I haven't but it sounds like you have become an early target of the latest innovation by scumsucking weasle spamsters.
Basically they find a site, register, and use software to 'walk through' the site and email as many people as possible with their latest fraud. Spamming via PMs is more effective than normal spam because you tend to believe a PM is legit.
Site owners (that would be you, Mohammed) can only block by using the 'what does this image represent' gizmo test like you use when joining a Yahoo site. This means an automatic system can't walk through the site.
All spammers should be fed to wild dogs. Then killed. /forums/images/graemlins/mad.gif