Tell me about the issue and I’ll help you find the solution you need.
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
Content provided by Microsoft
Applies to: Microsoft Exchange Server 2010 Service Pack 2, Exchange Server 2010 Enterprise, Exchange Server 2010 Standard
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.
This issue occurs because the Exchange Server 2010 server incorrectly sets the PidLidBusyStatus property of the meeting request to Busy if the X-MICROSOFT-CDO-INTENDEDSTATUS property is not present.
To resolve this issue, install the following update rollup:
2661854 Description of Update Rollup 2 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.
For more information about the X-MICROSOFT-CDO-INTENDEDSTATUS property, visit the following Microsoft website: