XADM: "The Server Is Not Operational" Error Message Occurs When You Move A Mailbox

When you try to move a mailbox from an Exchange Server 5.5 computer to an Exchange 2000 Server computer by using the Active Directory Users and Computers snap-in, you may receive the following error message:
Additionally, the following event ID messages may be logged in the Event Viewer Application log:

This behavior may occur if Lightweight Directory Access Protocol (LDAP) is not turned on at either the server or site level on the Exchange Server 5.5 computer.

To resolve this behavior, turn on LDAP on the Exchange Server 5.5 computer:

1. Log on to the Exchange Server 5.5 computer as an account that has Administrator permissions or as an account that has higher permissions in the Exchange Server site.
2. Click Start, point to Programs, point to Microsoft Exchange, and then click Microsoft Exchange Administrator.
3. Expand the site, expand Configuration, expand Servers, expand the Exchange server that you want, and then click Protocols.
4. In the right pane, double-click LDAP.
5. On the General tab, click to select the Enable protocol check box, and then click OK.

Try to move the mailbox and note that the operation is successful this time.