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Installing mailcow and Mailman 3 based on dockerized versions


This guide is a copy from dockerized-mailcow-mailman. Please post issues, questions and improvements in the issue tracker there.


mailcow is not responsible for any data loss, hardware damage or broken keyboards. This guide comes without any warranty. Make backups before starting, 'coze: No backup no pity!


This guide aims to install and configure mailcow-dockerized with docker-mailman and to provide some useful scripts. An essential condition is, to preserve mailcow and Mailman in their own installations for independent updates.

There are some guides and projects on the internet, but they are not up to date and/or incomplete in documentation or configuration. This guide is based on the work of:

After finishing this guide, mailcow-dockerized and docker-mailman will run and Apache as a reverse proxy will serve the web frontends.

The operating system used is an Ubuntu 20.04 LTS.


This guide is based on different steps:

  1. DNS setup
  2. Install Apache as a reverse proxy
  3. Obtain SSL certificates with Let's Encrypt
  4. Install mailcow with Mailman integration
  5. Install Mailman
  6. ๐Ÿƒ Run

DNS setup

Most of the configuration is covered by mailcows DNS setup. After finishing this setup add another subdomain for Mailman, e.g. that points to the same server:

# Name    Type       Value
lists     IN A
lists     IN AAAA    dead:beef

Install Apache as a reverse proxy

Install Apache, e.g. with this guide from Digital Ocean: How To Install the Apache Web Server on Ubuntu 20.04.

Activate certain Apache modules (as root or sudo):

a2enmod rewrite proxy proxy_http headers ssl wsgi proxy_uwsgi http2

Maybe you have to install further packages to get these modules. This PPA by Ondล™ej Surรฝ may help you.

vHost configuration

Copy the mailcow.conf and the mailman.conf in the Apache conf folder sites-available (e.g. under /etc/apache2/sites-available).

Change in mailcow.conf: - MAILCOW_HOSTNAME to your MAILCOW_HOSTNAME

Change in mailman.conf: - MAILMAN_DOMAIN to your Mailman domain (e.g.

Don't activate the configuration, as the ssl certificates and directories are missing yet.

Obtain SSL certificates with Let's Encrypt

Check if your DNS config is available over the internet and points to the right IP addresses, e.g. with MXToolBox:

Install certbot (as root or sudo):

apt install certbot

Get the desired certificates (as root or sudo):

certbot certonly -d MAILCOW_HOSTNAME
certbot certonly -d MAILMAN_DOMAIN

Install mailcow with Mailman integration

Install mailcow

Follow the mailcow installation. Omit step 5 and do not pull and start!

Configure mailcow

This is also Step 4 in the official mailcow installation (nano mailcow.conf). So change to your needs and alter the following variables:

HTTP_PORT=18080            # don't use 8080 as mailman needs it
HTTP_BIND=        #
HTTPS_PORT=18443           # you may use 8443
HTTPS_BIND=       #

SKIP_LETS_ENCRYPT=y        # reverse proxy will do the SSL termination

SNAT_TO_SOURCE=     # change this to your IPv4
SNAT6_TO_SOURCE=dead:beef  # change this to your global IPv6

Add Mailman integration

Create the file /opt/mailcow-dockerized/docker-compose.override.yml (e.g. with nano) and add the following lines:

      - /opt/mailman:/opt/mailman
      - docker-mailman_mailman

    external: true
The additional volume is used by Mailman to generate additional config files for mailcow postfix. The external network is build and used by Mailman. mailcow needs it to deliver incoming list mails to Mailman.

Create the file /opt/mailcow-dockerized/data/conf/postfix/ (e.g. with nano) and add the following lines:

# mailman

recipient_delimiter = +
unknown_local_recipient_reject_code = 550
owner_request_special = no

local_recipient_maps =
virtual_mailbox_maps =
transport_maps =
relay_domains =
relay_recipient_maps =
As we overwrite mailcow postfix configuration here, this step may break your normal mail transports. Check the original configuration files if anything changed.

