Comment 12 for bug 266068

I am unable to duplicate the problem in current Mailman, and as you have seen, there really aren't any changes between 2.1.9 and current that would affect this. I suspect it may be caused by this Debian patch <http://patch-tracking.debian.net/patch/series/view/mailman/1:2.1.9-7/77_header_folding_in_attachments.patch>, but I haven't tested this theory.