[exim] need fully-qualified hostname

I have configurated a Exim4 smtp-server. It works allrigth exept that i
cant send to one domain. when i try to send to thet domain i get the
following error in the mainlog:

2006-11-23 12:39:40 1GnCvc-0003Kp-7W ** xxxxxxxx@??? R=dnslookup
T=remote_smtp: SMTP error from remote mail server after RCPT
TO:<xxxxxxx@???>: host xxxxx.xxxxxxx.com [213.xxx.xxx.xx]: 504
<localhost>: Helo command rejected: need fully-qualified hostname

The domain of the email address differs from the host. Can that be a
problem.
I have tried google the answer but can't find it.
Is there any other logs or config files that i need to send.

I hope you can help me. Because i've run out of ideas.

Patrik