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14 <h1>HOWTO - Using Exim 4 and Mailman 2.1 together</h1>
16 <p>Mailman is a list manager with web front end and built in
17 archiving functions. Details can be found at <a
18 href="http://www.list.org/"> http://www.list.org/</a>. This
19 documentation describes the configuration of Exim (version 4) to
20 work with Mailman version 2.1</p>
22 <h2><a name="index">Index</a></h2>
25 <li><a href="#scope">Scope of this document</a></li>
26 <li><a href="#basic">Basic Configuration</a></li>
28 <li><a href="#mmconf">Mailman configuration</a></li>
29 <li><a href="#exconf">Exim configuration</a></li>
30 <li><a href="#maconf">Main configuration settings</a></li>
31 <li><a href="#roconf">Exim Router</a></li>
32 <li><a href="#taconf">Exim Transport</a></li>
34 <li><a href="#batune">Basic mailing list MTA tuning</a></li>
36 <li><a href="#retune">Receiver verification</a></li>
37 <li><a href="#rctune">Tuning of numbers of recipients</a></li>
38 <li><a href="#smtune">SMTP callback</a></li>
40 <li><a href="#verpin">Doing VERP and personalisation with exim
43 <li><a href="#verpmm">VERP within Mailman</a></li>
44 <li><a href="#persmm">Mailing list personalisation by Mailman</a></li>
45 <li><a href="#verpex">VERP expansion by Exim rather than
48 <li><a href="#virdom">Virtual domains</a></li>
49 <li><a href="#lispol">List policy management</a></li>
51 <li><a href="#conpol">Content scanning</a></li>
52 <li><a href="#incpol">Incoming message checks</a></li>
53 <li><a href="#mmapol">Mailman specific ACL checks</a></li>
55 <li><a href="#lisver">List verification</a></li>
56 <li><a href="#problem">Possible Problems</a></li>
57 <li><a href="#dochis">Document History</a></li>
60 <h2><a href="#index"><a name="scope">Scope of this document</a></a></h2>
62 <p>This document describes how to set up a basic working
63 configuration using Exim 4 as an MTA for the Mailman MLM. The
64 assumption is made that the receiving MTA, Mailman and the list
65 distribution MTA are all on the same machine, and that Mailman
66 talks to Exim using SMTP to address <tt>127.0.0.1</tt></p>
68 <p>It also describes ways of using VERP delivery, both
69 conventionally (doing VERP from Mailman), and an alternative more
70 efficient technique where VERP expansion is done within exim.</p>
72 <p>Tuning and setting appropriate mailing list protection policies
73 is also covered in passing.</p>
75 <p>General installation, use, running and administration of either
76 Mailman or exim is not covered here - the documentation for the
77 programs concerned should be read for this information.</p>
79 <h2><a href="#index"><a name="basic">Basic Configuration</a></a></h2>
81 <h3><a href="#index"><a name="mmconf">Mailman configuration</a></a></h3>
83 <p>For basic operation there is no Mailman configuration needed
84 other than the standard options detailed in the Mailman install
85 documentation. The user/group settings for Mailman must match
86 those in the config fragments given below, and you need to have at
87 least configured <tt>DEFAULT_URL_HOST</tt> and
88 <tt>DEFAULT_EMAIL_HOST</tt> within Mailman, for example by editing
89 <tt>~mailman/Mailman/mm_cfg.py</tt> and setting the following
90 (substituting in your own domains):-</p>
93 # The host part of the URL used for your mailman install
94 DEFAULT_URL_HOST = 'www.example.com'
96 # The email domain of your lists
97 DEFAULT_EMAIL_HOST = 'list.example.com'
99 # Let Mailman know that the MTA needs no aliases setting
103 <p>The final setting above informs Mailman that it does not need
104 to prompt you to add aliases when creating a list (like Sendmail),
105 or modify other settings (like Postfix). Not setting this will
106 mean that Mailman nags you to do things that aren't necessary in
107 an Exim configuration.</p>
109 <p>After making a change to the Mailman configuration file you
110 need to restart the Mailman queue runners.</p>
113 ~mailman/bin/mailmanctl restart
116 <p>Mailman should also be set to deliver to the MTA using SMTP -
117 this is done by having <tt>DELIVERY_MODULE = 'SMTPDirect'</tt> in
118 the config file (which is the default mode of operation)</p>
121 <h3><a href="#index"><a name="exconf">Exim configuration</a></a></h3>
123 <p>The Exim configuration is built so that a list created within
124 Mailman automatically appears to Exim without the need for
125 defining any additional aliases (however Mailman may helpfully
126 show or email you a list of required aliases when you create a
127 list - you can just ignore those - if you have set the
128 <tt>MTA</tt> parameter it will stop doing this).</p>
130 <p>The drawback of this configuration is that it will work poorly
131 on systems supporting lists in several different mail domains.
