[Dovecot] How to add the footer to multipart emails

I recently lerned that Mailman adds its footer to MIME multipart messages by putting the original message in the first part of a new multipart/mixed entity and the footer in the second part, with Content-Disposition: inline. It works well in Thunderbird at least, i.e. the footer is visible; the glitch is that the footer shows up as an attachment as well, as does my PGP/MIME signature.

Would this be something for EoC to adopt? It would allow non-ASCII characters as well (but not in text/plain messages).

-- Magnus Holmgren Linköping, Sweden