using (var httpClient = new WebClient())
{
IWebProxy objProxy = new WebProxy("proxy.myproxy.com", 1234);
httpClient.Proxy = objProxy;
httpClient.Headers.Add("User-Agent: Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.22 (KHTML, like Gecko) Chrome/25.0.1364.172 Safari/537.22");
httpClient.DownloadFile("https://fast.usps.com/fast/labelListFileDownloadFile.action?fileName=ALL_LABELS.ZIP" , LoggingHandler.LabelingListDataPath + GetFilename(filenames.LabelingListFile));
httpClient.Dispose();
}