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4 <title>HOWTO - Using Exim 4 and Mailman together</title>
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7 <h1>HOWTO - Using Exim 4 and Mailman 2.1 together</h1>
9 <p>Mailman is a list manager with web front end and built in
10 archiving functions. Details can be found at <a
11 href="http://www.list.org/"> http://www.list.org/</a>. This
12 documentation describes the configuration of Exim (version 4) to
13 work with Mailman version 2.1</p>
15 <a name="index"><h2>Index</h2></a>
18 <li><a href="#scope">Scope of this document</a></li>
19 <li><a href="#basic">Basic Configuration</a></li>
21 <li><a href="#mmconf">Mailman configuration</a></li>
22 <li><a href="#exconf">Exim configuration</a></li>
23 <li><a href="#maconf">Main configuration settings</a></li>
24 <li><a href="#roconf">Exim Router</a></li>
25 <li><a href="#taconf">Exim Transport</a></li>
27 <li><a href="#batune">Basic mailing list MTA tuning</a></li>
29 <li><a href="#retune">Receiver verification</a></li>
30 <li><a href="#rctune">Tuning of numbers of recipients</a></li>
31 <li><a href="#smtune">SMTP callback</a></li>
33 <li><a href="#verpin">Doing VERP and personalisation with exim
36 <li><a href="#verpmm">VERP within Mailman</a></li>
37 <li><a href="#persmm">Mailing list personalisation by Mailman</a></li>
38 <li><a href="#verpex">VERP expansion by Exim rather than
41 <li><a href="#virdom">Virtual domains</a></li>
42 <li><a href="#lispol">List policy management</a></li>
44 <li><a href="#conpol">Content scanning</a></li>
45 <li><a href="#incpol">Incoming message checks</a></li>
46 <li><a href="#mmapol">Mailman specific ACL checks</a></li>
48 <li><a href="#lisver">List verification</a></li>
49 <li><a href="#problem">Possible Problems</a></li>
50 <li><a href="#dochis">Document History</a></li>
53 <a name="scope"> </a>
54 <a href="#index"><h2>Scope of this document</h2></a>
56 <p>This document describes how to set up a basic working
57 configuration using Exim 4 as an MTA for the Mailman MLM. The
58 assumption is made that the receiving MTA, Mailman and the list
59 distribution MTA are all on the same machine, and that Mailman
60 talks to Exim using SMTP to address <tt>127.0.0.1</tt></p>
62 <p>It also describes ways of using VERP delivery, both
63 conventionally (doing VERP from Mailman), and an alternative more
64 efficient technique where VERP expansion is done within exim.</p>
66 <p>Tuning and setting appropriate mailing list protection policies
67 is also covered in passing.</p>
69 <p>General installation, use, running and administration of either
70 Mailman or exim is not covered here - the documentation for the
71 programs concerned should be read for this information.</p>
73 <a name="basic"> </a>
74 <a href="#index"><h2>Basic Configuration</h2></a>
76 <a name="mmconf"> </a>
77 <a href="#index"><h3>Mailman configuration</h3></a>
79 <p>For basic operation there is no Mailman configuration needed
80 other than the standard options detailed in the Mailman install
81 documentation. The user/group settings for Mailman must match
82 those in the config fragments given below, and you need to have at
83 least configured <tt>DEFAULT_URL_HOST</tt> and
84 <tt>DEFAULT_EMAIL_HOST</tt> within Mailman, for example by editing
85 <tt>~mailman/Mailman/mm_cfg.py</tt> and setting the following
86 (substituting in your own domains):-</p>
89 # The host part of the URL used for your mailman install
90 DEFAULT_URL_HOST = 'www.example.com'
92 # The email domain of your lists
93 DEFAULT_EMAIL_HOST = 'list.example.com'
95 # Let Mailman know that the MTA needs no aliases setting
99 <p>The final setting above informs Mailman that it does not need
100 to prompt you to add aliases when creating a list (like Sendmail),
101 or modify other settings (like Postfix). Not setting this will
102 mean that Mailman nags you to do things that aren't necessary in
103 an Exim configuration.</p>
105 <p>After making a change to the Mailman configuration file you
106 need to restart the Mailman queue runners.</p>
109 ~mailman/bin/mailmanctl restart
112 <p>Mailman should also be set to deliver to the MTA using SMTP -
113 this is done by having <tt>DELIVERY_MODULE = 'SMTPDirect'</tt> in
114 the config file (which is the default mode of operation)</p>
117 <a name="exconf"> </a>
118 <a href="#index"><h3>Exim configuration</h3></a>
120 <p>The Exim configuration is built so that a list created within
121 Mailman automatically appears to Exim without the need for
122 defining any additional aliases (however Mailman may helpfully
123 show or email you a list of required aliases when you create a
124 list - you can just ignore those - if you have set the
125 <tt>MTA</tt> parameter it will stop doing this).</p>
127 <p>The drawback of this configuration is that it will work poorly
128 on systems supporting lists in several different mail domains.
