Proton Bridge Setup Guide: Use Thunderbird, Apple Mail, and Outlook With End-to-End Encryption
Last updated: 2026-06-15
Bottom Line First
Proton Bridge works by running a local IMAP/SMTP proxy on your machine. Your email client talks to 127.0.0.1 on private ports, Bridge decrypts/re-encrypts on the fly using your Proton keys, and your messages never leave your device unencrypted. Once configured, it is invisible — email just works in your client of choice.
The three things that trip people up every time:
- The Bridge password is not your Proton account password. Bridge generates a separate credential. Use that one in your client.
- The Bridge TLS certificate is self-signed. You must explicitly trust it, or your client will refuse the connection.
- Bridge must be running. If it is not in your system tray, your email client will time out.
Get those three right and the rest is just clicking through account setup screens.
Install and Unlock Proton Bridge
Download Bridge from proton.me/mail/bridge and install it normally for your OS. On Linux, Bridge ships as a .deb, .rpm, or an AppImage.
On first launch, sign in with your Proton account credentials (email + password + 2FA if enabled). Bridge will sync your mailbox metadata — this can take a few minutes on large accounts.
Once signed in, Bridge sits in your system tray. Click the tray icon and open the main window. You will see:
- Your email address listed as a connected account
- A Bridge password (a generated string, not your Proton password) — copy this now
- IMAP port: 1143
- SMTP port: 1025
- Host: 127.0.0.1
Keep this window open while you configure your client. You will need the Bridge password repeatedly.
If you have a paid Proton account and want the best privacy stack for your whole workflow, Proton Unlimited bundles Mail, VPN, Drive, and Pass under one subscription — the Bridge feature is included.
Affiliate Disclosure: This article may contain affiliate links. If you make a purchase through these links, we may earn a small commission at no extra cost to you. We only recommend products we genuinely believe in. This helps support our work and allows us to continue providing free content.
Stay sharp on privacy tools. Join the PrivateAI letter — practical guides on encrypted workflows, no vendor fluff, unsubscribe any time.