MailStore - MailStore Home - A 100% free single-private-user desktop solution
Cryptomator - When it comes to saving your files on a cloud server, it is important to ensure the security of those files. Keeping your delicate files out of the wrong hands can save you a lot of time and hassle. Read more about Cryptomator.
MailSteward - MailSteward : The Ultimate E-mail Manager for Mac OS X
Axcrypt - AxCrypt - Password Protect Files With Strong Encryption. AxCrypt is the leading open source file encryption software for Windows.
Gmvault - Backup the emails in your Gmail account.
Microsoft BitLocker - BitLocker is a full disk encryption feature included with Windows Vista and later.