Updated 22 Jan 2019:
In order to foster open community knowledge and growth, I’ve moved the values to being listed in GitHub, here.
You’re more than welcome to make a pull-request, in order to keep the list up-to-date, should you find any new values in the wild.
NOTE: This post – drafted, composed, written, and published by me – originally appeared on https://blogs.technet.microsoft.com/johnbai and is potentially (c) Microsoft.
Now maintained here: http://www.iseelondoniseefrance.se/2018/08/01/how-msexchrecipientdisplaytype-and-msexchangerecipienttypedetails-relate-to-your-on-premises/