Helo command rejected: Host not found

Hi all, I'm hoping someone will be able to shed some light on the following

I'm a recent convert to Astaro, deploying ASG8 at home in front of a Server 2003 domain with Exchange 2003

I discovered recently a sender to my email address is receiving a bounce back as follows - mail from (as far as I can tell) all other senders is being received

From: System Administrator
Sent: 18 January 2012 17:56
To: Andrew Dancy
Subject: Undeliverable: Test email


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

Subject: Test email

Sent: 18/01/2012 17:56


The following recipient(s) cannot be reached:

jc@dc9.co.uk on 18/01/2012 17:56

You do not have permission to send to this recipient. For assistance, contact your system administrator.

<nh-vm-exchange.wiggledomain.wiggle.co.uk #5.7.1 smtp;550 5.7.1 <nh-vm-exchange.wiggledomain.wiggle.co.uk>: Helo command rejected: Host not found>


Can anyone point me in the right direction where I need to reconfigure

Many thanks

Jeremy