Rejected Mail Issue - Bad return address

All,

I am getting a small precentage of mail from my server returned with to my users with the error:

Your message was not delivered because the return address was refused.

The return address was '<john.doe@xyz.com>'

I cant find much more detail in the error logs, but Im assuming this mail is being rejected by the mail server of the intended recipient which is not in the same domain as mine. Is there anyway to verify which server is rejecting the mail? Is there anything I can do to fix this issue as both the sender and recipient are valid accounts. TIA>

Pete Serafin

[655 byte] By [705587] at [2007-11-25 8:45:53]