public function isValid($email)
    {
        // Does it look like an email address?
        if (! $this->isEmail($email)) {
            return false;
        }

        // Is is an example domain?
        if ($this->isExample($email)) {
            return false;
        }

        // Is is a it disposable?
        if ($this->isDisposable($email)) {
            return false;
        }

        // Is it role based?
        if ($this->isRole($email)) {
            return false;
        }

        // Does it have an MX record?
        if (! $this->hasMx($email)) {
            return false;
        }

        return true;
    }