title: How to get ADFS to respond to a query about an user's email address
body: <p>I'm working in a company that uses Microsoft Active Directory. We have an external company that provides an internal web site for a particular project. The site is external to the company. The sign on to the external site is the user's company email. </p>
  
  <p>We want a system whereby the external site calls into the organisation's AD to verify if an email address is still valid or if the user has left the company. It should be a simple call to Active Directory Federation Services or some sort of SAML interface. The call would be a simple request 'here's an email, is it valid?' and the response is either yes or no.</p>
  
  <p>Our IT department are trying to tell us that it's too complicated and I don't believe them. I think they just don't want to do it. </p>
  
  <p>Does anyone know how easy it would be to create a simple system that would allow an external service to do the query outlined above.</p>