Hi, I have a problem where some NDR sent to external addresses arrive back at GWIA but then disappear, they never transfer to the MTA and do not appear elsewhere (Defer/GWProb etc..)

So for example as a test I send an email to:
blahblahhd7yu3h3hy@hotmail.com

The message goes out, gets rejected and I see an incoming email on the SMTP smarthost server.

here is some of the content in the message"
------------------------------------------------------------------
From: postmaster@Smarthostserver.my.Domain
To: my@email.address.com
Date: Thu, 20 Aug 2009 16:03:00 +0930
MIME-Version: 1.0
Content-Type: multipart/report; report-type=delivery-status;boundary="9B095B5ADSN=_01CA20078CCAF97E0000 002CSMArthostserver.DOMAIN."
X-DSNContext: 7ce717b1 - 1196 - 00000002 - 00000000
Message-ID: <hwFutJLto00000018@Smarthostserver.my.Domain>
Subject: Delivery Status Notification (Failure)

This is a multi-part message in MIME format.

--9B095B5ADSN=_01CA20078CCAF97E0000002CSmarthostserv er.Domain.
Content-Type: text/plain; charset=unicode-1-1-utf-7
X-EC0D2A8E-5CB7-4969-9C36-46D859D137BE-PartID: 4EA49424-C1D6-4CEC-AD70-B856EDE9AB34

This is an automatically generated Delivery Status Notification.

Delivery to the following recipients failed.

blahblahhd7yu3h3hy@hotmail.com
-------------------------------------------------------------
OK so I can then see the message arrive at GWIA but then nothing:
16:09:32 7D5 MSG 156368 Recipient: my@email.address.com
16:09:32 7D5 MSG 156368 Recipient: postmaster@email.address.com
......this is where all trace of the message stops..

When what I should get is
16:09:32 7D5 MSG 156368 Recipient: my@email.address.com
16:09:32 7D5 MSG 156368 Recipient: postmaster@email.address.com
16:09:32 7D5 MSG 156368 Queuing to MTA

All other email/GW functions are working normally, internally/externally its just some NDR's. if I send to an invalid domain the message format is different and I get the NDR:
This is an automatically generated Delivery Status Notification.

Unable to deliver message to the following recipients, because the message was forwarded more than the maximum allowed times. This could indicate a mail loop.

Anaddress@hotmaiX.cou

Anyone have any ideas where to look, I have been tweaking GWIA to try and fix this but nothing has helped??

Cheers

Sean