In short, Direct Booking and all the associated mailbox delegation controls that were in Exchange 2003 became confusing in 2007 and became a mess in Exchange 2013.
This is a short, reference post.
At this point in time (Mid-2016) most people already experienced this pain but, through these links, I finally tracked down multiple issues with Room Resources not sending Accept/Reject emails to Delegates.
- Start with a simple explanation between the old and new ways: Exchange 2003 Auto Accept Agent vs. direct booking & Booking Delegation Vs. Classic Delegation.
- Then use this Powershell script to discover which mailboxes and/or resources have Direct Booking enabled: Use Exchange Web Services and PowerShell to Discover and Remove Direct Booking Settings. Then use the “write” method to actually make the changes to the desired mailboxes. Read the include README file closely for prerequisites.
- Simple PowerShell to confirm and modify resources one-by-one: Two ways to grant access to a Resource in #MSFTExchange
- Lastly, and because we have a manageable number of Room Resources, go one-by-one and save them using the EAC. Decent double check because in at least one Microsoft Exchange Team blog post they mentioned that EAC does cleanup when it is saved post-upgrade. Specifically, a few rooms under “Booking Delegates” had a setting “Use customized setting to accept or decline booking requests”. Change the Room Resource to either “Accept or decline…” or “Select delegates…”.
- Setting Calendar Options For Resource Mailboxes In Exchange 2010…
- How to Create and configure a meeting room mailbox with Exchange Server 2007
- A Look at Exchange Server 2013 Resource Mailboxes
- Working with Resource Mailboxes in Exchange Server 2016
- Tool before the PowerShell script above: SetAA – Tweak Auto Accept Settings Across Mailboxes and an article explaining how to use it: Disable Direct Booking For All Room Mailboxes.
- I found the last step, saving in EAC, does mailbox cleanup. If not you can manually remove the mailbox from a room resource: I can’t disable a resource mailbox? Sez Who?
- Before screenshot above which was not well documented: Resources Booking Delegates Fix (AutomateProcessing: AutoUpdate)
- Exchange 2007: Resource delegate never receives forwarded meeting requests for approval
- Useful method for appending information to meeting requests: Using Transport Rules to append text to Meeting Requests when Room Mailbox is selected as Resource