Sometimes it can happen that you have mail stuck in your mail queue stating:
status=deferred (delivery temporarily suspended: connect to 127.0.0.1[127.0.0.1]: Connection refused
This usually means that for some reason your content filter (amavisd) is not running.
The easiest way to check if amavisd-new is running is to issue:
ps -U clamav
(for Mac OS X 10.4.x)
ps -U _amavisd
(for Mac OS X 10.5.x)
among other things, you should see something along the lines of:
2393 ?? S 0:17.20 amavisd (ch7-avail)
2450 ?? S 0:16.82 amavisd (ch7-avail)
17823 ?? Ss 0:26.18 amavisd (master)
If you don’t see amavisd in the list, then it isn’t running and you need to further investigate the issue.