched SMTP are given in section
9b371988 3032&<<SECTincomingbatchedSMTP>>&.
168e428f 3033
9b371988
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3034.vitem &%-bs%&
3035.oindex "&%-bs%&"
3036.cindex "SMTP" "local input"
3037.cindex "local SMTP input"
168e428f
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3038This option causes Exim to accept one or more messages by reading SMTP commands
3039on the standard input, and producing SMTP replies on the standard output. SMTP
9b371988 3040policy controls, as defined in ACLs (see chapter &<<CHAPACL>>&) are applied.
168e428f
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3041Some user agents use this interface as a way of passing locally-generated
3042messages to the MTA.
9b371988 3043
168e428f 3044In
9b371988
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3045.cindex "sender" "source of"
3046this usage, if the caller of Exim is trusted, or &%untrusted_set_sender%& is
168e428f
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3047set, the senders of messages are taken from the SMTP MAIL commands.
3048Otherwise the content of these commands is ignored and the sender is set up as
3049the calling user. Unqualified addresses are automatically qualified using
9b371988
PH
3050&%qualify_domain%& and &%qualify_recipient%&, as appropriate, unless the
3051&%-bnq%& option is used.
3052
3053.cindex "inetd"
168e428f 3054The
9b371988
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3055&%-bs%& option is also used to run Exim from &'inetd'&, as an alternative to
3056using a listening daemon. Exim can distinguish the two cases by checking
3057whether the standard input is a TCP/IP socket. When Exim is called from
3058&'inetd'&, the source of the mail is assumed to be remote, and the comments
3059above concerning senders and qualification do not apply. In this situation,
3060Exim behaves in exactly the same way as it does when receiving a message via
3061the listening daemon.
3062
3063.vitem &%-bt%&
3064.oindex "&%-bt%&"
3065.cindex "testing" "addresses"
3066.cindex "address" "testing"
168e428f
PH
3067This option runs Exim in address testing mode, in which each argument is taken
3068as an address to be tested for deliverability. The results are written to the
3069standard output. If a test fails, and the caller is not an admin user, no
3070details of the failure are output, because these might contain sensitive
3071information such as usernames and passwords for database lookups.
9b371988 3072
168e428f
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3073If no arguments are given, Exim runs in an interactive manner, prompting with a
3074right angle bracket for addresses to be tested.
9b371988
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3075
3076Unlike the &%-be%& test option, you cannot arrange for Exim to use the
3077&[readline()]& function, because it is running as &'root'& and there are
168e428f 3078security issues.
9b371988 3079
168e428f 3080Each address is handled as if it were the recipient address of a message
9b371988 3081(compare the &%-bv%& option). It is passed to the routers and the result is
168e428f 3082written to the standard output. However, any router that has
9b371988 3083&%no_address_test%& set is bypassed. This can make &%-bt%& easier to use for
168e428f
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3084genuine routing tests if your first router passes everything to a scanner
3085program.
9b371988 3086
168e428f 3087The
9b371988 3088.cindex "return code" "for &%-bt%&"
168e428f
PH
3089return code is 2 if any address failed outright; it is 1 if no address
3090failed outright but at least one could not be resolved for some reason. Return
3091code 0 is given only when all addresses succeed.
9b371988
PH
3092
3093&*Warning*&: &%-bt%& can only do relatively simple testing. If any of the
168e428f
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3094routers in the configuration makes any tests on the sender address of a
3095message,
9b371988
PH
3096.cindex "&%-f%& option" "for address testing"
3097you can use the &%-f%& option to set an appropriate sender when running
3098&%-bt%& tests. Without it, the sender is assumed to be the calling user at the
168e428f
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3099default qualifying domain. However, if you have set up (for example) routers
3100whose behaviour depends on the contents of an incoming message, you cannot test
9b371988 3101those conditions using &%-bt%&. The &%-N%& option provides a possible way of
168e428f
PH
3102doing such tests.
3103
9b371988
PH
3104.vitem &%-bV%&
3105.oindex "&%-bV%&"
3106.cindex "version number of Exim" "verifying"
168e428f 3107This option causes Exim to write the current version number, compilation
9b371988 3108number, and compilation date of the &'exim'& binary to the standard output.
168e428f
PH
3109It also lists the DBM library this is being used, the optional modules (such as
3110specific lookup types), the drivers that are included in the binary, and the
3111name of the run time configuration file that is in use.
9b371988
PH
3112
3113As part of its operation, &%-bV%& causes Exim to read and syntax check its
168e428f
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3114configuration file. However, this is a static check only. It cannot check
3115values that are to be expanded. For example, although a misspelt ACL verb is
9b371988 3116detected, an error in the verb's arguments is not. You cannot rely on &%-bV%&
168e428f 3117alone to discover (for example) all the typos in the configuration; some
9b371988
PH
3118realistic testing is needed. The &%-bh%& and &%-N%& options provide more
3119dynamic testing facilities.
168e428f 3120
9b371988
PH
3121.vitem &%-bv%&