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GNU Mailman 3 Deployment with Docker


This repository hosts code for two docker images maxking/mailman-core and maxking/mailman-web both of which are meant to deploy GNU Mailman 3 in a production environment.

Docker is a container ecosystem which can run containers on several platforms. It consists of a tool called docker-compose which can be used to run multi-container applications. This repository consists of a docker-compose.yaml file which is a set of configurations that can be used to deploy the Mailman 3 Suite.

Please see release page for the releases and change log.


The tags for the images are assumed to be release versions for images. This is going to be a somewhat common philosophy of distributing Container images where the images with same tags are usually updated with the new functionality.

Releases will follow the following rules:

  • Images tagged like A.B.C will never change. If you want to pin down versions of Images, use these tags.

  • Images tagged with A.B will correspond to the latest A.B.C version released. Releases in A.B series are supposed to be backwards compatible, i.e., any existing installation should not break when upgrading between subversions of A.B.C. So, if you want the latest updates and want to frequently update your installation without having to change the version numbers, you can use this.

  • Any changes in the minor version of Mailman components of the images will cause a bump in the minor version, e.g., A.(B+1) can have one or more updated Mailman components from A.B. Also, significant change in functionality, that might change how Images work or how people interact with the containers can also cause a bump in the minor version.

  • Major versions will change either when there are backwards incompatible changes or when the releases reach a certain set milestone or when there are bugfix releases for the internal components or both.

Container Registries

The container images are available from multiple container registries. Do specify an explicit version tag (e.g. 0.4.5 , MAJOR.MINOR like 0.4 also works as floating tag pointing to latest patch version) as tag latest is not updated anymore.

Mailman Core


Mailman Web




Rolling Releases

Rolling releases are made up of Mailman Components installed from git source. Note that these releases are made up of un-released software and should be assumed to be beta quality.

Every commit is tested with Mailman's CI infrastructure and is included in rolling releases only if they have passed the complete test suite.

$ docker pull
$ docker pull

Rolling releases are built with every commit and also re-generated nightly. You can inspect the images to get which commit it was built using:

$ docker inspect --format '{{json .Config.Labels }}' mailman-core | python -m json.tool
    "version.git_commit": "45a4d7805b2b3d0e7c51679f59682d64ba02f05f",

$ docker inspect --format '{{json .Config.Labels }}' mailman-web | python -m json.tool
    "version.git_commit": "45a4d7805b2b3d0e7c51679f59682d64ba02f05f",

  • version.git_commit : This is the commit hash of the Dockerfile in the Github repo


  • Docker
  • Docker-compose

To install these on Ubuntu/Debian:

$ sudo apt install docker-compose

For other systems, you can read the official Docker documentation to install Docker from here and docker-compose from here.


Most of the common configuration is handled through environment variables in the docker-compose.yaml. However, there is need for some extra configuration that interacts directly with the application. There are two configuration files on the host that interact directly with Mailman's settings. These files exist on the host running the containers and are imported at runtime in the containers.

  • /opt/mailman/core/mailman-extra.cfg : This is the configuration for Mailman Core and anything that you add here will be added to Core's configuration. You need to restart your mailman-core container for the changes in this file to take effect.

  • /opt/mailman/web/ : This is the Django configuration that is imported by the existing configuration provided by the mailman-web container. This file is referred to as in most of the Postorius and Django documentation. To change or override any settings in Django/Postorius, you need to create/edit this file. A useful configuration for troubleshooting is DEBUG = True.

Also, note that if you need any other files to be accessible from the host to inside the container, you can place them at certain directories which are mounted inside the containers.

  • /opt/mailman/core in host maps to /opt/mailman/ in mailman-core container.
  • /opt/mailman/web in host maps to /opt/mailman-web-data in mailman-web container.


These are the settings that you MUST change in your docker-compose.yaml before deploying:

  • SERVE_FROM_DOMAIN: The domain name from which Django will be served. To be added to ALLOWED_HOSTS in django settings. Default value is not set. This also replaces Django's default SITE and becomes the default SITE (with SITE_ID=1).

