/**
  *
  * @param Expressomail_Backend_ImapProxy $_imap
  * @param type $_ids
  * @param type $_folderId
  * @return type 
  */
 protected function _getSummary(Expressomail_Backend_ImapProxy $_imap, $_ids, $_folderId)
 {
     $return = array();
     $pos = 0;
     $last = count($_ids) - 1;
     do {
         $ids = array_slice($_ids, $pos, 1000);
         $return = empty($return) ? $_imap->getSummary($ids, null, null, $_folderId) : array_merge($return, $_imap->getSummary($ids, null, null, $_folderId));
         $pos += count($ids);
     } while ($pos < $last);
     return $return;
 }