Messages are queued, and message delivery is delayed in an Exchange 2000 Server organization

After you apply hotfix 826948, you may experience the following symptoms in a Microsoft Exchange 2000 Server organization:

• Messages are queued in the Messages with an unreachable destination queue.
• Messages are queued in other queues. Additionally, message delivery is delayed.

Additionally, the following event is logged in the Application event log:

Event ID : 4000
Category : Connection Manager
Source : MSExchangeTransport
Type : Warning
Description : Message delivery to the remote domain "XXXXXX" failed for the following reason:

Note "XXXXXX" is an alphanumeric string that varies depending on the name of the remote routing group. The reason for the message delivery failure is not logged.

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, submit a request to Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

Prerequisites

No prerequisites are required to apply the hotfix.

Restart requirement

You do not have to restart the computer after you apply the hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfixes.

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

This problem may occur when the following conditions are true:

• The servers that are running Exchange 2000 Server have version 6.0.6516 or a later version of the phatq.dll file installed.
• The Exchange 2000 Server servers are deployed in a complex mesh topology.
• The Exchange 2000 Server servers are connected by using site connectors.

In this scenario, the link state is frequently disrupted. Frequent disruption causes unnecessary message rerouting and delayed message delivery.