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+ <head>
+ <title>HOWTO - Using exim and Mailman together</title>
+ </head>
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+ <body bgcolor="#FFFFFF" text="#00005A" link="#FF6600" alink="#FF9933" vlink="#990000">
+ <h1>HOWTO - Using exim and Mailman 2.1 together</h1>
+
+ <p>Mailman is a list manager with web front end and built in
+ archiving functions. Details can be found at <a href="http://www.list.org/">
+ http://www.list.org/</a>. This documentation describes the
+ configuration of Exim (version 3 or 4) to work with Mailman
+ version 2.1</p>
+
+
+
+ <h2>Mailman configuration</h2>
+
+ <p>There is no Mailman configuration needed other than the
+ standard options detailed in the Mailman install documentation.
+ The Exim configuration is transparent to Mailman. The user/group
+ settings for Mailman must match those in the config fragments
+ given below.</p>
+
+
+ <h2>Exim configuration</h2>
+
+ <p>The Exim configuration is built so that a list created within
+ Mailman automatically appears to Exim without the need for
+ defining any additional aliases.</p>
+
+ <p>The drawback of this configuration is that it will work poorly
+ on systems supporting lists in several different mail domains.
+ While Mailman handles virtual domains, it does not yet support
+ having two distinct lists with the same name in different virtual
+ domains, using the same Mailman installation. This will
+ eventually change. (But see below for a variation on this scheme
+ that should accomodate virtual domains better.)</p>
+
+ <p>The configuration file excerpts below are for use in an already
+ functional Exim configuration, which accepts mail for the domain
+ in which the list resides. If this domain is separate from the
+ others handled by your Exim configuration, then you'll need to:</p>
+
+ <ul>
+
+ <li>add the list domain, <tt>"my.list.domain"</tt> to local_domains</li>
+
+ <li>add a <tt>"domains=my.list.domain"</tt> option to the
+ director (router) for the list</li>
+
+ <li>(optional) exclude that domain from the other directors
+ (routers)</li>
+ </ul>
+
+ <p><i>[Note: the instructions in this document should work with
+ either Exim 3 or Exim 4. In Exim 3, you must have a
+ <tt>'local_domains'</tt> configuration setting; in Exim 4, you
+ most likely have a <tt>'local_domains'</tt> domainlist. If you
+ don't, you probably know what you're doing and can adjust
+ accordingly. Similarly, in Exim 4 the concept of "directors" has
+ disappeared -- there are only routers now. So if you're using
+ Exim 4, whenever this document says "director", read
+ "router".]</i></p>
+
+ <p>Whether you are using Exim 3 or Exim 4, you will need to add
+ some macros to the main section of your Exim config file. You
+ will also need to define one new transport. With Exim 3, you'll
+ need to add a new director; with Exim 4, a new router plays
+ the same role.</p>
+
+ <p>Finally, the configuration supplied here should allow
+ co-habiting Mailman 2.0 and 2.1 installations, with the proviso
+ that you'll probably want to use <tt>"mm21"</tt> in place of
+ <tt>"mailman"</tt> -- e.g., <tt>MM21_HOME</tt>,
+ <tt>mm21_transport</tt>, etc.</p>
+
+
+ <h2>Main configuration settings</h2>
+
+ <p>First, you need to add some macros to the top of your Exim
+ config file. These just make the directors (routers) and
+ transport below a bit cleaner. Obviously, you'll need to edit
+ these based on how you configured and installed Mailman.</p>
+
+<pre>
+ # Home dir for your Mailman installation -- aka Mailman's prefix
+ # directory.
+ MAILMAN_HOME=/usr/local/mailman
+ MAILMAN_WRAP=MAILMAN_HOME/mail/mailman
+
+ # User and group for Mailman, should match your --with-mail-gid
+ # switch to Mailman's configure script.
