For the guidelines and more information about the effects of assigning static ports of Exchange services, see the following article in the Microsoft Knowledge Base:
Article-ID: Q180795 Title: XADM: Intrasite Directory Replication Fails with Error 1720
For more information about Exchange services for Internet firewalls, see the following article in the Microsoft Knowledge Base:
Article-ID: Q155831 Title: XCLN: How to Force Static Mapping of Sockets