Had a very weird issue where users on prem couldnt access mailboxes for users online even though the permissions were correct.
The error was:
Cannot expand the folder. The set of folders cannot be opened.
Had a good google and the recommendations were to do the following which didnt work for me:
Connect to 365 and run:
Remove-MailboxPermission -Identity Manager@bohemiangrove.co.uk -User User1@bohemiangrove.co.uk -AccessRights FullAccess
Add-MailboxPermission -Identity Manager@bohemiangrove.co.uk -User User1@bohemiangrove.co.uk -AccessRights FullAccess -InheritanceType All -AutoMapping:$false
So what I did to fix this was to add this for
- Exit Outlook.
- Start Registry Editor. To do this, use one of the following procedures, as appropriate for your version of Windows:
- In Registry Editor, locate and then click the following registry subkey:
- On the Edit menu, point to New, and then click DWORD Value.
- Type AlwaysUseMSOAuthForAutoDiscover, and then press Enter.
- Right-click AlwaysUseMSOAuthForAutoDiscover, and then click Modify.
- In the Value data box, type 1, and then click OK.
- Exit Registry Editor.