使用 System.Web.Mail 发送电子邮件

我想用asp发送电子邮件。

我用这个代码

using System.Web.Mail;

MailMessage msg = new MailMessage();
msg.To = "[email protected] /cdn-cgi/l/email-protection";
msg.From = "[email protected] /cdn-cgi/l/email-protection";
msg.Subject = "Send mail sample";
msg.BodyFormat = MailFormat.Html;
string msgBody="Hello My Friend. This is a test.";
msg.Body = msgBody ;
SmtpMail.SmtpServer = "localhost";
SmtpMail.Send(msg);

但我收到错误：

命令顺序错误。服务器响应是：此邮件服务器在尝试发送到非本地电子邮件地址时需要身份验证。请检查您的邮件客户端设置或联系您的管理员以验证是否为此服务器定义了域或地址。

如何用asp发送邮件？

我用这个代码。

 MailMessage msg = new MailMessage();
 msg.Body = "Body";

 string smtpServer = "mail.DomainName";
 string userName = "[email protected] /cdn-cgi/l/email-protection";
 string password = "MyPassword";
 int cdoBasic = 1;
 int cdoSendUsingPort = 2;
 if (userName.Length > 0)
  {
    msg.Fields.Add("http://schemas.microsoft.com/cdo/configuration/smtpserver", smtpServer);
    msg.Fields.Add("http://schemas.microsoft.com/cdo/configuration/smtpserverport", 25);
    msg.Fields.Add("http://schemas.microsoft.com/cdo/configuration/sendusing", cdoSendUsingPort);
    msg.Fields.Add("http://schemas.microsoft.com/cdo/configuration/smtpauthenticate", cdoBasic);
    msg.Fields.Add("http://schemas.microsoft.com/cdo/configuration/sendusername", userName);
    msg.Fields.Add("http://schemas.microsoft.com/cdo/configuration/sendpassword", password);
    }
    msg.To = user.Email;
    msg.From = "[email protected] /cdn-cgi/l/email-protection";
    msg.Subject = "Subject";
    msg.BodyEncoding = System.Text.Encoding.UTF8;
    SmtpMail.SmtpServer = smtpServer;
   SmtpMail.Send(msg);