SmtpClient smtp = new SmtpClient();
smtp.Host = "smtp.163.com";
MailAddress Receive = new MailAddress("XXXXX@163.com");
MailAddress SendOut = new MailAddress("XXXXXX@163.com","XX");
MailMessage mail = new MailMessage(SendOut, Receive);
mail.Body = "Test";
mail.Subject = "Test";
NetworkCredential myCredentials = new NetworkCredential("XXXX@163.com", "********");
smtp.Credentials = myCredentials;
smtp.Send(mail);
Console.ReadKey();