footer & stylized text

I'm seeing something strange with my lists and am wondering if there is a fix. I'm using the script cited in the FAQ to add a short footer to every message sent to the list. This footer contains information on how to unsubscribe from the list. I'm noticing that messages containing stylized text are being forwarded by the list without the footer. Messages sent in plain text are forwarded with the footer. Is there a work-around for this (other than blocking stylized text?) Thanks, Irwin