Can't accept a meeting invitation for a room mailbox in Outlook if the delegate is a shared mailbox

Original KB number:   3191290

Problem

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.

Cause

This behavior is by design. Users who have access to the shared mailbox don't inherit permissions to the calendar of the room mailbox.

Workaround

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:

1. 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.

2. Run the following command:

   Add-MailboxFolderPermission -Identity room@contoso.com:\Calendar -User ed@contoso.com -AccessRights Editor
   

   Note

   In this command, replace room@contoso.com with the email address of the room, and replace ed@contoso.com with the email address of the user who has full access permissions to the shared mailbox.

More information

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