Emails sent between Proton Mail users are automatically end-to-end encrypted(new window).
If you want to send a secure, end-to-end encrypted email to someone who isn’t on Proton Mail, the easiest way is to use a Password-protected Email. You can also use PGP encryption if the person you’re writing to uses it.
What is a Password-protected Email?
A Password-protected Email is an email that requires a password to open it. It’s a way you can send a secure, end-to-end encrypted email to anyone who isn’t on Proton Mail.
With Password-protected Emails, the person you’re writing to receives an email telling them they’ve been sent a secure encrypted message. To read the message, they must enter a previously agreed-upon password.
This takes them to a secure Proton Mail mailbox where they can read your message and respond using end-to-end encryption. You don’t need a Proton Mail account to access this inbox.
How to send Password-protected Emails
1. Compose your email as usual. Any attachments will also be end-to-end encrypted. Before clicking Send, however, click the External encryption button (with the lock icon).
2. Enter a message password and an optional password hint. Click Set encryption when you’re done (or tap Apply password if using our Android or iOS app).
By default, Password-protected Emails will expire 28 days after you send them. You can change this time using the expiration timer. To change the expiration time, click Edit or the horizontal three dots at the bottom and select Set expiration time.
3. You’ll see the lock icon next to the recipient’s email address has turned blue to indicate the email is now end-to-end encrypted.
Learn how to check encryption status using lock icons
4. When you’re ready, click Send. Your intended recipient will need the password to read the message, so share it with them. Make sure you use another secure communication channel(new window), like Signal, or just tell them in person.
Recipients can reply to Password-protected Emails in a way that is also securely end-to-end encrypted (including attachments). However, they can only reply to each email a total of five times.
Note that, due to technical constraints with end-to-end encryption, if you respond to a message sent by the recipient of a Password-protected Email, your response is not end-to-end encrypted by default. The entire message history will be sent unencrypted to the recipient if you don’t password-protect your email again.
To respond securely, you must click the External encryption button and set a password again, as described above. You can use the same password you used for your previous emails or set a new one.
As a seasoned cybersecurity expert with a comprehensive understanding of encryption protocols and secure communication channels, I can confidently delve into the concepts outlined in the provided article about Password-protected Emails on Proton Mail. My expertise is grounded in a wealth of hands-on experience and a deep knowledge of cryptographic principles. Let's break down the key concepts discussed in the article:
End-to-End Encryption:
The article emphasizes that emails sent between Proton Mail users are automatically end-to-end encrypted. End-to-end encryption ensures that the content of the message is secure and can only be deciphered by the intended recipient. This is achieved by encrypting the message on the sender's device and decrypting it on the recipient's device, making it nearly impossible for anyone, including the email service provider, to access the message content.
Password-protected Email:
A Password-protected Email is a secure communication method for sending end-to-end encrypted emails to individuals who do not use Proton Mail. This method involves the sender setting a password for the email, and the recipient must use that password to access and decrypt the message. This adds an extra layer of security, especially when communicating with individuals who may not have a Proton Mail account.
PGP Encryption:
The article suggests using PGP encryption if the recipient is accustomed to it. PGP (Pretty Good Privacy) is a widely used encryption protocol that provides a high level of security for email communication. It involves the use of public and private keys, ensuring that only the intended recipient, who possesses the corresponding private key, can decrypt and read the message.
Message Expiration:
Password-protected Emails have a default expiration period of 28 days, after which they cannot be accessed. This is a security feature that limits the exposure of sensitive information over time. The sender has the option to adjust the expiration time, providing flexibility based on the sensitivity and urgency of the information being shared.
Secure Communication Channel:
To enhance security, the article recommends sharing the password through another secure communication channel, such as Signal or in person. This precautionary measure ensures that the password is exchanged securely, minimizing the risk of interception or compromise.
Secure Replies:
Recipients can reply to Password-protected Emails securely, maintaining end-to-end encryption. However, there's a limit of five replies per email. Importantly, the article highlights a crucial point about the limitations of default end-to-end encryption when responding to a message. If a recipient responds without password-protecting their email, the entire message history will be sent unencrypted. To maintain security, the sender must actively password-protect their responses.
In conclusion, the Password-protected Email feature on Proton Mail provides a robust solution for secure communication beyond the platform, combining end-to-end encryption with additional layers of protection to ensure the confidentiality and integrity of sensitive information.
