Exchange 2016 coexistance Ex2010 multi tennant

Question

We have an exchange 2010 6 server dag, 3 cas and 3 mbx with multiple clients on it and its being upgrade to 2016 3 server dag cas/mbx but I need to move 1 client at a time to 2016, so if we have org1, org2 and org3 and I move org1 to the 2016 system and update all dns to point to the new servers, I am assuming we need to put a legacy connector in so that when people still on exchange 2010 (org2 and org3) can access there mailboxes from OWA, outlook, active sync etc

My question is does anyone know of any documentation on the this legacy connector ? I have seen it on other systems but cannot find any documentation on how it is done.

Thanks in advance

Answer 1

What does the "legacy connector" refer to? Do you mean the receive and send connectors?
In the coexistence environment, we don't have to create additionally connectors. The mail flow works with default connectors. If needed, you just have to create new send connectors on Exchange 2016, and remove them from Exchange 2010.

Based on your description, you may worry about the client connectivity. When Exchange 2010 coexists with Exchange 2016, if you use the same FQDN for virtual directory URLs, and point to Exchange 2016, Exchange 2016 can proxy the request to Exchange 2010 CAS server for mailboxes on Exchange 2010.

Additionally, for Exchange 2010 mailboxes, internal Outlook clients using RPC/TCP connectivity, and it no longer exists for Exchange 2016 mailboxes. Exchange 2016 mailboxes use Outlook Anywhere (RPC/HTTP) or MAPI/HTTP for Outlook client side. If you have CAS array, Exchange 2010 mailboxes still connect to the CAS array endpoint, and make sure the FQDN used for CAS array points is not the same for URLs on Exchange 2016.

You can check these for more details about the client connectivity: Client Connectivity in an Exchange 2016 Coexistence Environment with Exchange 2010.