132 While Mailman handles virtual domains, it does not yet support
133 having two distinct lists with the same name in different virtual
134 domains, using the same Mailman installation. This will
135 eventually change. (But see below for a variation on this scheme
136 that should accommodate virtual domains better.)</p>
138 <p>The configuration file excerpts below are for use in an already
139 functional Exim configuration. You also need to have an alias for
140 <tt>mailman</tt> within the <tt>mm_domains</tt>, this picks up
141 mail sent to the site list (or basically just sent in error), and
142 should forward to the Mailman Administrator. It appears that a
143 couple of Mailman messages mention the <tt>mailman-admin</tt>
144 address (this appears to be an error in Mailman or maybe a
145 packaging error), so I would suggest that <tt>mailman-admin</tt>
146 is aliased also to the Mailman Administrator.</p>
148 <p><i>[Note: the instructions in this document will work only with
149 Exim 4. It may be possible to adapt them for Exim 3, but frankly
150 it is not worth the trouble]</i></p>
152 <p>You will need to add some macros to the main section of your
153 Exim config file. You will also need to define one new transport
154 and add new routers. Additional ACLs may be used to handle policy
155 enforcement. Remember that the exim daemon needs restarting
156 before it sees configuration changes.</p>
158 <h3><a href="#index"><a name="maconf">Main configuration settings</a></a></h3>
160 <p>First, you need to add some macros to the top of your Exim
161 config file. These just make the routers and transport below a
162 bit cleaner. Obviously, you'll need to edit these based on how
163 you configured and installed Mailman.</p>
166 # Home dir for your Mailman installation -- aka Mailman's prefix
168 # By default this is set to "/usr/local/mailman"
169 # On a Red Hat/Fedora system using the RPM use "/var/mailman"
170 # On Debian using the deb package use "/var/lib/mailman"
171 # This is normally the same as ~mailman
174 # User and group for Mailman, should match your --with-mail-gid
175 # switch to Mailman's configure script.
176 # Value is normally "mailman"
180 # Domains that your lists are in - colon separated list
181 # you may wish to add these into local_domains as well
182 domainlist mm_domains=list.example.com
184 # -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
186 # These values are derived from the ones above and should not need
187 # editing unless you have munged your mailman installation
189 # The path of the Mailman mail wrapper script
190 MM_WRAP=MM_HOME/mail/mailman
192 # The path of the list config file (used as a required file when
193 # verifying list addresses)
194 MM_LISTCHK=MM_HOME/lists/${lc::$local_part}/config.pck
197 <h3><a href="#index"><a name="roconf">Exim Router</a></a></h3>
199 <p>This router picks up all the addresses going to the Mailman
200 lists. Initially it selects only the domains that have may have
201 lists in, then selects where <tt>local_part</tt> matches a list
202 name (ie you can see a list config file). The suffixes pick up
203 all the Mailman admin addresses<p>
205 <p>The router should be placed in the router section (ie somewhere
206 after the <tt>"begin routers"</tt> line of your config file).
