Exchange 5.5 altering headers on outbound mail

[hapklaar]

When I send a mail using Outlook (tried 2003 and 98) through Exchange 5.5 SP4 and include a message as an attachment, the header of the attached message becomes corrupted like this (3 different messages):

X-Mailer: Internet Mail Service (5.5.2653.19)
X-Mailer: Microsoft CDO for Windows 2000
Content-Class: Microsoft CDO for Windows 2000
X-MimeOLE: Microsoft CDO for Windows 2000

X-Mailer: Internet Mail Service (5.5.2653.19)
X-MDRcpt-To: sales@kabel.netvisit.nl
X-MDRemoteIP: sales@kabel.netvisit.nl
X-Return-Path: sales@kabel.netvisit.nl

X-Mailer: Internet Mail Service (5.5.2653.19)
X-Mailer: Version 5.03.9257.6402
X-MDRcpt-To: Version 5.03.9257.6402
X-MDRemoteIP: Version 5.03.9257.6402

For some reason the value of the field following X-Mailer gets repeated to all following fields. This problem had been identified to only exist when sending through Exchange 5.5. Furthermore a lot of header info seems missing on forwarded messages (forwarded as attachment).

Does anyone know a fix for this behaviour?