Noptin_New_Subscriber_Trigger::is_rule_valid_for_args( $rule,  $args,  $subscriber,  $action )

    public function is_rule_valid_for_args( $rule, $args, $subscriber, $action ) {

        $settings = $rule->trigger_settings;

        // Are we filtering by subscription method?
        if ( empty( $settings['subscribed_via'] ) || '-1' === $settings['subscribed_via'] ) {
            return true;
        }

        return $settings['subscribed_via'] === $subscriber->_subscriber_via;

    }