SpamAssassin - Use this program to "Unspam" your mailbox(es).
TinyWall - Lightweight and non-intrusive firewall
MailScanner - MailScanner is a open source email security system design for Linux-based email gateways.
SonicWall - SonicWall security solutions protects your network, systems, users and data from cyber threats.
Rspamd - Rspamd is an advanced spam filtering system that allows evaluation of messages by a number of rules...
Windows 10 Firewall Control - Windows 10 Firewall Control: simple and exhaustive solution for applications network activity controlling and monitoring.