Topic Last Modified: 2005-11-18

The Microsoft® Exchange Server Analyzer Tool reads a series of registry keys to determine the level of message transfer agent (MTA) diagnostic logging set on the Exchange server. The registry keys reside at:


The default value for these keys is 0. If the Exchange Server Analyzer finds the value of any of these keys to be more than 1 but less than 6, a non-default configuration message is displayed.

These registry keys are set by Exchange System Manager when you tune the logging levels on the Diagnostic Logging tab of a specified server's property page. Exchange System Manager allows an administrator to set a specified logging level to None, Minimum, Medium, and Maximum. The corresponding values of the registry keys, respectively, are 0, 1, 3, or 5.

The following table shows the MTA logging categories as they are listed on the Diagnostic Logging tab in Exchange System Manager and their corresponding key names in the registry.

Category as displayed in Exchange System Manager Corresponding registry key name

X.400 Service

1 X.400 Service


2 Resource


3 Security


4 Interface

Field Engineering

5 Field Engineering

MTA Administration

6 MTA Administration


7 Configuration

Directory Access

8 Directory Access

Operating System

9 Operating System

Internal Processing

10 Internal Processing


11 Interoperability

APDU (Application Protocol Data Unit)


The reference at the end of this article provides more information about what each MTA category logs.

The general best practice for diagnostic logging is to set the logging for each MTA category at None (0) unless you are actively troubleshooting. The reason for this recommendation is to maintain a manageable number of events being logged. Even a level of Minimum (1) will likely produce hundreds of event logs over the course of a few days, depending on the category where the level is set.

If you are not currently troubleshooting, it is likely that these values were set higher during a troubleshooting exercise and were unintentionally left set. Consider setting the logging level to None (0) for each MTA diagnostic logging category.

To correct this error on Exchange Server 2003 or Exchange 2000 Server

  1. Open Exchange System Manager.

  2. In the console tree, expand Servers, expand the server that you want, and then click Properties.

  3. In <Server> Properties, click the Diagnostic Logging tab.

  4. Under Services, select MSExchangeMTA.

  5. For each entry under Categories, set the logging level to none by selecting the category and then selecting None under Logging level.

  6. When you have set all categories to None, click Apply, and then click OK.

To correct this error on Exchange Server version 5.5

  1. Start the Microsoft Exchange Server Administrator program.

  2. Open the object that represents the server that is having difficulties with the MTA.

  3. Double-click the Message Transfer Agent object in the right pane.

  4. On the Diagnostics Logging tab, select the X.400 Service, and then click Maximum.

  5. Select Resource.

  6. Hold down the CTRL key, and then click each resource you want to debug.

  7. Click Option for a logging level of None.

  8. Click OK.

For more information about MTA diagnostic logging on Exchange 2000 Server, see the Microsoft Knowledge Base article 163033, "XCON: Description of Diagnostics Categories for MTA" (

For more information about rolling back advanced logging on Exchange Server 5.5, see the Knowledge Base article 168906, "XCON: Setting up Advanced Logging on the Exchange 5.0 and 5.5 MTAs" (

For more information about MTA diagnostic logging on Exchange Server 5.5, see the Knowledge Base article 163032, "XCON: Description of Diagnostics Categories for MTA" (