SERVER ACTIVITY 100%, PROCESS "perl5.10.0" the Culprit, How to Cure?

I noticed this AM my Snow Leopard 10.6.4 server installation (on a Mac Mini) had the fans running full tilt. Looking at the server the activity meters (from Activity Monitor) were pinned at 100% for about five hours. Activity Monitor shows "perl5.10.0 - amavisd" as the culprit. I don't know what this is, why it's running at such a frenzied level, and how to fix.

I did force quit it, but it came back shortly thereafter. Also tried reinstalling the 10.6.4 updater. No change.

It's been fine for some time and has had no tweaking for quite a while.

Any suggestions would be appreciated?