+ MAILMAN_UID=mailman
+ MAILMAN_GID=mailman
+</pre>
+
+ <h2>Transport for Exim 3</h2>
+
+ <p>Add this to the transports section of your Exim config file,
+ i.e. somewhere between the first and second "end" line:</p>
+
+<pre>
+ mailman_transport:
+ driver = pipe
+ command = MAILMAN_WRAP \
+ '${if def:local_part_suffix \
+ {${sg{$local_part_suffix}{-(\\w+)(\\+.*)?}{\$1}}} \
+ {post}}' \
+ $local_part
+ current_directory = MAILMAN_HOME
+ home_directory = MAILMAN_HOME
+ user = MAILMAN_UID
+ group = MAILMAN_GID
+</pre>
+
+ <p><i>(XXX this is untested by me under Exim 3! Can someone using
+ Exim 3 please let me know if it works?)</i></p>
+
+
+ <h2>Director for Exim 3</h2>
+
+
+ <p>If you're using Exim 3, you'll need to add the following
+ director to your config file (directors go between the second and
+ third "end" lines). Also, don't forget that order matters --
+ eg. you can make Mailman lists take precedence over system aliases
+ by putting this directors in front of your aliasfile director, or
+ vice-versa.</p>
+
+<pre>
+ # Handle all addresses related to a list 'foo': the posting address.
+ # Automatically detects list existence by looking
+ # for lists/$local_part/config.pck under MAILMAN_HOME.
+ mailman_director:
+ driver = smartuser
+ require_files = MAILMAN_HOME/lists/$local_part/config.pck
+ suffix_optional
+ suffix = -bounces : -bounces+* : \
+ -confirm+* : -join : -leave : \
+ -owner : -request : -admin
+ transport = mailman_transport
+</pre>
+
+ <h2>Router for Exim 4</h2>
+
+ <p>In Exim 4, there are no such things as directors -- you instead
+ need to add a router. Also, the canonical order of the
+ configuration file was changed so routers come before transports,
+ so the routers for Exim 4 come first here. Put these two routers
+ somewhere after the <tt>"begin routers"</tt> line of your config
+ file, and remember that order matters.</p>
+
+<pre>
+ mailman_router:
+ driver = accept
+ require_files = MAILMAN_HOME/lists/$local_part/config.pck
+ local_part_suffix_optional
+ local_part_suffix = -bounces : -bounces+* : \
+ -confirm+* : -join : -leave : \
+ -owner : -request : -admin
+ transport = mailman_transport
+</pre>
+
+ <h2>Transports for Exim 4</h2>
+
+ <p>The transport for Exim 4 is the same as for Exim 3; just copy
+ the transport given above to somewhere under the "begin
+ transports" line of your Exim config file.</p>
+
+
+ <h2>Notes</h2>
+
+ <p>Exim should be configured to allow reasonable volume --
+ e.g. don't set max_recipients down to a silly value -- and with
+ normal degrees of security -- specifically, be sure to allow
+ relaying from 127.0.0.1, but pretty much nothing else. Parallel
+ deliveries and other tweaks can also be used if you like;
+ experiment with your setup to see what works. Delay warning
+ messages should be switched off or configured to only happen for
+ non-list mail, unless you like receiving tons of mail when some
+ random host is down.</p>
+
+
+ <h2>Problems</h2>
+
+ <ul>
+
+ <li> Mailman will send as many <tt>MAIL FROM/RCPT TO</tt> as it
+ needs. It may result in more than 10 or 100 messages sent in one
+ connection, which will exceed the default value of Exim's
+ smtp_accept_queue_per_connection This is bad because it will
+ cause Exim to switch into queue mode and severely delay delivery
+ of your list messages. The way to fix this is to set mailman's
+ <tt>SMTP_MAX_SESSIONS_PER_CONNECTION</tt> (in
+ <tt>~mailman/Mailman/mm_cfg.py</tt>) to a smaller value than
+ Exim's <tt>smtp_accept_queue_per_connection</tt></li>
+
+ <li>Mailman should ignore Exim delay warning messages, even
+ though Exim should never send this to list messages. Mailman
+ 2.1's general bounce detection and VERP support should greatly
+ improve the bounce detector's hit rates.</li>
+
+ <li>List existence is determined by the existence of a
+ config.pck file for a list. If you delete lists by foul means,
+ be aware of this.</li>
+
+ <li>If you are getting Exim or Mailman complaining about user
+ ids when you send mail to a list, check that the
+ <tt>MAILMAN_UID</tt> and <tt>MAILMAN_GID</tt> match those of
+ Mailman itself (i.e. what were used in the configure script).
