public function addHeader($name, $value, $append = false)
    {
        $prohibit = array('to', 'cc', 'bcc', 'from', 'subject',
                          'reply-to', 'return-path',
                          'date', 'message-id',
                         );
        if (in_array(strtolower($name), $prohibit)) {
            /**
             * @see Zend_Mail_Exception
             */
            // require_once 'Zend/Mail/Exception.php';
            throw new Zend_Mail_Exception('Cannot set standard header from addHeader()');
        }

        $value = $this->_filterOther($value);
        $value = $this->_encodeHeader($value);
        $this->_storeHeader($name, $value, $append);

        return $this;
    }