GNU Mailman project uses Weblate for translations. If you are interested to port Mailman to various languages, please head over to Weblate and create an account to get started with translations.

Weblate has very good documentation on how to use it:

Please do not create Merge Requests for translations since it can create merge conflicts when pulling changes from Weblate and break automation which pulls and pushes changes between Gitlab and Weblate.

If you have existing translated .po files, you can reach out to

Integration with Weblate

Integration with source control in Gitlab and translation project in Weblate works using webhooks and some scripts.

Weblate supports webhooks for notifications when there are changes to the source control. This allows pulling changes to source strings from Gitlab by adding a webhook notification in Gitlab.

Although Weblate also supports pushing the translations back to the source control routinely, this hasn’t been enabled yet as it would require giving out push access to the main repository to a 3rd party service.

Mailman maintainers run a routine script that runs every day to pull changes from Weblate and create Merge Request on the respective projects.