code: public void commandFailed(ImapCommand command,
                                String responseCode,
                                String reason) {
          tag();
          message(NO);
          responseCode(responseCode);
          commandName(command);
          message("failed.");
          message(reason);
          end();
      }
docs: Writes a standard NO response on command failure, together with a
  descriptive message.
  Response is writen as:
  <pre>     a01 NO [responseCode] COMMAND_NAME failed. <reason></pre>
  
  @param command      The ImapCommand which failed.
  @param responseCode The Imap response code to send.
  @param reason       A message describing why the command failed.