Exchange 5.5 SP3 Mailbox Manager conflicts with Site Server's LDAP Service

When you open Mailbox Manager properties and click the Server Selections tab, the following error message may be displayed:

This behavior can occur if Microsoft Site Server is installed on the computer from the Microsoft Windows NT Option Pack. Site Server installs the Microsoft Lightweight Directory Access Protocol (LDAP) service and causes a conflict with Mailbox Manager, which uses LDAP to query the directory.

To resolve this behavior, use the following steps:

1.	If you are not using Site Server, either stop and set the LDAP Service to manual in Control Panel Services or uninstall Site Server.
2.	If you are using the Site Server LDAP service, you need to change the LDAP Port number in Exchange Server. To do this, use the following steps: a. Start Exchange Server Administrator. b. Click Site Container, click Configuration, and then click Protocols.
3.	When the LDAP Directory Site Defaults properties page is displayed, change the port number to a different number (for example, 390). NOTE: For more information, click the following article number to view the article in the Microsoft Knowledge Base: 224447 How to change LDAP port assignments in Exchange Server
4.	Click the Authentication tab.
5.	Make sure the Windows NT Challenge/Response check box is selected. No other options are required to be selected.
6.	Stop the Directory service, and then restart the Exchange Server services for the new port number to take effect.
7.	Ensure Mailbox Manager is working and no error messages are displayed.