  • HYPERKITTY_API_KEY: Hyperkitty's API Key, should be set to the same value as set for the mailman-core. (Not needed in case of Postorius-only version.)

  • MAILMAN_ADMIN_USER: The username for the admin user to be created by default.

  • MAILMAN_ADMIN_EMAIL: The email for the admin user to be created by default.

  • SECRET_KEY: Django's secret key, mainly used for signing cookies and others.

Please note here that if you choose to create the admin user using the environment variables mentioned above (MAILMAN_ADMIN_USER & MAILMAN_ADMIN_EMAIL), no password is set for your admin account. To set a password, plese follow the "Forgot Password" link on the "Sign In" page.

Mailman web is already configured to send emails through $SMTP_HOST as the MTA's address. If you want to modify it, you can set the value in under docker-compose.yaml for mailman-web container. By default, SMTP_HOST points to the gateway of the web container, which is the host itself.

You can also use the environment variables SMTP_HOST (defaults to the container's gateway), SMTP_PORT (defaults to 25), SMTP_HOST_USER (defaults to an empty string), SMTP_HOST_PASSWORD (defaults to an empty string), SMTP_USE_TLS (defaults to False) and SMTP_USE_SSL (defaults to False).

This is required in addition to the Setup your MTA section below, which covers email setup for Mailman Core.

For more details on how to configure this image, please look at Mailman-web's Readme


These are the variables that you MUST change in your docker-compose.yaml before deploying:

  • HYPERKITTY_API_KEY: Hyperkitty's API Key, should be set to the same value as set for the mailman-web. Skip the variable in case of non-Hyperkitty deployment.

  • DATABASE_URL: URL of the type driver://user:password@hostname:port/databasename for the django to use. If not set, the default is set to sqlite:///opt/mailman-web-data/mailmanweb.db. The standard docker-compose.yaml comes with it set to a postgres database. There is no need to change this if you are happy with PostgreSQL.

  • DATABASE_TYPE: Its value can be one of sqlite, postgres or mysql as these are the only three database types that Mailman 3 supports. Its default value is set to sqlite along with the default database class and default database url above.

  • DATABASE_CLASS: Default value is mailman.database.sqlite.SQLiteDatabase. The values for this can be found in the mailman's documentation here.

  • SMTP_HOST : outgoing host for SMTP connections
  • SMTP_PORT : use this port. 25, 587, whatever your host asks for.
  • SMTP_HOST_USER: authenticate this user
  • SMTP_HOST_PASSWORD: and use this password
  • SMTP_SECURE_MODE: security mode for smtp connection - can be smtp (no encryption), smtps or starttls
  • SMTP_VERIFY_HOSTNAME: defaults to true - verify, that certificate hostname is identical to SMTP_HOST
  • SMTP_VERIFY_CERT: defaults to true - verify, that certificate is valid

For more details on how to configure this image, please look Mailman-core's Readme

While the above configuration will allow you to run the images and possibly view the Web Frontend, it won't be functional until it is fully configured to to send emails.

To configure the mailman-core container to send emails, see the Setting your MTA section below.


To run the containers, simply run:

$ mkdir -p /opt/mailman/core
$ mkdir -p /opt/mailman/web
$ git clone
$ cd docker-mailman
# Change some configuration variables as mentioned above.
$ docker-compose up -d

Note that the web frontend in the mailman-web container is, by default, only configured to serve dynamic content. Anything static like stylesheets, etc., is expected to be served directly by the web server. The static content exists at /opt/mailman/web/static and should be aliased to /static/ in the web server configuration.

See the nginx configuration as an example.

This command will do several things, most importantly:

  • Run a wsgi server using uwsgi for the Mailman's Django-based web frontend listening on port 8000. It will run 2 worker processes with 4 threads each. You may want to change the setting ALLOWED_HOSTS in the settings before deploying the application in production.

  • Run a PostgreSQL server with a default database, username, and password as mentioned in the docker-compose.yaml. You will have to change configuration files too if you change any of these.

  • Run mailman-core listening on port 8001 for REST API and port 8024 (LMTP server) for messages from your MTA. You will have to configure your MTA to send messages at this address.

