We have one front-end Exchange 2000 Server system and one back-end Exchange 2000 system. Before we upgraded to Service Pack 2 (SP2), our Messaging API (MAPI) clients could resolve names in their profiles against the front-end server. Now they can't. Is this change intentional?
In Exchange 2000 and Exchange 2000 SP1, the DSProxy service runs on front-end servers. Among other duties, DSProxy implements the Name Service Provider Interface (NSPI) that MAPI clients use to make name-resolution requests. With NSPI running, your front-end servers could correctly resolve a client's mailbox server name. However, front-end servers aren't supposed to talk to MAPI clients, so SP2 turns off the DSProxy service—along with the Mailbox Manager, the Internet Free/Busy service, and the Recipient Update Service (RUS)—on these servers. However, if you need to keep DSProxy running, you can add a new REG_DWORD value named Enable DSProxy Service under the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeSA\Parameters registry subkey. Set Enable DSProxy Service's value to 1, then stop and restart the Exchange System Attendant.