title: How to check DKIM signature of incoming email in Java Google App Engine
body: <p>I am looking for a way to validate the DKIM signature of the incoming email.</p>
  
  <p>I know how to do it in Java SE but it will use classes like <code>javax.naming.directory.DirContext</code> to get data from DNS server and this class is not white listed in App Engine. </p>
  
  <p>Any idea how to communicate with DNS form Google App engine?</p>
  
  <p><a href="http://blog.jhltechservices.com/2011/01/how-to-verify-dkim-is-working-for-your.html" rel="nofollow">There is a blog post that says:</a></p>
  
  <blockquote>
    <p>Once you've configured DKIM, just send
    an email from your Google Apps account
    to:</p>
    
    <p><strong>dkim@dkim-test.appspotmail.com</strong></p>
    
    <p>within minutes, you should get back an
    email that says "PASS" or "FAIL". If
    your test passed, you're all set!</p>
  </blockquote>
  
  <p>I tried it and it works!
  It seems like a Google App Engine Application. How is it done?! </p>