这段代码可以发送本地的邮件，但是发外面的发不了，什么原因？
MailMessage mlMsg = new MailMessage();mlMsg.From = new MailAddress("mi.lin@);
mlMsg.To.Add(new MailAddress("mi.lin@));
mlMsg.Subject = "Title";
mlMsg.Body = "Test Mail";
mlMsg.IsBodyHtml = false;
//SmtpClient smtpClient = new SmtpClient("192.168.101.8");
SmtpClient smtpClient = new SmtpClient("mail.,25);
smtpClient.Credentials = new NetworkCredential("mail., "july limmit","DoMainName");
smtpClient.Timeout = 50000;
smtpClient.EnableSsl = false;
smtpClient.Send(mlMsg);
MessageBox.Show("Finish");
