C#發送郵件失敗，使用System.Net.Mail.SmtpClient發送失敗解決，推薦用System.Web.Mail.SmtpMail發送郵件，一次成功

System.Net.Mail.SmtpClient一般發送如果啓用了ssl則他會先從25端口去建立握手，一般郵件服務器都會禁用25端口，因此會發送報錯，遠程服務器無響應，連接超時

推薦用web方式發送郵件，這樣成功率很高，需要引用C#的程序集組件System.Web

參考代碼：

   public static void SendEmail()
        {
            //發件人
            const string sendAddress = "[email protected]";
            //發件人密碼
            const string sendPassword = "123456";
            //收件人
            const string receiveAddress = "[email protected]";

            System.Web.Mail.MailMessage mail = new System.Web.Mail.MailMessage();
            try
            {
                mail.From = sendAddress;
                mail.To = receiveAddress;
                mail.Subject = "whl測試發送郵件2-26-1";
                mail.BodyFormat = System.Web.Mail.MailFormat.Html;
                mail.Body = "whl發送的測試郵件" + DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss");

                mail.Fields.Add("http://schemas.microsoft.com/cdo/configuration/smtpauthenticate", "1"); //basic authentication
                mail.Fields.Add("http://schemas.microsoft.com/cdo/configuration/sendusername", sendAddress); //set your username here 發件人郵箱
                mail.Fields.Add("http://schemas.microsoft.com/cdo/configuration/sendpassword", sendPassword); //set your password here 發件人郵箱密碼
                mail.Fields.Add("http://schemas.microsoft.com/cdo/configuration/smtpserverport", 465);//發送端口號
                mail.Fields.Add("http://schemas.microsoft.com/cdo/configuration/smtpusessl", "true");//是否啓用ssl
                
                //需要引用組件System.Web
                System.Web.Mail.SmtpMail.SmtpServer = "msg.petrochina.com.cn";
                System.Web.Mail.SmtpMail.Send(mail);

                Console.WriteLine("發送郵件成功");
            }
            catch (Exception ex)
            {
                var exg = ex.InnerException ?? ex;
                string msg = exg.ToString();
                Console.WriteLine(msg);
            }
        }

 

轉載：

https://blog.csdn.net/molu474305148/article/details/99713389

https://www.cnblogs.com/tsql/p/9078163.html