게시판을 검색해봤는데 명쾌한 해답이 없더군요.
제목과 같은 현상이 발생하는 원인과 해결방법을 알고싶습니다.

+++++++ 메일 원문 ++++++++++++++++++++++++++


From: "young-telecom.co.kr PostMaster" <****@****>
To: <****@****>
Sent: Monday, July 21, 2003 11:38 AM
Subject: !Nmail Send error 550 이 도메인은 릴레이가 허락되지 않습니다. relaying mail to sktellink.com is not allowed


>
> Error Message : 550 이 도메인은 릴레이가 허락되지 않습니다. relaying mail to sktellink.com is not allowed
>
> -- You SendMail --
>
> >> Received: from hoyeul (192.168.0.224)
> >> by young-telecom.co.kr (61.77.240.88) with [Nmail V3.2 20020608(S)]
> >> for <****@****> from <****@****>;
> >> Mon, 21 Jul 2003 11:38:19 +0900
> >> Message-ID: <009201c34f31$0c941910$****@****>
> >> Reply-To: "Chung Hoyeul" <****@****>
> >> From: "Chung Hoyeul" <****@****>
> >> To: "=?ks_c_5601-1987?B?seggvLrIrw==?=" <****@****>
> >> Subject: =?ks_c_5601-1987?B?v7XF2re5xN4=?=
> >> Date: Mon, 21 Jul 2003 11:37:37 +0900
> >> MIME-Version: 1.0
> >> Content-Type: multipart/alternative;
> >> boundary="----=_NextPart_000_008F_01C34F7C.7C092920"
> >> X-Priority: 3
> >> X-MSMail-Priority: Normal
> >> X-Mailer: Microsoft Outlook Express 6.***-****-****
> >> X-MimeOLE: Produced By Microsoft MimeOLE V6.***-****-****