Topic Last Modified: 2006-08-21

The Microsoft® Exchange Server Analyzer Tool includes a performance data collection engine that is used to query performance counter objects on computers that are running Exchange 2000 Server or Exchange Server 2003. The performance data collection engine collects data from the Cat: Categorizations in progress performance counter of the SMTP Server performance object to analyze performance data.

The Cat: Categorizations in progress performance counter shows the number of categorizations in progress.

For this query, the Exchange Server Analyzer retrieves a sample every 6 seconds for a two-minute period. The Exchange Server Analyzer reports the average value for the performance counter during the collection interval.

If the Exchange Server Analyzer determines that the average number of categorizations in progress over the sample period exceeds 800, the Exchange Server Analyzer displays an error.

The categorizer performs the following core operations:

This error may indicate that the server is experiencing an extraordinary load or has a performance related issue.

To resolve this error:

The message categorizer performance counters are published separately for each Simple Mail Transfer Protocol (SMTP) virtual server instance. For a list of the available performance counters related to the Message Categorizer, see Microsoft Knowledge Base article 231734, "XCON: Performance Monitor Counters for Message Categorizer" (