>>> MAIL From:<base@ioc_korea> SIZE=59
451 4.1.8 Domain of sender address base@ioc_korea does not resolve
kokorea at kebi.com... Deferred: 451 4.1.8 Domain of sender address base@ioc_korea does
 이런 메시지가 나오는데 뭐가 잘못되서 저런 메세지가 나오는거져?