With the vast knowledge of the people who frequent MR, I thought I'd pose this question to you. I'm looking for a free Outlook plugin for filtering spam. This is in an office environment using an MS Exchange server, so I need one that isn't simply "free for personal use". I do intend to fully comply with the licensing agreement. I'm particularly interested in one with white/black lists, bayesian filtering, and image filtering (for text images).
I'm currently using SpamIntelligence, but it doesn't have white/black lists.
On a separate level, does anyone know of an effective spam filter for an Exchange server, which doesn't cost a small fortune? The one we're currently using is pathetic.