Cannot send message to self using external smtp server

If I send a message to myself using a 3rd party SMTP server, sa-exim rejects 
the message and I receive the following message in the returned mail:

<[email protected]>: host mail.northfolk.ca[220.234.29.148] said: 500 error
    (in reply to MAIL FROM command)

There is no record of the mail in either mainlog, rejectlog, or paniclog.

If I set SAEximRunCond: 0 in sa-exim.conf and restart exim the same message 
gets through.

I can send to myself with sa-exim enabled if I use my own server for SMTP.

Below are the headers from the offending mail with sa-exim is disabled:



Return-path: <[email protected]>
Envelope-to: [email protected]
Delivery-date: Sat, 01 Apr 2006 13:22:59 +0800
Received: from out1.smtp.messagingengine.com ([66.111.4.25])
	by aurora.northfolk.ca with esmtp (Exim 4.50)
	id 1FPYZe-00034Z-Kp
	for [email protected]; Sat, 01 Apr 2006 13:22:59 +0800
Received: from frontend2.internal (frontend2.internal [10.202.2.151])
	by frontend1.messagingengine.com (Postfix) with ESMTP id 16ED7D4393B
	for <[email protected]>; Sat,  1 Apr 2006 00:22:56 -0500 (EST)
Received: from frontend3.messagingengine.com ([10.202.2.152])
  by frontend2.internal (MEProxy); Sat, 01 Apr 2006 00:22:54 -0500
X-Sasl-enc: ZMawXja4OsHHA9/ENyIWuLKmYLn8MLp42vtoCtiIvi01 1143868973
Received: from king-graham (unknown [220.234.29.148])
	by frontend3.messagingengine.com (Postfix) with ESMTP id 622E3B45
	for <[email protected]>; Sat,  1 Apr 2006 00:22:53 -0500 (EST)
From: Chris Purves <[email protected]>
To: [email protected]
Subject: test
Date: Sat, 1 Apr 2006 13:25:29 +0800
User-Agent: KMail/1.8.3
MIME-Version: 1.0
Content-Type: text/plain;
  charset="iso-8859-15"
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
Message-Id: <[email protected]>
X-SA-Exim-Connect-IP: 66.111.4.25
X-SA-Exim-Mail-From: [email protected]
X-SA-Exim-Scanned: No (on aurora.northfolk.ca); SAEximRunCond expanded to 
false
X-UID: 2898
X-Length: 1426

test
-- 
Good day, eh.
Chris


-- 
Good day, eh.
Chris