public function actionDownloadMail($file)
    {
        $filePath = Yii::getAlias($this->module->panels['mail']->mailPath) . '/' . basename($file);

        if ((mb_strpos($file, '\\') !== false || mb_strpos($file, '/') !== false) || !is_file($filePath)) {
            throw new NotFoundHttpException('Mail file not found');
        }

        return Yii::$app->response->sendFile($filePath);
    }