When migrating resource mailboxes from Exchange 2003 to Exchange 2007 or 2010, if you have been using Direct Booking for the resources, you need to make sure to follow this article to the letter:
In this case, we verified the customer had done exactly this. We verified that Direct Booking was off with an Outlook client logged into the mailbox and also determine that the CalendarProcessing settings were correct to the automatic booking.
At that point, the next thing to do was to look at the mailbox and see if the messages were sitting in the mailbox and not being processed. This is where it got interesting. None of our test meeting requests showed up anywhere in our room mailbox.
Next we looked to see if the messages were being delivered. Using the GUI message tracking interface in the Exchange 2010 ECP, we could see that the messages were indeed being delivered to the store. Using Get-MessageTrackingLog as indicated below gave us more interesting output:
Get-MessageTrackingLog -Start "03/13/2010 9:00AM" -End "03/15/2010 5:00PM" -Sender firstname.lastname@example.org
Looking at that output, we saw that not only was the message being delivered to the store, but then a message was being sent to another internal mail address. However, looking at Rules, etc. indicated no rules in effect.
That’s when it finally struck me - THE MAILBOX HAD A DELEGATE SET ON IT, and the "Deliver meeting requests addressed to me and responses to meeting requests where I am the organizer to:" was set to "My delegates only".
We went into the Delegate Access settings:
We removed the delegate and then sent a new Meeting Request to the resource - VOILA! It worked!
So, if you have a mailbox (resource or otherwise) and you find Meeting Requests aren’t getting delivered to the mailbox, check the delegate settings.