Challenge Response System

[webstriker]

I am an admirer of the Plesk control panel and am seriously considering purchasing it, but I'm wondering what anti-spam features are available. Is there a challenge/response system available? Or, is the SpamAssassin solution the only anti-spam available which employs heuristic analysis and baeyesian filtering. Can anyone attest to how well the Plesk anti-spam solution works? Are there options to tag email, reject it, or move it to a folder? I wish SWsoft provided more information about the anti-spam. Thanks for your help!