using System; using System.Collections.Generic; using System.Text; using System.Net.Mail; using System.Diagnostics; namespace MailTest {      class Program      {          static void Main(string[] args)          {               Encoding encoding = Encoding.GetEncoding("GB2312");               MailAddress from = new MailAddress("youmailname@163.com", "19850101", encoding);               MailAddress to = new MailAddress("youmailname@163.com");               MailMessage mail = new MailMessage(from, to);               mail.Subject = "test";               mail.Body = "hello world";               mail.SubjectEncoding = encoding;               mail.BodyEncoding = encoding;               SmtpClient smtp = new SmtpClient("smtp.163.com");               smtp.DeliveryMethod = SmtpDeliveryMethod.Network;               smtp.UseDefaultCredentials = true;             smtp.Credentials = new System.Net.NetworkCredential("rjgcwwdz@163.com", "19850101");               smtp.Send(mail);          }      } }