SSL certificates

As we proxying mailcow, we need to copy the SSL certificates into the mailcow file structure. This task will do the script for us:

  • Copy the file to /opt/mailcow-dockerized
  • Change mailcow_HOSTNAME to your mailcow hostname
  • Make it executable (chmod a+x
  • Do not run it yet, as we first need Mailman

You have to create a cronjob, so that new certificates will be copied. Execute as root or sudo:

crontab -e

To run the script every day at 5am, add:

0   5  *   *   *     /opt/mailcow-dockerized/

Install Mailman

Basicly follow the instructions at docker-mailman. As they are a lot, here is in a nuthshell what to do:

As root or sudo:

cd /opt
mkdir -p mailman/core
mkdir -p mailman/web
git clone
cd docker-mailman

Configure Mailman

Create a long key for Hyperkitty, e.g. with the linux command cat /dev/urandom | tr -dc a-zA-Z0-9 | head -c30; echo. Save this key for a moment as HYPERKITTY_KEY.

Create a long password for the database, e.g. with the linux command cat /dev/urandom | tr -dc a-zA-Z0-9 | head -c30; echo. Save this password for a moment as DBPASS.

Create a long key for Django, e.g. with the linux command cat /dev/urandom | tr -dc a-zA-Z0-9 | head -c30; echo. Save this key for a moment as DJANGO_KEY.

Create the file /opt/docker-mailman/docker compose.override.yaml and replace HYPERKITTY_KEY, DBPASS and DJANGO_KEY with the generated values:

    - DATABASE_URL=postgresql://mailman:DBPASS@database/mailmandb
    - TZ=Europe/Berlin
    - MTA=postfix
    restart: always
      - mailman

    - DATABASE_URL=postgresql://mailman:DBPASS@database/mailmandb
    - TZ=Europe/Berlin
    - MAILMAN_ADMIN_USER=admin # the admin user
    - # the admin mail address
    - UWSGI_STATIC_MAP=/static=/opt/mailman-web-data/static
    restart: always

    restart: always

At mailman-web fill in correct values for SERVE_FROM_DOMAIN (e.g., MAILMAN_ADMIN_USER and MAILMAN_ADMIN_EMAIL. You need the admin credentials to log into the web interface (Postorius). For setting the password for the first time use the Forgot password function in the web interface.

About other configuration options read Mailman-web and Mailman-core documentation.

Configure Mailman core and Mailman web

Create the file /opt/mailman/core/mailman-extra.cfg with the following content. should be pointing to a valid mail box or redirection.

default_language: de

Create the file /opt/mailman/web/ with the following content. should be pointing to a valid mail box or redirection.

# locale

# disable social authentication

# change it

DEBUG = False
You can change LANGUAGE_CODE and SOCIALACCOUNT_PROVIDERS to your needs.

๐Ÿƒ Run

Run (as root or sudo)

a2ensite mailcow.conf
a2ensite mailman.conf
systemctl restart apache2

cd /opt/docker-mailman
docker compose pull
docker compose up -d

cd /opt/mailcow-dockerized/
docker compose pull
a2ensite mailcow.conf
a2ensite mailman.conf
systemctl restart apache2

cd /opt/docker-mailman
docker-compose pull
docker-compose up -d

cd /opt/mailcow-dockerized/
docker-compose pull

Wait a few minutes! The containers have to create there databases and config files. This can last up to 1 minute and more.


New lists aren't recognized by postfix instantly

When you create a new list and try to immediately send an e-mail, postfix responses with User doesn't exist, because postfix won't deliver it to Mailman yet. The configuration at /opt/mailman/core/var/data/postfix_lmtp is not instantly updated. If you need the list instantly, restart postifx manually:

cd /opt/mailcow-dockerized
docker compose restart postfix-mailcow
cd /opt/mailcow-dockerized
docker-compose restart postfix-mailcow


mailcow has it's own update script in /opt/mailcow-dockerized/, see the docs.

For Mailman just fetch the newest version from the github repository.


mailcow has an own backup script. Read the docs for further informations.

Mailman won't state backup instructions in the In the gitbucket of pgollor is a script that may be helpful.


install script

Write a script like in mailman-mailcow-integration/ as many of the steps are automatable.

  1. Ask for all the configuration variables and create passwords and keys.
  2. Do a (semi-)automatic installation.
  3. Have fun!