+ Also make sure you do not have aliases in the main alias file
+ for the list.</li>
+
+ </ul>
+
+
+ <h2>Receiver Verification</h2>
+
+ <P>Exim's receiver verification feature is very useful -- it lets
+ Exim reject unrouteable addresses at SMTP time. However, this is
+ most useful for externally-originating mail that is addresses to
+ mail in one of your local domains. For Mailman list traffic, mail
+ originates on your server, and is addressed to random external
+ domains that are not under your control. Furthermore, each
+ message is addressed to many recipients -- up to 500 if you use
+ Mailman's default configuration, and don't tweak
+ <tt>SMTP_MAX_RCPTS</tt>.</p>
+
+ <p>Doing receiver verification on Mailman list traffic is a recipe
+ for trouble. In particular, Exim will attempt to route every
+ recipient addresses in outgoing Mailman list posts. Even though
+ this requires nothing more than a few DNS lookups for each
+ address, it can still introduce significant delays. Therefore,
+ you should disable recipient verification for Mailman traffic.</p>
+
+ <p>Under Exim 3, put this in your main configuration section:</p>
+<pre>
+ receiver_verify_hosts = !127.0.0.1
+</pre>
+
+ <p>Under Exim 4, this is probably already taken care of for you by
+ the default recipient verification ACL statement (in the "RCPT TO"
+ ACL):</p>
+
+<pre>
+ accept domains = +local_domains
+ endpass
+ message = unknown user
+ verify = recipient
+</pre>
+
+ <p>which only does recipient verification on addresses in your
+ domain. (That's not exactly the same as doing recipient
+ verification only on messages coming from non-127.0.0.1 hosts, but
+ it should do the trick for Mailman.)</p>
+
+
+ <h2>SMTP Callback</h2>
+
+ <p>Exim's SMTP callback feature is an even more powerful way to
+ detect bogus sender addresses than normal sender verification.
+ Unfortunately, lots of servers send bounce messages with a bogus
+ address in the header, and there are plenty that sound bounces
+ with bogus envelope senders (even though they're supposed to just
+ use an epmty envelope sender for bounces).</p>
+
+ <p>In order to ensure that Mailman can disable/remove bouncing
+ addresses, you generally want to receive bounces for Mailman
+ lists, even if those bounces are themselves not bouncable. Thus,
+ you might want to disable SMTP callback on bounce messages.</p>
+
+ <p>If you do header and envelope callbacks, you can disable them
+ for bounces to mailman lists (it is quite common for internal
+ hosts to bounce with a non reachable internal address). The idea
+ is that you typically don't want non bounceable Email, but you'd
+ better accept bounces to mailman lists so that you can unsubscribe
+ the people who are bouncing.</p>
+
+ <p>With Exim 4, you can accomplish this using something like the
+ following in your <tt>"RCPT TO"</tt> ACL:</p>
+
+<pre>
+ # Accept bounces to lists even if callbacks or other checks would fail
+ warn message = X-WhitelistedRCPT-nohdrfromcallback: Yes
+ condition = \
+ ${if and {{match{$local_part}{(.*)-bounces\+.*}}
+ {exists {MAILMAN_HOME/lists/$1/config.pck}}} \
+ {yes}{no}}
+ {yes}{no}}
+
+ accept condition = \
+ ${if and {{match{$local_part}{(.*)-bounces\+.*}}
+ {exists {MAILMAN_HOME/lists/$1/config.pck}}} \
+ {yes}{no}}
+ {yes}{no}}
+
+ # Now, check sender address with SMTP callback.
