Sending chinese HTML with javamail - is there no definitive answer ?

Question

I'm using the following code to send a HTML and text e-mail
(text for people with HTML-challenged email clients). I sent
2 emails to 2 email addresses which reside on the same server
- eg. [email protected] and [email protected] - and read the
emails with the same e-mail client (Eudora) on the same PC.
The HTML and Chinese displays perfectly when it's sent to one
of the email addresses ([email protected]) but the HTML and
Chinese are always corrupt when I send them to the other.
This is a repeatable error and it has me completely stumped.
     // Example Initial values (drawn from a database) :
     String smtpHost = "mail.mydomain.com";
     String sender = "[email protected]";
     String subject = "Give me strength.... ";
     InternetAddress sender = new InternetAddress("[email protected]");
     InternetAddress receiver = new InternetAddress("[email protected]");
     String txtMsg = "a long text message blah...";
     String htmlMsg = "<h1>Wooo</h1><img src='http://mydomain.com/blink.gif'>";
     String language = "zh-tw" // can also be "en-us" or "zh-cn"
     // CREATE MAIL MESSAGE & HEADERS
     Properties props = System.getProperties();
     props.put("mail.smtp.host", smtpHost);
     Session session = Session.getDefaultInstance(props, null);
     Message msg = new MimeMessage(session);
     msg.setFrom(sender);
     msg.addRecipient(Message.RecipientType.TO, receiver);
     msg.setSubject(subject);
     msg.setSentDate(new Date());
     msg.setHeader("Mime-Version" , "1.0" );
     msg.setHeader("Content-Transfer-Encoding", "quoted-printable");
     // MESSAGE BODY - TEXT & HTML
     MimeMultipart mimeAllContent = new MimeMultipart("alternative");
     MimeBodyPart mimeText = new MimeBodyPart();
     MimeBodyPart mimeHtml = new MimeBodyPart();
     mimeText.setText(textMsg);
     mimeText.setHeader("Mime-Version" , "1.0" );
     mimeText.setHeader("Content-Type" , "text/plain");
     mimeText.addHeader("Content-Type", "charset=UTF-8");
     if (!language.equals("")) {
          mimeText.setHeader("Content-Language", language);
     mimeText.setHeader("Content-Transfer-Encoding", "quoted-printable");
     mimeHtml.setContent(htmlMsg, "text/html");
     mimeHtml.setHeader("Mime-Version" , "1.0" );
     mimeHtml.setHeader("Content-Type" , "text/html");
     mimeHtml.addHeader("Content-Type", "charset=UTF-8");
     if (!language.equals("")) {
          mimeHtml.setHeader("Content-Language", language);
     mimeHtml.setHeader("Content-Transfer-Encoding", "quoted-printable");
     mimeAllContent.addBodyPart(mimeText);
     mimeAllContent.addBodyPart(mimeHtml);
     msg.setContent(mimeAllContent);
     msg.setHeader("Content-Type" , mimeAllContent.getContentType());
     // SEND THE MESSAGE
     msg.saveChanges();
     Transport.send(msg);
     return true;
Let me repeat - Using the code below, a HTML & Text ("Alternative"
MimeMultiPart) message is sent, and arrives at the recipient's
mailbox. When it is sent to one user ([email protected]), it never
renders properly. When it is sent to another ([email protected]), it's
OK. The destination server, email client, PC are the same in both
cases and the only variable is the recipient's email address.
How can this be ?
I think I've gone overboard by setting the Content-Transfer-Encoding
for both the HTML and Text MimeParts as well as the actual Message.
Could somebody please confirm which parts I should set the Content-
-Language, Content-Transfer-Encoding and Content-Type b/c I'm
going in circles at the moment.
Thanks indeed, to anybody who has experience sending doublebyte
with Javamail and can help me clear this up once and for all.
I find it incredible that after 3 years, there is still no
definitive answer to accomplishing this, and it remains an
elusive black art.
Regards,
chas
ps. The data being sent is in MySQL not that that matters at all.

Answer 1

Try adding code to validate submitted email addresses before they go into your database.
String emailAddress = (from where ever)
if(emailAddress != null) emailAddress = emailAddress.trim();
if(emailAddress == null) // skip this address
// I also check for a list of illegal internet email address characters, as I think the email addresses allowed by Javamail are too lenient.