207 Normally you would place it just after the aliases router (since
208 that will pick up the <tt>mailman</tt> master contact
214 domains = +mm_domains
215 require_files = MM_LISTCHK
216 local_part_suffix_optional
217 local_part_suffix = -admin : \
218 -bounces : -bounces+* : \
219 -confirm : -confirm+* : \
221 -owner : -request : \
222 -subscribe : -unsubscribe
223 transport = mailman_transport
226 <h3><a href="#index"><a name="taconf">Exim Transport</a></a></h3>
228 <p>The transport for Exim 4 can be placed anywhere where under the
229 <tt>begin transports</tt> line of your Exim config file.</p>
231 <p>The <tt>if def:local_part_suffix</tt> section selects whether
232 the suffix is used as the mailman command, or whether there is no
233 suffix and so <tt>post</tt> is passed as a command.</p>
235 <p>The <tt>sg</tt> phrase strips the VERP information (if any)
242 '${if def:local_part_suffix \
243 {${sg{$local_part_suffix}{-(\\w+)(\\+.*)?}{\$1}}} \
246 current_directory = MM_HOME
247 home_directory = MM_HOME
253 <h2><a href="#index"><a name="batune">Basic mailing list MTA tuning</a></a></h2>
255 <p>Exim has a lot configurability, especially where the ACL
256 (Access Control Lists) used during SMTP reception are concerned.
257 MTA policy needs to be tuned so that list traffic is not affected
258 by ACLs intended for qualifying traffic coming in from outside.
259 Later in this document some suggestions are made regarding
260 filtering traffic that is going into the mailing list, however
263 <h3><a href="#index"><a name="retune">Receiver verification</a></a></h3>
265 <p>Exim's receiver verification feature is very useful -- it lets
266 Exim reject unrouteable addresses at SMTP time. However, this is
267 most useful for externally-originating mail that is addresses to
268 mail in one of your local domains. For Mailman list traffic, mail
269 originates on your server, and is addressed to random external
270 domains that are not under your control. Furthermore, each
271 message is addressed to many recipients -- up to 500 if you use
272 Mailman's default configuration, and don't tweak
273 <tt>SMTP_MAX_RCPTS</tt>.</p>
275 <p>Doing receiver verification on Mailman list traffic is a recipe
276 for trouble. In particular, Exim will attempt to route every
277 recipient addresses in outgoing Mailman list posts. Even though
278 this requires nothing more than a few DNS lookups for each
279 address, it can still introduce significant delays (because these
280 verifications have to be done serially as you attempt handoff to
281 exim). Therefore, you should disable recipient verification for
284 <p>Under Exim 4, this is probably already taken care of for you by
285 the default recipient verification ACL statement (in the "RCPT TO"
289 accept domains = +local_domains
291 message = unknown user
295 <p>which only does recipient verification on addresses in your
296 domain. (That's not exactly the same as doing recipient
297 verification only on messages coming from non-127.0.0.1 hosts, but
298 it should do the trick for Mailman). Obviously if the next ACL
299 does verification on non-local addresses you will need to deal
302 <p>Alternatively you can add an early get-out in the "RCPT TO"
303 ACL), which <i>trusts</i> all traffic coming from the loopback IP
307 accept hosts = 127.0.0.1
310 <h3><a href="#index"><a name="rctune">Tuning of numbers of recipients</a></a></h3>
312 <p>By default Mailman will send up to 500 recipients on each
313 message it injects into exim. However this is not necessarily a
314 good configuration for exim since it will route all those
315 recipients before starting deliveries to any of them.
