The Mail::factory PHP Script does not like to play well with some of our servers,
Instruct the client instead to use this one - https://github.com/PHPMailer/PHPMailer
When sending emails in cPanel, mailer script must utilize smtp authentication and PHP-Pear module or mails will not go out. To verify if Pear module is installed, login to cpanel > PHP PEAR Packages > show system installed modules.
Then, mailer script can be tailored/modified as per below: