title: Checking a user exists in Azure Active Directory B2C
body: <p>I am creating a new Azure AD B2C authenticated site to replace an older Forms Authenticated one. In the new site, I am asking the user to initially enter their email address so I can check if they exist in Azure B2C and send them to the appropriate sign-in page and if not send them to the older Forms Authenticated site.</p>
  
  <p>The issue is I have when following Microsoft's tutorials, is that they show user management but they all require you to have logged in with your Azure account first and obviously this is not possible given the system I am trying to build. Is what I am doing even possible?</p>
  
  <p>Thanks in advance!</p>
  
  <p>MS tutorials: <a href="https://azure.microsoft.com/en-gb/documentation/articles/active-directory-code-samples/" rel="nofollow">https://azure.microsoft.com/en-gb/documentation/articles/active-directory-code-samples/</a></p>