메일을 보낼때 아래와 같이 에러메시지와 함께 메일이 되돌아 오네요.
어떤 문제인지 도와주세요.
  The original message was received at Fri, 25 Aug 2000 10:09:10 +0900
from [211.117.54.242]
    ----- The following addresses had permanent fatal errors -----
<bans at neoffice.com>
    ----- Transcript of session follows -----
... while talking to mail.neoffice.com.:
>>> RCPT To:<bans at neoffice.com>
<<< 550 5.7.1 <bans at neoffice.com>... Relaying denied. IP name possibly
forged [211.172.65.35]
550 <bans at neoffice.com>... User unknown