Another way for spammers to get your address is to legitamately purchase it. They buy a list
which was purchased from a site who purchased it from a site who bought it from Yahoo or
Hotmail.

Yes, you're right of course, but please, people, read the question before replying... sigh

We're speaking about private domains, owned and managed by the users themselves (at least in 3 of the 5 cases), not about some Hotmail accounts. I'm quite sure I didn't sell my private domain's e-mail addresses to anybody, and I can say as much for two others.