Exchange 2007 Queue filling up with blank senders

http://msexchangeteam.com/archive/2006/12/28/432013.aspx (Allowing application servers to relay off Exchange Server 2007 )
http://msexchangeteam.com/archive/2006/10/25/429345.aspx (Recipient and server filtering in Exchange 2007 console )
http://support.microsoft.com/kb/555924 (How to install Microsoft Anti Spam Agents on Exchange 2007)
http://www.petri.co.il/reduce-spam-exchange-server-2007-safe-list-aggregation-safe-senders.htm (Reduce Spam with Exchange 2007 Server Safe List Aggregation)