With this class you can send email that is both in HTML format and text format. Don't let the word 'class' scare you it is extremely easy to use.
Go to the following site and download this class.
http://phpmailer.sourceforge.net
Then put the following line in your PHP code.
require_once($DOCUMENT_ROOT . "/full_path_to_the_file/class.phpmailer.php");
They have some good examples of how to use this the learning curve of implementing this class is literally a 1 on a 1-10 scale.
~Eugene Kelly