ProtonMail Bridge is an open-source application that allows you to fully integrate your ProtonMail 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 mail as it enters and leaves your computer.
Once you’ve installed and added your account(s) to ProtonMail Bridge, you will need to configure your email client. ProtonMail Bridge works with most email clients and applications that support IMAP / SMTP connections. In this guide, we provide step-by-step instructions for configuring Microsoft Outlook 2013 for Windows for use with ProtonMail Bridge.
How to set up Outlook 2013 for ProtonMail Bridge
1. Open Outlook and go to File tab → Account Information → Add account.
2. Select New.
3. Select Manually configure server settings or additional server types and click Next.
4. Select POP or IMAP and click Next.
5. Enter the account details given in the ProtonMail Bridge app, then click More Settings….
Note: Do not use your regular ProtonMail account details. You must use the account details provided in ProtonMail Bridge under Mailbox details.
6. Select the Outgoing Server tab, check My outgoing server (SMTP) requires authentication, check Log on using and enter the same User Name and Password (from ProtonMail Bridge) that you entered above.
7. Select the Advanced tab and enter the Server information from Proton Bridge. Make sure the encrypted connection type is TLS for both IMAP and SMTP and the ports are set correctly as 1143 for IMAP and 1025 for SMTP.
Under Sent Items, check Do not save copies of sent items, and under Deleted Items check Purge items when switching folders while online.
Click OK when you’re done.
8. Back on the POP and IMAP Account Settings page, click Next.
9. You may see a security warning. If you do, click Yes.
Setup is now complete.
1. In split addresses mode every IMAP account that you set up with ProtonMail Bridge is address-specific, and will only be able to send and receive emails from the address it is set up with.
You can add any number of addresses to Outlook, but wait for one address to download before adding another.
2. In combined address mode, Outlook has no way to add more than one address to send with.