Mihai Moldovan writes:
But, all this said, mailman-web is typically already a wrapper calling su -s /bin/bash -c "python3 .../path/to/manage.py $*" www-data, so why should it be wrapped in another wrapper with a different user? The list user is typically used by the mailman-wrapper wrapper.
This isn't "typical" nowadays, except for .deb installations as far as I know. IIRC modern .rpm distros use our Python scripts for the 'mailman' and 'mailmanweb' commands, and we recommend using the same user for mailman and mailman-web services (we call it 'mailman' but of course 'list' will do if you already have one), because there's normally no reason www-data should need filesystem access to Mailman data and vice-versa.
For best support, you'll find that assuming we are only vaguely aware of what your startup scripts and utility tools look like is helpful. When we ask you to run a simple test, it's probably a good idea to run it even if you're pretty sure what the outcome is. Then you can say, "the outcome was X, which is what I expected because Y". You lose a minute or two, and we learn something about your system (X and Y). Otherwise you lose hours or days of calendar time if you say "no point, because Y" and we reply, "please run it anyway" and something you didn't expect happens.
-- GNU Mailman consultant (installation, migration, customization) Sirus Open Source https://www.siriusopensource.com/ Software systems consulting in Europe, North America, and Japan