From the Model Mayhem FAQ:
I seem to get spam emails to my email address.
First off, MM will not give your email address to anyone without your expressed permission. If you are receiving spam emails after setting up an MM profile, it is likely that you are listing your email address somewhere on your profile or elsewhere. Unfortunately there are people out there who will see this and use it in deeply evil and nefarious ways. Bwahahaha. That is how those people laugh.