I don't know what I did to deserve this...

I keep getting emails with viruses in them that I never sent bounced back to me from email addresses that are total strangers to me. Does anyone know how this happens and what I can do about it? I'm afraid that my emai address is going to wind up on those anti-Scam lists. Now who hates me enough to do something like this? Or am I just the victim of some randomly executed plot that someone thinks is a fun thing to do?