Spam Filter ISP is an Anti-spam server software for Windows that acts as a gateway/proxy to your existing SMTP server (MTA). Spam Filter filters email based on MAPS RBL and DNS based ORBS and SURBL blacklists, Greylisting, Bayesian statistical filtering and SPF filters. An antivirus plugin is available for anti virus support. A web interface for end-user access to the spam quarantine is available.