Last month I upgraded this desktop from Buster to Bullseye. It was a
fresh installation since something went wrong on that particular day
with 'apt dist-upgrade'. Oh well.
Anyway, with the current neoumtt package whenever I forward an email
that is MIME encoded and has an HTML attachment wrapped in a
multipart/alternative MIME block, the HTML attachment is dropped. The
message I am forwarding is to a local hobbyist mailing list and I was
notified by one of the list members a few weeks back that he could not
open the HTML mail as usual and my investigation has revealed the
problem began with the newest version of neomutt. My ~/.mutt/muttrc is
unchanged since March 27, 2020 and this feature had worked without issue
for years until the upgrade to the neomutt version in Bullseye.