Sending a X509Certificate with JavaMail attachment

[Sverre Moe]

I have a java.security.cert.X509Certificate object that I want to send via e-mail.
How do I wrap this object in an e-mail attachment?

Would this work:

    private void postMail(String recipient, String subject, String messageText, X509Certificate attachment, String from) throws MessagingException {
        Session session = Session.getDefaultInstance(mailProperties, null);
        Message message = new MimeMessage(session);

        InternetAddress addressFrom = new InternetAddress(from);
        message.setFrom(addressFrom);
        message.setRecipient(Message.RecipientType.TO, new InternetAddress(recipient));
        message.setSubject(subject);
        message.setContent(messageText, "text/plain");

        if (attachment != null) {
            BodyPart messageBodyPart = new MimeBodyPart();
            messageBodyPart.setContent(attachment, "application/pkcs7-mime"); //application/pkcs7-signature
            messageBodyPart.setFileName("certificate.cer");

            Multipart multipart = new MimeMultipart();
            multipart.addBodyPart(messageBodyPart);
            message.setContent(multipart);
        }

        Transport.send(message);
    }

Most examples I have seen uses the following attachment method, but I do not have a regular file.

        MimeBodyPart attachmentPart = new MimeBodyPart();
        FileDataSource fileDataSource = new FileDataSource(filename) {
            @Override
            public String getContentType() {
                return "application/octet-stream";
            }
        };
        attachmentPart.setDataHandler(new DataHandler(fileDataSource));
        attachmentPart.setFileName(filename);

I found that Spring offers some JavaMail implementations:
Using Spring I have devised the following two solutions:

Using MimeMessagePreparator

        JavaMailSender javaMailSender;

        MimeMessagePreparator preparator = new MimeMessagePreparator() {
            @Override
            public void prepare(MimeMessage mimeMessage) throws Exception {
                mimeMessage.setRecipient(Message.RecipientType.TO, new InternetAddress(emailaddress));
                mimeMessage.setFrom(new InternetAddress(fromAddress));
                mimeMessage.setText(messageText);
                mimeMessage.setFileName("certificate.cer");
                mimeMessage.setContent(attachment, "application/pkcs7-mime");
            }
        };

        try {
            javaMailSender.send(preparator);
        } catch (MailException ex) {
            // simply log it and go on...
            System.err.println(ex.getMessage());            
        }

Using MimeMessageHelper and ByteArrayResource:

        JavaMailSender javaMailSender;

        InputStreamSource source = new ByteArrayResource(attachment.getEncoded());
        MimeMessage mimeMessage = javaMailSender.createMimeMessage();
        MimeMessageHelper helper = new MimeMessageHelper(mimeMessage);
        helper.setTo(new InternetAddress(emailaddress));
        helper.setFrom(new InternetAddress(fromAddress));
        helper.setText(messageText);
        helper.addAttachment("certificate.cer", source, "application/pkcs7-mime");

        try {
            javaMailSender.send(mimeMessage);
        } catch (MailException ex) {
            // simply log it and go on...
            System.err.println(ex.getMessage());            
        }