The Anti-Spam SMTP Proxy (ASSP) Server project aims to create an open source platform-independent SMTP Proxy server which implements auto-whitelists, Bayesian, Greylisting and multiple filter methods. Click ‘Browse all files’ to download the professional version 2.1.1 build 11364.
Features : 

• Multiple Weighted DNSBLs
• Multiple Weighted URIBLs
• Greylisting
• Weighted Regular Expression Filtering
• Bayesian
• Penalty Box
• SenderBase
• SSL/TLS
• SPF/SRS
• Attachment Blocking
• ClamAV and FileScan
• Blocking Reporting
• LDAP support
• Backscatter Detection
• V2 – recipient replacement / GUI user access rights management
• V2 – MIME charset conversion / DKIM check and signing
• V2 – DB support for all hashes / level based open plugin support
• V2 – transparent proxy support / BATV check and signing
• V2 – Plugins: archive, full attachment check and replacement, OCR
• V2 – damping (steal spammers time)
• V2 – AUTH to relay host / POP3 collector
• V2 – configuration value and file synchronization
• V2 – Block Reports design could be customized
• V2 – Razor2 and DCC support via Plugin
• V2 – SNMP support (monitoring, configuring, controll-API)
• V2 – user group import (file or LDAP or command based)
• V2 – automatic crash analyzer Hidden Markov Model
• V2 – IPv6 socket support
• V2 – word stemming (several languages) for Bayesian analyzer
• V2 – Perl module autoupdate via PPM or CPAN
• V2 – Hidden Markov Model spam detection engine

Download in here | or read more in here