You disable the Display sender’s name on messages option in the Exchange Management Console (EMC) in Microsoft Exchange Server 2007 Service Pack 2 (SP2) or in Microsoft Exchange Server 2007 Service Pack 3 (SP3). Then, you send a meeting request to an external recipient over the Internet. In this situation, the meeting request may not open correctly for the external recipient.
This issue occurs because the syntax in iCalendar (iCAL) is incorrect. An unnecessary colon is added after the CN parameter in the Organizer property and in the Attendee property.
To resolve this issue, install the following update rollup:
2530488 Description of Update Rollup 3 for Exchange Server 2007 Service Pack 3
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.