Some more details about what the above system achieves is mentioned below. If you are only going to deploy a simple configuration, you don't need to read this. However, these are very easy to understand if you know how docker works.

  • First create a bridge network called mailman in the docker-compose.yaml. It will probably be named something else in your machine. All the containers mentioned (mailman-core, mailman-web, database) will join this network and are assigned static IPs. The host operating system is the default gateway from within these containers.

  • Spin off a mailman-core container attached to the mailman bridge network created above. It has GNU Mailman 3 core running inside it. Mailman core's REST API is available at port 8001 and LMTP server listens at port 8024.

  • Spin off a mailman-web container which has a Django application running with both Mailman's web frontend Postorius and Mailman's web-based Archiver running. Uwsgi server is used to run a web server with the configuration provided in this repository here. You may want to change the setting ALLOWED_HOSTS in the settings before deploying the application in production. You can do that by adding a /opt/mailman/web/ which is imported by the Django when running.

  • Spin off a PostgreSQL database container which is used by both mailman-core and mailman-web as their primary database.

  • mailman-core mounts /opt/mailman/core from host OS at /opt/mailman in the container. Mailman's var directory is stored there so that it is accessible from the host operating system. Configuration for Mailman core is generated on every run from the environment variables provided. Extra configuration can also be provided at /opt/mailman/core/mailman-extra.cfg (on host), and will be added to generated configuration file. Mailman also needs another configuration file called mailman-hyperkitty.cfg and is also expected to be at /opt/mailman/core/ on the host OS.

  • mailman-web mounts /opt/mailman/web from the host OS to /opt/mailman-web-data in the container. It consists of the logs and file for Django.

  • database mounts /opt/mailman/database at /var/lib/postgresql/data so that PostgreSQL can persist its data even if the database containers are updated/changed/removed.

Setting up your MTA

The provided docker containers do not have an MTA in-built. You can either run your own MTA inside a container and have them relay emails to the mailman-core container or just install an MTA on the host and have them relay emails.


To use Exim4, it should be setup to relay emails from mailman-core and mailman-web. The mailman specific configuration is provided in the repository at core/assets/exim. There are three files

  • 25_mm3_macros to be placed at /etc/exim4/conf.d/main/25_mm3_macros in a typical Debian install of exim4. Please change MY_DOMAIN_NAME to the domain name that will be used to serve mailman. Multi-domain setups will be added later.

  • 455_mm3_router to be placed at /etc/exim4/conf.d/router/455_mm3_router in a typical Debian install of exim4.

  • 55_mm3_transport to be placed at /etc/exim4/conf.d/transport/55_mm3_transport in a typical Debian install of exim4.

Also, the default configuration inside the mailman-core image has the MTA set to Exim, but just for reference, it looks like this:

# mailman.cfg
incoming: mailman.mta.exim4.LMTP
outgoing: mailman.mta.deliver.deliver
lmtp_host: $MM_HOSTNAME
lmtp_port: 8024
smtp_host: $SMTP_HOST
smtp_port: $SMTP_PORT
configuration: python:mailman.config.exim4


To use Postfix, edit the configuration file, which is typically at /etc/postfix/ on Debian-based operating systems. Add mailman-core and mailman-web to mynetworks so it will relay emails from the containers and add the following configuration lines:


# Support the default VERP delimiter.
recipient_delimiter = +
unknown_local_recipient_reject_code = 550
owner_request_special = no

transport_maps =
local_recipient_maps =
relay_domains =

To configure Mailman to use Postfix, add MTA=postfix under mailman-core's environment section in the docker-compose.yaml:

    - MTA=postfix

This will auto-generate the configuration to talk to Postfix assuming that Postfix is available at the gateway address for the container's bridge network at port 25. The final configuration can be found by executing:

$ docker exec mailman-core cat /etc/mailman.cfg

The postfix configuration that is generated looks like this:

incoming: mailman.mta.postfix.LMTP
outgoing: mailman.mta.deliver.deliver
lmtp_host: $MM_HOSTNAME
lmtp_port: 8024
smtp_host: $SMTP_HOST
smtp_port: $SMTP_PORT
configuration: /etc/postfix-mailman.cfg

So, if you need to update the values, you can set SMTP_HOST, SMTP_PORT, MM_HOSTNAME environment variables in mailman-core container.

