Remember the pit of an email push, c # sending emails using Tencent corporate mailbox based on smtp always fails, the reason for timeout

First paste the code first

try 
            { 
                MailAddress receiver = new MailAddress ("zhan.com", "Mailbox"); 
                MailAddress sender = new MailAddress (WebSettingsConfig.SenderAddress, "PC"); 
                MailMessage message = new MailMessage (); 
                message.From = sender; // Sender 
                message.To.Add (receiver); // Recipient // message.CC.Add ( sender ); // 
                CC sender message.Subject 
                = model.Title; // Title 
                message.Body = "Content : "+ Model.Content +" <br> Contact name: "+ model.SenderName +" <br> Contact email: "+ model.SenderEmail +" <br> Phone number: "+ model.SenderPhone; // Content 
                message .IsBodyHtml = true;// Whether the supported content is HTML 

                SmtpClient client = new SmtpClient ();// Whether the content is supported by HTML 
                client.Host = "smtp.exmail.qq.com"; //
                client.Port = 587; 
                client.EnableSsl = true; // Whether SSL is enabled 
                //client.Timeout = 10000; // Timeout 
                client.DeliveryMethod = SmtpDeliveryMethod.Network; 
                client.UseDefaultCredentials = false; 
                client.Credentials = new NetworkCredential (WebSettingsConfig .SenderAddress, WebSettingsConfig.SenderPassword); 
                client.Send (message); 
                return this.Json (new ResultU (true, ConstResult.success, "mail sent successfully!")); 
            } 
            Catch (Exception ex)
            {
                LogFile.WriteErrorLog (DateTime.Now + "mail sending failed:" + ex.Message);
                return this.Json (new ResultU (false, ConstResult.fail, "Failed to send email!")); 
            }

　　There is nothing special about the code for sending emails, but because of the failure of sending with Tencent's corporate email, it always prompts for timeout. There are also some solutions found online, almost all do not use SSL, use port 25. Not feeling good

Look at Tencent's official setup instructions, using SSL, port number 465, but if you press the configuration, it always prompts timeout. No way, googled and found that the port number should be 587

You can check it out here  https://stackoverflow.com/questions/15796530/what-is-the-difference-between-ports-465-and-587

So in fact it is not misleading by Tencent, it can only be said that it is lack of knowledge