316 Additionally some ACL configurations have tests on the maximum
317 number of recipients (which is a good reason for having a get out
318 ACL for list traffic as described above)</p>
320 <p>I would suggest setting Mailman to send a maximum of 5 to 50
321 recipients on a single mail (setting it lower decreases list
322 latency, but increases the work that Mailman and exim have to do),
323 and change it to send a maximum of 30 messages per SMTP
324 connection. To reflect this you should also change the exim
325 parameter <tt>smtp_accept_queue_per_connection</tt> to be 30 as
328 <p>For example, add the following lines to
329 <tt>~mailman/Mailman/mm_cfg.py</tt>:</p>
332 # Max recipients for each message
334 # Max messages sent in each SMTP connection
335 SMTP_MAX_SESSIONS_PER_CONNECTION = 30
338 <p>Tuning a mailing list system is very much a black art, and
339 depends on the type of lists you host, their throughput, size and
340 the bandwidth available. In general, tuning is only a significant
341 issue if you are pushing your system near its operational
344 <h2><a href="#index"><a name="verpin">Doing VERP and personalisation with exim and Mailman</a></a></h2>
346 <h3><a href="#index"><a name="verpmm">VERP within Mailman</a></a></h3>
348 <p><a href="http://cr.yp.to/proto/verp.txt">VERP</a> (Variable
349 Envelope Return Paths) encodes the (original) receipient address
350 in the sender address. The reason for doing this is that it means
351 bounces are sent to an address which has the original recipient
352 address encoded in it - meaning you know which recipient address
353 caused the bounce. This makes automatic bounce handling very
354 effective - the normal method of parsing the bouncing address out
355 of the bounce message is very prone to failure, especially in the
356 case of foreign MTAs which use different addressing standards, or
357 where mail forwarding is involved.</p>
359 <p>VERP will send one email, with a separate envelope sender
360 (return path), for each of your subscribers - this means that it
361 will generate more traffic since you cannot bundle up deliveries
363 href="http://www.python.org/cgi-bin/faqw-mm.py?req=show%26file=faq04.012.htp">analysis
364 of the costs of VERP</a> can be found in the <a
365 href="http://www.python.org/cgi-bin/faqw-mm.py">Mailman FAQ
368 <p>VERP settings within Mailman are done on a per-installation
369 basis - ie they affect all the lists within the installation. To
370 configure VERP within Mailman read the information in
371 <tt>~mailman/Mailman/Default.py</tt> for the options that start
372 with <tt>VERP</tt>. In a nutshell, all you need to do to enable
373 VERP with Exim is to add these lines to
374 <tt>~mailman/Mailman/mm_cfg.py</tt>:</p>
377 VERP_PASSWORD_REMINDERS = 1
378 VERP_PERSONALIZED_DELIVERIES = 1
379 VERP_CONFIRMATIONS = 1
380 VERP_DELIVERY_INTERVAL = 1
383 <p>(The router and ACLs above are smart enough to deal with VERP
386 <p>This configuration on its own will make the monthly password
387 reminders, confirmations and all list postings be sent out using
390 <p>If you wish to have the advantages of VERP with a lower
391 bandwidth cost, you can enable VERP on occasional list postings
392 rather than on every posting. Mailman will still VERP on all
393 password reminders and confirmations (these are already inherently
394 single recipient mailings), but only on occasional list postings.
395 To make Mailman use VERP on every twentieth list posting (using
396 bulk delivery for the other 19), change:-</p>
399 VERP_DELIVERY_INTERVAL = 20
402 <p>The downside to doing this is that Mailman may fail to notice a
403 bouncing address if it does not receive at least one bounce per
404 day, so ideally this approach should only be taken if the lists
405 have more than 20 message per day throughput.</p>
407 <h3><a href="#index"><a name="persmm">Mailing list personalisation by Mailman</a></a></h3>
409 <p>Mailman can also personalise each message it sends out on a
410 list. This allows, for example, the recipient's own address to
411 appear as the To: header, or information specific to them to be
412 placed in the mail footer (although at present personalisation can
413 only be done for normal mail delivery - not for digest
414 subscribers). This personalisation comes at a cost of an
415 individual message per recipient (ie same bandwidth requirements
