c# - 为什么会出现此错误：尝试对无法访问的网络进行套接字操作 [2a00:1450:4008:c01::6c]:25

Question

我正在尝试从 C# 桌面应用程序发送电子邮件，我在此页面上引用了此页面，这http://www.emailarchitect.net/easendmail/kb/csharp.aspx?cat=0是我的代码，但它给了我以下异常

A socket operation was attempted to an unreachable network [2a00:1450:4008:c01::6c]:25

在这条线上

oSmtp.SendMail(oServer, oMail); 我哪里错了

private void sendmail()
        {
            SmtpMail oMail = new SmtpMail("TryIt");
            EASendMail.SmtpClient oSmtp = new EASendMail.SmtpClient();

            oMail.From = "mo@gmail.com";

            oMail.To = "mo@gmail.com";

            oMail.Subject = "test email from c# project";

            oMail.TextBody = "this is a test email sent from c# project, do not reply";

            // Your SMTP server address
            SmtpServer oServer = new SmtpServer("smtp.gmail.com");

            // User and password for ESMTP authentication,            
            oServer.User = "mo@gmail.com";
            oServer.Password = "account password here";   


            try
            {
                Console.WriteLine("start to send email ...");
                oSmtp.SendMail(oServer, oMail);//getting error here
                Console.WriteLine("email was sent successfully!");
            }
            catch (Exception ep)
            {
                Console.WriteLine("failed to send email with the following error:");
                Console.WriteLine(ep.Message);
            }