Anti-Spam SMTP Proxy Server

Anti-Spam SMTP Proxy (ASSP) Server is an open source platform-independent SMTP Proxy server, which is used for Greylisting, DNSBL, DNSWL, URIBL, SPF, SRS, Backscatter, Virus scanning, attachment blocking, Senderbase and multiple other filter methods. 

The main features of ASSP include:

• Whitelisting
• Greylisting
• Hidden Markov Model spam filtering
• Bayesian spam filtering
• Penalty Box (PB) trapping
• DNSBL/RBL (Realtime Blackhole Listing)
• URIBL (Uniform Resource Identifier Black Listing)
• Multi-level attachment blocking
• Multiple RFC validation mechanisms.
• Multi-threaded
• Platform independent
• Multi-level SPF Validation and Blocking
• DKIM Signing and Validation
• DMARC validation and reporting
• SRS (Sender Rewriting Scheme) fix-up
• Sender validation and recipient validation