SpamAssassin - Use this program to "Unspam" your mailbox(es).
HackerOne - HackerOne provides a platform designed to streamline vulnerability coordination and bug bounty program by enlisting hackers.
MailScanner - MailScanner is a open source email security system design for Linux-based email gateways.
Intruder - Intruder is a security monitoring platform for internet-facing systems.
Rspamd - Rspamd is an advanced spam filtering system that allows evaluation of messages by a number of rules...
Nessus - Nessus Professional is a security platform designed for businesses who want to protect the security of themselves, their clients, and their customers.