function DownloadFile(SourceFile, DestFile: string): Boolean; 
begin 
  try 
    Result := UrlDownloadToFile(nil, PChar(SourceFile), PChar(DestFile), 0, nil) = 0; 
  except 
    Result := False; 
  end; 
end; 

procedure JPEGtoBMP(const FileName: TFileName);
var
  jpeg: TJPEGImage; 
  bmp:  TBitmap;
begin
  jpeg := TJPEGImage.Create;
  try 
    jpeg.CompressionQuality := 100; {Default Value}
    jpeg.LoadFromFile(FileName);
    bmp := TBitmap.Create;
    try 
      bmp.Assign(jpeg);
      bmp.SaveTofile(ChangeFileExt(FileName, '.bmp'));
    finally 
      bmp.Free 
    end; 
  finally 
    jpeg.Free 
  end;
end;

procedure TForm1.FormCreate(Sender: TObject);
const
  SourceFile = 'http://mailsend.kiber-zona.org/captcha/index.php';
  DestFile = 'index.jpeg';
begin
DownloadFile(SourceFile, DestFile);
JPEGtoBMP('index.jpeg');
image1.Picture.LoadFromFile('index.bmp');
end;

procedure TForm1.BitBtn1Click(Sender: TObject);
var
response: string;
formData: TIdMultiPartFormDataStream;
begin
  formData := TIdMultiPartFormDataStream.Create;
  formData.AddFormField('usrurl',Edit1.text);
  formData.AddFormField('mail',Edit2.text);
  formData.AddFormField('simbols',Edit3.text);
  response := idHTTP1.Post('http://mailsend.kiber-zona.org/index.php',formData);
end;