Proton Mail Bridge docker

A docker version of the Proton mail Bridge command line interface. It creates a local SMTP server, so other docker containers can send emails via your Proton email account.

!WARNING! As of the time of this writing, you need a paid plan (Mail Plus, Proton Unlimited or Proton for Business) to be able to log in. It won't work for free account.

(Merci Korben pour le logo)

Install

Download the latest docker image from:

docker pull ghcr.io/videocurio/proton-mail-bridge:latest

(Alternative) Or the lightweight version based on Alpine Linux:

docker pull ghcr.io/videocurio/proton-mail-bridge-alpine:latest

(Optional) It is recommended to set up a custom docker network for all of your containers to use, for DNS / network-alias resolution:

sudo docker network create --subnet 172.20.0.0/16 network20

Launch it with the following command to expose TCP ports 12025 for SMTP and 12143 for IMAP on your local network interface. You SHOULD provide a path volume storage (mkdir /path/to/your/volume/storage).

docker run -d --name=protonmail_bridge -v /path/to/your/volume/storage:/root -p 127.0.0.1:12025:25/tcp -p 127.0.0.1:12143:143/tcp --network network20 --restart=unless-stopped ghcr.io/videocurio/proton-mail-bridge:latest

(Optional) Make sure the container is running:

docker ps
CONTAINER ID   IMAGE                                          COMMAND                  CREATED              STATUS              PORTS                                                  NAMES
d9932fb7136b   ghcr.io/videocurio/proton-mail-bridge:latest   "/app/entrypoint.sh"     About a minute ago   Up About a minute   127.0.0.1:12025->1025/tcp, 127.0.0.1:12143->1143/tcp   protonmail_bridge

Setup

Now, you need to open a bash terminal on the current running container and use the Proton Bridge interactive command line:

docker exec -it protonmail_bridge /bin/bash

# First we need to kill the default bridge startup instance (only one instance of bridge can run at the same time)
root@8972584f86d4:/app# pkill bridge
# Login to your Proton account:
root@8972584f86d4:/app# /app/bridge --cli
....
      Welcome to Proton Mail Bridge interactive shell
....
>>> info
No active accounts. Please add account to continue.

# Type help for a list of all commands:
>>> help
# Login to a Proton account (!MUST! be a paid plan to use this client), follow the instructions on screen:
# Tip: Use Ctrl+Shift+V to paste on most Linux terminal.
>>> login
Username: test_account@proton.me
Password: 
Authenticating ...
Two factor code: 123456
Account test_account was added successfully.
>>> A sync has begun for test_account.
Sync (test_account): 1.0% (Elapsed: 0.5s, ETA: 46.0s)
...
Sync (test_account): 99.9% (Elapsed: 50.4s, ETA: 0.4s)
A sync has finished for test_account.
>>>
# Success !

IF you are using multiple domain names or email addresses, you SHOULD switch to split address mode (it will set credentials for each address in the account).

It will sync the account again, time to grab a coffee.

>>> change mode 0
Are you sure you want to change the mode for account test_account to split? yes/no: yes
Address mode for account test_account changed to split
>>> A sync has begun for test_account.
Sync (test_account): 1.0% (Elapsed: 0.3s, ETA: 32.6s)
...
Sync (test_account): 99.9% (Elapsed: 50.4s, ETA: 0.4s)
A sync has finished for test_account.
>>>

Use the following information to connect via an SMTP client. The port numbers for the SMTP/IMAP connections are 12025 and 12143 (see your previous Docker container launch command), not the one provided by the infocommand.

You MUST copy the username AND password from the info command (the password is random and different from your Proton account):

>>> info
Configuration for test_account@proton.me
IMAP Settings
Address:   127.0.0.1
IMAP port: 1143
Username:  test_account@proton.me
Password:  abcedfGHI12345
Security:  STARTTLS

SMTP Settings
Address:   127.0.0.1
SMTP port: 1025
Username:  test_account@proton.me
Password:  abcedfGHI12345
Security:  STARTTLS

Configuration for another_account@proton.me
....

# Exit
>>> exit
root@8972584f86d4:/app# exit

See a list of all Proton bridge commands available here or use the help command.

We have killed the default bridge instance by exiting it during the previous step, so we MUST restart the container:

docker container restart protonmail_bridge

(Optional) You can check the bridge command line output with:

docker container logs protonmail_bridge

It should end with A sync has finished for test_account

Notes

Your email client might complain about the self-signed certificate used by Proton mail bridge server.
If you want other docker containers to only be able to send emails, you should only expose SMTP port 25.

TrueNAS Scale

The docker image was tested on the latest stable version of TrueNAS Scale (at the time of writing), follow the installation custom app screen documentation.

The recommended parameters are:

Container images - Image repository: ghcr.io/videocurio/proton-mail-bridge / Image tag: latest / Image pull policy: Always pull...
Container Entrypoint - Command: /app/entrypoint.sh
Container Environment Variables - Add > Environment Variable Name: PROTON_BRIDGE_SMTP_PORT / Environment Variable Value: 1026
Port Forwarding - Add > Container Port: 25 / Node Port: 12025 (Or any other non-used port) / Protocol: TCP
Storage - Volumes > Mount Path: /root / Dataset name: protonmail
Resource limits - Check Enable resource limits, configure the limits to your liking.

About point 3 of the recommended parameters, on Kubernetes (used by TrueNAS Scale for Applications) the Proton Mail Bridge applications seems to listening on localhost TCP port 1026 instead of port 1025. In order to confirm this setting, launch a console on your running Proton Mail bridge pod and see the results of a netstat -ltpn command, you are looking for a bridge program name on 127.0.0.1:1026address.

If everything is set correctly, on a TrueNAS Scale console the following command:

sudo k3s kubectl get service --all-namespaces

should report the Proton bridge mail as:

ix-protonmail-bridge    protonmail-bridge-ix-chart      NodePort    172.17.22.33    <none>  25:12025/TCP        1h

The SMTP server is now available from TCP port 12025 on your server's LAN IP address.

Changelogs

2024/04/30: updated to Proton Mail Bridge v3.11.0
2024/03/04: Initial public release, Proton Mail Bridge v3.9.1

Developers notes

Build / test docker image, see: Docker documentation

# Local tests:
docker pull golang:bookworm
# and/or
docker pull golang:1.22-alpine

git clone https://github.com/VideoCurio/ProtonMailBridgeDocker.git
cd /path/to/ProtonMailBridgeDocker/
docker build --tag=ghcr.io/videocurio/proton-mail-bridge .
docker images | grep videocurio

docker run -it --rm --entrypoint /bin/bash ghcr.io/videocurio/proton-mail-bridge:latest

docker image tag ghcr.io/videocurio/proton-mail-bridge:latest ghcr.io/videocurio/proton-mail-bridge:3.9.1a
docker push ghcr.io/videocurio/proton-mail-bridge:3.9.1a
docker push ghcr.io/videocurio/proton-mail-bridge:latest

### TrueNAS
ping -c 4 protonmail-bridge-ix-chart.ix-protonmail-bridge.svc.cluster.local
nslookup protonmail-bridge-ix-chart.ix-protonmail-bridge.svc.cluster.local 172.17.0.10

There is a testing branch available if you want to submit a patch.

An Alpine Linux version for a small image base footprint is available in the Alpine directory.

License

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see https://www.gnu.org/licenses/.

Sources:

Made from Debian 12 (bookworm) Go image and Proton Mail Bridge sources v3.9.1