Consider the following scenario in a mixed Microsoft Exchange Server 2010 and Exchange Server 2007 environment:
You have a resource mailbox that is located on an Exchange Server 2007 server.
Public folder replication occurs between the Exchange Server 2007 server and an Exchange Server 2010.
A user sends a meeting request to the resource mailbox by using Outlook Web App (OWA).
In this scenario, the user cannot view the free/busy information of the resource mailbox and the free/busy information of other Microsoft Office Outlook 2003 user by using Outlook 2003. Additionally, the following event is logged in the Application log on the Exchange Server 2007 server:
This issue occurs because the Microsoft Exchange System Attendant service (Mad.exe) cannot publish or update free/busy information to an Exchange Server 2010 public folder.
To resolve this issue, install the following update rollup:
2645995 Description of Update Rollup 1 for Exchange Server 2010 Service Pack 2
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.