public String getMessage(String s) {

        if (s != null) {

            int suchMessageNummer = Integer.parseInt(s);
            String suchFile = "";
            int count = 0;

            for (File box : dir.listFiles()) {
                for (File file : box.listFiles()) {
                    if (file.isFile() && file.getName().endsWith(".mail") && suchMessageNummer == ++count) {
                        try {
                            suchFile = restoreMailFromFile(file).getEmail();
                        } catch (IOException e) {
                            e.printStackTrace();
                        } catch (ClassNotFoundException e) {
                            e.printStackTrace();
                        }
                        return "+OK message " + s + file.length() + CRLF + suchFile + CRLF;
                    }
                }
            }

        }
        return "-ERR no such message " + s + CRLF;
    }