416 as full VERP) and some processing costs for Mailman.</p>
418 <p>To enable personalisation, add the following configuration item
419 to <tt>~mailman/Mailman/mm_cfg.py</tt> (you should also set the
420 VERP settings from above since you have already incurred the costs
424 OWNERS_CAN_ENABLE_PERSONALIZATION = 1
427 <p>You will then find that in the list administration web
428 interface a new set of options has appeared in the <i>Non-digest
429 options</i> section.</p>
431 <h3><a href="#index"><a name="verpex">VERP expansion by exim rather than Mailman</a></a></h3>
433 <p>One drawback of VERP is that as well as increasing the
434 bandwidth outgoing mail requires, it also causes Mailman to send
435 one separate message per recipient from Mailman to exim - causing
436 exim to have many many more queue entries and consequently more
437 queue disk space. For example a 20,000 recipient list would
438 require 400MB minimum temporary queue storage for each 20KB
439 message sent to the list. There are also issues of increasing
440 disk traffic/throughput and losing some disk caching
443 <p>These local load problems can be overcome by doing the VERP
444 expansion as the message is sent out from the MTA over network
445 SMTP rather than as the message is injected into the MTA. It will
446 come as no surprise that exim can be configured to do just
449 <p>Firstly we need to pick up outgoing Mailman mail and send it to
450 a specialised VERP transport. This is done using a router which
451 should be placed just before your normal <tt>dnslookup</tt> router
452 for remote addresses:-</p>
455 # Pick up on messages from our local mailman and route them via our
456 # special VERP-enabled transport
460 # we only consider messages sent in through loopback
461 condition = ${if eq{$sender_host_address}{127.0.0.1}{yes}{no}}
462 # we do not do this for traffic going to the local machine
463 domains = !+local_domains:!+mm_domains
464 ignore_target_hosts = <; 0.0.0.0; \
469 # only the un-VERPed bounce addresses are handled
470 senders = "*-bounces@*"
471 transport = mailman_verp_smtp
474 <p>Addresses selected by this router should then be passed on to
475 an SMTP transport that does VERP expansion. This should be placed
476 anywhere within the transport section:-</p>
479 # Mailman VERP envelope sender address formatting. This seems not to use
480 # quoted-printable encoding of the address, but instead just replaces the
481 # '@' in the recipient address with '='.
485 # put recipient address into return_path
487 ${local_part:$return_path}+$local_part=$domain@${domain:$return_path}
488 # must restrict to one recipient at a time
490 # Errors-To: may carry old return_path
491 headers_remove = Errors-To
492 headers_add = Errors-To: \
493 ${local_part:$return_path}+$local_part=$domain@${domain:$return_path}
496 <p>Once this has been configured, Mailman can be set to not do
497 VERP expansion on normal list deliveries - the VERP
498 configuration should now look like:-</p>
500 VERP_PASSWORD_REMINDERS = 1
501 VERP_PERSONALIZED_DELIVERIES = 1
502 VERP_CONFIRMATIONS = 1
503 VERP_DELIVERY_INTERVAL = 0
506 <p>If you have set personalisation on any list, this will still be
507 handled, and VERPed, by Mailman.</p>
509 <h2><a href="#index"><a name="virdom">Virtual domains</a></a></h2>
511 <p>One approach to handling virtual domains is to use a separate
512 Mailman installation for each virtual domain. (Currently, this is
513 the only way to have lists with the same name in different virtual
514 domains handled by the same machine.)</p>
516 <p>In this case, you must change the <tt>MM_HOME</tt> macro to
517 something like this:-</p>
520 MM_HOME=/virtual/${lc::$domain}/mailman
523 <p>and modify the <tt>mm_domains</tt> domain list appropriately.</p>
525 <h2><a href="#index"><a name="lispol">List policy management</a></a></h2>
527 <p>Most list policy handling is done within Mailman using the Web
528 GUI. However some issues may be better handled by the MTA,
529 especially matters of overall site policy (not just mailing list
530 policy). For example you may wish to do virus or spam scanning on
531 incoming messages.</p>
533 <p>In general you exclude outgoing list mail from any policy
534 controls. This is because outgoing list mail has already been
535 through the policy controls on the way into the system.
