Planet Ergo

When you run Kolab, or Postfix and Cyrus IMAP, you may have any number of your users subscribed to a mailing list.

As such, many mailing list posts may delivered to a large number of users separately, increasing the data footprint on disk, and processing, while only including some of your users in the loop on what may be interesting content for everyone.

You may want to have one shared folder to deliver new mailing list messages to, to which individual users can then subscribe. Here's how (in a nutshell):

• Create a Cyrus IMAP user that is called 'shared',
• Set the postuser to 'shared' in /etc/imapd.conf
• Set the sharedprefix to 'shared' in /etc/imapd.conf
• Create a shared/lists mailbox (cm shared/lists@kolabsys.com in my case),
• Create some subfolders you want mailing list posts be delivered to, like shared/lists/kolab.org/devel@kolabsys.com,
• Make sure that at the very least 'anyone' as the 'lrsip' permissions on the mailbox,
• Give yourself 'all' privileges on the mailbox,
• Make sure the recipient_delimiter is set to '+' in /etc/postfix/main.cf,
• Make sure shared@kolabsys.com is listed in /etc/postfix/transport with transport lmtp:unix:/var/lib/imap/socket/lmtp
• Reload what you need to reload,
• Send a test message to shared+shared/lists/kolab.org/devel@kolabsys.com,
• It should end up in the correct folder.

Note, for those of you not using virtual domain support in Cyrus, skip the @kolabsys.com at the end of folder names to be created and you should be good to go.

Also note that for each individual user that wants to post messages to the mailing list, they still need to be subscribed to the mailing list themselves; they can then disable delivery through the mailing list preferences pages if available, reading the list through the shared folder.