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();
    }
}

指定路径

'i18n' => [ 
		'translations' => [ 
			'*' => [ 
				'class' => 'yii\i18n\PhpMessageSource',
				'basePath' => '@common/messages',
				'sourceLanguage' => 'zh-CN',
				'fileMap' => [ 
				'app' => 'app.php',
				'app/error' => 'error.php', 
				'nav' => 'nav.php',
		] 
        ],