docs: public String getMessageInfoType(BaseMessage externalMessage)
      {
          String strSubject = (String)externalMessage.getMessageHeader().get(EmailMessageTransport.SUBJECT_PARAM);
          if (strSubject != null)
              if (strSubject.toUpperCase().startsWith("RE:"))
                  return MessageInfoTypeModel.REPLY;   // This is (most likely) a reply to my message.
          return super.getMessageInfoType(externalMessage);
      }