using System.Web.Mail to send email

there are many demos for send a email with c sharp language .however,you will find that most of them will be failed because of SMTPServer.Especially,authorization is required.

public void SendEMail()
        ...{
            MailMessage mail = new MailMessage();
            mail.Priority = MailPriority.High;
            mail.From = "cccc@gmail.com";
            mail.To = "cccc@163.com";
            mail.Subject = "Send EMail System Demo";
            mail.Body = "Just for test.";
            mail.BodyEncoding = Encoding.UTF8;

            // authorization
            mail.Fields.Add("http://schemas.microsoft.com/cdo/configuration/sendusing", 1);
            mail.Fields.Add("http://schemas.microsoft.com/cdo/configuration/sendemailaddress", mail.From);
            mail.Fields.Add("http://schemas.microsoft.com/cdo/configuration/smtpuserreplyemailaddress", mail.From);
            mail.Fields.Add("http://schemas.microsoft.com/cdo/configuration/smtpaccountname", "cccc@163.com");
            mail.Fields.Add("http://schemas.microsoft.com/cdo/configuration/sendpassword", "cccc");
            mail.Fields.Add("http://schemas.microsoft.com/cdo/configuration/smtpauthenticate", 1);
            mail.Fields.Add("http://schemas.microsoft.com/cdo/configuration/smtpserver", "smtp.163.com");

            SmtpMail.SmtpServer = "smtp.163.com";
            SmtpMail.Send(mail);
        }
        #endregion