pfSense - pfSense is a free and open source firewall and router that also features unified threat management, load balancing, multi WAN, and more
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.
OPNsense - OPNsense® you next open source firewall. Free Download. High-end Security Made Easy™. Offers Intrusion Prevention, Captive Portal, Traffic Shaping and more.
Proofpoint Email Security and Protection - Learn about Proofpoint's email security solutions that protect organizations against threats such as email fraud, phishing, spam, bulk email, and viruses.
IPFire - IPFire is a server distribution with intended to use as a firewall.
Cisco Email Security - Cisco Email Security protects against ransomware, business email compromise, spoofing, and phishing.