def msg_tmp_dir
      @dir_count += 1
      dir = File.expand_path(File.join(@media_dir, "#{@dir_count}"))
      FileUtils.mkdir_p(dir)
      dir
    end
def msg_tmp_dir
      @dir_count += 1
      dir = File.expand_path(File.join(@media_dir, "#{@dir_count}"))
      FileUtils.mkdir_p(dir)
      dir
    end
Helper to temp_file to create a unique temporary directory that is a
 child of tmp_dir  This version is based on the message_id of the mail.