I was an earlier adopter of Protonmail and have had my account maybe for a year or so now. Protonmail is a swiss based email provider that offers true secure email through your web browser (and mobile app). This email service lets you send encrypted emails and attachments to others on other email systems like Gmail, yahoo, etc. They are a little slow in releasing new features but are methodical in their development and provide a solid product. They have started offering some great tools like custom domain names and iOS and Android Apps, and providing additional storage and a great user interface.
A good friend of mine always says security and convenience are always in tension – it is very difficult to have both. We must evaluate the level of security needed in relation to the ease of use which is often diminished. Protonmail would likely be troublesome for some as they requires two (2) passwords. One for account login and one to decrypt your mailbox. This means you should use two unique passwords that you don’t use for any other website logins…right?