Postfix - Postfix is a mail transfer agent (MTA) that routes and delivers electronic mail.
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.
PowerMTA - PowerMTA is an industrial-strength software for high-volume email delivery.
Symantec Email Security.cloud - Symantec Email Security.cloud provides always-on, inbound and outbound email security against malware, targeted attacks, and advanced threats
EmailSuccess - EmailSuccess is an advanced MTA built to handle the most critical reliability, performance, security, and deliverability requirements.
FortiMail - Fortinet Email security is designed to block ransomware, phishing, and other cyber threats seeking entry via incoming email and outgoing messages don’t improperly leak sensitive data.