getPartClass example

        $boundary = $this->getHeaderField('content-type', 'boundary');
        if (!$boundary) {
            /** * @see Zend_Mail_Exception */
            throw new Zend_Mail_Exception('no boundary found in content type to split message');
        }
        $parts = Zend_Mime_Decode::splitMessageStruct($this->_content, $boundary);
        if ($parts === null) {
            return;
        }
        $partClass = $this->getPartClass();
        $counter = 1;
        foreach ($parts as $part) {
            $this->_parts[$counter++] = new $partClass(array('headers' => $part['header'], 'content' => $part['body']));
        }
    }

    /** * Get part of multipart message * * @param int $num number of part starting with 1 for first part * @return Zend_Mail_Part wanted part * @throws Zend_Mail_Exception */