UserAgent

 bulider.AppendLine("User-Agent: Mozilla/5.0 (Windows NT 6.1; IE 9.0)");

  sbSend.Append("User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; .NET CLR 1.1.4322)\r\n");

requestHeaders.Add("User-Agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; SV1; .NET CLR 1.1.4322; .NET CLR 2.0.50727)");