If you want to send some emails with your Java application, you may also want to format these mails using HTML. To achieve this, you have to build a correct multipart message defined in RFC 2045 and RFC 2046 and some more.
The header information of an email, like recipient, subject, etc., differs not from plain text mails:
MimeMessage mimeMessage = new MimeMessage((Session) null);
mimeMessage.setFrom("foo@example.com");
mimeMessage.addRecipient(Message.RecipientType.TO, new InternetAddress("bar@example.com", "Mr. Bar"));
mimeMessage.setSubject("My Subject", "UTF-8");
You should use a common character encoding for subjects. UTF-8 is a recommended and public supported one. This also applies for message content.
Now create the message body:
//create multipart
MimeMultipart content = new MimeMultipart("alternative");
//create simple textpart; content-type text/plain
MimeBodyPart textPart = new MimeBodyPart();
textPart.setText("content which is displayed, if mail client did not support HTML mails", "UTF-8");
//adds text part to multipart
content.addBodyPart(textPart);
//create html textpart; content-type text/html
MimeBodyPart htmlPart = new MimeBodyPart();
htmlPart.setText("<html><body><p>My Mailtext</p></body></html>, "UTF-8", "html");
content.addBodyPart(htmlPart);
//set content of mail to be multipart
mimeMessage.setContent(content);