Hi,

>>
Can I amend the header in an email I'm sending? some emails are sent using West-Wind tools, others using Outlook.
>>

I'm afraid I'm unfamiliar with both the West-Wind tools and the Outlook object model so I don't know if either of these can manipulate headers. At the end of the day an email is a simple text file - if you can access this then you can add a header. For example a *.eml file in a windows SMTP folder looks something like this:

X-Receiver: 100111.2716@compuserve.com
X-Sender: QCHG-Server413
From: <QCHG Server>
To: <100111.2716@compuserve.com>
Subject: Unexpected Error occurred updating Sheet Data
Date: Tue, 24 Aug 2004 12:16:22 +0100
Message-ID: <000201c489cb$c9553ef0$7900a8c0@QCHG-server413>
MIME-Version: 1.0
Content-Type: text/plain;
	charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
X-Mailer: Microsoft CDO for Windows 2000
Thread-Index: AcSJy8lV35vff3FmS4OO9CdSRpMiXg==
Content-Class: urn:content-classes:message
X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106

The following error caused the Sheet update to abort:System.Exception: =
Deliberate Throw
   at LVDataLayer.SheetAllocCollector.GetNewScrambles() in etc...

You could add a line like 'MyData: Reference 12345' anywhere in the header section without affecting the subsequent transmission/display of the message..

HTH,
Viv