title: Resolving a Proxy Authentication Required Issue
body: <p>I've written a Delphi application which requires communication with a remote web server. I pass INTERNET_OPEN_TYPE_PRECONFIG flag into the InternetOpen function to initialise my app's use of the WinINet functions and by doing so my app to retrieve the user's Internet configuration from the registry. </p>
  
  <pre><code>  NetHandle := InternetOpen('WebTool', INTERNET_OPEN_TYPE_PRECONFIG, nil, nil, 0);
    if Assigned(NetHandle) then
    begin
      try
        hConnect := InternetConnect(NetHandle, PChar(ServerName), ServerPort,
                        nil, nil, INTERNET_SERVICE_HTTP, 0, 1);
        if Assigned(hConnect) then
        begin
          try
            // Open the request
            hRequest := HttpOpenRequest(hConnect, PChar('POST'),
                            PChar(ServerScript), nil, nil, nil,
                            HTTPOpenRequestFlags, 0);
            if Assigned(hRequest) then
            begin
  </code></pre>
  
  <p>Perhaps due to my ignorance, I believed this enabled communication with the remote web server using the user's particular Internet settings whether direct connection or via a proxy. It certainly works via my company's proxy server.</p>
  
  <p>However, I've now encountered one customer for whom the above does not allow him access. He sees a "Proxy Authentication Required" (HTTP status code 407) instead.</p>
  
  <p>Is this something that my app should be handling (e.g. provide a form to enter proxy authentication details and pass them with my HTTP requests)? Is there a way of picking up this information automatically? </p>
  
  <p>Or is this simply down to a configuration issue that the customer's IT department can easily resolve?</p>
  
  <p>Any pointers would be much appreciated.</p>