Asking about send mail

System.Net.Mail.MailMessage mail = new System.Net.Mail.MailMessage();
           SmtpClient SmtpServer = new SmtpClient("smtp.gmail.com");

           mail.From = new MailAddress("Sender email id"); // enter senders email address here
           mail.To.Add("receivers email id");
           mail.Subject = "subject";
           mail.Body = "avc";
         //  Attachment data = new Attachment("D:\\file.bmp");
           //  Attachment data = new Attachment(@"D:\file.pdf");
         //  mail.Attachments.Add(data);
           SmtpServer.Port = 587;
           SmtpServer.Credentials = new System.Net.NetworkCredential("Sender ", "password"); ///// enter email address of the sender nd password of the sender here in parameters
           SmtpServer.EnableSsl = true;

           SmtpServer.Send(mail);