Judging by my inbox over the last few days, a lot of people I know seem to have been taken in by the spammongers at FanBox, one of the more disreputable sites out there that masquerade as legitimate social networking services.
If you get an email involving FanBox, just delete it. Don't click on any of its links (least of all, one for unsubscribing, which merely lets them know your email works and will ensure yet more emails coming your way). It's most likely not an attempt by a real human being to communicate with you, but rather an attempt to suck you into its network (in fact, this applies to most messages from websites you've never heard or signed up for). If you sign up for this "service" will spam everybody in your address book with similarly useless and annoying messages, the purpose of which is to harvest functioning emails for various slimy marketing schemes.
The company appears to be really exploitative of its employees, too, so yet another reason not get suckered by these guys.
If you've already signed up, add a filter to delete all messages from them. Here are instructions for doing it with Yahoo Mail.