Hello,
Good question!
There are a lot of Q and A about NS as Email Server but no such guide.
Probably because are many scenarios to use NS as Email Server:
- NS as dedicated Email Server placed in DMZ
- NS as AiO
- NS as DC with Email Server function
- NS as Email Server for multiple domains
and the list can continue.
After that, what Groupware can be used: SOGo, WebTop, Roundcube.
I think many of us can share their own experience regarding emailserver setup.