PHP mail with SMTP

I'm using this code for my mail scr开发者_开发技巧ipt with SMTP (without ssl): http://email.about.com/od/emailprogrammingtips/qt/PHP_Email_SMTP_Authentication.htm

In line two, the script wants to include a mail.php, but I can't find the code for this mail.php anywhere on this site. When I'm excluding mail.php php tells me that it can't find the class 'mail'. PEAR Package is installed. What code do I have to include?

You must install the PEAR::Mail package as well ("pear install Mail" from the command line)