成功发送邮件后成功消息提醒

Question

成功消息提醒无效...
我的代码：

$from="contactus@test.com.au";
$to = $email;
$subject = "Sign Up Mail verification ";
$message = 'test';

if(mail($to,$subject,$message,$headers)){
    //echo "Your Account Activate will be Soon";
    echo '<script type="text/javascript">alert("Confirmation sent to your registered email. 
        Please check your inbox.");</script>';
    echo '<script type="text/javascript">window.location.assign("http://test.com.au/register/");
        </script>';
}

此代码有什么问题？