This happens to people all the time, unfortunately. Spammers are unscrupulous bastards, and they don't care at all who they hurt, piss off, or otherwise trouble. In other words, you may be overreacting somewhat, since this is a well-known spammer tactic, and it's usually a one-time thing (at least, I've never known anyone have it happen to them more than once). Spammers pick an email address or domain from their spam list and put that in the "return" field, simple as that. bonni (spam hater for many years)

"When a man gives his opinion, he's a man. When a woman gives her opinion, she's a bitch." - Bette Davis