using (var client = new SmtpClient()) { client.UseDefaultCredentials = false; client.Host = setting.Host; client.Port = setting.Port; client.EnableSsl = setting.EnableSsl; CredentialCache cache = new CredentialCache(); // authentication type: gssapi, ntlm, WDigest, login cache.Add(setting.Host, setting.Port, "login", new NetworkCredential(setting.UserName, setting.Password)); client.Credentials = cache; using (var message = new MailMessage()) { var body = System.IO.File.ReadAllText("content.email"); message.From = new MailAddress(setting.Sender); message.ReplyToList.Add(new MailAddress(setting.Email)); message.To.Add(new MailAddress(setting.Receiver)); message.IsBodyHtml = true; message.Body = body; message.Subject = setting.Subject; message.BodyEncoding = Encoding.UTF8; message.SubjectEncoding = Encoding.UTF8; try { client.Send(message); } catch (Exception ex) { Log.Write(ex); } } }