The Microsoft Exchange Dynamic RAS Connector doesn't deliver mail over NetBEUI because by default, the MTA (Message Transfer Agent) only supports TCP/IP, IPXSPX and Banyan Vines IP.
To enable NetBEUI over DRAS, use Regedt32, on both computers, to navigate to:
Double-click the RPC_SVR_BINDING_ORDER value and add NCACN_NB_NB.
Stop and re-start the MSExchangeMTA service.
The data in RPC_SVR_BINDING_ORDER is read serially, so it is important that the sequence is the same on both computers.
If NCACN_NB_NB is first, the MTA will attempt to use NetBEUI first. If both TCP/IP and NetBEUI are present, and TCP/IP is first, TCP/IP will be used.
Do not use NetBEUI as the only protocol with DRAS, as it is likely to cause delays with modem disconnect. Use TCP/IP also.
NOTE: DRAS ignores dialing prefix and suffix in the Phone Book. Add any required prefix or suffix to the phone number.