Exchange Server 2007 provides anti-spam protection, however it must be installed and configured separately. To install the Microsoft Anti Spam Agents on Exchange Server 2007, follow these instructions. Now, you have to configure auto-update to receive anti-spam updates. Now it’s ready to go!
We recently installed Exchange Server 2007 and noticed that any new distribution lists were not receiving email from any outside addresses. Turns out that this is turned off by default in Exchange Server 2007 and needs to be enabled. The Exchange Server Share blog has an article describing how to fix this.