I have two Exchange 2013 CU5 Standard servers in a DAG. Both servers have both the CAS and Mailboxes roles installed. The servers are running Server 2012 Standard. The DAG uses a file share witness server. The witness server and one Exchange server, which is usually the active server, are on the same subnet in our primary data centre. The second Exchange server is on a different subnet in our backup data centre across town.
The domain that these servers are in is part of a forest with another domain. That domain is, physically, in another jurisdiction. The domains share a namespace. All users in both domains have username at name.com as their e-mail address.
The other domain has two Exchange 2013 servers in a DAG. It also has one Exchange 2007 server, that is being phased out. All messages that my domain users send to external recipients pass though the Exchange servers in my domain, a firewall for my domain, an Internet connection, a firewall in the other domain, the Exchange servers in the other domain, the firewall for the other domain, and then out to the external recipients. The reverse path is followed for inbound mail from external senders.
All ActiveSync traffic for my users passes through the Exchange servers and a proxy server in the other domain. I have a self-signed SAN certificate on the Exchange servers in my domain. That certificate is also deployed on all of the mobile devices that my users have.
I have been asked to see if I can set things up so that a test user can send and receive e-mail with their mobile device, and have that traffic go from my Exchange servers, through the firewall for my domain, and out to external recipients. Due to a lack of test systems, I have been asked to develop this on my production servers, without disrupting the existing mail flow. Is that possible? What would need to be done to accomplish this? If the test is possible, and successful, my Exchange servers, and all other relevant systems, would be changed so that all mail traffic from my domain no longer goes through the other domain.