public static function to()
    {
        $args = func_get_args();

        $receivers = [];

        foreach ($args as $arg) {
            if (is_string($arg)) {
                $receivers[] = $arg;
            } elseif (is_array($arg)) {
                foreach ($arg as $value) {
                    $receivers[] = $value;
                }
            }
        }

        $mail = new self();
        $mail->setDestination($receivers);

        return $mail;
    }