I was just about to try what you suggested (it does seem like it would work) but now my rule wizard is showing an option to look for specific words in the message header (which I'm *SURE* was not there before).

So what I've done is set a rule that moves all emails to the Junk Mail Folder that contains "hanmail" anywhere in the message header, and it works great.

This is what my rule reads now:

Apply this rule after message arrives
with hanmail in the message header
and on this machine only
move it to the Junk E-mail folder

I'll keep you guys posted whether this rule continues to work or not, in case others encounter this problem.