Anti-Spam SMTP Proxy
# Anti-Spam SMTP Proxy

The Anti-Spam SMTP Proxy (ASSP) is an open-source, Perl based, platform-independent transparent SMTP proxy server.

## Features

Some ASSP's features are:

* Hidden Markov Model spam filtering
* Bayesian spam filtering
* whitelisting
* Penalty Box (PB) trapping
* DNSBL/RBL (Realtime Blackhole Listing)
* URIBL (Uniform Resource Identifier Black Listing)
* Multi-level SPF (Sender Policy Framework) validation and blocking
* DKIM signing and validation
* DMARC validation and reporting
* SRS (Sender Rewriting Scheme) fix-up
* Session Delaying/Greylisting and connection response delaying
* Sender validation and recipient validation
* Multi-level attachment blocking (based on block lists or allow lists or content based executable blocking)
* As well as multiple RFC validation mechanisms.
* Multi-threaded (Since version 2.x)
* Platform independent (Written in Perl)
