@eggerts2k     It may have been an old post but THANKS for the note regarding the .Net 3.5 installation.  I spend 4 hrs trying to figure out why I was having this problem after enabling mail on a 2012 server I inherited.  I saw your note and checked the installed features. Net4.0 was installed but 3.5 was not.  5 minutes later 3.5 was installed and the problem was resolved.