MailStore - MailStore Home - A 100% free single-private-user desktop solution
ProtonMail - Secure email with absolutely no compromises. Get your free encrypted email account today.
Mail Backup X - Your one stop mail backup and archiving tool for Mac.
Enigmail - Security extension to Mozilla Thunderbird and SeaMonkey
Gmvault - Backup the emails in your Gmail account.
Skizzle Email - Skizzle is the most secure way to share end-to-end encrypted files through email, backed by blockchain