Thanks for the advice.
I only run into a problem with the Exchange Autodiscover.
That does not want to work.
Since I played to mush with the live environment now, i’ll create a test one to test the Exchange Autodiscover.
And see how that works out.
Since the Autodiscover protocol works with multiple steps and weird ways.
Maybe someone knows? And how to get this working with Caddy.
Except Outlook does not agree with auto discover (Windows and Mac)
Everything else works fine even iPhone 
with Autodiscover of settings.