536 Additionally spam scanning (for example) is a machine intensive
537 operation, and scanning a message that has already been scanned,
538 and then replicated to many recipients, is going to be very
539 expensive as well as ineffective. For this reason you will
540 normally have an <tt>accept</tt> clause early on in your ACLs that
541 causes Mailman generated traffic to bypass the machine intensive
544 <h3><a href="#index"><a name="conpol">Content scanning</a></a></h3>
546 <p>I would recommend that mailing lists now scan for both spam and
547 viruses on incoming mail - this is due to the potential for a
548 compromised windows machine belonging to a subscriber managing to
549 distribute unwanted content via the list. This causes problems
550 not only to the list reputation, but also to the list manager who
551 will get many many bounces from subscribers who do content
552 scanning on their own incoming mail.</p>
554 <p>The best way to do this is using the <a
555 href="http://duncanthrax.net/exiscan-acl/">exiscan</a> extension
556 along with a virus scanner such as <a
557 href="http://duncanthrax.net/exiscan-acl/">clam-av</a> and a spam
558 content scanner such as <a
559 href="http://www.spamassassin.org/">SpamAssassin</a>. Configuring
560 these is beyond the scope of this document, however Tim Jackson
561 has a very good set of <a
562 href="http://www.timj.co.uk/linux/Exim-SpamAndVirusScanning.pdf">PDF
563 documentation</a> on integrating these.</p>
565 <p>One thing to note is that if you add full SpamAssassin headers
566 onto list messages this bulks up the messages significantly.
567 These headers are also available to list subscribers, which might
568 make it easier for someone malicious to work out how to evade your
569 spam scanning strategy. I would suggest that Spam headers are not
570 added for Mailman incoming mail, or minimal (short) headers added,
571 or that they are stripped somewhere. However having minimal
572 headers on means that you can, for example, moderate all messages
573 which have a given spam rating (as well as bouncing messages with
574 a very high rating).</p>
576 <h3><a href="#index"><a name="incpol">Incoming message checks</a></a></h3>
578 <p>You may wish to apply various checks to incoming messages to
579 ensure that they are sane. These may include:-</p>
582 <li>DNSBL checks</li>
583 <li>Header checks</li>
584 <li>Sender callback verification</li>
587 <p>However all of these do have some degree of false positive
588 ratings. You need to be aware of how much of your user base you
589 may alienate by imposing too strict a set of controls, and balance
590 that against the reduced amount of unwanted bulk mail.</p>
592 <h3><a href="#index"><a name="mmapol">Mailman specific ACL checks</a></a></h3>
594 <p>Lists should never receive bounce messages to the posting
595 address unless the bounced message is either a forgery using the
596 list address as the sender address, or the bouncing MTA is
597 terminally broken. In either of these cases we really are not
598 interested in receiving the messages and can reject them at SMTP
599 time with a clear conscience. The ACL to do this (as part of the
603 # Reject bounce (null sender) messages to the list
604 reject message = "Recipient never sends mail so cannot cause bounces"
606 domains = +mm_domains
607 condition = ${if exists{MM_LISTCHK} {yes}{no}}
610 <p>Additionally other mailman addresses do not generate mail (as
611 the envelope sender, although they may be mentioned in the header
612 addresses. The ACL is split into 2 so that it can be written
613 without the local_part condition wrapping.</p>
616 # Reject bounce (null sender) messages to the list
617 reject message = "Recipient never sends mail so cannot cause bounces"
619 domains = +mm_domains
620 local_parts = \N^.*-(admin|join|leave|owner|request)$\N
621 reject message = "Recipient never sends mail so cannot cause bounces"
623 domains = +mm_domains
624 local_parts = \N^.*-(subscribe|unsubscribe)$\N
627 <h3><a href="#index"><a name="smtune">SMTP callbacks</a></a></h3>
629 <p>Exim's SMTP callback feature is an even more powerful way to
630 detect bogus sender addresses than normal sender verification.
