sendmail 오류입니다

  **********************************************
    **      THIS IS A WARNING MESSAGE ONLY      **
    **  YOU DO NOT NEED TO RESEND YOUR MESSAGE  **
    **********************************************

The original message was received at Fri, 27 Sep 2002 08:44:47 +0900
from [000.000.000.000] <-사설IP

   ----- The following addresses had transient non-fatal errors -----
@xxx.com>

   ----- Transcript of session follows -----
... while talking to mcomail02.maxtor.com.:
>>> MAIL From:.co.kr> SIZE=3763
<<< 451 4.1.8 Domain of sender address xxxx@xxxx.co.kr does not resolve
... while talking to mcomail01.maxtor.com.:
>>> MAIL From:xxx@xxxx.co.kr> SIZE=3763
<<< 451 4.1.8 Domain of sender address xxxx@xxxx.co.kr does not resolvexxx@xxx.com>... Deferred: 451 4.1.8 Domain of sender address xxxx@xxxx.co.kr does not resolve
Warning: message still undelivered after 4 hours
Will keep trying until message is 5 days old

위의 메세지의 내용을 알고싶습니다.

메일의 ID 와 HOST를 가린것을 이해해주시고,

아시는 분은 답변을 부탁드립니다