You are the messaging engineer for your company. Your network contains a single Microsoft Exchange Server 2003 server with Service Pack 2 installed. The Intelligent Message Filter has been enabled on the Exchange Server 2003 server. You plan to transition your messaging environment from Exchange Server 2003 to Exchange Server 2007. You do not plan to deploy an Edge Transport server. You need to ensure that anti-spam filtering is enabled for your organization after the transition to Exchange Server 2007. What should you do?