the error:
Warning: require_once(Mail.php) [function.require-once]: failed to open stream: No such file or directory in /vservers/cindydaigleo/htdocs/webassist/email/PEAR_Mail_using_SMTP_php.php on line 115
means that the path to pear is not correct.
you will need to contact the host to determine the correct path to pear.