public function createAttachment($body,
                                     $mimeType    = Zend_Mime::TYPE_OCTETSTREAM,
                                     $disposition = Zend_Mime::DISPOSITION_ATTACHMENT,
                                     $encoding    = Zend_Mime::ENCODING_BASE64,
                                     $filename    = null)
    {

        $mp = new Zend_Mime_Part($body);
        $mp->encoding = $encoding;
        $mp->type = $mimeType;
        $mp->disposition = $disposition;
        $mp->filename = $filename;

        $this->addAttachment($mp);

        return $mp;
    }