Topic Last Modified: 2005-11-18

The Microsoft® Exchange Server Analyzer Tool reads the following registry entry to determine whether the default LdapResultTimeout has been changed:


If the Exchange Server Analyzer finds that the LdapResultTimeout registry key has been manually created, changing the default Exchange server binary setting of 121 seconds, the Exchange Server Analyzer displays a non-default warning message. By default, the LdapResultTimeout registry key is not created by an Exchange Server installation. However, the LdapResultTimeout registry key can be manually created after the Exchange Server installation in order to change the time-out value. LdapResultTimeout is the maximum time in seconds that the LDAP completion threads, for categorizer’s LDAP connections, waits for processing. If the time-out expires and no new results have been received from a global catalog server, the pending searches fails on the connection with LDAP_SERVER_DOWN. This process then enables those pending searches to be reissued to new connections. If the registry value is manually created and the setting for the registry value is configured incorrectly, the Exchange server may experience message transport problems.

It is recommended that the LdapResultTimeout registry value be created or modified only after serious consideration. The default values in the binaries for Exchange Server were carefully selected for optimal performance for use in most Exchange Server environments. A general best practice is to address the root cause of the problem instead of modifying the default behavior of Exchange by manually configuring the registry. To comply with best practices, if the LdapResultTimeout registry value exists, you may want to delete this registry value to configure the Exchange server back to the default binary setting.

The Exchange Server Analyzer reports this configuration for informational purposes only. However, you may want to change the registry value back to the default setting by editing the registry.

This article contains information about editing the registry. Before you edit the registry, make sure you understand how to restore it if a problem occurs. For information about how to do this, view the "Restore the Registry" Help topic in Regedit.exe or Regedt32.exe.
To correct this warning
  1. Click Start, click Run, type Regedit, and then click OK.

  2. In the console tree locate and then click the following registry key: HKEY_LOCAL_MACHINE System\CurrentControlSet\Services\SMTPSvc\Parameters

  3. In the details pane right-click the LdapResultTimeout registry value. Change value data to 121.

  4. Optionally, in the details pane you can right-click the LdapResultTimeout registry value and then click Delete. Confirm the deletion of the registry value by clicking Yes in the dialog box.

  5. Restart the Exchange server.

Before you edit the registry, and for information about how to edit the registry, see Microsoft Knowledge Base article 256986, "Description of the Microsoft Windows registry" (

For more information about editing the Microsoft Windows registry see the following Microsoft Knowledge Base articles: