SpamAssassin - Use this program to "Unspam" your mailbox(es).
Rspamd - Rspamd is an advanced spam filtering system that allows evaluation of messages by a number of rules...
MailScanner - MailScanner is a open source email security system design for Linux-based email gateways.
Oikik Antispam - Oikik is a cloud-based email filtering service that works with your existing email service.
Broadcom Email Security - Anti-spam gateway blocks more than 99% of spam with less than one in 1 million false positives and...
Zimbra - Zimbra is trusted by over 500 million users to increase productivity with a complete set of collaboration tools while maintaining total control over security and privacy.