외부에서 메세지를 보내면...리턴되는데..
리턴된 메일의 내용입니다.
어떻게 해야하는지 알려주세여~

The original message was received at Thu, 22 Aug 2002 17:11:34 +0900
from www21.hanmail.net [211.32.117.201]

----- The following addresses had permanent fatal errors -----
<****@****>
(reason: 550 Not Pop3 Before authentication)

----- Transcript of session follows -----
... while talking to cel.cau.ac.kr.:
>>> RCPT To:<****@****>
<<< 550 Not Pop3 Before authentication
550 5.1.1 <****@****>... User unknown


Reporting-MTA: dns; smail-105.hanmail.net
Arrival-Date: Thu, 22 Aug 2002 17:11:34 +0900

Final-Recipient: RFC822; ****@****
Action: failed
Status: 5.1.1
Remote-MTA: DNS; cel.cau.ac.kr
Diagnostic-Code: SMTP; 550 Not Pop3 Before authentication
Last-Attempt-Date: Thu, 22 Aug 2002 17:11:36 +0900