129 While Mailman handles virtual domains, it does not yet support
130 having two distinct lists with the same name in different virtual
131 domains, using the same Mailman installation. This will
132 eventually change. (But see below for a variation on this scheme
133 that should accommodate virtual domains better.)</p>
135 <p>The configuration file excerpts below are for use in an already
136 functional Exim configuration. You also need to have an alias for
137 <tt>mailman</tt> within the <tt>mm_domains</tt>, this picks up
138 mail sent to the site list (or basically just sent in error), and
139 should forward to the Mailman Administrator. It appears that a
140 couple of Mailman messages mention the <tt>mailman-admin</tt>
141 address (this appears to be an error in Mailman or maybe a
142 packaging error), so I would suggest that <tt>mailman-admin</tt>
143 is aliased also to the Mailman Administrator.</p>
145 <p><i>[Note: the instructions in this document will work only with
146 Exim 4. It may be possible to adapt them for Exim 3, but frankly
147 it is not worth the trouble]</i></p>
149 <p>You will need to add some macros to the main section of your
150 Exim config file. You will also need to define one new transport
151 and add new routers. Additional ACLs may be used to handle policy
152 enforcement. Remember that the exim daemon needs restarting
153 before it sees configuration changes.</p>
155 <a name="maconf"> </a>
156 <a href="#index"><h3>Main configuration settings</h3></a>
158 <p>First, you need to add some macros to the top of your Exim
159 config file. These just make the routers and transport below a
160 bit cleaner. Obviously, you'll need to edit these based on how
161 you configured and installed Mailman.</p>
164 # Home dir for your Mailman installation -- aka Mailman's prefix
166 # By default this is set to "/usr/local/mailman"
167 # On a Red Hat/Fedora system using the RPM use "/var/mailman"
168 # On Debian using the deb package use "/var/lib/mailman"
169 # This is normally the same as ~mailman
172 # User and group for Mailman, should match your --with-mail-gid
173 # switch to Mailman's configure script.
174 # Value is normally "mailman"
178 # Domains that your lists are in - colon separated list
179 # you may wish to add these into local_domains as well
180 domainlist mm_domains=list.example.com
182 # -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
184 # These values are derived from the ones above and should not need
185 # editing unless you have munged your mailman installation
187 # The path of the Mailman mail wrapper script
188 MM_WRAP=MM_HOME/mail/mailman
190 # The path of the list config file (used as a required file when
191 # verifying list addresses)
192 MM_LISTCHK=MM_HOME/lists/${lc::$local_part}/config.pck
195 <a name="roconf"> </a>
196 <a href="#index"><h3>Exim Router</h3></a>
198 <p>This router picks up all the addresses going to the Mailman
199 lists. Initially it selects only the domains that have may have
200 lists in, then selects where <tt>local_part</tt> matches a list
201 name (ie you can see a list config file). The suffixes pick up
202 all the Mailman admin addresses<p>
204 <p>The router should be placed in the router section (ie somewhere
205 after the <tt>"begin routers"</tt> line of your config file).
