I'd assume spambot of some sort. It'll have gotten your email from somewhere - either you've posted it publicly online (possibly without realising - privacy is surprisingly hard on the internet) or a friend with it in their address book has been infected. Dunno how it could have matched your private email up to jazz2online if you've never posted it here, it may have just guessed or may have tried to link it up based on other information (e.g. username, instant messaging accounts).