Copy these files class.phpmailer.php to your web server:
If you are using the SMTP mailer then copy class.smtp.php as well.
If you do not have control of the include directory and you are
running PHP 4.0 or higher you can use this function to set it to the
path of your files:
$mail->PluginDir = "/path/to/phpmailer/dir";
The total size of the libraries and language files is approximately 100 Kb.