Topic Last Modified: 2005-11-18

The Microsoft® Exchange Server Analyzer Tool queries the Active Directory® directory service to determine the value for the msExchAlternateServer attribute of each Simple Mail Transfer Protocol (SMTP) virtual server. By default, the msExchAlternateServer attribute value is not set. If the Exchange Server Analyzer finds that the msExchAlternateServer attribute has been set, the Exchange Server Analyzer displays a non-default configuration message.

You would set the msExchAlternateServer attribute in the following example scenario. You share an SMTP address space, such as an SMTP domain, between Exchange Server 2003 and another e-mail system. In this scenario, Exchange Server 2003 accepts incoming mail from the Internet. Exchange Server 2003 looks for a matching recipient in the Exchange Server organization. If a match is not found, Exchange Server forwards the mail to the foreign mail system. The receiving system also may look for a match. If a match is not found, it may forward the mail to a third e-mail system. The final system in the chain must be authoritative for the domain. The final receiving system must look for a matching recipient. If a matching recipient is not found, a non-delivery report (NDR) must be generated for the message. If a receiving system looks for a match and then forwards the message back to the original system when a match is not found, looping messages occur.

To change the msExchAlternateServer attribute
  1. In Exchange System Manager, expand Servers, expand <Server Name>, expand Protocols, and then expand SMTP.

  2. Right-click your SMTP virtual server, and then click Properties.

  3. In the SMTP virtual server's Properties, click the Messages tab.

  4. In the Forward all messages with unresolved recipients to host box, type the FQDN of the server that will receive the unresolved mail. You may also enter the IP address of the server in square brackets ([ ]).

  5. Click OK.

For more information about sharing SMTP address spaces, see Microsoft Knowledge Base article 321721, "Sharing SMTP address spaces in Exchange 2000 Server and Exchange Server 2003" (

For more information about deployment scenarios for Internet connectivity, see "Deployment Scenarios for Internet Connectivity" in the Exchange Server 2003 Transport and Routing Guide (