This is a community maintained fork that should allow for in-place upgrade from mailman2 on python2 to python3. This here is also another fork of this at https://github.com/cpanel/mailman2-python3 which you can/should also review.

This is being used in production today.

An installer for Ubuntu 26.04 (which should be translatable to other modern Linux systems) is available in the ‎doc/install-ubuntu/ directory.