Proton Mail Bridge frequently asked questions

7 mins
Using Bridge

What is Proton Mail Bridge?

Proton Mail Bridge(new window) is an open-source application that allows you to fully integrate your Proton Mail account with any program that supports IMAP and SMTP. This includes Microsoft Outlook, Mozilla Thunderbird, and Apple Mail.

It runs in the background on your computer and seamlessly encrypts and decrypts your email as it enters and leaves your computer.

How do I get Proton Mail Bridge?

Proton Mail Bridge is available for all paid users on Windows, macOS, and Linux. 

Learn how to install Proton Mail Bridge(new window)

Which email clients are supported?

We have fully tested and officially support Proton Mail Bridge on the following email clients:



Windows, macOS, and Linux

Every client implements the IMAP standard slightly differently, so we cannot make any guarantees about how Proton Mail Bridge will behave on clients other than the ones listed.

Why do I see an Invalid password error when setting up my client?

When setting up your email client, you must use your Proton Mail Bridge password, not your normal Proton Account password. Your Proton Mail Bridge password can be found in the Mailbox details section of the app.  

How to find your Bridge password
(new window)

Which password should I use when setting up my client?

When you add your Proton Mail account to Bridge, you will be given a Proton Mail Bridge password. This is the password you should use for setting up your email client.

Where is my Starred folder?

Every email client has a different way of handling Starred emails. 

  • On Apple Mail and Outlook, stars are shown as flags and your Starred folder is called Flagged.
  • On Thunderbird, you can view all of the starred emails in a mailbox by clicking the star at the top of the mailbox listing.

What is the difference between combined addresses mode and split addresses mode?

When you add an account to Proton Mail Bridge, it will initially be in combined addresses mode. This means emails from all addresses in your account will be received in the same mailboxes, and by default will be sent using your primary email address. 

If you would like to keep emails associated with each of your addresses separate, then you can switch to split addresses mode. In split addresses mode, you will need to add each of your email addresses to your client separately, and emails will be segregated by address into different mailboxes. 

Unfortunately, in Outlook, it is not possible to add additional sending addresses when in combined addresses mode. Split addresses mode is therefore required if you would like to send from email addresses other than your primary email address.

Does Proton Mail Bridge support Linux?

Proton Mail Bridge is available for Linux as a DEB, RPM, or PKGBUILD file. It is supported on:

  • Debian-based distributions, including Debian itself, Ubuntu, and Mint
  • Red Hat Linux-based distributions such RHEL, CentOS, and Fedora
  • Arch (including Manjaro and Garuda Linux)

How do labels work in Proton Mail Bridge?

Proton Mail labels are represented as folders in your email client. To create a new label, add a new folder under the Labels folder.

To label a message without removing it from its current location, copy the message into the relevant label folder. This works the same way as labeling on the web and mobile applications. To label a message and remove it from its current location, drag the message into that label folder.

Will Proton Mail Bridge be available on mobile platforms like iOS and Android?

Proton Mail Bridge has not been designed to work on mobile platforms. We recommend using dedicated native mobile Proton Mail apps instead.

Can I use multiple accounts?

Yes, you can add multiple accounts, and you will get a different Proton Mail Bridge password for each of them. You will have to add these accounts separately to your client of choice. 

To add an account, open the app, and click the plus button on the bottom left side of the window. 

Add an account
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Why am I seeing a Port is already occupied error?

Proton Mail Bridge uses ports 1143 (IMAP) and 1025 (SMTP)  by default, but sometimes one or both of these is already in use. To change these:

1. Open the app and click on the Settings (gear) icon.

Proton Mail Bridge settings
(new window)

2. Go to Advanced settingsDefault ports.

How to change ports 1
(new window)

3. You can change the port numbers incrementally (for example 1144 for IMAP and 1026 for SMTP) until you have ones that are not occupied by another application. Click Save and restart when you’re done.

How to change ports 2
(new window)

After changing the port numbers, make sure you also update the port settings in your email client.

How do I configure Proton Mail Bridge to automatically start when I turn on my computer?

This feature is enabled by default. To disable or re-enable it:

1. Open the app and click on the Settings (gear) icon.

Proton Mail Bridge settings
(new window)

2. Switch the Open on startup switch off or on

Toggle Open on Startup on or off
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In some cases, you may see an error indicating that autostart is not possible due to your OS permissions settings. To fix this on:


1. Open Finder and in the menu bar go to GoGo to Folder…

2. In the Go to Folder search field enter ~/Library. This takes to your Library folder in Finder. 

3. In the Library folder, right-click (or Ctrl-click) the LaunchAgents folder → Get info. Under Sharing and Permissions, ensure the user and administrator have both Read & Write permissions.

macOS permissions
(new window)

Windows 10 & 11

Open Explorer and find your Startup folder (C:\ProgramData\Microsoft\Windows\Start Menu\Programs\StartUp). Right-click on it and ensure the user has both Read and Write permissions.

Windows permissions
(new window)

Which operating systems are supported by Bridge?

Proton Mail Bridge is supported on Windows 10 and above and macOS 10.12 (Sierra) and above. Bridge for GNU/Linux is available for 64-bit machines as DEB, RPM, or PKGBUILD files.

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