SpamAssassin - Use this program to "Unspam" your mailbox(es).
ModSecurity - ModSecurity is an Open Source web application firewall developed by Trustwave's SpiderLabs.
Oikik Antispam - Oikik is a cloud-based email filtering service that works with your existing email service.
Naxsi - NAXSI means Nginx Anti XSS & SQL Injection.
Rspamd - Rspamd is an advanced spam filtering system that allows evaluation of messages by a number of rules...
Shadow Daemon - Shadow Daemon is a collection of tools to detect, record and prevent attacks on web applications.