Anti-Spam SMTP Proxy Server, Free and Open-source Projects
Anti-Spam SMTP Proxy Server implements multiple spam filters
The Anti-Spam SMTP Proxy (ASSP) Server project provides an open-source, platform-independent SMTP Proxy server designed to enhance email security by implementing a variety of filtering techniques.
Key features include auto-whitelists, self-learning Hidden-Markov-Model and Bayesian filters, Greylisting, DNSBL, DNSWL, URIBL, SPF, SRS, Backscatter protection, virus scanning, attachment blocking, and Senderbase integration.
The project offers a professional version (V2.8.1 build 23131) and ready-to-run OVA files for Linux (Ubuntu 20.04 LTS) and FreeBSD 12.2. Development on V1 has ceased since 2014, with only potential bug fixes in the future.
![](https://medevel.com/content/images/2024/08/1--4-.jpeg)
Users are encouraged to upgrade to V2, which continues to receive active maintenance.
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
- recipient replacement / GUI user access rights management
- MIME charset conversion / DKIM check and signing
- multi DB support for all hashes / level based open plugin support
- transparent TCP proxy support
- Plugins: archive, full attachment check and replacement, OCR
- damping (steal spammers time)
- AUTH to relay host / POP3 collector
- configuration value and file synchronization
- Block Reports design could be customized
- Razor2 and DCC support using Plugin
- SNMP support (monitoring, configuring, controll-API)
- user group import (file or LDAP or command based)
- automatic crash analyzer Hidden Markov Model
- IPv6 socket support
- word stemming (several languages) for Bayesian analyzer
- Perl module autoupdate via PPM or CPAN
- Hidden Markov Model spam detection engine
- full unicode support
- DMARC support
- privat Whitelist (legacy, domain based, user based)
- privat IP and Domain lists (legacy, domain based, user based)
- CPU affinity settings
- web file commander
- graphical statistic output (SVG)
- native SSL support for target hosts
- client SSL-certificate validation
- privat SMIME signing
- corporate SMIME signing, using a single privat certificate
- content based executable attachment blocking
- content based compressed attachment blocking
- BATV check and signing
- Message-ID signing and check FBMTV
- remote support
- Authenticated Received Chain (ARC) processing and signing
- RSS feeds for blocked emails using Plugin
- zero day virus detection
- VirusTotal API
Systems
- Windows
- Linux
- macOS
License
GNU General Public License version 2.0 (GPLv2)