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...
ModSecurity - ModSecurity is an Open Source web application firewall developed by Trustwave's SpiderLabs.
SpamAssassin - Use this program to "Unspam" your mailbox(es).
CloudFlare - Cloudflare is a global network designed to make everything you connect to the Internet secure, private, fast, and reliable.
Proxmox Mail Gateway - Protect mail server against spam, viruses and malware with Proxmox Mail Gateway security for businesses, government, education and non-profit organizations.