XCON: Message Transfer Agent Uses Node IP Address Instead of Cluster IP Address

When you have two Exchange Server computers in two sites that are connected with a site connector through a firewall as follows: If the firewall between the sites opens only to the Cluster Server IP address, no mail can be sent or received.

This issue can occur if the message transfer agent (MTA) uses the active node IP address instead of the Exchange Server Cluster Server group IP address to initiate a connection.

To resolve this problem, obtain the latest service pack for Exchange Server 5.5. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

To work around this issue:

• Move to an X.400 Connector and fix the address.For additional information, click the article number below to view the article in the Microsoft Knowledge Base:
  197378  (http://support.microsoft.com/kb/197378/EN-US/ ) XCON: MTA Generates 9301 Events on Incoming Connections
• Open the IP addresses of the nodes in the firewall.

Microsoft has confirmed that this is a problem in Microsoft Exchange Server version 5.5 Service Pack 3. This problem was first corrected in Exchange Server 5.5 Service Pack 4.