The mailing lists are now running with the standard Debian packaged version of Mailman.

The Mailman setup for Exim is in /etc/exim4/symbiosis.d/20-routes/11-mailman and /etc/exim4/symbiosis.d/30-transports/11-mailman. It's standard Mailman/exim setup.

There is one non-standard extension, the LongSig handler. I have copied the Python code for the LongSig handler into /usr/lib/mailman/Mailman/Handlers.

LongSig is currently enabled only on accu-general. The process is described in this Mailman FAQ item. The input filename for the modified accu-general pipeline is in /etc/mailman.

Given the appropriate Mailman login, you can create a new list from the web interface.

Unfortunately, it appears that while the list is created, some of the list files lack the correct permissions.

# chown -R list:www-data /var/lib/mailman/archives/private/<list-name>*

appears to be necessary.

There are lists which have been moribund for a while, and which we have disabled, to save the list admins from having to handle spam messages.

There is no official way in Mailman to disable a list. The closest you can get to is emergency moderation, which just makes all lists moderate every post.

So I've disabled the mailing lists by chmod 000 /var/lib/mailman/lists/<list>. Also, I've modified the Exim Mailman router to check explicitly that the list file is accessible by group list:

mailman_router:
 debug_print = "R: mailman_router for $local_part@$domain"
  driver = accept
  require_files = root,list:MM_HOME/lists/$local_part/config.pck
  local_part_suffix_optional
  local_part_suffix = -bounces : -bounces+* : \
                      -confirm+* : -join : -leave : \
                      -owner : -request : -admin
  transport = mailman_transport

This means that the list address is no longer routable, and the list no longer appears on the list of mailing lists. All list configuration and archives are preserved.