Potential spammers use bots to trawl through random web pages picking up email addresses. I found this happened to a site I had created only after listing it on Yahoo's pages.(posted 8520 days ago)Unfortunately free web based emails like yahoo.com and hotmail.com attract an awful lot of spam. I use a hotmail address sometimes and I've even had spam mail supposedly sent from myself! The subjects are usually along the lines of get credit easy, you've been pre- approved a loan etc etc. One of these is from a fsnet.co.uk address on a regular basis and on investigation is actually from a US based source.
You can use www.spamcop.net to report spam and to find out where the emails have really come from. If you use spamcop, click on "I understand and agree" link and then cut and paste the headers and body of the email.
Pendle