You can use the Intelligent IM Filter tool to block URLs that contain certain characters in a Microsoft Office Communications Server 2007 R2 environment. However, the Intelligent IM filter does not work if the URL contains one of the following characters:
This issue occurs because these characters are not included in the ValidUrlChars definition list.
To fix this problem, install the following cumulative update:
978008 Description of cumulative update for Office Communications Server 2007 R2: April, 2010
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.