Question

I am writing an Android GMail client application.

When it creates a message, I add a header to it like this:

MimeMessage msg = new MimeMessage(session);
msg.setFrom(new InternetAddress(username));
msg.setSubject(subject);
msg.setText(message);
msg.setRecipient(Message.RecipientType.TO, new InternetAddress(to));

long time = someTime; 
msg.addHeader("My_Header", Long.toString(time));

//IMAPFolder f declaration & initialization

    f.open(Folder.READ_WRITE);
f.addMessages(new Message[]{msg});
f.close(true);

It all works fine and I am able to see the header correctly added to the message when viewing my GMail account on my PC. However, when I later try to retrieve the header information, it gets very weird.

When I call

String[] str = msg.getHeader("My_Header");

getHeader() returns null if I am running the app. However, when I debug the app and set a breakpoint before the getHeader() call, it returns the header value corrently.

My source code:

MimeMessage msg = getNextMessage();
String subject = msg.getSubject();
InternetAddresses to[] = msg.getAllRecipients()

String when[] = msg.getHeader(GMailClient.TIME_TO_SEND);        
if (when == null) {
            Log.i(TAG, "Null Header");
} else {
    long time = Long.parseLong(when[0]);
            Log.i(TAG, "Value retrieved: " + when[0]);
}

Answer 1

Possibly Gmail isn’t returning the header information correctly via IMAP? You might want to look at the protocol trace to see exactly what the server is returning for your request.

Also, try writing out the entire message using (e.g.)

msg.writeTo(new FileOutputStream("msg.txt"));

and see if the header is there. If it is, and the protocol trace shows that it’s not being returned for the getHeader call, it’s a bug in the server. In that case, see the JavaMail FAQ entry for how to work around such server bugs.