On a normal Exchange Server 2007 deployment an Edge server role is setup facing the Internet and the Hub Transport role is hosted on an internal server. Anti-Spam agents such as Content Filtering, Connection filtering, Sender ID, Sender Filtering, Recipient Filtering and Sender Reputation are only installed by default on the public facing edge server role.
If you have a small Exchange 2007 deployment where all roles are hosted on one server you will not be using a edge server role. Instead, you will be using the Hub Transport role to send and receive messages. Since that is not the typical way to setup Exchange the anti-spam agents are not installed on the Hub Transport role by default.
You can easily installed the Anti-Spam agents on the Hub Transport role by running a simple powershell script. Open up the Exchange Management Shell and navigate to the exchange scripts directory C:\Program Files\Microsoft\Exchange Server\Scripts. Then type in install-AntispamAgents.ps1 and hit Enter.
After the agents are installed type in Restart-Service MSExchangeTransport and hit Enter to restart the Hub Transport role.
You can now configure each of the Anti-Spam agent settings.