+ deny !verify = sender/callout=90s/check_postmaster
+</pre>
+
+ <p>If you also do SMTP callbacks on header addresses, you'll want
+ something like this in your "DATA" ACL:</p>
+
+<pre>
+ deny !condition = $header_X-WhitelistedRCPT-nohdrfromcallback:
+ !verify = header_sender/callout=90s/check_postmaster
+</pre>
+
+ <p><i>[XXX all this stuff is completely untested by me!
+ -Greg]</i></p>
+
+
+ <h2>Doing VERP with Exim and Mailman</h2>
+
+ <p>VERP will send one email, with a separate envelope sender
+ (return path), for each of your subscribers -- read the
+ information in <tt>~mailman/Mailman/Default.py</tt> for the
+ options that start with <tt>VERP</tt>. In a nutshell, all you
+ need to do to enable VERP with Exim is to add these lines to
+ <tt>~mailman/Mailman/mm_cfg.py</tt>:</p>
+
+<pre>
+ VERP_PASSWORD_REMINDERS = 1
+ VERP_PERSONALIZED_DELIVERIES = 1
+ VERP_DELIVERY_INTERVAL = 1
+ VERP_CONFIRMATIONS = 1
+</pre>
+
+ <p>(The directors/routers above are smart enough to deal with VERP
+ bounces.)</p>
+
+
+<h2>Virtual Domains</h2>
+
+ <p>One approach to handling virtual domains is to use a separate
+ Mailman installation for each virtual domain. (Currently, this is
+ the only way to have lists with the same name in different virtual
+ domains handled by the same machine.)</p>
+
+ <p>In this case, the <tt>MAILMAN_HOME</tt> and
+ <tt>MAILMAN_WRAP</tt> macros are useless -- you can remove them.
+ Change your director (router) to something like this:</p>
+
+<pre>
+ require_files = /virtual/${domain}/mailman/lists/${lc:$local_part}/config.pck
+</pre>
+
+ <p>and change your transport like this:</p>
+
+<pre>
+ command = /virtual/${domain}/mailman/mail/mailman \
+ ${if def:local_part_suffix \
+ {${sg{$local_part_suffix}{-(\\w+)(\\+.*)?}{\$1}}}
+ {post}} \
+ $local_part
+ current_directory = /virtual/${domain}/mailman
+ home_directory = /virtual/${domain}/mailman
+</pre>
+
+<h2>List Verification</h2>
+
+ <p>This is how a set of address tests for the Exim lists look on a
+ working system. The list in question is
+ <tt>quixote-users@mems-exchange.org</tt>, and these commands were
+ run on the <tt>mems-exchange.org</tt> mail server (<tt>"% "</tt>
+ indicates the Unix shell prompt):</p>
+
+<pre>
+ % exim -bt quixote-users
+ quixote-users@mems-exchange.org
+ router = mailman_main_router, transport = mailman_transport
+
+ % exim -bt quixote-users-request
+ quixote-users-request@mems-exchange.org
+ router = mailman_router, transport = mailman_transport
+
+ % exim -bt quixote-users-bounces
+ quixote-users-bounces@mems-exchange.org
+ router = mailman_router, transport = mailman_transport
+
+ % exim -bt quixote-users-bounces+luser=example.com
+ quixote-users-bounces+luser=example.com@mems-exchange.org
+ router = mailman_router, transport = mailman_transport
+</pre>
+
+ <p>If your <tt>"exim -bt"</tt> output looks something like this,
+ that's a start: at least it means Exim will pass the right
+ messages to the right Mailman commands. It by no means guarantees
+ that your Exim/Mailman installation is functioning perfectly,
+ though!</p>
+
+
+ <h2>Document History</h2>
+
+ <p>Originally written by Nigel Metheringham. Updated by Marc
+ Merlin for Mailman 2.1, Exim 4.
+ Overhauled/reformatted/clarified/simplified by Greg Ward.</p>
+
+ <hr>
+ <h4>$Id: mailman.html,v 1.3 2002/06/14 10:42:18 nigel Exp $</h4>
+ </body>
+</html>
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