Java Enterprise Best Practices

Accommodate Various Client Capabilities

Email messages sent by an application must support the widest variety of email clients possible. While the majority of Internet email users have by now upgraded to mail clients that support HTML content, a sizeable minority have not. You’ve just seen how to send a simple email with a plain-text body and create HTML or plain-text output according to user preferences known ahead of time. The latter is an ideal solution when generating customized content for known users but breaks down a bit when sending more generic messages, such as system announcements or newsletters, to larger groups of users in which user preference information isn’t available. Add in the users who can support HTML mail but have intentionally turned off the feature in their client, and it turns out that sending HTML mail exclusively alienates a large portion of your potential audience.

One possible solution is simply to avoid HTML mail entirely and cater to the lowest common denominator. This is the way to go if maximum accessibility is important. However, the MIME standard does offer another option. When a MIME-compliant email program reads a normal multipart message, it treats the first part as the message body, which is displayed to the user, and the subsequent parts as file attachments:

Multipart mp = new MimeMultipart("alternative"); MimeBodyPart mbp1 = new MimeBodyPart( ); mbp1.setContent("Log file for today is attached.", "text/plain"); mp.addBodyPart(mbp1); . . . ...