function delete_message($auth_user, $accountid, $message_id)
{
  // delete a single message from the server
  
  $imap = open_mailbox($auth_user, $accountid);
  if($imap)
  {
    imap_delete($imap, $message_id);
    imap_expunge($imap);
    imap_close($imap);
    return true;
  }
  return false;
}