Exchange, Firewalls, and Support… Oh, my!
Over the years Exchange Server architecture has gone through a number of changes. As a product matures over time you may see us change what is supported as we react to changes in the product architecture, the state of technology as a whole, or major support issues we see come in through our support infrastructure.
Over the years a large volume of support calls have ended up being caused by communication issues between Exchange servers or between Exchange servers and domain controllers. Often times this results from a network device between the servers not allowing some port or protocol to communicate to the other servers.