이게 무슨 에러죠?

javax.mail.SendFailedException: Sending failed;
nested exception is:
class javax.mail.MessagingException: 502 Unknown command!



아래와 같이 리턴되네요

Error Message : 504 You are registered as relay area

-- You SendMail --

>> Received: from mail.seowon.com (210.223.183.200)
>> by seowon.com (210.223.183.200) with [Nmail V3.2 20020608(S)]
>> for from ;
>> Thu, 19 Jun 2003 09:58:25 +0900
>> From: =?ks_c_5601-1987?b?sPy4rsDa?=
>> Subject: 1
>> To: ****@****
>> MIME-Version: 1.0
>> X-Mailer: SM
>> Date: Thu, 19 Jun 2003 09:58:25 +0900
>> Content-Type: text/html; charset=euc-kr
>> Content-Transfer-Encoding: 8bit