Using LastPass with ProtonMail

LastPass is a popular (but proprietary and closed-source) cloud-based password manager. In this guide, we provide step-by-step instructions to using LastPass to log in to your ProtonMail account.


LastPass offers desktop browser add-ons for Firefox, Chrome, Microsoft Edge Chromium, Microsoft Edge Legacy, and Opera.

1. Sign up for a LastPass account, install the LastPass browser add-on for your browser, and Log in.

Image of LastPass desktop 1

2 . Visit the ProtonMail login page at Open the LastPass browser add-on and click Add item.

Image of LastPass desktop 2

  1. Click Password.

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4. A new browser tab will open showing the LastPass Add password form. Fill in your ProtonMail Username and Password, then click Save. LastPass will auto-fill the Name and URL from the web page you are on.

Image of LastPass desktop 4
5. Back on the ProtonMail login page, click the LastPass icon on the right side of the Email or username field and select the ProtonMail entry you just created. LastPass will now auto-fill your ProtonMail login details.

Image of LastPass desktop 5


1. Install the LastPass app and Log in using your existing LastPass credentials, or Sign-up if you don’t have a LastPass account yet. 

2. We strongly suggest enabling Use Touch ID for ease of use.

Image of LastPass iOS 1

3. If this is your first time using LastPass, you will be prompted to Add First Password. If you’ve used LastPass before, go to VaultPasswordsAddAdd New Password.

Image of LastPass iOS 2
4. Give the entry a name (such as ProtonMail) and fill in your ProtonMail Username and Password. For the URL, use Tap Save when you are ready.

5. Open the ProtonMail app and tap Passwords (above your keyboard).  

Image of iOS login
6. Tap your newly created entry to auto-fill the password into the ProtonMail app.

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If this is your first time using LastPass in iOS, you will be prompted with Let’s enable AutoFill. We recommend doing this using the instructions provided. 

Image of LastPass iOS AutoFill


Note that it is not possible to take screenshots of LastPass in Android due to a security policy, but it looks similar to the iOS version.

1. Install the LastPass app and Log in using your existing LastPass details or Create account if you don’t have one yet. 

2. You will be prompted to enable the Android Auto-fill Service for LastPass. To do this (recommended, follow the instructions provided).

3. Tap the + button to add a new entry → Password.

4. Give the entry a name (such as ProtonMail) and fill in your ProtonMail Username and Password. For the URL, use Tap Save when you are ready.

5. Open the ProtonMail app and select the ProtonMail auto-fill entry.

Post Comment


  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.

Comments are closed.