631 They are specially useful for checking envelope sender addresses
632 at RCPT time within SMTP, and have been to date the most effective
633 single anti-SPAM measure (however it should be noted that CBV is
634 hated vehemently by some mail admins, and does increase both
635 latency and traffic, as well as theoretically being a means to set
636 up a DDOS situation).</p>
638 <p>It is recommended that SMTP Sender CBV is not carried out on
639 messages to the Mailman bounce handlers, so that broken remote
640 MTAs (specifcally ones which send bounces with something other
641 than a null sender address) do not get excluded from being taken
642 off mailing lists</p>
645 # Do callback verification unless Mailman incoming bounce
646 reject !local_parts = *-bounces : *-bounces+*
647 !verify = sender/callout=30s,defer_ok
651 <p>Callback verification can also be done on header addresses, but
652 care should be taken not to reject messages unnecessarily,
653 especially when the message is going to Mailman's bounce
656 <h2><a href="#index"><a name="lisver">List verification</a></a></h2>
658 <p>This is how a set of address tests for the Exim lists look on a
659 working system. The list in question is
660 <tt>testlist@list.example.com</tt>, and these commands were
661 run on the <tt>list.example.com</tt> mail server (<tt>"% "</tt>
662 indicates the Unix shell prompt):</p>
665 % exim -bt testlist@list.example.com
666 testlist@list.example.com
667 router = mailman_router, transport = mailman_transport
669 % exim -bt testlist-request@list.example.com
670 testlist-request@list.example.com
671 router = mailman_router, transport = mailman_transport
673 % exim -bt testlist-bounces@list.example.com
674 testlist-bounces@list.example.com
675 router = mailman_router, transport = mailman_transport
677 % exim -bt testlist-bounces+luser=example.com@list.example.com
678 testlist-bounces+luser=example.com@list.example.com
679 router = mailman_router, transport = mailman_transport
682 <p>If your <tt>"exim -bt"</tt> output looks something like this,
683 that's a start: at least it means Exim will pass the right
684 messages to the right Mailman commands. It by no means guarantees
685 that your Exim/Mailman installation is functioning perfectly,
688 <h2><a href="#index"><a name="problem">Possible Problems</a></a></h2>
692 <li> Mailman will send as many <tt>MAIL FROM/RCPT TO</tt> as it
693 needs. It may result in more than 10 or 100 messages sent in one
694 connection, which will exceed the default value of Exim's
695 smtp_accept_queue_per_connection This is bad because it will
696 cause Exim to switch into queue mode and severely delay delivery
697 of your list messages. The way to fix this is to set mailman's
698 <tt>SMTP_MAX_SESSIONS_PER_CONNECTION</tt> (in
699 <tt>~mailman/Mailman/mm_cfg.py</tt>) to a smaller value than
700 Exim's <tt>smtp_accept_queue_per_connection</tt></li>
702 <li>Mailman should ignore Exim delay warning messages, even
703 though Exim should never send this to list messages. Mailman
704 2.1's general bounce detection and VERP support should greatly
705 improve the bounce detector's hit rates.</li>
707 <li>List existence is determined by the existence of a
708 <tt>config.pck</tt> file for a list. If you delete lists by
709 foul means, be aware of this.</li>
711 <li>If you are getting Exim or Mailman complaining about user
712 ids when you send mail to a list, check that the
713 <tt>MM_UID</tt> and <tt>MM_GID</tt> match those of
714 Mailman itself (i.e. what were used in the configure script).
715 Also make sure you do not have aliases in the main alias file
720 <h2><a href="#index"><a name="dochis">Document History</a></a></h2>
723 <li>Originally written by Nigel Metheringham.</li>
724 <li>Updated by Marc Merlin for Mailman 2.1, Exim 4</li>
725 <li>Overhauled/reformatted/clarified/simplified by Greg
727 <li>Rehashed again by Nigel Metheringham</li>
730 <p>Like many documents of this type, it has evolved and taken on
731 contributions by many many helpful folks, mainly those on the
732 Mailman and exim mailing lists. To all of you, who have made
733 contributions yet had their names shamefully lost by me, <i>Thank
737 <h4>$Id: mailman21.html,v 1.3 2004/06/09 11:36:59 nigel Exp $</h4>