Exim4 + Mailman as Mailing List Manager on Debian

So, let's say you are a Debian server administrator and you want to set up a mailing list for your users. You have already configured Exim4 as MTA and installed Mailman from offical repositories. With smile on face you are sending a message on {list}@{server} and...

 pipe to |/var/lib/mailman/mail/mailman post ...
    generated by .......
    local delivery failed

The following text was generated during the delivery attempt:

------ pipe to |/var/lib/mailman/mail/mailman post ...
       generated by ....------

Group mismatch error.  Mailman expected the mail
wrapper script to be executed as group "daemon", but
the system's mail server executed the mail script as
group "Debian-exim".  Try tweaking the mail server to run the
script as group "daemon", or re-run configure, 
providing the command line option `--with-mail-gid=Debian-exim'.

This is a well known problem with group permissions. Forums all over the world explain the problem but none of those have right clues to deal with it.

In short words - it is a bug in Debian package. Maintainer of mailman-2.1.9 somehow forgot to change default group of mailman from "deamon" to "Debian-exim" (which is required by Exim4 to recognize Mailman and deal with pipe of messages encoded in /etc/aliases). Also - I really do not know why packager set default path to /var/lib! The way to solve it is recompiling Mailman with option:
--with-mail-gid=Debian-exim
..but, wait a minute. The default path of Debian's mailman is not compatible with default path of source package. Changing the path with configure options is really bad idea.

Few minutes ago I finally got over it. Path of mailman source local installation is /usr/local/mailman, so we must manually override some starting scripts of mailman. Here's a solution. Right when we configure, make and make install our new Mailing List Manager we must create a init.d script for running it with correct permissions.

#!/bin/bash

echo "Starting mailman..."
su mailman -c 'python mailmanctl -s -q start' &
sleep 1
su mailman -c 'python /usr/local/mailman/bin/qrunner --runner=ArchRunner:0:1 -s' &
su mailman -c 'python /usr/local/mailman/bin/qrunner --runner=BounceRunner:0:1 -s' &
su mailman -c 'python /usr/local/mailman/bin/qrunner --runner=CommandRunner:0:1 -s' &
su mailman -c 'python /usr/local/mailman/bin/qrunner --runner=IncomingRunner:0:1 -s' &
su mailman -c 'python /usr/local/mailman/bin/qrunner --runner=NewsRunner:0:1 -s' &
su mailman -c 'python /usr/local/mailman/bin/qrunner --runner=OutgoingRunner:0:1 -s' &
su mailman -c 'python /usr/local/mailman/bin/qrunner --runner=VirginRunner:0:1 -s' &
su mailman -c 'python /usr/local/mailman/bin/qrunner --runner=RetryRunner:0:1 -s' &

Remember! Run "newlist" directly from /usr/local/mailman/bin to create lists (not command "newlist" from default path /usr/bin!) and don't forget to run "newaliases" after modifying /etc/aliases. Also, you have to configure your httpd.conf for cgi-bin scripts which is provider with mailman source package.

ScriptAlias /mailman/ /usr/local/mailman/cgi-bin/
<Directory /usr/local/mailman/cgi-bin/>
    AllowOverride None
    Options ExecCGI
    Order allow,deny
    Allow from all
</Directory>
Alias /pipermail/ /usr/local/mailman/archives/public/
<Directory /usr/local/mailman/archives/public>
    Options Indexes MultiViews FollowSymLinks
    AllowOverride None
    Order allow,deny
    Allow from all
</Directory>
Alias /mmimages/ /usr/share/doc/mailman/images/
<Directory /usr/share/doc/mailman/images>
    Options Indexes MultiViews
    AllowOverride None
    Order allow,deny
    Allow from all
</Directory>

After that, restart apache and mailman (with your changed script!). Now your Web Control Panel is fully configured and set up. Add subscribers and enjoy it! :)

Other way to solve the problem is contact maintainer of package mailman or build our own package mailman-exim4-2.1.9. I will try to do both.

At last - please contact me if you encountered the same problem. I realize that this mini-solution is not a full HowTo. A bunch of links that helped me or point me at good way to look:
http://www.exim.org/howto/mailman.html"
http://tectonic.co.za/view.php?id=538
http://mail.python.org/pipermail/mailman-users/2004-January/033817.html
http://archives.free.net.ph/message/20070306.165258.c83599e1.en.html