206 Normally you would place it just after the aliases router (since
207 that will pick up the <tt>mailman</tt> master contact
213 domains = +mm_domains
214 require_files = MM_LISTCHK
215 local_part_suffix_optional
216 local_part_suffix = -admin : \
217 -bounces : -bounces+* : \
218 -confirm : -confirm+* : \
220 -owner : -request : \
221 -subscribe : -unsubscribe
222 transport = mailman_transport
225 <a name="taconf"> </a>
226 <a href="#index"><h3>Exim Transport</h3></a>
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 <a name="batune"> </a>
254 <a href="#index"><h2>Basic mailing list MTA tuning</h2></a>
256 <p>Exim has a lot configurability, especially where the ACL
257 (Access Control Lists) used during SMTP reception are concerned.
258 MTA policy needs to be tuned so that list traffic is not affected
259 by ACLs intended for qualifying traffic coming in from outside.
260 Later in this document some suggestions are made regarding
261 filtering traffic that is going into the mailing list, however
264 <a name="retune"> </a>
265 <a href="#index"><h3>Receiver verification</h3></a>
267 <p>Exim's receiver verification feature is very useful -- it lets
268 Exim reject unrouteable addresses at SMTP time. However, this is
269 most useful for externally-originating mail that is addresses to
270 mail in one of your local domains. For Mailman list traffic, mail
271 originates on your server, and is addressed to random external
272 domains that are not under your control. Furthermore, each
273 message is addressed to many recipients -- up to 500 if you use
274 Mailman's default configuration, and don't tweak
275 <tt>SMTP_MAX_RCPTS</tt>.</p>
277 <p>Doing receiver verification on Mailman list traffic is a recipe
278 for trouble. In particular, Exim will attempt to route every
279 recipient addresses in outgoing Mailman list posts. Even though
280 this requires nothing more than a few DNS lookups for each
281 address, it can still introduce significant delays (because these
282 verifications have to be done serially as you attempt handoff to
283 exim). Therefore, you should disable recipient verification for
286 <p>Under Exim 4, this is probably already taken care of for you by
287 the default recipient verification ACL statement (in the "RCPT TO"
291 accept domains = +local_domains
293 message = unknown user
297 <p>which only does recipient verification on addresses in your
298 domain. (That's not exactly the same as doing recipient
299 verification only on messages coming from non-127.0.0.1 hosts, but
300 it should do the trick for Mailman). Obviously if the next ACL
301 does verification on non-local addresses you will need to deal
304 <p>Alternatively you can add an early get-out in the "RCPT TO"
305 ACL), which <i>trusts</i> all traffic coming from the loopback IP
309 accept hosts = 127.0.0.1
312 <a name="rctune"> </a>
313 <a href="#index"><h3>Tuning of numbers of recipients</h3></a>
315 <p>By default Mailman will send up to 500 recipients on each
316 message it injects into exim. However this is not necessarily a
317 good configuration for exim since it will route all those
318 recipients before starting deliveries to any of them.
