In December 2009 I reported a bug in TMG GUI to Microsoft.
If you wanted to use E-mail Policy in TMG at the time there were some restrictions in e.g. "Blocked sender" GUI. More specifically the GUI didn't allow me to enter "hotmail-sender@hotmail.com" as blocked address. If you did TMG returned an error: "The Sender address in empty or not valid. Please enter a valid e-mail address."
Further investigation into this problem I found out that TMG would not accept the following characters ! # $ % & ' * + - / = ? ^ _ ` { | } ~ which are legal characters according to
RFC.
Microsoft
acknowledged the bug. Patch was released in January 2010 as part of hotfix update package for TMG 2010. They also released
KB 97925