private void uidNext(Responder responder, MessageManager.MetaData metaData)
     throws MailboxException {
   final MessageUid uid = metaData.getUidNext();
   final StatusResponse untaggedOk =
       statusResponseFactory.untaggedOk(HumanReadableText.UIDNEXT, ResponseCode.uidNext(uid));
   responder.respond(untaggedOk);
 }