Java Network Programming, Second Edition

Sending Email

The most basic email need of a Java program is to send messages. While email clients like Eudora and mailing list managers like listproc are the only common programs that receive messages, all sorts of programs send messages. For instance, web browsers can submit HTML forms via email. Security scanning tools like Satan can run in the background and email their results to the administrator when they’re done. When the Unix cron program detects a misconfigured crontab file, it emails the error to the owner. Books & Writers runs a service that’s very popular with authors to track the sales rank of their books on Amazon.com and notify them periodically via email. (See http://www.booksandwriters.com/rank.html.) A massively parallel computation like the SETI@home project can submit individual results via email. Some multiplayer games like chess can be played across the network by emailing the moves back and forth (though this scheme wouldn’t work for faster-moving games like Quake or even for speed chess). And these are just a few of the different kinds of programs that send email. In today’s wired world, by far the simplest way to notify a user of an event when he’s not currently sitting in front of the computer that the program is running on is to send him email.

The JavaMail API provides everything your programs need to send email. To send a message, a program just follows these eight steps:

1. Set the mail.host property to point to the local mail server.

2. Start a mail session ...