Many moons ago I needed a simple and free ISP control like tool. Most of the options were either paid or crap. But then there was ISPConfig. Nothing fancy, but it did all the options I would expect, in a nice web interface.
After some time I switched to my home grown puppet and ansible code over the years to manage webhosting clients instead of using a control panel. And that worked well for the websites I manage.
But now I need self hosted mail again. As I need to move a domain from the free G-suite plan that will become extinct soon, I figured using ISPConfig would do the job nicely to manage mailboxes and some mailinglists. And after revisiting ISPConfig after some years, it now comes with a mostly automated installer to configure every aspect of the mail/web hosting.
So setting up the hosting server in Hetzner including the ISPConfig setup was done within the hour. Nice!