You are configuring Autodiscover for your Exchange network and wish to test that it works properly. However, you haven't opened up any ports yet to the outside world and can only test internally, so you can't use the Microsoft Remote Connectivity Tester to verify that autodiscover and ActiveSync work via the Internet.
Per a really good Petri.co.il article on Autodiscover, Microsoft Outlook 2010 has a feature to do just this.
- Start Outlook 2010 as you normally would.
- Outlook will place an icon in the System Tray.
- Hit the <CTRL> key, right-click the Outlook System Tray icon, and choose "Test E-mail Autoconfiguration".
- Enter your email address, password, and ONLY select Use Autodiscover.
- Run the test!