Re: The internet is not the ordinary world
mail is sent from somewhere. Is there an automated utility that you could use to scan headers, find out the original sender, and generate a complaint to the 'abuse@' for the owning mail server owner and/or netblock containing that IP address??
(it's a fair bet that it was hijacked, right? Telling them may cut down on it. It's a lot of work, though. And I admit I generally do not file complaints on EVERYthing trapped by my system, but the more heinous examples become "my new special friend")