319 Additionally some ACL configurations have tests on the maximum
320 number of recipients (which is a good reason for having a get out
321 ACL for list traffic as described above)</p>
323 <p>I would suggest setting Mailman to send a maximum of 5 to 50
324 recipients on a single mail (setting it lower decreases list
325 latency, but increases the work that Mailman and exim have to do),
326 and change it to send a maximum of 30 messages per SMTP
327 connection. To reflect this you should also change the exim
328 parameter <tt>smtp_accept_queue_per_connection</tt> to be 30 as
331 <p>For example, add the following lines to
332 <tt>~mailman/Mailman/mm_cfg.py</tt>:</p>
335 # Max recipients for each message
337 # Max messages sent in each SMTP connection
338 SMTP_MAX_SESSIONS_PER_CONNECTION = 30
341 <p>Tuning a mailing list system is very much a black art, and
342 depends on the type of lists you host, their throughput, size and
343 the bandwidth available. In general, tuning is only a significant
344 issue if you are pushing your system near its operational
347 <a name="verpin"> </a>
348 <a href="#index"><h2>Doing VERP and personalisation with exim and Mailman</h2></a>
350 <a name="verpmm"> </a>
351 <a href="#index"><h3>VERP within Mailman</h3></a>
353 <p><a href="http://cr.yp.to/proto/verp.txt">VERP</a> (Variable
354 Envelope Return Paths) encodes the (original) receipient address
355 in the sender address. The reason for doing this is that it means
356 bounces are sent to an address which has the original recipient
357 address encoded in it - meaning you know which recipient address
358 caused the bounce. This makes automatic bounce handling very
359 effective - the normal method of parsing the bouncing address out
360 of the bounce message is very prone to failure, especially in the
361 case of foreign MTAs which use different addressing standards, or
362 where mail forwarding is involved.</p>
364 <p>VERP will send one email, with a separate envelope sender
365 (return path), for each of your subscribers - this means that it
366 will generate more traffic since you cannot bundle up deliveries
368 href="http://www.python.org/cgi-bin/faqw-mm.py?req=show&file=faq04.012.htp">analysis
369 of the costs of VERP</a> can be found in the <a
370 href="http://www.python.org/cgi-bin/faqw-mm.py">Mailman FAQ
373 <p>VERP settings within Mailman are done on a per-installation
374 basis - ie they affect all the lists within the installation. To
375 configure VERP within Mailman read the information in
376 <tt>~mailman/Mailman/Default.py</tt> for the options that start
377 with <tt>VERP</tt>. In a nutshell, all you need to do to enable
378 VERP with Exim is to add these lines to
379 <tt>~mailman/Mailman/mm_cfg.py</tt>:</p>
382 VERP_PASSWORD_REMINDERS = 1
383 VERP_PERSONALIZED_DELIVERIES = 1
384 VERP_CONFIRMATIONS = 1
385 VERP_DELIVERY_INTERVAL = 1
388 <p>(The router and ACLs above are smart enough to deal with VERP
391 <p>This configuration on its own will make the monthly password
392 reminders, confirmations and all list postings be sent out using
395 <p>If you wish to have the advantages of VERP with a lower
396 bandwidth cost, you can enable VERP on occasional list postings
397 rather than on every posting. Mailman will still VERP on all
398 password reminders and confirmations (these are already inherently
399 single recipient mailings), but only on occasional list postings.
400 To make Mailman use VERP on every twentieth list posting (using
401 bulk delivery for the other 19), change:-</p>
404 VERP_DELIVERY_INTERVAL = 20
407 <p>The downside to doing this is that Mailman may fail to notice a
408 bouncing address if it does not receive at least one bounce per
409 day, so ideally this approach should only be taken if the lists
410 have more than 20 message per day throughput.</p>
412 <a name="persmm"> </a>
413 <a href="#index"><h3>Mailing list personalisation by Mailman</h3></a>
415 <p>Mailman can also personalise each message it sends out on a
416 list. This allows, for example, the recipient's own address to
417 appear as the To: header, or information specific to them to be
418 placed in the mail footer (although at present personalisation can
419 only be done for normal mail delivery - not for digest
420 subscribers). This personalisation comes at a cost of an
421 individual message per recipient (ie same bandwidth requirements
