You can send emails from any of the email addresses you have added to c.Email by choosing from the drop-down menu in the From field. You can change your default email address by clicking the button to show your active accounts in the top right of your inbox.
You can send emails with four different security levels:
Not secure: Not authenticated or encrypted. Unencrypted emails can be read by email providers and hackers – leaving you vulnerable to surveillance, data theft, and fraud. Not recommended.
Authenticated: Signed with cryptographic proof of the sender’s identity.
Secure: Authenticated and protected with post-quantum secure encryption. Can only be read by you and the intended recipient. For when privacy and trust matter.
For Your Eyes Only: Authenticated and only decrypted when the intended recipient is looking at the screen. The reader must pass a continuous liveness check using our face unlock technology and a template of the biometric data from their initial identity verification (which is stored on their device, nowhere else). For when absolute secrecy matters.
If you haven’t confirmed your identity in the app, you won’t be able to authenticate or encrypt your emails.
By default, all your drafts will be encrypted automatically. c.Email will also prompt you to confirm your identity via face unlock when sending encrypted emails. You can turn both of these off in your c.Email settings.
It is possible to send encrypted emails to someone who is not yet on c.Email. This is made possible through identity-based encryption (IBE): the sender encrypts the message to the recipient's email address, so no previously published recipient public key is required. The recipient receives only an email with a link to install the app; the message itself remains encrypted.
When the recipient onboards and proves control of the email address, a decentralised group of key authorities then jointly issues the decryption key associated with that email address, allowing the recipient to open messages that were sent before they joined. Because the recipient proves email ownership on installing c.Email, and because no single key authority can issue the decryption key alone, only the recipient can read the encrypted email. Once the recipient is on c.Email, encryption proceeds as normal.