ufw - Ufw stands for Uncomplicated Firewall, and is program for managing a netfilter firewall.

Barracuda Email Security Gateway - Barracuda's Email Security Gateway is a powerful antivirus filter specifically designed to identify and eliminate email-borne threats, stopping hazards before they reach the network.

LuLu by Objective-See - LuLu is the free open-source macOS firewall that aims to block unauthorized (outgoing) network...

Symantec Email Security.cloud - Symantec Email Security.cloud provides always-on, inbound and outbound email security against malware, targeted attacks, and advanced threats

Plasma Firewall - Plasma Firewall is an open-source control panel with which you can manage your system firewall.

Cisco Email Security - Cisco Email Security protects against ransomware, business email compromise, spoofing, and phishing.