SpamTitan - Comprehensive Email Protection. 99.99% Spam Detection. Blocks phishing, viruses, malware and other email threats.
SpamAssassin - Use this program to "Unspam" your mailbox(es).
Sanebox - SaneBox is a cloud-based service that allows users to filter and manage their emails.
MailScanner - MailScanner is a open source email security system design for Linux-based email gateways.
ZeroSpam - Cloud email security & anti-spam solution
Rspamd - Rspamd is an advanced spam filtering system that allows evaluation of messages by a number of rules...