1  163邮箱 HOST:smtp.163.com

public static string CreateTimeoutTestMessage(string server)          {              string Success = "发送成功";              try              {                  string _to = "1035092449@qq.com";                  string _from = "young-20@163.com";                  string _subject = "Using the new SMTP client.";                  string _body = @"Using this new feature, you can send an e-mail message from an application very easily.";                  MailMessage message = new MailMessage();                  message.From = new MailAddress(_from);                  //可以利用MailMessage.To.Add方法增加要发送的邮件地址                  message .To .Add (new MailAddress ("652105072@qq.com"));                  message.To.Add(new MailAddress(_to));                  message.Subject = _subject;                  message.Body = _body;                    //添加附件                  Attachment a = new Attachment(@"C:/Users/Administrator/Desktop/smtpclient.rar");                  message.Attachments.Add(a);                  //设置邮箱的地址或IP                  SmtpClient client = new SmtpClient(server);                  //设置邮箱端口，pop3端口:110, smtp端口是:25                   client.Port = 25;                                    //设置超时时间                  client.Timeout = 9999;                                    //要输入邮箱用户名与密码                                    client.Credentials = new NetworkCredential("young-20@163.com", "******");                  client.Send(message);              }              catch (Exception ex)              {                  Success = ex.ToString();              }              return Success;          }

2 QQ邮箱

  QQ邮箱默认的SMTP服务是关闭的，要自己去开通。

  HOST:smtp.qq.com

try              {                                    SmtpClient client = new SmtpClient();                  client.Host = "smtp.qq.com";                  MailMessage mm = new MailMessage();                  client.Port = 25;                                    mm.From = new MailAddress("652105072@qq.com");                                  mm.To.Add(new MailAddress("1035092449@qq.com"));                  mm.Subject = "Hello~!";                  mm.Body = "HIthere.here is a post ";                  mm.IsBodyHtml = false;                  mm.Priority = MailPriority.High;                    client.Credentials = new NetworkCredential("652105072@qq.com", "******");                  client .Send (mm);                                 }              catch (Exception ex)              {                  MessageBox.Show(ex.Message);              }