Is this enX-Brightmail-Tracker

we are running GW 7.0.3. One of my users is receiving email from a client that employs Symantecs Brightmail-Tracker. In the middle of the text of the email, the Is this enX -Brightmail-Tracker.......appears followed by lines of code. I thought this was a header. Has anyone else encountered this and is there a way to correct it?

thanks
ed