Most of the world uses (still) majordomo as ML manager.

Quite some time ago I stumbled across Sympa (https://www.sympa.org) and it convinced me enough to migrate from majordomo to Sympa. It scales for large ML installations - even the Unesco is using it https://www.sympa.org/users/custom.

I think it could make a worthy addition to the phalanx of TKL appliances.

There is a lot of documentation, ongoing development and a vibrant community, so I believe that's also the right horse to bet on. https://sympa-community.github.io/manual/customize/friendly-automatic-lists.html