422 as full VERP) and some processing costs for Mailman.</p>
424 <p>To enable personalisation, add the following configuration item
425 to <tt>~mailman/Mailman/mm_cfg.py</tt> (you should also set the
426 VERP settings from above since you have already incurred the costs
430 OWNERS_CAN_ENABLE_PERSONALIZATION = 1
433 <p>You will then find that in the list administration web
434 interface a new set of options has appeared in the <i>Non-digest
435 options</i> section.</p>
437 <a name="verpex"> </a>
438 <a href="#index"><h3>VERP expansion by exim rather than Mailman</h3></a>
440 <p>One drawback of VERP is that as well as increasing the
441 bandwidth outgoing mail requires, it also causes Mailman to send
442 one separate message per recipient from Mailman to exim - causing
443 exim to have many many more queue entries and consequently more
444 queue disk space. For example a 20,000 recipient list would
445 require 400MB minimum temporary queue storage for each 20KB
446 message sent to the list. There are also issues of increasing
447 disk traffic/throughput and losing some disk caching
450 <p>These local load problems can be overcome by doing the VERP
451 expansion as the message is sent out from the MTA over network
452 SMTP rather than as the message is injected into the MTA. It will
453 come as no surprise that exim can be configured to do just
456 <p>Firstly we need to pick up outgoing Mailman mail and send it to
457 a specialised VERP transport. This is done using a router which
458 should be placed just before your normal <tt>dnslookup</tt> router
459 for remote addresses:-</p>
462 # Pick up on messages from our local mailman and route them via our
463 # special VERP-enabled transport
467 # we only consider messages sent in through loopback
468 condition = ${if eq{$sender_host_address}{127.0.0.1}{yes}{no}}
469 # we do not do this for traffic going to the local machine
470 domains = !+local_domains:!+mm_domains
471 ignore_target_hosts = <; 0.0.0.0; \
476 # only the un-VERPed bounce addresses are handled
477 senders = "*-bounces@*"
478 transport = mailman_verp_smtp
481 <p>Addresses selected by this router should then be passed on to
482 an SMTP transport that does VERP expansion. This should be placed
483 anywhere within the transport section:-</p>
486 # Mailman VERP envelope sender address formatting. This seems not to use
487 # quoted-printable encoding of the address, but instead just replaces the
488 # '@' in the recipient address with '='.
492 # put recipient address into return_path
494 ${local_part:$return_path}+$local_part=$domain@${domain:$return_path}
495 # must restrict to one recipient at a time
497 # Errors-To: may carry old return_path
498 headers_remove = Errors-To
499 headers_add = Errors-To: \
500 ${local_part:$return_path}+$local_part=$domain@${domain:$return_path}
503 <p>Once this has been configured, Mailman can be set to not do
504 VERP expansion on normal list deliveries - the VERP
505 configuration should now look like:-</p>
507 VERP_PASSWORD_REMINDERS = 1
508 VERP_PERSONALIZED_DELIVERIES = 1
509 VERP_CONFIRMATIONS = 1
510 VERP_DELIVERY_INTERVAL = 0
513 <p>If you have set personalisation on any list, this will still be
514 handled, and VERPed, by Mailman.</p>
516 <a name="virdom"> </a>
517 <a href="#index"><h2>Virtual domains</h2></a>
519 <p>One approach to handling virtual domains is to use a separate
520 Mailman installation for each virtual domain. (Currently, this is
521 the only way to have lists with the same name in different virtual
522 domains handled by the same machine.)</p>
524 <p>In this case, you must change the <tt>MM_HOME</tt> macro to
525 something like this:-</p>
528 MM_HOME=/virtual/${lc::$domain}/mailman
531 <p>and modify the <tt>mm_domains</tt> domain list appropriately.</p>
533 <a name="lispol"> </a>
534 <a href="#index"><h2>List policy management</h2></a>
536 <p>Most list policy handling is done within Mailman using the Web
537 GUI. However some issues may be better handled by the MTA,
538 especially matters of overall site policy (not just mailing list
539 policy). For example you may wish to do virus or spam scanning on
540 incoming messages.</p>
542 <p>In general you exclude outgoing list mail from any policy
543 controls. This is because outgoing list mail has already been
544 through the policy controls on the way into the system.
