GPGMail - GPGMail is an open source plugin for Apple Mail.
Cellcrypt - Cellcrypt app provides features so you can enjoy secure conference calling, messaging, and sharing of documents.
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
WhatsRemoved+ - WhatsRemoved+ is a mobile tool developed and published by Development Color for Android devices only.