Spammers can get your mail-address just by guessing it!
Theres programs that you can put the en of the program like: @yahoo.com and @hotmail.com
and words and numbers that should be before it like anna, cat, dog, 5, 3, then it makes addresses of them like anna53@hotmail.com and sends a mail with pic there, and when anna opens her inbox she(or he

) downloads the pic from net and that way shows that it`s real address...
That way they can get your address even without selling it to nobody.
And Microsoft/Hotmail won`t propably sell your address cause the profit isn`t big enough...