I agree about the two paths and I share a preference for the non-vendor one. Yet at the very least I need an OS that out of the box accepts say an email user@or

I agree about the two paths and I share a preference for the non-vendor one. Yet at the very least I need an OS that out of the box accepts say an email user@org.tld as username and automatically contacts org‘s directory to check for authorisation and pull email credentials at the very least. This seems so basic to me that it should exist outside of commercial solutions.