Outlook 2003 clients see folders at root of mailbox with Exchange 2010

I recently found an interesting but equally strange issue at a client site where we did an Exchange 2010 deployment. The first part of the user migration involved people who all had cached mode turned on for Outlook 2003. The second, and much larger portion of the project involved migrating users who didn't use cached mode (a.k.a online mode).

After migrating a few users over in a pre-pilot, we noticed some people complain about folders appearing at the root of their mailbox folder structure. When viewed in OWA, they weren't there. The project had undergone a Symantec Enterprise Vault 'un-vaulting' process so we quickly assumed it had something to do with that task which caused this abnormality. To make things more troublesome we noticed that if you closed Outlook and re-opened it, a different set of folders would appear, sometimes a larger or smaller set.

After doing some research internally at Microsoft I found several cases of users reporting this issue with a resolution stating it was fixed in SP1 for Exchange 2010. So here is my brief synopsis:

SYMPTOM:

Outlook 2003 users in non-cached mode (a.k.a. “Online mode”) show nested subfolders in the root of the user’s mailbox. Closing an re-opening Outlook produces mixed results with some cases the view having a different set of folders showing up. This appears to not affect Outlook 2003 clients in cached mode, 2007/2010 clients, and OWA users.

CAUSE:

An issue exists with Exchange 2010 RTM (pre-SP1).

RESOLUTION:

Resolved in Service Pack 1 for Exchange 2010.


Cheers!