Spam filter for Mac OS X (10.3)?

Can anyone recommend a good third party spam filter for Mac OS X?

Isn't sanity really just a one trick pony, anyway?

http://www.tvtome.com/tvtome/servlet/GuidePageServlet/showid-5235/epid-100814/

Tick: Isn't sanity really just a one trick pony, anyway? I mean, all you get is one trick, rational thinking! But when you're good and crazy…ooh hoo hoo hoo…the sky's the limit!

Tick: My mind has always been my Achilles heel!