Upgrading Mailman 3

This includes the requirements to upgrade to Mailman 3 suite, which includes:

If you are interested in the full change log for each component, please refer to documentation of each project.


Python 3

Postorius, Django-mailman3 and Hyperkitty have been ported to Python 3 now. Generally the last few versions of Python and Django are supported but the supported versions keep on changing over time. Release announcements should have information about which vesions of Python are supported.

Migration Steps

Distro packages

If you are using distro packages, they should handle the upgrade process themselves. You may need to perform some changes after the upgrade is done, please check with the distro package’s documentation for those instructions.

Docker images

If you are using container images please refer to their documentation or release notes on steps to upgrade a new version.

Virtualenv Install

If you are following virtualenv installation guide from here, these are the steps to upgrade to a newer version of Mailman Core.


First, you need to stop the running Mailman services before the upgrade to make sure that you don’t endup in a bad state. You can stop the two systemd services, for Core and Mailman-Web:

$ sudo systemctl stop mailman3
$ sudo systemctl stop mailmanweb

Then you need to switch to mailman user, activate the virtualenv:

$ sudo su mailman
$ source /opt/mailman/venv/bin/activate

Upgrade package

Finally, upgrade your packages:

(venv) $ pip install -U mailman postorius django-mailman3 hyperkitty mailman-web


It is important to upgrade all the packages together since they depend on each other for critical functionality. There are no compatability guarantees with a new version of one package and an old version of another package.

We often update the minimum version required for a dependency in Packages’ metadata but that doesn’t always result in new versions being installed. There is also no direct dependency between django packages and mailman package, but they still expect the latest version of Mailman core.

Post upgrade

Post upgrade, you need to do a bunch of other tasks. First would be to make sure that your database schema is updated to handle the new versions:

(venv) $ mailman-web migrate

Then, make sure that all the static files, like stylesheets, javascript, images etc are copied to a single place. This is required to have the CSS and Javascript displayed correctly:

(venv) $ mailman-web compress
(venv) $ mailman-web collectstatic

Update your i18n translation caches to make sure that your installation can pickup any new changes to strings and their translations:

(venv) $ mailman-web compilemessages

Finally, you can re-start the services to bring up the Web Interface and Mailman Core:

$ sudo systemctl start mailman3
$ sudo systemctl start mailmanweb

Upgrade to 3.2.0

These are specific instructions to upgrade to Mailman Core 3.2.0 or 1.2.0 for mailman-web components (like, Postorius, Hyperkitty) from an older version.


Postorius added a new required configuration flag POSTORIUS_TEMPLATE_BASE_URL which should be set to URL that Postorius is expected to be listening at. You should set it to whatever URL your WSGI server is listening at.

Extra Migration Steps

  • Full text index for Hyperkitty needs to be re-built since our indexing engine doesn’t maintain compatibility between index created in Python 2 and Python 3.

    Simplest way to do this to run python manage.py rebuild_index in your Django project. Note that if your project has a huge number of lists, this will take a lot of time.

    A new command python manage.py update_index_one_list <listname@example.com> was added to Hyperkitty so that you can rebuild your index one-by-one, if you prefer that.

Upgrade from <3.3.1 to >=3.3.1

Mailman core 3.3.1 is the first release that actually processes bounces. Prior to this release, bounces were recorded in the bounceevent table in the database, but not processed. This leads to a situation where upgrading to core >=3.3.1 can cause many old, stale bounces to be processed resulting in disabling delivery to some list members who are not currently bouncing.

There are two ways to avoid this when upgrading. The preferred way is to enable VERP probes. Instead of immediately suspending delivery when a member’s bounce score reaches threshold, a probe message is sent to the member and delivery is suspended only if the probe bounces. This is done by putting:

verp_probes: yes

in mailman.cfg before upgrading.

The other way to avoid this is to set the processed flag on all the rows of the bounceevent table before upgrading with a query like:

UPDATE bounceevent SET processed = 1;