code: protected SMailPostalParkingLot createPostalParkingLot() {
          final SMailPostalParkingLot parkingLot = new SMailPostalParkingLot();
          final SMailPostalMotorbike motorbike = new SMailPostalMotorbike();
          final String hostAndPort = fessConfig.getMailSmtpServerMainHostAndPort();
          final List<String> hostPortList = DfStringUtil.splitListTrimmed(hostAndPort, ":");
          motorbike.registerConnectionInfo(hostPortList.get(0), Integer.parseInt(hostPortList.get(1)));
          motorbike.registerReturnPath(fessConfig.getMailReturnPath());
          parkingLot.registerMotorbikeAsMain(motorbike);
          return parkingLot;
      }
docs: ------------------