Created attachment 346667 [details] message to send to yourself to illustrate this bug Send yourself the attached message. In thunderbird, Note that when viewing it in thunderbird, it has both a "body" and a "footer". Now forward it inline. Observe how the "body" disappears from the forward. Yes, the HTML in the message is bad, but (a) that's how I received it (although obviously I've removed all the non-markup text for illustrative purposes), so somebody's generating this bad HTML and thunderbird needs to cope with it, and (b) if thunderbird can handle displaying it properly, then it should be able to handle forwarding it properly.
We filed this bug in the upstream database (https://bugzilla.mozilla.org/show_bug.cgi?id=496723) and believe that it is more appropriate to let it be resolved upstream. We will continue to track the issue in the centralized upstream bug tracker, and will review any bug fixes that become available for consideration in future updates. Thank you for the bug report.