How can I restrict users to viewing the address list of their own organization, not the entire Global Address List (GAL)?

Using ADSIEdit Administrators can edit the msExchQueryBaseDN attribute to restrict users to either viewing either

a) A limited Global Address List that consists of users in the same Active Directory Organizational Unit; or

b) A custom Exchange Address List.�

To make this configuration change, refer to http://support.microsoft.com/?kbid=272197