VisNetic MailServer Pro - VisNetic MailServer is a high performance POP3, SMTP, IMAP, LDAP email server for Windows operating systems. It features a powerful, comprehensive antispam engine that uses three proven spam filtering technologies to ensure the highest possible level of spam protection. Integrated antivirus support, a built-in Instant Messaging server, Web Mail, and support for VisNetic GroupWare combine to make it a superior messaging solution for customers reliant upon email for business communications. VisNetic MailServer includes Instant AntiSpam, a powerful Anti Spam tool that employs: A Bayesian filter that statistically calculates the probability that each inbound message is spam; The SpamAssassin rules-set, recognized as the most exhaustive list of spam filters to date; A Challenge-Response system that ensures that messages are being sent from a human being, as opposed to machines. VisNetic MailServer also features standard relay checking, reverse DNS lookup, and MX record verification.