Earlier quoted context omitted.
> Email is one of the bastions of the decentralised Internet and we should hang on to it. This. I hope someone will eventually create an "E-mail server in a box" package for Ubuntu LTS, so that more people can run their own E-mail. I'm not saying it has to be super-easy for everyone, just that it should avoid unnecessary chore work (like configuring postfix to always use TLS, or plugging postgrey into postfix).
As long as you know Docker, this is pretty much what you are asking: https://github.com/tomav/docker-mailserver . I use it in combination with the rainloop webmail client: https://github.com/jprjr/docker-rainloop . Everything is configured with a single docker-compose, read about it here: https://news.ycombinator.com/item?id=11748036
It has a decent web admin panel built-in to the box and also a copy of RoundCube Webmail. It'll even automatically set-up LetsEncrypt SSL for you.
You might want to set-up rainloop manually though because RoundCube isn't the best.