A couple of the things I've been seeing a lot of lately is using "leet" speak and HTML with lots of <!--Dave in them. Even filtering out the "leet" speak would probably solve a lot of your spam.

Something simple like /[a-zA-Z]\d/would be cause to flag the message as an offender I would think. Or at the very least it's a start.

Also, and someone will correct me if I'm mistaken here, I can't see any need to have comments in an HTML e-mail message that contain my name. To me, anytime I see html comments, it's suspect.

Good luck!

There is no emoticon for what I'm feeling now.