Consider the following scenario:
You create a meeting request by using an Exchange Web Services (EWS) application in a Microsoft Exchange Server 2010 environment. The body of the meeting request is in HTML format.
You send the meeting request.
An attendee opens the meeting request by using Microsoft Outlook in online mode.
In this scenario, the body of the meeting request is in plain text format instead of HTML format. This may cause the content of the message to be rendered improperly.
This issue occurs because the Exchange server does not convert the body of the calendar item that is created by an EWS application to the correct format.
To resolve this issue, install the update rollup that is described in the following article in the Microsoft Knowledge Base:
2685289 Description of Update Rollup 3 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 message formats in Outlook and content conversion, go to the following Microsoft website: