How to set up SMTP to use business applications or devices with Proton Mail

4 mins
Proton for business
Proton Mail

With Proton Mail’s SMTP, you can set up your business applications or devices (e.g. printers) to send emails from your Proton Mail address(es).

These apps or devices will integrate with Proton Mail to send automated emails on your behalf, allowing you to benefit from added security and email delivery enhancements. This feature is currently only available for select Proton for Business customers and those with Visionary and Family accounts with a custom domain addresses.

How does it work?
How to set up SMTP
How to disable SMTP

How does it work?

This feature allows apps or devices without mail servers to send emails from your Proton Mail address(es), using Proton Mail’s high reputation IP’s and anti-spam protections.

Examples include allowing WordPress websites, customer relationship management (CRM) systems, enterprise resource planning (ERP) systems, or printers to send emails through Proton Mail.

The first step is to generate a special SMTP token in your Proton Mail Settings for a custom domain email address. Then, you can use the email address and the newly-generated SMTP password to set up your device or business application. 

Once our servers authenticate your email address and SMTP password, the application or device will be able to send emails with your email address as the sender (i.e. the From: field), while respecting any anti-spoofing protections (e.g. SPF/DKIM/DMARC) you’ve set up for your custom domain.

You can see emails sent via SMTP in your regular Sent folder. Note that emails sent using SMTP are not end-to-end encrypted. However, they’re still stored with zero-access encryption like any other emails in your Proton Mail inbox.

Learn about end-to end-encryption when using Proton Mail


This SMTP feature can only be used for sending emails (“Submission”), unlike the IMAP protocol used by third-party email clients to fetch received emails to your inbox.

To receive emails using a third-party client like Outlook or Apple Mail, you can set up Proton Mail Bridge on your computer.

How to set up SMTP

  1. In your browser, sign in to your Proton Mail account and select Settings → All settings → Proton Mail → IMAP/SMTP → SMTP tokens.
  1. Click Generate token.
  2. Enter the following details to create a new SMTP token:

    Token name: Select a name so you’ll remember where this token is used, such as the service or device name. If you need to allow multiple third-party clients to use SMTP, generate a different token for each client so you can manage their permissions independently. This increases security as you can remove a client’s SMTP permission by deleting its token without affecting the other clients.

    Email address: Select one of your active custom domain addresses to pair with your token. Copy this email address and use it as the username in the third-party client. If you have multiple addresses, generate a different token for each address.
Field to generate and name an SMTP token
  1. Click Generate.
  2. Enter your Proton Mail Account password.
Field to enter your password

Your SMTP username and SMTP token (password) will be generated. You can now enter them as the username and password of your Proton Account in the third-party client.

You may also be asked for the following information in your third-party client:

SMTP host:
Authentication method: PLAIN
Encryption: STARTTLS

Note that some clients may only offer “SSL/TLS” or “TLS” encryption, and you may have to experiment with different settings. In general, if STARTTLS isn’t available, TLS is the next best option.

After closing the popup, you will not be able to see this SMTP token (password) again for security reasons. You can always generate more tokens if you need to rotate passwords or allow more clients and addresses to use SMTP.

Note: Your Proton Mail login or mailbox passwords will not work with SMTP, and you should never use them with third-party clients.

Popup showing your SMTP username and SMTP token
  1. Close the popup to see the new token with its name, email address, time of creation, and when it was last used. Any emails sent using your third-party client will be kept in your Sent folder.
Settings page showing your SMTP tokens

How to disable SMTP

If you’re changing the password for a third-party client, make sure to switch the client to the new token before deleting the old token. This ensures minimal downtime for the client.

  1. In your browser, sign in to your Proton Mail account and select Settings → All settings → Proton Mail → IMAP/SMTP → SMTP tokens. You should be able to see all active SMTP tokens.
  2. Click Delete next to the token you’d like to remove.
Settings page showing your SMTP tokens
  1. Click Delete to remove this token.

    Note: You cannot undo a token deletion, but you can always generate new tokens.
Confirmation button to delete a token

4. This token is now deleted. Any client with this token will no longer be able to send any emails from your Proton Mail address(es).

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