public function getRaw($stream = true)
    {
        if ($stream) {
            $hdr = new Horde_Stream();
            $hdr->add($this->_headers->toString(), true);
            return Horde_Stream_Wrapper_Combine::getStream(
                array($hdr->stream,
                      $this->getBasePart()->toString(
                        array('stream' => true, 'encode' => Horde_Mime_Part::ENCODE_7BIT | Horde_Mime_Part::ENCODE_8BIT | Horde_Mime_Part::ENCODE_BINARY))
                )
            );
        }

        return $this->_headers->toString() . $this->getBasePart()->toString();
    }