First, make sure your e-mail return address is well spoofed, with
more than
just writing spam in the middle of it.

I would venture a guess that someone (or you) is using e-bay, google groups,
or one of another million ways to get your address. It only has to be out
there once,..... then soon millions of spam lists will have your info on
them.

Best advise - filter, delete, ignore, or... change your e-mail address.

Or just create some crap address at hotmail and use that for public
postings and for sites that you register for stuff at...