Mail Rules have stopped working and I can't restart them.

Question

Here is the System Log entry. Can some help?
Jun 20 21:51:15 mail com.apple.emailrules[22464]: 2011-06-20 21:51:15+0100 [-]   File "/usr/share/caldavd/lib/python/twisted/internet/tcp.py", line 855, in startListening
Jun 20 21:51:15 mail com.apple.emailrules[22464]: 2011-06-20 21:51:15+0100 [-]     raise CannotListenError, (self.interface, self.port, le)
Jun 20 21:51:15 mail com.apple.emailrules[22464]: 2011-06-20 21:51:15+0100 [-] twisted.internet.error.CannotListenError: Couldn't listen on any:8089: [Errno 48] Address already in use.
Jun 20 21:51:15 mail com.apple.launchd[1] (com.apple.emailrules[22464]): Exited with exit code: 1

Answer 1

Generically it looks like Mail is trying to bind and listen on port 8089 but that something is already bound and listening on that port. This could be a zombie process or something that appears to be listening when it actually isn't or a conflict raised by some other process being bound to the port first before Mail tries to bind.
Has this survived an actual restart? A restart with Mail not running and then started after restart? It's possible for a port to be bound by a process and remain bound when if that process exits unexpectedly and then interfere with the same process rebinding to the same port. This can also come in form or a file that signifies a process being bound to a port and deleting the file while the service is off can free up that port.
Also there is are groups specifically for OS X Server 10.6 and 10.5 (whichever you are using) that would probably be more appropriate for your post since this isn't an Xserve or Server problem specifically. You may get more eyes associated with Mail conflicts over there.
Good Luck,
=Tod