[Exim] exim woes

extract from exim.conf
----------------------

exchange_router:
driver = manualroute
domains = +local_domains
local_parts = /etc/mail/exchange_users
route_data = ww.xx.yy.zz
transport = remote_smtp
no_verify

Extract from mainlog:

<= root@??? U=root P=local S=296 T="Testing"
2004-01-08 17:26:13 1Aec33-00042W-0V ** user@???
R=exchange_router T=remote_smtp: SMTP error from remote mailer after
RCPT TO:<craigsc@???>: host ww.xx.yy.zz [ww.xx.yy.zz]: 550 5.7.1
Unable to relay for user@???
2004-01-08 17:26:13 1Aec33-00042Z-3h <= <> R=1Aec33-00042W-0V U=mail
P=local S=1194 T="Mail delivery failed: returning message to sender"
2004-01-08 17:26:13 1Aec33-00042W-0V Completed

Anyone have any ideas or can see anything immidiately wrong please help.

..C