Smtp异常需要完美的答案

Question

我有几个月前运行良好的这段代码。现在它抛出两个异常。

连接尝试失败，因为一段时间后连接方未正确响应，或者连接建立失败，因为连接的主机未能响应199.168.188.194:25

1. System.Net.Mail.SmtpException：'发送邮件失败'-WebException：无法连接到远程服务器

2. SocketException：连接尝试失败，因为一段时间后连接方未正确响应，或者由于连接的主机未能响应，建立的连接失败。

   MailMessage email_msg = new MailMessage("test@email.com", "test@email.com", "Order Confirm", "Dear ss! your Order Has Been Confirmed. Thanx For Shoping");
   email_msg.IsBodyHtml = true;
   SmtpClient mailclient = new SmtpClient();
   System.Net.NetworkCredential basic = new System.Net.NetworkCredential("username", "password");
   mailclient.Host = "mail.testdeva.com";
   mailclient.UseDefaultCredentials = false;
   mailclient.Credentials = basic;
   mailclient.DeliveryMethod = SmtpDeliveryMethod.Network;
   mailclient.Send(email_msg);
   
   email_msg.Dispose();
   email_msg = null;
   mailclient.Dispose();
   mailclient = null;
   

真的很感谢答案