Hi We have users based in London, Paris and Dubai. Our Exchange servers are based in London. Today, we had WAN connection problems between London and Dubai. So users there had difficulty accessing their Outlook, as to be expected. Weird thing was, users in London who accessed the same shared mailboxes as those in Dubai also had issues accessing those same shared mailboxes. One of the example shared mailboxes is Marketing. The Dubai users had issues opening the mailbox as we'd expect, but people in London also did too. Could it be that Dubai users were somehow 'locking' this shared mailbox as a result of the poor network connection? Exchange 2007/ Outlook 2007.

Hi, What error you got when trying to open the shared mailbox?Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread. Thanks Gen Lin-MSFT

Hi, What error you got when trying to open the shared mailbox? Please try to re-share the mailbox and see if the issue persists. Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread. Thanks Gen Lin-MSFT