Resolve Users from Another Windows 2000 Forest
Users in a different Windows 2000 Active Directory forest can read and post messages in your Exchange organization's public folders, provided the external forest is trusted by your own. However, the names of these external users may not be resolved, resulting in blank From fields. Although local users will be able to post replies to the postings of these unresolved users, no one will be able to send mail directly to unresolved external users.
Outlook Web Access will read an external user's security identifier (SID) and then contact a global catalog server in another forest to find domain and e-mail alias information corresponding to the SID. When the following registry key is turned on (with the value of 1), Outlook Web Access will then attempt to find a contact object in the local forest that matches the e-mail alias information it obtained from the external forest. If a unique contact object is found, Outlook Web Access will use the display name and e-mail address from that contact when the external user posts to a public folder.
Warning Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk.
For information about how to edit the registry, view the "Add and Delete Information in the Registry" and "Edit Registry Data" Help topics in Regedt32.exe. Note that you should back up the registry before you edit it, and you should also update your Emergency Repair Disk (ERD).
To resolve users from another forest: