특정 사이트에 메일전송이 안될때

특정사이트 아래와같이 posco로만 보내면 아래와같은 에러가 뜨는데...

어디가 잘못인지 -.- 감이 안오네영

답변부탁드릴께요~

참고로 리눅스 까지버젼에 sendmail을 쓰구있어여   

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The original message was received at Fri, 9 Aug 2002 17:02:34 +0900
from [210.111.1.41]

   ----- The following addresses had transient non-fatal errors -----
<lim56@posco.co.kr>

   ----- Transcript of session follows -----
<lim56@posco.co.kr>... Deferred: Connection timed out with oversea2.posco.co.kr.
Warning: message still undelivered after 4 hours
Will keep trying until message is 5 days old