Volksie your email addy has most probably been spoofed. I would’nt worry about it as there are many ways to spoof mail (if your Email account has been hacked/cracked, forget changing the password because it wont work, they save the autologin cookie which enables them to still be able to log into your account even if you change passwords). If you get these annoying E-Mail’s via Outlook right click on it and select ‘properties’ the IP of the sender will be shown under the properties tab (this dont work if you received the mail via Hotmail/MSN).
Check these links out for info on how to ‘spoof’ mail, it very, very easy to do.