ok.. maybe this is just my wacked out server but I run plesk 7.5.2 on RHEL3 and some unknown entity (i suspect up2date but i'm not sure) changed some mailman settings.

/var/mailman/Mailman/Defaults.py
had "SMTPPORT = 0" set...

now i'm not sure if Defaults.py got changed or if it was my mm_cfg.py that got changed but regardless you need to add:

SMTPHOST = 'localhost'
SMTPPORT = '25'

to your /var/mailman/Mailman/mm_cfg.py if you are getting errors like this in your mailman smtp-failure logs:

Apr 16 11:44:46 2005 (29955) Low level smtp error: [Errno 110] Connection timed out, msgid: None
Apr 16 11:44:46 2005 (29955) delivery to [removed]@gmail.com failed with code -1: [Errno 110] Connection timed out
Apr 16 11:44:46 2005 (29955) delivery to [removed]@yahoo.com failed with code -1: [Errno 110] Connection timed out

luckily all undelivered posts were queued and received after i fixed that setting and restarted mailman. be caerful if you have really busy lists cause its goign to dump all that queued mail on you at once.