Toolsley PGPigeon - Simple but powerful OpenPGP-compatible message encryption webapp.
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.
DeliverySlip - DeliverySlip helps simplify, secure, and expedite the burdensome elements of online collaboration...
Barracuda Email Security Service - Secure Email Gateway
GPGTools - Use GPG Suite to encrypt, decrypt, sign and verify files or messages.
SonicWALL Email Security Series Appliances - SonicWall Email Security appliances are ideal for organizations that need a dedicated on-premises solution.