How to Encrypt Email With Proton Mail

Updated 8 November 2026 · Standard formula, shown below

Proton Mail can protect messages between Proton Mail users automatically, and it can send password-protected messages to people using other email services. Before you write, decide which type of recipient you have: the encryption method and what the recipient needs to open the message depend on that.

What You’ll Need

A Proton Mail account and access to it in the Proton Mail app or at the Proton Mail website.
The recipient’s correct email address.
For a password-protected message to a non-Proton address, a password to share with the recipient through a separate, secure channel.
If using OpenPGP encryption with a non-Proton recipient, their public key and a way to verify that the key belongs to them.

Step-by-Step

Start a new message. Sign in to Proton Mail, select Compose, and enter the recipient’s email address. Check the address carefully; encryption does not prevent sending a message to the wrong person.
Check whether the recipient uses Proton Mail. Messages sent to another Proton Mail user are end-to-end encrypted automatically. You generally do not need to turn on a separate encryption setting. Write the subject and message, add any attachments, then send. The message is encrypted for the recipient’s account, and they open it after signing in.
For another email provider, choose how to protect the message. Proton Mail can use password-based encryption for recipients who do not use Proton Mail. In the composer, select the lock or encryption control (its appearance and location can differ by app or interface), then choose the option to encrypt the message with a password. If that option is not visible, check the compose toolbar or its more-options menu.
Set a strong message password. Use a long, unique password that is difficult to guess. Do not reuse your email account password or a password used elsewhere. Add a hint only if it does not reveal the password to someone who sees the email.
Share the password separately. Send it through a different channel, such as a phone call or a secure messaging app. Do not put the password in the same email, in the subject line, or in an attachment sent with that email. Make sure the recipient knows which message it unlocks.
Set an expiration if appropriate. If the composer offers a message-expiration control, choose a time that gives the recipient enough opportunity to read and respond. Expiration can limit how long the protected message remains available, but it cannot prevent someone from copying, photographing, or otherwise retaining information they can view.
Review before sending. Confirm the recipient, subject, message text, attachments, and encryption method. Email addresses and subject lines may not receive the same protection as the message body, so avoid putting sensitive details in the subject. Select Send.
Tell the recipient how to open it. A non-Proton recipient typically receives an email with a link to open the protected message in a browser. They enter the password you shared separately. If Proton Mail offers a reply option for the protected message, the recipient can use it to reply securely through the message page.
Use OpenPGP when both sides need that workflow. If the recipient has an OpenPGP public key, you can use it to encrypt mail so that their compatible email software can decrypt it with the corresponding private key. Import or obtain the recipient’s public key using Proton Mail’s available key-management tools, and verify its fingerprint with the recipient through a trusted channel before relying on it. Key steps vary by app and account setup; do not treat an unverified key as proof of identity.

Common Mistakes

Assuming every message is encrypted in the same way. Proton-to-Proton messages are automatically end-to-end encrypted. Messages to other providers need password-based encryption or a compatible public-key setup for end-to-end protection.
Sending the password alongside the message. Anyone who gains access to that email could get both the message and its password. Use a separate channel.
Putting confidential information in the subject. The subject and other message details may not be protected like the encrypted body. Keep sensitive content in the message itself.
Trusting an unverified public key. A public key that appears to match a person’s name may not belong to that person. Confirm its fingerprint with them independently.
Forgetting about attachments or recipients. Check that the correct files are attached and that all recipients should be able to read the message. Avoid adding people who do not need access.

Tips

Use password-based encryption for a one-off message when the recipient does not use Proton Mail and does not have a compatible OpenPGP setup.
Agree on a password-sharing method with frequent recipients in advance. A long passphrase is usually easier to share accurately than a short string of random characters.
Send a brief test message first if the recipient is unfamiliar with password-protected email. Ask them to confirm they can open it before sending time-sensitive or important information.
Keep your Proton Mail account protected with a strong, unique account password and available account-security features. Message encryption does not protect an account that someone else can access.
Remember that encryption protects content in transit and, depending on the method, from access by the email provider. It does not protect content after a recipient views or saves it on an unlocked device.

Troubleshooting

The encryption control is missing: Check the compose toolbar and its overflow or more-options menu. Try the official Proton Mail app or website, and make sure you are composing a new message rather than replying in an interface that has different controls. Available options can vary by platform and account configuration.
The recipient cannot open the message: Confirm that they are using the link in the notification email and entering the exact password, including capitalization and spaces. Resend the password through the separate channel if needed. If the message expired, compose and send a new one.
The recipient did not receive the notification: Ask them to check spam or junk folders and verify the address. You can resend the message after confirming the correct address.
An OpenPGP message will not decrypt: Check that the recipient has the private key corresponding to the public key used to encrypt it. Confirm that the key has not changed and that the recipient’s mail app supports the message format. Do not ask them to send you their private key; it should remain secret.
You are unsure whether a message was protected: Check the message details or encryption indicator in Proton Mail, and confirm the method used with the recipient. If sensitive information may have gone to the wrong person or was sent without the intended protection, contact the recipient promptly and follow your organization’s incident-reporting process if applicable.

Frequently Asked Questions

Are Proton Mail messages encrypted automatically?
Messages between Proton Mail users are end-to-end encrypted automatically. For a recipient using another provider, use password-based encryption or a compatible OpenPGP setup for end-to-end protection.

Can I encrypt an email to someone who does not use Proton Mail?
Yes. Use password-based encryption, then share the password separately. The recipient opens the protected message through a browser link.

Does the recipient need a Proton Mail account?
No, not for a password-protected message. They need the message link and the password. OpenPGP messages instead require compatible software and the matching private key.

Is the subject line encrypted?
Do not assume it is protected like the message body. Keep confidential information out of the subject and use the encrypted body for sensitive details.

Can I recall an encrypted email after sending it?
Do not rely on recall as a way to erase a message already viewed or copied. Expiration may restrict access through the protected message, but it cannot remove copies or screenshots a recipient has made.

Is a password-protected message the same as OpenPGP?
No. Password-based encryption lets a recipient open a message using a shared password. OpenPGP uses the recipient’s public key to encrypt and their private key to decrypt.

Method: the standard formula for this calculation, rounded as each result states. See how the calculators work or report an error.