Can’t Get Raw MIME in Transport Event in Exchange 2007 SP1

If you wrote a Transport Agent for Exchange 2007 RTM which was accessing the raw MIME message which doesn’t seem to work after installing SP1, there’s a good reason for that. In SP1, we moved content conversion to after the OnRoutedMessage event. This leaves you in the predicament of not having access to raw MIME content in any Transport Agent even for messages bound for external recipients. The change was by design to enhance some pipeline tracing features.

While you don’t have access to raw MIME anymore, you can use the TnefReader class and the MailItem object you’re given to access message data and do your business logic there.

Your other option is to set up a Send Connector to route outbound mail through an SMTP server and create an OnArrival SMTP sink. You should be able to get raw MIME there.