I've checked everywhere I can and tried various methods and fixed numerous other problems but still cannot fix this one. The user is running Outlook 2010, we run an Exchange 2010 server that was upgraded from an Exchange 2003 server about 4 months ago. All of a sudden we've had a few users not able to access shared mailboxes. We have one user in particular which has 2 additional mailboxes on his Outlook 2010 automatically added since he has full access permissions to them. He works out on a site via our VPN to access back into our network. The user can access one of the shared mailboxes but not the other, but there are 4 other users at that site that can access both, so there isn't an issue with the link/vpn and other users with the same permissions can access the mailboxes. The user had access to the mailboxes while we were on Exchange 2003 as well. His AutoConfiguration AutoDiscover works well and gets the right settings. The weird thing is, if I open his Outlook, try to open the shared mailbox and get the error, then I add the mailbox as an additional mailbox it shows up under the one that won't expand and it will actually work, but after he restarts his Outlook it merges it with the auto-added shared mailbox and won't open. Can anyone please explain why he could access one shared mailbox that was created before the problem one, but not the problem one that others can access at the same site and same Outlook with the same permissions? He gets the "Unable to Expand Folders" error saying he has network issues with exchange. PS: I've also re-added his permissions via EMC and PowerShell to check if it was that.

Try a new MAPI profile and another PC where the user hasn't logged on. Try in cache and online mode.Sukh

Try a new MAPI profile and another PC where the user hasn't logged on. Try in cache and online mode.Sukh

I tried two users on a Windows 2008 R2 RDS server with Outlook 2010 installed, it worked fine without a problem. I also got them to try on another PC at the site/office they're at and it also worked. One of them I erased the mail profile and outlook files from their profile and created a new mail profile. The new one hasn't yet auto-mapped the mailboxes they have access to but seem to work when manually added via Additional Mailboxes, but that may stop working tomorrow or later on. So the main user with the two shared mailboxes where one works and one doesn't, is going to come in during the morning tomorrow and I'll be recreating his Windows profile on the laptop to see if that will fix it. I can't imagine why it wouldn't, but we'll see. Is there something cached in Windows XP/7 profiles that stores Exchange server info that may cause problems months after the new Exchange 2010 server has been in and the 2003 server removed? It seems the problem possibly relates to their Windows profile and auto-mapped mailboxes.

Couldn't say but it seems like that the the profile may be the issue. here.Sukh

Couldn't say but it seems like that the the profile may be the issue. here.Sukh

Hi Sukh828, I've had the user in this morning and recreated his Windows profile, added the Outlook profile and it seems to be working fine. The issue seems to be something cached in the user profile though I've previously cleared the Outlook folders under Roaming and Local in the user profile without any difference. Is there a different fix for this that doesn't require as much work? Our users are roaming and store quite a bit on their computers (against our wishes) it does take some time to change them and they need to be in one of our Offices so an easier fix would be better.

Hi Sukh828, I've had the user in this morning and recreated his Windows profile, added the Outlook profile and it seems to be working fine. The issue seems to be something cached in the user profile though I've previously cleared the Outlook folders under Roaming and Local in the user profile without any difference. Is there a different fix for this that doesn't require as much work? Our users are roaming and store quite a bit on their computers (against our wishes) it does take some time to change them and they need to be in one of our Offices so an easier fix would be better.

These types of issues require in depth troubleshooting, at this stage I would just recommend a profile rebuild, however depending on how wide spread the problem is, you may want to open a call with MSFT, but these types of issues happen frequently in my experience.Sukh

These types of issues require in depth troubleshooting, at this stage I would just recommend a profile rebuild, however depending on how wide spread the problem is, you may want to open a call with MSFT, but these types of issues happen frequently in my experience.Sukh