루트메일로 자꾸 -_- 이상한 메일들이...

Mail Delivery Subsystem <MAILER-DAEMON@domain.com>

Warning: could not send message for past 4 hours

    **********************************************
    **      THIS IS A WARNING MESSAGE ONLY      **
    **  YOU DO NOT NEED TO RESEND YOUR MESSAGE  **
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The original message was received at Wed, 7 Jul 2004 06:00:28 +0900
from localhost.localdomain [127.0.0.1]

   ----- Transcript of session follows -----
<drunken7067@korea.com>... Deferred
Warning: message still undelivered after 4 hours
Will keep trying until message is 5 days old

저런식으로 수백통의 메일이 날아오네요.

무슨 문제가 있는듯한데...

sendmail 쓰고 있습니다.

왜 이러한 메일들이 자꾸 날아오는 것일까요?

시간나실때 고수분들 답변 부탁드립니다.