mailcow - An open source mailserver suite.
SpamAssassin - Use this program to "Unspam" your mailbox(es).
Mail-in-a-box - Mail-in-a-Box provides webmail and an IMAP/SMTP server for use with mobile devices and desktop mail software and also includes contacts and calendar synchronization.
MailScanner - MailScanner is a open source email security system design for Linux-based email gateways.
Mailu - Mailu is a simple yet full-featured mail server as a set of Docker images.
Rspamd - Rspamd is an advanced spam filtering system that allows evaluation of messages by a number of rules...