545 Additionally spam scanning (for example) is a machine intensive
546 operation, and scanning a message that has already been scanned,
547 and then replicated to many recipients, is going to be very
548 expensive as well as ineffective. For this reason you will
549 normally have an <tt>accept</tt> clause early on in your ACLs that
550 causes Mailman generated traffic to bypass the machine intensive
553 <a name="conpol"> </a>
554 <a href="#index"><h3>Content scanning</h3></a>
556 <p>I would recommend that mailing lists now scan for both spam and
557 viruses on incoming mail - this is due to the potential for a
558 compromised windows machine belonging to a subscriber managing to
559 distribute unwanted content via the list. This causes problems
560 not only to the list reputation, but also to the list manager who
561 will get many many bounces from subscribers who do content
562 scanning on their own incoming mail.</p>
564 <p>The best way to do this is using the <a
565 href="http://duncanthrax.net/exiscan-acl/">exiscan</a> extension
566 along with a virus scanner such as <a
567 href="http://duncanthrax.net/exiscan-acl/">clam-av</a> and a spam
568 content scanner such as <a
569 href="http://www.spamassassin.org/">SpamAssassin</a>. Configuring
570 these is beyond the scope of this document, however Tim Jackson
571 has a very good set of <a
572 href="http://www.timj.co.uk/linux/Exim-SpamAndVirusScanning.pdf">PDF
573 documentation</a> on integrating these.</p>
575 <p>One thing to note is that if you add full SpamAssassin headers
576 onto list messages this bulks up the messages significantly.
577 These headers are also available to list subscribers, which might
578 make it easier for someone malicious to work out how to evade your
579 spam scanning strategy. I would suggest that Spam headers are not
580 added for Mailman incoming mail, or minimal (short) headers added,
581 or that they are stripped somewhere. However having minimal
582 headers on means that you can, for example, moderate all messages
583 which have a given spam rating (as well as bouncing messages with
584 a very high rating).</p>
586 <a name="incpol"> </a>
587 <a href="#index"><h3>Incoming message checks</h3></a>
589 <p>You may wish to apply various checks to incoming messages to
590 ensure that they are sane. These may include:-</p>
593 <li>DNSBL checks</li>
594 <li>Header checks</li>
595 <li>Sender callback verification</li>
598 <p>However all of these do have some degree of false positive
599 ratings. You need to be aware of how much of your user base you
600 may alienate by imposing too strict a set of controls, and balance
601 that against the reduced amount of unwanted bulk mail.</p>
603 <a name="mmapol"> </a>
604 <a href="#index"><h3>Mailman specific ACL checks</h3></a>
606 <p>Lists should never receive bounce messages to the posting
607 address unless the bounced message is either a forgery using the
608 list address as the sender address, or the bouncing MTA is
609 terminally broken. In either of these cases we really are not
610 interested in receiving the messages and can reject them at SMTP
611 time with a clear conscience. The ACL to do this (as part of the
615 # Reject bounce (null sender) messages to the list
616 reject message = "Recipient never sends mail so cannot cause bounces"
618 domains = +mm_domains
619 condition = ${if exists{MM_LISTCHK} {yes}{no}}
622 <p>Additionally other mailman addresses do not generate mail (as
623 the envelope sender, although they may be mentioned in the header
624 addresses. The ACL is split into 2 so that it can be written
625 without the local_part condition wrapping.</p>
628 # Reject bounce (null sender) messages to the list
629 reject message = "Recipient never sends mail so cannot cause bounces"
631 domains = +mm_domains
632 local_parts = \N^.*-(admin|join|leave|owner|request)$\N
633 reject message = "Recipient never sends mail so cannot cause bounces"
635 domains = +mm_domains
636 local_parts = \N^.*-(subscribe|unsubscribe)$\N
639 <a name="smtune"> </a>
640 <a href="#index"><h3>SMTP callbacks</h3></a>
642 <p>Exim's SMTP callback feature is an even more powerful way to
643 detect bogus sender addresses than normal sender verification.
