Larry Stone wrote:
I know almost nothing about the internals of forking processes and daemonizing but if I have it right, when 'mailmanctl start' is run, it forks a second copy which daemonizes. Meanwhile, the first copy of mailmanctl exits. My guess is that the first copy was exiting and the process terminating before the second copy had performed whatever magic it does to deamonize and run on its own.
It probably has nothing to do with this, but through Mailman 2.1.13, mailmanctl forks the eventual daemon with file descriptors for stdin, stdout and stderr, possibly attached to the terminal. Normally, the only symptom is if you start Mailman in a terminal session and then log out, the session doesn't completely close until you physically disconnect, but this may have an effect on your situation. I do have an Intel iMac amongst several other machines, but I know essentially nothing about launchd.
Anyway, there is a patch to mailmanctl at http://bazaar.launchpad.net/~mailman-coders/mailman/2.1/revision/1221 which probably won't make a difference to your case, but might.