Unable to read custom header from email

Question

I am adding custom header while sending email in Java. If anybody gives reply to that email I need to store the content of that email in database. I might receive multiple reply for that mail. So for identification I am adding custom header with unique value.

While reading unread email from inbox folder from imaps store, I am unable to read custom header. Other than custom header I am able to read other header.

I am reading email using below Class

public class OutLookReader_imaps {

    Folder inbox;
    public OutLookReader_imaps() throws IOException {
        System.out.println("Inside MailReader()...");
        final String SSL_FACTORY = "javax.net.ssl.SSLSocketFactory";
        Properties props = System.getProperties();
        props.setProperty("mail.imaps.socketFactory.class", SSL_FACTORY);
        props.setProperty("mail.imaps.socketFactory.fallback", "false");
        props.setProperty("mail.imaps.port", "993");
        props.setProperty("mail.imaps.socketFactory.port", "993");
        props.put("mail.imaps.host", "outlook.office365.com");


        try {
            /* Create the session and get the store for read the mail. */

            Session session = Session.getDefaultInstance(System.getProperties(), null);
            Store store = session.getStore("imaps");

            store.connect("outlook.office365.com", 993, "[email protected]", "password");
            inbox = store.getFolder("INBOX");
            inbox.open(Folder.READ_WRITE);            
            Flags seen = new Flags(Flags.Flag.SEEN);
            FlagTerm unseenFlagTerm = new FlagTerm(seen, false);
            Message messages[] = inbox.search(unseenFlagTerm);
            if (messages.length == 0) System.out.println("No messages found.");

            System.out.println("No. of Unread Messages : " + inbox.getUnreadMessageCount());
            System.out.println("No. of Messages : " + inbox.getMessageCount());
            System.out.println("No. of Deleted Messages : " + inbox.getMode());

            for (int i = 0; i < messages.length; i++) {
              if (i > 10) {
                System.exit(0);
                inbox.close(true);
                store.close();
              }

              System.out.println("Message " + (i + 1));
              System.out.println("From : " + messages[i].getFrom()[0]);
              System.out.println("Subject : " + messages[i].getSubject());
              System.out.println("Sent Date : " + messages[i].getSentDate());
              System.out.println("Header : " + messages[i].getAllHeaders());
              System.out.println("Content : " + messages[i].getContent().toString());
              System.out.println("Content Type : " + messages[i].getContentType());
              System.out.println("Description : " + messages[i].getDescription());messages[i].getContent());         

              System.out.println("Unique Header : " + messages[i].getHeader("X-Universally-Unique-Identifier"));

              System.out.println("Header uni : " + messages[i].getHeader("X-Uniform-Type-Identifier"));  

              Enumeration allHeaders = messages[i].getAllHeaders();
                while (allHeaders.hasMoreElements()) {
                    Header header = (Header) allHeaders.nextElement();
                    String headerName = header.getName();
                    String headerVal = header.getValue();

                    System.out.println("Header Name : " + headerName);
                    System.out.println("Header Value : " + headerVal);
                }
            }         

            try {

                inbox.close(true);
                store.close();

            } catch (Exception ex) {
                System.out.println("Exception arise at the time of read mail");
                ex.printStackTrace();
            }

        } catch (MessagingException e) {
            System.out.println("Exception while connecting to server: " + e.getLocalizedMessage());
            e.printStackTrace();
            System.exit(2);
        }

    }

    public void printAllMessages(Message[] msgs) throws Exception {
        for (int i = 0; i < msgs.length; i++) {
            System.out.println("MESSAGE #" + (i + 1) + ":");
            printEnvelope(msgs[i]);
        }
    }

    public void printEnvelope(Message message) throws Exception {

        Address[] a;

        if ((a = message.getFrom()) != null) {
            for (int j = 0; j < a.length; j++) {
                System.out.println("Email From : " + a[j].toString());
            }
        }

        String subject = message.getSubject();

        Date receivedDate = message.getReceivedDate();
        Date sentDate = message.getSentDate(); 

        SimpleDateFormat df = new SimpleDateFormat("dd/MM/yyyy");

        System.out.println("Email Subject : " + subject);

        if (receivedDate != null) {
            System.out.println("Received Date: " + df.format(receivedDate));
        }

        System.out.println("Sent Date : " + df.format(sentDate));
    }


    public static void main(String args[]) throws IOException {
        new OutLookReader_imaps();
    }

}

Answer 1

Custom headers that you add to messages you send will not be added to messages that reply to the message you sent. There will usually be an In-Reply-To header or References header that includes the Message-ID of the message you sent, but even those are not guaranteed to be present. The most reliable way of associating replies with sent messages is probably to include a unique ID in the Subject of the message you sent.