In the demo VMs you have Outlook installed and connected to a basic email server. This is used in many places like alerts, workflow, etc. You can also use the sync features that exist in the AX CRM. For example syncing Contacts, Appointments, Tasks etc.
This video walk through the process of setting up an employee to sync to Outlook:
Double click to watch full screen

Setting up Outlook Sync from Dynamics AX - Reflections on Microsoft Dynamics AX - Site Home - MSDN Blogs