ProtonMail - Secure email with absolutely no compromises. Get your free encrypted email account today.
Pignus Encryption - Pignus Encryption is an encryption platform that allows users to encrypt their messages and documents.
Enigmail - Security extension to Mozilla Thunderbird and SeaMonkey
Skizzle Email - Skizzle is the most secure way to share end-to-end encrypted files through email, backed by blockchain
Toolsley PGPigeon - Simple but powerful OpenPGP-compatible message encryption webapp.
Tutanota - Get your encrypted mailbox for free.