How do we explain email to an “expert”?
Horsepuckey.  Hosting your own data services is not dangerous, if you do your homework.  Email is not <i>that</i> complex  (compared to something like a federated Kerberos environment), and there are several good, concise, HOWTOs, books, etc on the subject.  Running your own stack makes you a first-class citizen of the &#x27;net, and more people should do it.