有知道怎么用dektrium/yii2-user这个扩展的吗？注册后验证邮件发送失败 [ 2.0 版本 ]

这是反垃圾邮件系统约束条件，501 mail from address must be same as authorization user 已经讲得很清楚了。

修改一下Mailer.php的sendMessage()函数中的setFrom($this->sender)语句的参数，改成和你配置mailer时用的邮件地址一样即可。

    /**
     * @param string $to
     * @param string $subject
     * @param string $view
     * @param array  $params
     *
     * @return bool
     */
    protected function sendMessage($to, $subject, $view, $params = [])
    {
        /** @var \yii\mail\BaseMailer $mailer */
        $mailer = Yii::$app->mailer;
        $mailer->viewPath = $this->viewPath;
        $mailer->getView()->theme = Yii::$app->view->theme;
        if ($this->sender === null) {
            $this->sender = isset(Yii::$app->params['adminEmail']) ? Yii::$app->params['adminEmail'] : 'no-reply@example.com';
        }
        return $mailer->compose(['html' => $view, 'text' => 'text/' . $view], $params)
            ->setTo($to)
            ->setFrom($this->sender)
            ->setSubject($subject)
            ->send();
    }
}