Retrieve the generated Message-ID before sending email using Spring JavaMail

Question

I am using org.springframework.mail.javamail.JavaMailSender to send email using SMTP and in that I need to retrieve the Message-ID header. The below code

message.getMimeMessage().getMessageID()  

is returning null. How to retrieve the Message-ID?

public void notifyByMail(final NotificationRequest request)
{
    MimeMessagePreparator preparator = new MimeMessagePreparator()
    {
        public void prepare(MimeMessage mimeMessage) throws Exception
        {
            MimeMessageHelper message = null;
            message = new MimeMessageHelper(mimeMessage, UTF_8);
            message.setTo(request.getTo());
            message.setCc(request.getCc());
            message.setFrom(request.getFrom());
            message.setReplyTo(request.getReplyTo());
            message.setSubject(request.getSubject());
            message.setText("some text", true);

            //Need to retrieve the Message-ID here
            System.out.println("Message - ID : " + message.getMimeMessage().getMessageID());
        }

    };
    getMailSender().send(preparator);
}

Answer 1

Try message.getMimeMessage().saveChanges() before message.getMimeMessage().getMessageID().

You also need this when creating the message:

        MimeMessage msg = new MimeMessage(session) {
            protected void updateMessageID() throws MessagingException {
                if (getHeader("Message-ID") == null)
                    super.updateMessageID();
            }
        };

That causes the Message-ID header to only be set the first time if it's not already set.