Here is a tip from Gary North's newsletter:

 Another reader sent me this tip on how to keep your e-
mail program from sending out virus-infected messages.  Go
to your address book.  Add this name: 000 0000.  His
address is 0...@0000.  This, my informant insists, will
confuse any invading virus/worm that gets into your address
book in search of the next batch of victims.  I'm willing
to try this.  It can't hurt.

Kevin Nolan