Mail delivery failed: returning message to sender

Hi hope you can help (first time here)
When using Mail on the mac ,can not send to this email (see below),but i can it i use Microsoft Entourage?
hope some one can help thanks


This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:

cpeace@chadneybulgin.co.uk
SMTP error from remote mail server after end of data:
host mail.chadneybulgin.co.uk [80.68.57.211]:
550 5.7.1 Requested action not taken: message refused

------ This is a copy of the message, including all the headers. ------

Return-path: <ben@enclosure-engineering.co.uk>
Received: from host86-186-32-165.range86-186.btcentralplus.com ([86.186.32.165] helo=[192.168.178.65])
by jaguar.purple-paw.com with esmtpa (Exim 4.69)
(envelope-from <ben@enclosure-engineering.co.uk>)
id 1O2JNE-0000tF-H1
for cpeace@chadneybulgin.co.uk; Thu, 15 Apr 2010 07:20:28 +0000
From: benjamin peace <ben@enclosure-engineering.co.uk>
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Subject: hi
Date: Thu, 15 Apr 2010 08:20:11 +0100
Message-Id: <CB578C39-CD7C-4012-83CF-90024185180E@enclosure-engineering.co.uk>
To: Cally Peace <cpeace@chadneybulgin.co.uk>
Mime-Version: 1.0 (Apple Message framework v1078)
X-Mailer: Apple Mail (2.1078)

thanks ben