i hate broken virus checkers
i would not notice the latest windows/outlook mail virus (w32/sobig.c@mm), except for the problem of all those people with fundamentally broken virus checking software that blindly replies to the reported sender. if you know it is a virus that spoofs the sender, don't bother the sender! (and better yet, do your virus checking in your smtp server before ever accepting the message for delivery by using an smtp dæmon like qpsmtpd.)