ProtonMail from The Best free Email services of 2018

ProtonMail is one of the few free email providers that has an end-to-end encrypted mail system. It was created in 2014 at CERN (yes, the guys who created the Large Hadron Collider). If you sent emails from ProtonMail to e-mail addresses other than ProtonMail, you can optionally send them as plain text or through end-to-end encryption.