با نوشتن کد زیر برای ارسال ایمیل 
MailMessage msg = new MailMessage();

            msg.From = new MailAddress("ali@MyCompany.com");

            msg.To.Add("ali@MyCompany.com");

            msg.Subject = "for test";

            msg.Body = "this is for test";

            SmtpClient smtp = new SmtpClient("mail.MyCompany.com", 25);

            smtp.UseDefaultCredentials = false;

            smtp.Credentials = new NetworkCredential("ali@MyCompany.com", "MyPassword");

            try

            {

                smtp.Send(msg);

            }

            catch (Exception ex)

            {

                MessageBox.Show(ex.Message);

            }

با خطای زیر روبر می شوم لطفا راهنمایی کنید
 "An established connection was aborted by the software in your host machine"