VisNetic MailPermit Gateway Edition - Deerfield.com's VisNetic MailPermit represents a comprehensive new approach to spam prevention, combining SpamAssasin's advanced rules -- based and Bayesian filtering technology with a proprietary challenge-response system to create a powerful barrier between your business and costly, time-consuming spam. Additionally, MailPermitÆs messaging component -- derived from technology found in VisNetic MailServer -- adds value in the way of a robust SMTP engine and integrated support for antivirus protection.