Topic Last Modified: 2005-11-18

The Microsoft® Exchange Server Analyzer Tool reads the data found in the LM/SmtpSvc/%SMTPInstance%/RoutingSources property in the Internet Information Services (IIS) metabase to determine the Message Categorizer state for each SMTP virtual server instance (VSI) on computers that are running Exchange 2000 Server or Exchange Server 2003.

The Exchange Server Analyzer determines whether the SMTPDSUseCat key exists in the IIS metabase and then reports the findings. If the Exchange Server Analyzer finds that the SMTPDSUseCat exists and is set to disabled, 0X000000, the Exchange Server Analyzer displays an error. If the Message Categorizer is disabled, the Exchange server experiences severe mail flow issues.

By default, when the SMTP service is installed on a computer that is running Microsoft Windows®°2000 Server or Microsoft Windows Server™ 2003, the SMTPDSUseCat key is created in the IIS metabase. By default, the SMTPDSUseCat key is disabled (0). When Exchange Server is installed, the SMTPDSUseCat IIS metabase key is removed. This enables the Message Categorizer. When the SMTP service or Exchange Server is installed on a computer that is running Windows 2000 Server or Windows Server 2003, a default (1) STMP VSI is created. The Message Categorizer may become disabled in situations in which Exchange Server is installed and the SMTP service uninstalled and then re-installed on the computer. The Message Categorizer may also be disabled when third party software is installed or an administrative configuration error occurs.

Each SMTP virtual server instance on the Exchange server has independent control of the Message Categorizer state.

The Message Categorizer examines every message that come into each SMTP VSI and determines the options. The messages may be destined for the local store, a remote host through the message transfer agent (MTA), or a remote host by through SMTP. The Message Categorizer also handles Distribution List (DL) expansion. The Message Categorizer examines messages that come to an SMTP server and determines what to do with the messages. The Message Categorizer is a plug-in to the advanced queuing engine that performs Lightweight Directory Access Protocol (LDAP) queries against global catalog servers on TCP port 3268. The Message Categorizer is essentially a collection of event sinks that perform advanced address resolution on every message that travels through the advanced queuing engine.

The SMTP Reinstall Tool (Smtpreinstall.exe) is located on the Exchange 2000 Server SP2 CD-ROM in the \SUPPORT\UTILS\I386 folder.
To enable the Message Categorizer by using the SMTP Reinstall Tool
  1. Copy Smtpreinstall.exe to the \Exchsrvr\Bin folder.

  2. Double-click Smtpreinstall.exe from the \Exchsrvr\Bin folder.

  3. Click OK in the Microsoft Exchange SMTP Reinstall dialog box to restart the Exchange server.

If you have to view the properties in the IIS metabase, you can do so by installing the Metaedit 2.2 utility for IIS 4.0/5.0 or the IIS Metabase Explorer utility on IIS 6.0.

Directly editing the metabase is not a recommended practice.

For more information about the message categorizer or available IIS metabase utilities, see the following Microsoft Knowledge Base articles:

To download IIS 6.0 Resource Kit Tools, see Internet Information Services (IIS) 6.0 Resource Kit Tools (