Prepare to spend a whole day if you want a setup like this. And if you want web mail, you are only half done ... Then you would also want to make a script to reproduce it, in case you had to reinstall your server. I'm thinking there's a business opportunity here, to provide a maintained container, for e-mail in particular. But also to make linux "apps"/servers more modular.

I would also like to thank everyone who write tutorials like this for free.