public function notifyResponsible($event)
    {
        // first email address should be admin@domain.com because from other email address mail can't be sent
        $from = [Yii::$app->params['email']['from'] => 'not-reply'];
        // add real sender
        $from[$this->author->email] = $this->author->name;
        // receiver
        $receiver = Yii::$app->params['email']['receiver']['comment'];
        $to = Yii::$app->params['email']['to'][$receiver];
        return Yii::$app->mailer->compose()
            ->setTo($to)
            ->setFrom($from)
            ->setSubject(Module::t('core', 'New comment for') . ' - ' . Lookup::item('CommentFor', $this->model))
            ->setTextBody($this->content)
            ->send();
    }