The original issue can be reproduced when sending with an unpatched
`mutt` or `neomutt` an email with an attachement which as han `.asc`
extension. This will be interpreted as `application/pgp-encrypted` which
experiences special logic, in the end the attachement will contain
"Version: 1"[1][2][3]
Right now, there are the following issues in the {,neo}mutt packages:
* `mutt.override { smimeSupport = true }` fails to build since the
Debian patch results in a 404. Debian moved their packages to
`salsa.debian.org`.
However we can't use a versioned URL for this as Debian only tracks
the Mutt versions that are available in their releases. The patch
doesn't touch Mutt's core and is therefore simple to rebase, so
sticking to the 1.10.2 patch for now should be sufficient.
* The original issue was never fixed in NeoMutt, currently we use the
S/MIME database from `pkgs.mime-types` which contains the issue with
`application/pgp-encrypted` as well.
After some discussion[4] it seems to be the best decision to use the
`mailcap` database distributed by Fedora[5] which fixes the issue
rather than `mime-types` v9 from 2012.
[1] https://bugs.archlinux.org/task/43319
[2] https://bugs.gentoo.org/534658
[3] https://github.com/neomutt/neomutt/blob/neomutt-20180716/sendlib.c#L490-L496
[4] https://github.com/NixOS/nixpkgs/pull/50927#issuecomment-441383260
[5] https://pagure.io/mailcap
991d4bf68c