You can override the Mail class and in this way you have controll of all the emails that are sent through presta
class Mail extends MailCore
{
public static function Send($id_lang, $template, $subject, $template_vars, $to, $to_name = null, $from = null, $from_name = null, $file_attachment = null, $mode_smtp = null, $template_path = _PS_MAIL_DIR_, $die = false, $id_shop = null)
{
switch ($template)
{
// do whatever you wish
}
}
}