You've been using Outlook for years now and you've probably established some delivery rules for yourself. Maybe mail from your manager is automatically routed to a subfolder of your inbox. If you're using Outlook 2003 or later, you've got an automatically maintained rule to handle junk mail. If you've ever set your Out Of Office, that's handled by a rule too.
But how do rules actually work? What's the implementation like? Obviously, I won't get into the grimy details (trade secrets and all), but I can pass along the basics.
First, the rules infrastructure is fully documented on MSDN. Those among you brave enough to explore this documentation may be inspired to write a little app which will enumerate your inbox rules and print them out on the console for detailed inspection of just what Outlook creates. I wrote such an app for internal diagnostic purposes (which means I most likely can't share it with you, sorry). Oh wait! Someone else has already published something here!