I managed to get mail flowing again by turning off antivirus in the web admin, then flushing the postfix queues with postqueue -f. I have since re-enabled antivirus and it still is not starting correctly, but mail is not accumulating in the deferred queue. 'zmcontrol status' gives:
You are possibly correct that the antivirus install is damaged, but I need to look closer at reinstalling it. This is an OS X machine and I need to see if I can pull the antivirus out of the complete packaged installer. There are no failure messages in clamd.log, just lots of startup messages.
zmclamdctl is not running
swatch is not running