Question : Your message did not reach some or all of the intended recipients.

Client is having problem sending email to only one address. When they attempt to send an email to this person they receive this error message with in a minute of hitting the send button:

The message reached the recipient's e-mail system, but delivery was refused.  Attempt to resend the message.  If it still fails, contact your system administrator.
            < toroondcbmts08.bellnexxia.net #5.2.0>

There server is not blacklisted as best I can tell. Tested it on three different sites and everything seems fine.

Exchange server is running SP2 and is Ver6.5 Build 7638.2.

Everything else including email to other external and internal people is working well.

I have tried to disabling there spam filter to see if that any affect but it did not.

Any ideas on how to fix this?

Answer : Your message did not reach some or all of the intended recipients.

Please have a read of my FAQ which might highlight a problem or two with your configuration.  The fact that the message was refused suggests that your domain may be missing something like SPF (or it is setup incrrectly), Reverse DNS, or is blacklisted somewhere.

http://www.it-eye.co.uk/faqs/readQuestion.php?qid=2