Can't accept a meeting invitation for a room mailbox in Outlook if the delegate is a shared mailbox
Original KB number: 3191290
Consider the following scenario.
You add a shared mailbox as a delegate for a room mailbox by running the following PowerShell command:
Set-CalendarProcessing room -ResourceDelegates sharedmbx -AllBookInPolicy $false -AllRequestInPolicy $true
When a user tries to accept the meeting invitation from the Inbox of the shared mailbox in Microsoft Outlook, they receive an error message that resembles the following:
Cannot open the Calendar folder for user "room alias". The operation failed.
The user can accept the meeting request from the Inbox of the shared mailbox in Outlook on the web. However, the user who sent the meeting request doesn't receive an email message that confirms that the meeting was accepted.
This behavior is by design. Users who have access to the shared mailbox don't inherit permissions to the calendar of the room mailbox.
Users who have full access permission to the shared mailbox must have explicit editing permissions to the calendar of the room mailbox. To assign editing permission to users for the calendar of the room mailbox, follow these steps:
Do one of the following, as appropriate for your situation:
- Connect to Exchange Online by using remote PowerShell. For more info, see Connect to Exchange Online PowerShell.
- Open the on-premises Exchange Management Shell.
Run the following command:
Add-MailboxFolderPermission -Identity email@example.com:\Calendar -User firstname.lastname@example.org -AccessRights Editor
In this command, replace email@example.com with the email address of the room, and replace firstname.lastname@example.org with the email address of the user who has full access permissions to the shared mailbox.
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