Toolsley PGPigeon - Simple but powerful OpenPGP-compatible message encryption webapp.
SpamTitan - Comprehensive Email Protection. 99.99% Spam Detection. Blocks phishing, viruses, malware and other email threats.
GPGTools - Use GPG Suite to encrypt, decrypt, sign and verify files or messages.
MailCleaner - Cloud & on-premise anti spam software for businesses
Lockbin - Lockbin is a web application for sending private email messages and files.
Vade Secure - Email security to protect against email-borne phishing, spear phishing, malware, and ransomware. Email security and management based on artificial intelligence.