title: Mark mail as unread
body: <p>I know there has to be an easy answer to this but I can't find one anywhere. How do I mark a email as unread? I know I can open the stream as read only, but on some occasions I need to manipulate the message (mark as seen, move to a different folder, etc.), so I need the stream to be read/write. I also know about the "Seen" flag and how to remove it. 
  So is there a way to mark an email as unread after it has been marked as read? </p>
  
  <p><strong>Edit:</strong> As requested, the code which is removing the 'Seen' flag from the mail</p>
  
  <pre><code>imap_clearflag_full($this-&gt;mbox, $mId, '\\Seen', ST_UID);
  </code></pre>