Our environment: Two AD 2003 Forests (full trusts in both directions) One Exchange 2007CCR Deployment in each forest We use linked mailboxes for a few users, so the users login to ForestA, but their mailboxes reside in ForestB. So their Outlook is configured to point to the ForestB exchange server. This configuration has worked flawlessly for many months. Yesterday, we applied 29 Windows Update Patches (Only Windows, not Exchange) to the Mailbox Servers. Today, the users with Linked Mailboxes that logged off of their systems yesterday, were prompted with a login prompt after launching Outlook. Outlook no longer accepts their credentials, BUT only in the format of ForestA\Username. If the credentials are provided via Username@ForestA.com, then there is no problem. OWA works fine when providing ForestA\Username. Any ideas? I've compiled the list of the patches that were applied, so I'm about to go through and see if any of them could possibly be responsible for this, but I figure this might save me a bunch of work Any help is greatly appreciated. Cheers! Matt

No ideas? I've narrowed it down to what I suspect is this patch which seems to have caused plenty of problems for others KB948496.

Hi Matt, Would you please let me know whether all the users who have Linked Mailbox encountered the problem? If all the users encountered the problem, please review the Application log on Exchange server to check whether the event 9646 is logged. If I am right, please check following article for more information: http://support.microsoft.com/kb/84202/en-us http://msexchangeteam.com/archive/2007/07/18/446400.aspx Mike

Hey Mike, Yes, it has affected all of them, and yes event 9646 is logged. I'll have a look through the post you've provided. Thanks, Matt

Matt, Please feel free to let me know the result. If the issue still persists, please post the entire 9646 log here for further check. Mike

Hi I just configured 2 x forest. Forest A with users account and forest b with exchange 2007. I have created trustrelatinship, created linked mailbox all seems to be good. I can access mailbox using OWA but I am not able to configure the outlook. Question is does linked mailbox works with oulook 2007 or only owa. is there any process or steps to configure outlook 2007. am i missing any thing. As can't find any document on how to configure outlook for linked mailbox. It is not able to resolve the name when i try to add the mailbox. error message while trying to configure outlook isThe name cannot be resolved. the name cannot be matched to a name in the address list...please help...sanjeev rauniyar