title: EnsureUser using email address in SharePoint client object model
body: <p>I need to update a FieldUserValue field in sharepoint 2013. i am only given an email address data. I can't user EnsureUser since it only accepts the logonName. i used the FromUser method but it gives me an error that says "the user does not exist or is not unique"</p>
  
  <pre><code>FieldUserValue user = FieldUserValue.FromUser(email);
  </code></pre>
  
  <p>it worked when i tried using my email address but when i use the email addresses in my data it results in an error. how do i fix the issue?</p>