Please forgive any wrong terminology. I'm hope it's still clear what I'm looking for.
I would like to install an email server and UI to my public web platform that offers a number of open source alternatives to common web apps.
since this will be public and I'm not that strong with CLI, it's important to me that the email platform has extensive GUI admin features and spam control. Strong emphasis on outgoing spam control and statistics monitoring
It's also important to me that the platform is completely open source and copyleft. Not because I don't want to pay, but because I don't believe in copyright and want others to be able to install the same platform if they chose to.
Another requirement would be to allow other organizations to administrate their own domains through my installation with dedicated admins that only have control over their domain.
I've been looking at:
Mail-in-a-box: seems to have a lot of fans, but also sounds like it's more basic in features. Also I can't find any online Demo.
Horde5 groupware: Seems like a nice suite, but also looks quite outdated. By playing with the online Demo I can't really tell how good the admin GUI is.
Iredmail: Is very easy to set up and would be fine for personal use. But the GUI of the basic version is missing a lot of necessary admin options and the pro version is copyrighted, so it's not an option
ISPconfig: Seems to be a good option and I would like to have virtual hosting and email in one. But support seems to be limited
Modoboa: Looks like a good allaround solution, but support is very expensive.
Mailcow: looks good and has an online demo. I like the support options, but it seems to be less popular than others.
So the question here is for those running their own small / mid sized email service provider. What completely open source stack do you recommend?
I'm feeling partial to Mailcow or ISPConfig, but accept any warnings you may have
I'm also open to recommendations that aren't on my list here.