public function actionSignup($defaultUrl = null)
    {
        $user = $this->module->model('User');
        $configProfileForm = [
            'user' => $user,
            'scenario' => ProfileForm::SCENARIO_CREATE,
            'captchaActionUid' => $this->uniqueId . '/' . static::$captchaActionId,
        ];
        $model = $this->module->model('ProfileForm', [$configProfileForm]);

        $post = Yii::$app->request->post();
        $loaded = $model->load($post);
        if ($loaded && $model->save(true)) {
            $this->sendSignupEmail($model);
            if ($defaultUrl === null) {
                $defaultUrl = Yii::$app->getHomeUrl(); // not null because sometimes go back to signup (without POST) will error
            }
            return $this->goBack($defaultUrl);
        } else {
            return $this->render('profile-form', [
                'model' => $model,
            ]);
        }
    }