title: From email address find the user in multi-domain AD environment
body: <p>I have an email address, and now I want to find in multi-domain AD environment the user that owns this email address.</p>
  
  <p>Is there any other way than querying all AD domains, one by one? If not, then how can I find the list of AD domains available?</p>
  
  <p>First, I thought the upn and the primary email adress to be the same, which - of course - is a misconception. 
  I also tried to guesstimate the ad domain to be <code>intra.contoso.com</code> for all email addresses ending on <code>intra.contoso.com</code>, but this is another misconception... :(</p>
  
  <p>For a start, only getting from the primary email address to the user (UPN or SID) would suffice.</p>