I've been running my own mail server with https://mailinabox.email for ~2 years and can heartily recommend it.
Still, even with that there are gotchas if you want to be able to send messages from your server to Google et al, eg. reverse-DNS-records, DKIM, SPF.
Not for the pressed-for-time.
The integration with Let's Encrypt and a relatively smooth upgrade process has made it one of the more enjoyable services I manage. I would highly recommend it.
I also have no trouble sending email to Gmail users after carefully following all the steps in the manual! The only sticky point I had was that it required fancy DNS records that Namecheap doesn't support -- I think if I were doing it all over again I'd transfer domains over to a better nameserver.
It's fantastic.
Can't configure post-install? At all? This seems like it would be a showstopper for some.