new to james

[subash gopalaswamy]

Hi,
I configured james with my service providers dns entries, but the error is no mail is 
being sent to any email ids except to the local addresses.
(james is the default mailserver for a local network- all mails frm users are routed 
thru james to outside domains). I tried the win98 config and also the changed the 
config.xml file. still no mail is sent outside [ 504(warsaw) valid host name required 
-- is the error i got ].
what i have to do in this case . somebody advice.