New Spam/Virus

Apparently there's a new virus going around in Germany that will make people reconsider their catchall email accounts.  It makes up a bunch of email addresses, presumably by random or by looking at the local name of addresses in your address book, and then it sends them all to each mail domain in your address book.  So a few times an hour, I've been getting batches of 20-50 emails from the same zombie computer.  Looks like I may have to start filtering out dynamic IP addresses with our mail server. :(