How Exchange Online Room Mailboxes Use AutoUpdate and AutoAccept

A New Default for Room Mailbox Automatic Processing

Today, Microsoft published Office 365 Message Center update MC151582 to tell tenants that from November 15, 2018, new room mailboxes will be created with their AutoProcessing property set to AutoAccept. Previously, the default value for the property was AutoUpdate.

The documentation for the Set-CalendarProcessing cmdlet explains the values as:

• AutoUpdate: Only the Calendar Attendant processes meeting requests and responses. Meeting requests are tentative in the calendar until they’re approved by a delegate. Meeting organizers receive only decisions from delegates.
• AutoAccept: Both the Calendar Attendant and resource booking attendant are enabled on the mailbox. This means that the Calendar Attendant updates the calendar, and then the resource booking assistant accepts the meeting based upon the policies. Eligible meeting organizers receive the decision directly without human intervention (free = accept; busy = decline). [New Default]

A Little PowerShell Error

The Message Center update includes some PowerShell to help tenant administrators check the value assigned to existing room mailboxes. Unfortunately, there’s an error in the code as it omits a call to the Get-CalendarProcessing cmdlet. To see the values, you need to run this PowerShell code:

Get-Mailbox -RecipientTypeDetails @("Equipment","RoomMailbox") -ResultSize unlimited | Get-CalendarProcessing

Identity                  AutomateProcessing
--------                  ------------------
Room 104                  AutoUpdate
Room 101                  AutoAccept
Room 102                  AutoAccept
Room 103                  AutoAccept
Las Vegas Conference Room AutoAccept
San Francisco Room        AutoAccept
Nikon Room                AutoAccept
VCR Recorder              AutoUpdate

Updating Existing Room Mailboxes

If you want to update existing rooms to the new default, run this PowerShell code:

Get-Mailbox -RecipientTypeDetails @("Equipment","RoomMailbox") -ResultSize unlimited | Get-CalendarProcessing | Where-Object {$_.AutomateProcessing -eq "AutoUpdate"} | Set-CalendarProcessing -AutomateProcessing AutoAccept

And as the update says, make sure that any scripts you use to create new room mailboxes specify whatever value you want for this property. Room mailboxes created from the Microsoft 365 admin center have AutomateProcessing set to AutoUpdate.

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The Office 365 for IT Pros eBook covers this kind of information in Chapter 5, which is where we get to grips with Exchange Online mailboxes.