LastPass with ProtonMail

LastPass provides a cloud based hosted password manager solution. Here is a step by step guide to setting up LastPass to auto-login to your ProtonMail account.

Web Browser

To set up your Login password:

1) Go to the Sites tab

Lastpass Sites tab
2) Click on Add Site

Lastpass add site


3) Configure you ProtonMail login and click on the Save button.

LastPass configure


*Please note that our current login URL is: This may change in the future.

To configure your Mailbox password login:

1) Go to the website login page
2) LastPass will autofill the username and password as normal.

LastPass with ProtonMail login

3) Then click the LastPass logo in the browser, then click on matching sites.

LastPass and ProtonMail autofill login

4) Then Click on Edit

ProtonMail and LastPass password creation

5) Next, click on Edit Form Fields

How to add ProtonMail mailbox password to LastPass

6) Click on Add Form Fields

When you click on Add Form Fields the follow will appear, fill it in as below. Change Field Value to your mailbox decryption password

Then next time you login to Protonmail it will auto-fill the username and password.
Click on login, it will ask for the mailbox decryption password, LastPass will now auto-fill this is too.

If you experience any trouble with your LastPass manager working with your Mailbox password, please ensure you are using the latest version of Lastpass. This may require you to manually update the app. You can learn more here.


For more information on how to setup LastPass on your mobile device please see this article provided by Last Pass

This guide was brought to you by your ProtonMail community member.

Thank you @RedPacketSec!

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  1. Austin Meyer

    I get “error setting authentication cookies”

  2. ProtonMail Support

    Please contact us through the Report Bug button.

  3. sun

    there is no picture for ‘Add Form Field’ in the document even though it says ‘When you click on Add Form Fields the follow will appear, fill it in as below’.
    please add text atleast in terms of what is the field name to be provided

  4. sun

    these steps do not work for IOS protonmail app using lastpass login.they work for desktop Ios is the only option to create 2 sites?

  5. ProtonMail Support

    Not all password managers work with the apps, this depends on how the password manager is configured to store passwords. Because of the two passwords we use, most password managers can’t store the two, they can only store one.

  6. rolothedog

    This doesn’t seem to work for me. It gets through the initial logon and then doesn’t populate the mailbox encryption. What is the name of the Form Field it “MailboxPassword” ??? Using Firefox/Windows 10

  7. ProtonMail Support

    We have updated the picture. Please try following the tutorial.

  8. grant

    there is no picture for ‘Add Form Field’ in the document as mentioned above. What is the text that should be used?

  9. ProtonMail Support

    We have corrected this. You should see the final screenshot now.

  10. grant

    The article with proper instructions is here: and the missing screenshot/field name from the info above is “MailboxPassword” so as to auto-fill the second stage using LP.

  11. ProtonMail Support

    We have added the last screenshot or the mailbox password. Thanks for the assistance.

  12. michaelpuermayr

    In the last step, there is no field for “Form Name”. Lastpass also fills the decryption field with the login-pw (does not work).

  13. ProtonMail Support

    You need to add an additional Form field in LastPass for the mailbox password.

  14. daltondr

    This isn’t working. The “Add Form Field” window shown here is not the same as what shows up in my settings. I only have an option to add “field name”, “field type” and “field value”. Adding another field name, and calling it MailboxPassword” and using “Password” and my decryption password doesn’t work. It still uses the main login password for the decryption password. It ignores my added field.

  15. Anonymous

    instructions are obsolete

  16. Kimberly Johnson

    Are there any updated instructions on how to setup the passwords in LastPass? Unfortunately, these instructions no longer work.
    Any assistance would be greatly appreciated.

  17. Cary

    For anyone reading this in 2017, protonmail at some point renamed that form field from “MailboxPassword” to “mailbox-password”. Lastpass has gotten better about picking up these kinds of things automatically, but if you need to set it up manually, make sure you are using the new name.

  18. chris

    Following these instructions exactly does not work for me. I’m using Firefox in Debian Linux.
    I’ve tried several values for the field, based on various tags in the HTML source:
    – MailboxPassword
    – mailbox-password
    – mailboxPassword

    For each, LastPass looks like it is just offering to fill in the initial password and I get an error that it is incorrect from ProtonMail. The only thing that worked for me was to add a second site with this specific URL:

    For that second entry, I included a password only (the mailbox key) and no username.

    Maybe this will help if others run into the same issue.


  19. Jan

    Please, update this tutorial. It can be confusing (or even dangerous) for less tech-savvy users. Without getting it right, LastPass always proposes to override the other password.

    To make it work, inspecting HTML, I set all inputs manually:

    – name: username, type: text, value: …
    – name: password, type: password, value: …
    – name: password-mailbox, type: password, value: …

  20. Scott Palmer

    Mine hangs every time at mailbox decryption running Firefox 71.0 with LastPass extension

    Right clicking and selecting re-check page seems to get auto-fills but doesn’t submit.

    Is this broken for Firefox users?

  21. ProtonMail Support

    Hi! We haven’t noticed any issues with this browser/extension combination. Please open a support ticket at so our team can gather more details.

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