PROTONMAIL

#ProtonMail welcome message

What data is encrypted?

The bodies of emails you exchange with other ProtonMail users are always automatically end-to-end encrypted. End-to-end encryption means the message is encrypted on the sender's computer and not decrypted until the recipient unlocks it on his computer; no servers in between, including ProtonMail's, have the key to decrypt it. Attachments and subject lines are not encrypted right now but will be in the future. You can tell if an incoming email is end-to-end encrypted by whether there is a purple lock next to it:

welcome_lock.gif

If you don't have friends on ProtonMail yet to benefit from end-to-end encryption, ProtonMail still provides extra security and privacy. For all non-end-to-end encrypted emails, the message bodies are still stored encrypted so that only you, with the correct mailbox password, can decrypt them.
Can I use this with my friends who use Gmail?

Yes! However, the messages they send to you will not be end-to-end encrypted. You can send messages to outside users as well. For outgoing messages to non-ProtonMail users, the default is unencrypted emails, which are sent just like any other email.

PM → PM (end-to-end encrypted)

Gmail → PM (not end-to-end encrypted)

PM → Gmail (not end-to-end encrypted by default, can be encrypted)

You can send a friend using Gmail an end-to-end encrypted message by selecting Encrypt for Outside Users. You will be prompted to set a message password to encrypt the message - this is the password you give to your friend through another channel. When your friend receives your encrypted email, they simply click on a link in the email, enter the password, and the message is instantly decrypted for them!

On the other hand, messages exchanged between ProtonMail users are automatically encrypted without requiring passwords for individual messages, so invite your friends to also use ProtonMail!
What is protonmail.ch vs. protonmail.com?

The .ch is the top-level domain for Switzerland and since v1.14, users can send and receive emails with both [email protected] and [email protected]. Go to the Settings page to pick your default alias.
What is Message Expiration?

With ProtonMail, you have more control of your data. For ProtonMail to ProtonMail emails, you can set how long you want an email to exist after it is sent. After the expiration time has elapsed, it is automatically deleted forever. If you are sending to an outside user however, this feature only works if you encrypt the message. Keep in mind one can forward an email with expiration to keep permanent copies of it.
How to use ProtonMail on mobile devices or mail clients?

ProtonMail can be accessed from most updated browsers, including those on mobile devices. Currently, we do not support POP/IMAP for mail clients due to our encryption. However, we are working on mobile apps that will make mobile access even easier and more secure.