I have found the cause and applied a workaround to fix it. My apologies Steve, my auto notification didn't tell me there were replies to this thread. Still can't open in Outlook as either an AutoMap or AutoOpen mailbox. Recreate as a new user with licence, login to the web interface to initialise. Archive the email, then delete the previously shared mailbox.Changed the shared mailbox to a user, assigned a licence.Disabled / re-enabled MAPI for both UserA and the shared mailbox (suggested as a response to this issue in another thread).I had to cancel out every time.īecoming increasingly deranged/desperate I then: UserA, I could select the mailbox to add, but Outlook would not accept the 'OK' button to complete the process. I removed the Automapping and told Outlook to AutoOpen the shared mailbox on startup and this worked. Using another mailbox (on another computer), the same issue exists. Login as UserA on another computer, configure Outlook to connect to Exchange, issue still exists.Delete access rights, re-assign access rights using PowerShell.Change UserA from cached to online mode.Both email domains areĬonnected to the same Office365 organisation with the DNS configured correctly (for AutoDiscover). The business runs a charitable foundation as well, and this user has a shared mailbox which has maybe 100 messages in it. Scenario: - primary mailbox, the user has a lot of mail. The attempt to log on to Microsoft Exchange has failed'Įnvironment: Outlook 2010 (with all publicly available updates) / Office 365 Exchange. The user has full access rights to the mailbox and when they try to open the shared mailbox they get the dreaded 'The set of folders cannot be opened.

I have a user that cannot open a shared mailbox.

Outlook 365 open shared mailbox