Yes, this thread is from over a year ago on a different topic … please in the future create a new thread. @Adam1
example.com is your domain … box.domain.com will be the hostname for the server running MiaB. The install scripts take care of everything needed automatically. If you have no website at box.example.com, that is fine … if you only want to use email addresses in the format of user@box.example.com that also is fine, create the initial email address in that format - but beware if you do there is an issue with the install script where when you are prompted for the hostname it will autofill it as box.box.example.com … please be sure that you use box.example.com.