createMultipartMessage(Session session) {

	MimeMessage m = new MimeMessge(session);

	... // set headers as before

	MimeBodyPart bp1 = new MimeBodyPart();
	bp1.setText("text content in part 1");

	MimeBodyPart bp2 = new MimeBodyPart();
	bp2.setText("text content in part 2");

	MimeMultipart mp = new MimeMimeMultipart()
	mp.addBodyPart(bp1);
	mp.addBodyPart(bp2);

	msg.setContent(mp);
}