Problem: On Mac OS X 10.3 Server, after an ungraceful restart (e.g., power cycle, loss of power, etc), mail delivery to Mailman mailing lists stops. No bounces are generated, no mail is delivered to list members.

Solution: At a shell prompt on the server, run:

sudo /usr/share/mailman/bin/mailmanctl -s restart

Background: Mailman’s qrunner (the process that is responsible for processing incoming mail) creates a lock file in /private/var/mailman/locks. When such a file exists, qrunner refuses to start. An ungraceful restart leaves behind a stale lock file, thus preventing qrunner from starting. The -s argument to mailmanctl forces it to clean up stale lock files.