Just saw this for the first time:
Content-Disposition: =?utf-8?Q?inline?=
.. causing "mhshow: extraneous information in message 126's
Content-Disposition: field (=?utf-8?Q?inline?=)". As far as I can see
this is a MUST NOT do, but probably not too hard to accept and DTRT.
Ooof. That's a MAJOR "do not do". Also, it seems like we wouldn't be
the only ones who break on that! I'm wondering what broken code generates
THAT. It seems, however, we should simply follow RFC 2183 and treat it
as an "unknown" disposition (which means "default as attachment").
--Ken