title: PHP imap_search UNSEEN SINCE date with time
body: <p>I am using PHP imap_search to fetch list of unseen messages since a given date like this:</p>
  
  <pre><code>imap_search($stream, 'UNSEEN SINCE 20-Sep-2015');
  </code></pre>
  
  <p>This is working fine. However, I am periodically every few minutes checking for new emails and then storing the last check time in a session. I want to be able to run the imap_search with the UNSEEN SINCE date including time. But it just does not seem to work. I've tried:</p>
  
  <pre><code>imap_search($stream, 'UNSEEN SINCE 20-Sep-2015 12:35:03 +0000 (UTC)');
  imap_search($stream, 'UNSEEN SINCE 20-Sep-2015 12:35:03 +0000');
  imap_search($stream, 'UNSEEN SINCE 20-Sep-2015 12:35:03');
  </code></pre>
  
  <p>Nothing seems to work. Any ideas if this can be done?</p>