Michael Lu (the Program Manager for Performance, Email, Outlook, and Contact Management) has a great screencast (with voice) posted on his site: Configuring the CRM 4.0 Email Router with POP3. This screencast is especially useful as it uses Gmail as the POP3 service. Gmail has a rather tricky POP3 configuration which many people seemed to have struggled with. Mike's screencast demystifies this configuration and explains the various features/functions of the router.