…but I want to avoid Discord, too…

There’s docker-mailserver which runs the entire stack in one container.

Pedantic side-note: you don’t run “a docker”. You run a container, and you happen to use docker to do so. Just like you don’t send someone an Outlook or Chrome their website. Docker is just a way of running OCI containers, not the whole tech.

…this truly is the weirdest timeline.