Hi, From your description, when you double book a resource, both outlook 2007 and outlook 2010 will receive different information as tips. And it is by design. You want outlook 2010 users to get the same error information with outlook 2007 when double booking a resource. As per my knowledge, it is not possible to achieve it. And you can ask Outlook forum to get more. Hope it helps. ThanksSophia Xu TechNet Community Support

We currently have a mixed Outlook 2007 / Outlook 2010 environment and I have run into an issue with resource scheduling on Exchange 2010. When an Outlook 2007 client tries to double book a resource, the user receives an error and the user is prevented from booking the resource. With Outlook 2010, the user is allowed to book the resource but is then sent an email notifying him that "Your request was declined because there are conflicts." The issue is that any of the original meeting attendees received the initial meeting request and only the meeting organizer receives the "declined" email notification. I have searched quite a bit and some threads suggest modifying a registry key on the Outlook 2010 users machine, other threads make a reference to changing a setting on the Exchange 2010 server without really stating what that change is. So my question is how to prevent this from happening so that the Outlook 2010 receives the same warning as the Outlook 2007 user and is prevented from double booking the resource?

You might want to post your question to the Outlook forum http://social.technet.microsoft.com/Forums/en-US/outlook/threads. Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."

Hi, From your description, when you double book a resource, both outlook 2007 and outlook 2010 will receive different information as tips. And it is by design. You want outlook 2010 users to get the same error information with outlook 2007 when double booking a resource. As per my knowledge, it is not possible to achieve it. And you can ask Outlook forum to get more. Hope it helps. ThanksSophia Xu TechNet Community Support