XADM: A Backlog Occurs in the SMTP Remote Delivery Queues Because of Waiting Threads in Message Tracking

In Exchange 2000 Server, messages may build up in the Simple Mail Transfer Protocol (SMTP) remote queues for many hours. During this time, the server performs as it typically does and does not experience any unexpected load. The SMTP remote queues build up for some time, and then suddenly start flushing out the mail.

After the SMTP remote queue is clear, it starts to build up again for many hours. All message flow on the servers in the site may be delayed, and messages may take many hours to be delivered.

This issue may occur if Exchange 2000 servers are running in a mixed mode organization and one or more of following error messages are repeated in the Application event log: The event ID 9153 and 8213 error messages indicate that the system attendant service is trying to create a Messaging Application Programming Interface (MAPI) session with the Microsoft Exchange Server version 5.5 computer. The thread in the system attendant that is trying to create the MAPI session is waiting on a Microsoft Windows NT Security Identifier (SID) lookup for the Microsoft Windows NT 4.0 service account.

In some cases, this SID lookup may take a long time to resolve. Because of this, the threads in the system attendant that are responsible for the message tracking remote procedure call (RPC) calls do not respond quickly.

For additional information about how to resolve the event ID 9153 and 8213 error messages, click the article number below to view the article in the Microsoft Knowledge Base:

The event ID 9153 and 8213 error messages in the Application event log may indicate that a security problem exists in the administrative group in which the Exchange 2000 server exists.

To resolve this issue:

• If no Exchange Server 5.5 computer exists in your organization, convert your organization from mixed mode to native mode.For additional information about how to convert an organization from mixed mode to native mode, click the article number below to view the article in the Microsoft Knowledge Base:
  270143� XADM: Mixed Mode vs. Native Mode
• If your Exchange 2000 servers are in a mixed mode organization, use the procedures in Microsoft Knowledge Base articles Q296151 to resolve this issue.For additional information, click the article number below to view the article in the Microsoft Knowledge Base:
  296151� XADM: Event 8213 Appears in Exchange 2000 Server Event Viewer

To work around this issue, disable message tracking on the server.

In the current architecture, the system attendant uses a single critical section that is required for each message tracking entry. This may cause a queue backlog in the SMTP remote queue because Exchange 2000 cannot move these messages without completing the message tracking information.