ProtonMail – an email client that uses end-to-end encryption for secure messaging. The software uses special methods of data transferring which ensure that only users involved in communication will have access to messages. ProtonMail prevents your mailbox from being viewed by anyone else, including email providers. The software allows you to send encrypted messages to users of other mail services, but without entering a password, it is impossible to access the email. ProtonMail offers a unique password hint so that the recipient can decrypt your message if you did not tell him the password. Also, ProtonMail automatically deletes encrypted messages when they expire.