Please verify the output for [mta] section to ensure that it points to the right smtp_host (address to reach postfix from mailman-core container) and lmtp_host (address to reach mailman-core container from postfix).

The configuration file /etc/postfix-mailman.cfg is also generated automatically inside the mailman-core container and contains the configuration specific for Postfix.

Site Owner

Setup site owner address. By default, mailman is setup with the site_owner set to '[email protected]'. This should be pointing to a valid mailbox. Add the following to the '/opt/mailman/core/mailman-extra.cfg'.

# This address is the "site owner" address.  Certain messages which must be
# delivered to a human, but which can't be delivered to a list owner (e.g. a
# bounce from a list owner), will be sent to this address.  It should point to
# a human.
site_owner: [email protected]

Setting up search indexing

Hyperkitty in mailman-web image support full-text indexing. The current default indexing engine is Whoosh for historical reasons. It is highly recommended that you instead use Xapian for production use cases. The default will change when the next major version bump happens.

To configure your Mailman-web container to use Xapian, add the following to your

    'default': {
        'ENGINE': 'xapian_backend.XapianEngine',
        'PATH': "/opt/mailman-web-data/fulltext_index",

If you have been using the default search indexing engine, you might have to re-index emails using the following command:

$ docker-compose exec mailman-web ./ rebuild_index

This command can take some time if you a lot of emails, so please be patient!

Setting up your web server

It is advisable to run your Django (interfaced through WSGI server) through an actual webserver in production for better performance.

If you are using v0.1.0, the uwsgi server is configured to listen to requests at port 8000 using the HTTP protocol. Make sure that you preserve the HOST header when you proxy the requests from your Web Server. In Nginx you can do that by adding the following to your configuration:

    # Nginx configuration.
    location /static {
        alias /opt/mailman/web/static;
        autoindex off;

    location / {
          include uwsgi_params;
          uwsgi_read_timeout 300;
          proxy_set_header Host $host;
          proxy_set_header X-Forwarded-For $remote_addr;

Make sure you are using proxy_pass for the HTTP protocol.


Starting from v0.1.1, the uwsgi server is configured to listen to requests at port 8000 with the http protocol and port 8080 for the uwsgi protocol.

Please make sure that you are using port 8080 for uwsgi protocol.

It is advised to use the uwsgi protocol as it has better performance. Both Apache and Nginx have native support for the uwsgi protocol through plugins which are generally included in the distro packages.

To move to uwsgi protocol in the above nginx configuration use this

    # Nginx configuration.
    location /static {
        alias /opt/mailman/web/static;
        autoindex off;

    location / {
          uwsgi_pass localhost:8080;
          include uwsgi_params;
          uwsgi_read_timeout 300;

Please make sure that you are using v0.1.1 or greater if you use this configuration.

Serving static files

UWSGI by default doesn't serve static files so, when running mailman-web using the provided docker-compose.yaml file, you won't see any CSS or JS files being served.

To enable serving of static files using UWSGI, add the following environment variable to your docker-compose.yaml file under mailman-web:


It is recommended to use web-server to serve static files instead of UWSGI for better performance. You will have to add an alias rule in your web server to serve the static files. See here for instructions on how to configure your web server. The STATIC_ROOT for you would be /opt/mailman/web/static.

SSL certificates

SSL Certificates from Lets Encrypt need to be renewed every 90 days. You can setup a cron job to do the job. I have this small shell script ( that you can put up in /etc/cron.monthly to get the job done.

#! /bin/bash

cd /opt/letsencrypt/
./certbot-auto --config /etc/letsencrypt/renewal/MY_DOMAIN_NAME.conf certonly

if [ $? -ne 0 ]
        ERRORLOG=`tail /var/log/letsencrypt/letsencrypt.log`
        echo -e "The Let's Encrypt cert has not been renewed! \n \n" \
        nginx -s reload

exit 0

Please do not forget to make the script executable (chmod +x


This repository is licensed under the MIT License. Please see the LICENSE file for more details.