When Microsoft Exchange Server 2010 processes a transport rule for an email message in which the From field is empty, the EdgeTransport.exe process crashes on the Hub Transport server. Additionally, the following event is logged in the Application log:
This issue occurs because an empty string is sent to the constructor of a class and the validation routine returns "false." Therefore, a System.ArgumentOutOfRangeException exception is thrown.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.