title: When changing an Azure B2C email adress, do I need to change the UPN as well
body: <p>In Azure B2C with the GraphAPI I can change the email address of an existing user with a http PATCH command:
  <a href="https://azure.microsoft.com/nl-nl/documentation/articles/active-directory-b2c-devquickstarts-graph-dotnet/" rel="noreferrer">https://azure.microsoft.com/nl-nl/documentation/articles/active-directory-b2c-devquickstarts-graph-dotnet/</a></p>
  
  <pre><code>"SignInNames": [
  {
    "type": "emailAddress",
    "value": "demo@domain.com"
  }
  </code></pre>
  
  <p>This works, and I can login with the new email address.</p>
  
  <p>But this leaves the <code>UPN</code> at the old value, do I need to set the <code>UPN</code> as well, or is there no harm in having the <code>UPN</code> stay at the old email address?</p>