아래 링크 참고 하셔서 PTR 레코드 등록해서 사용하십시오.

http://passkorea.net/Board/ViewDoc.aspx?brdNo=8&docNo=29293&page=1&brdType=

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The original message was received at Mon, 6 Apr 2009 17:51:16 +0900 from cleansmtp1.unimo.co.kr [211.42.201.137]

   ----- Transcript of session follows ----- ... while talking to mx.servizi.fweds-spc.it.:
>>> DATA
<<< 450 4.7.1 Client host rejected: cannot find your reverse hostname, [211.42.201.138] <****@****>... Deferred: 450 4.7.1 Client host rejected: cannot find your reverse hostname, [211.42.201.138] <<< 554 5.5.1 Error: no valid recipients ... while talking to mx-2.servizi.fweds-spc.it.:
>>> DATA
<<< 450 4.7.1 Client host rejected: cannot find your reverse hostname, [211.42.201.138] <****@****>... Deferred: 450 4.7.1 Client host rejected: cannot find your reverse hostname, [211.42.201.138] <<< 554 5.5.1 Error: no valid recipients ... while talking to mx-1.servizi.fweds-spc.it.:
>>> DATA
<<< 450 4.7.1 Client host rejected: cannot find your reverse hostname, [211.42.201.138] <****@****>... Deferred: 450 4.7.1 Client host rejected: cannot find your reverse hostname, [211.42.201.138] <<< 554 5.5.1 Error: no valid recipients
Warning: message still undelivered after 4 hours Will keep trying until message is 5 days old