A meeting request that is sent by an external user or by using a non-Microsoft email system is stamped as Busy instead of Tentative in an Exchange Server 2010 environment

Assume that you receive a meeting request that is sent by an external user or by using a non-Microsoft email system in a Microsoft Exchange Server 2010 environment. However, when you open the calendar in Microsoft Outlook or in Microsoft Outlook Web App, the meeting request is stamped as Busy in the calendar. The expected behavior is that the meeting request is stamped as Tentative until you accept or decline the meeting request.