Microsoft introduced the Exchange Web Services (EWS) to expand the ways in which client applications could communicate with the Exchange server. EWS provide access to almost the same Exchange information that is made available through, for example, Outlook. This allows third-party vendors to easily integrate that information within their own applications.

EWS clients (which can be anything from a third-party application to a PowerShell script) can communicate with the server-side EWS by exchanging SOAP calls that are being sent over HTTP.

To control on what endpoints (URLs) the Exchange Web Services are available on a Client Access Server, you configure the InternalUrl and ExternalUrl properties on the Web Services Virtual Directory. The values you configure here will be passed on to your clients through the Autodiscover process, overcoming the need to manually configure these endpoints on your clients. Typically, you wouldn't want to change the value of these...