644 They are specially useful for checking envelope sender addresses
645 at RCPT time within SMTP, and have been to date the most effective
646 single anti-SPAM measure (however it should be noted that CBV is
647 hated vehemently by some mail admins, and does increase both
648 latency and traffic, as well as theoretically being a means to set
649 up a DDOS situation).</p>
651 <p>It is recommended that SMTP Sender CBV is not carried out on
652 messages to the Mailman bounce handlers, so that broken remote
653 MTAs (specifcally ones which send bounces with something other
654 than a null sender address) do not get excluded from being taken
655 off mailing lists</p>
658 # Do callback verification unless Mailman incoming bounce
659 reject !local_parts = *-bounces : *-bounces+*
660 !verify = sender/callout=30s,defer_ok
664 <p>Callback verification can also be done on header addresses, but
665 care should be taken not to reject messages unnecessarily,
666 especially when the message is going to Mailman's bounce
669 <a name="lisver"> </a>
670 <a href="#index"><h2>List verification</h2></a>
672 <p>This is how a set of address tests for the Exim lists look on a
673 working system. The list in question is
674 <tt>testlist@list.example.com</tt>, and these commands were
675 run on the <tt>list.example.com</tt> mail server (<tt>"% "</tt>
676 indicates the Unix shell prompt):</p>
679 % exim -bt testlist@list.example.com
680 testlist@list.example.com
681 router = mailman_router, transport = mailman_transport
683 % exim -bt testlist-request@list.example.com
684 testlist-request@list.example.com
685 router = mailman_router, transport = mailman_transport
687 % exim -bt testlist-bounces@list.example.com
688 testlist-bounces@list.example.com
689 router = mailman_router, transport = mailman_transport
691 % exim -bt testlist-bounces+luser=example.com@list.example.com
692 testlist-bounces+luser=example.com@list.example.com
693 router = mailman_router, transport = mailman_transport
696 <p>If your <tt>"exim -bt"</tt> output looks something like this,
697 that's a start: at least it means Exim will pass the right
698 messages to the right Mailman commands. It by no means guarantees
699 that your Exim/Mailman installation is functioning perfectly,
702 <a name="problem"> </a>
703 <a href="#index"><h2>Possible Problems</h2></a>
707 <li> Mailman will send as many <tt>MAIL FROM/RCPT TO</tt> as it
708 needs. It may result in more than 10 or 100 messages sent in one
709 connection, which will exceed the default value of Exim's
710 smtp_accept_queue_per_connection This is bad because it will
711 cause Exim to switch into queue mode and severely delay delivery
712 of your list messages. The way to fix this is to set mailman's
713 <tt>SMTP_MAX_SESSIONS_PER_CONNECTION</tt> (in
714 <tt>~mailman/Mailman/mm_cfg.py</tt>) to a smaller value than
715 Exim's <tt>smtp_accept_queue_per_connection</tt></li>
717 <li>Mailman should ignore Exim delay warning messages, even
718 though Exim should never send this to list messages. Mailman
719 2.1's general bounce detection and VERP support should greatly
720 improve the bounce detector's hit rates.</li>
722 <li>List existence is determined by the existence of a
723 <tt>config.pck</tt> file for a list. If you delete lists by
724 foul means, be aware of this.</li>
726 <li>If you are getting Exim or Mailman complaining about user
727 ids when you send mail to a list, check that the
728 <tt>MM_UID</tt> and <tt>MM_GID</tt> match those of
729 Mailman itself (i.e. what were used in the configure script).
730 Also make sure you do not have aliases in the main alias file
735 <a name="dochis"> </a>
736 <a href="#index"><h2>Document History</h2></a>
739 <li>Originally written by Nigel Metheringham.</li>
740 <li>Updated by Marc Merlin for Mailman 2.1, Exim 4</li>
741 <li>Overhauled/reformatted/clarified/simplified by Greg
743 <li>Rehashed again by Nigel Metheringham</li>
746 <p>Like many documents of this type, it has evolved and taken on
747 contributions by many many helpful folks, mainly those on the
748 Mailman and exim mailing lists. To all of you, who have made
749 contributions yet had their names shamefully lost by me, <i>Thank
753 <h4>$Id: mailman21.html,v 1.7 2004/06/07 12:14:31 nigel Exp $</h4>