ProtonMail - Secure email with absolutely no compromises. Get your free encrypted email account today.
WAMR - WAMR – Recover Deleted Messages and Status Download is a powerful app that helps you recover text messages and media attachments.
Enigmail - Security extension to Mozilla Thunderbird and SeaMonkey
YAATA - YAATA app offers features that let you send multimedia files such as images, videos, audio, and GIFs, etc.
Skizzle Email - Skizzle is the most secure way to share end-to-end encrypted files through email, backed by blockchain
NetSfere Secure Messaging - NetSfere Secure Messaging is a secure messaging app that enables you to send messages by using 256-bit device-to-device encryption features.