That is a pretty cool new capability on Exchange Server 2016 Preview, a new server can be added into an Exchange Server 2013 Organization and the current Exchange Server 2013 can proxy requests to the new servers. In the past, we had to move the new servers to receive all the requests, and then those new servers would proxy the requests for legacy servers.
To test the capability, let’s use the scenario below where we have one Exchange Server 2013 and one Exchange Server 2016, each one has a mailbox as shown in the image below.
The first test is to log on using Exchange Server 2013 OWA with a mailbox that is on Exchange Server 2013 (Number6), and there is no surprises there, just works.
Here is the interesting part, using the same URL that we used before (connecting to the Exchange Server 2013) and logging on with a mailbox that is hosted on Exchange Server 2016 Preview, we have the OWA experience of the new version.
In this Tutorial we went over the new capability that allows Exchange Server 2013 to proxy requests to new Exchange Server 2016 Preview servers.