Stopping GIF spam in Thunderbird

I've been deluged with spam lately with the attached GIF files. The GIF files are even using OCR defeating technology now!!! Gag. I don't have Spam Bayes or other advanced spam filtering implemented at the moment, so what am I to do?

I just found this web site that details how to create a message filter that really helps and has great step by step instructions. It doesn't actually look for a GIF attachment but looks for email that is multi-part and the sender isn't in any address book. What can I say except that it seems to work! (for the time being. {g})

http://compserv.physics.harvard.edu/imagespam