Open-source spam and virus filtering

5 spam and virus filtering whose code is public under an OSI-approved license, rated for privacy with evidence. Picks first, then by score.

1. Amavis Grade B

   Self-hosted content filter written in Perl that sits between a mail server and scanners such as SpamAssassin and ClamAV, passing each message to them and acting on the results.

   Licensed under the GNU GPL version 2. Source code

2. Apache SpamAssassin Grade B

   Self-hosted spam filter from the Apache Software Foundation that scores mail with rules, DNS blocklists and Bayesian filtering, used alongside mail servers such as Postfix.

   Licensed under the Apache License 2.0. Source code

3. MailScanner Grade B

   Self-hosted email security system written in Perl that scans mail for spam, viruses and phishing using SpamAssassin and antivirus engines, with Postfix, Sendmail and Exim.

   Licensed under the GNU GPL version 2. Source code

4. Rspamd Grade B

   Self-hosted spam filtering system written in C and Lua that checks mail with rules, statistics, fuzzy hashes and DNS lists, and integrates with Postfix, Exim and other mail servers.

   Licensed under the Apache License 2.0. Source code

5. Proxmox Mail Gateway Grade C

   Self-hosted email gateway distribution from Proxmox that filters inbound and outbound mail for spam, viruses and phishing, managed through a web interface.

   Licensed under the GNU AGPL version 3. Paid subscriptions add support and the enterprise update repository. Source code

Compare all 19 spam and virus filtering, open source or not.