uses wininet; 
 
function ProxyServer(var Proxy: string): boolean; 
var 
  lg: DWord; 
  IPI: PInternetProxyInfo; 
begin 
  lg := $1000; 
  GetMem(IPI, lg); 
  try 
    if InternetQueryOption(nil, INTERNET_OPTION_PROXY, IPI, lg) and 
      (IPI^.dwAccessType = INTERNET_OPEN_TYPE_PROXY) then begin 
      Result := True; 
      Proxy := IPI^.lpszProxy; 
    end else Result := False; 
  finally 
    FreeMem(IPI); 
  end; 
end; 
 
 
procedure TForm1.Button2Click(Sender: TObject); 
var s: string; 
begin 
  if ProxyServer(s) then 
    showmessage(s) else 
    showmessage('kein Proxy'); 
end;