#1042487 neomutt: ANSI headers not decoded

Package:
neomutt
Source:
neomutt
Description:
command line mail reader based on Mutt, with added features
Submitter:
Date:
2023-07-29 09:51:04 UTC
Severity:
normal
Tags:
#1042487#5
Date:
2023-07-29 08:25:03 UTC
From:
To:
When the From: field contains an umlaut (“ö”), such as:

  Andreas Rönnquist <redacted>

it then gets encoded for transport and the literal
text is:

  From: Andreas =?UTF-8?B?UsO2bm5xdWlzdA==?= <redacted>

Neomutt properly treats that UTF-8 encoding. However, the 33mail.com
forwarding service apparently re-encodes it in ANSI as follows:

  From: "=?ANSI_X3.4-1968?Q?Andreas_R=3Fnnquist?= 'redacted' via 33Mail" <sender@mailer1.33mail.com>

Neomutt does not decode that particular string. In Neomutt the
=?ANSI… junk appears literally.

Steps to reproduce:

1. Download the mbox file for the following comment:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1027753;msg=10

2. Replace the /From:/ field with:
   From: "=?ANSI_X3.4-1968?Q?Andreas_R=3Fnnquist?= 'redacted' via 33Mail" <sender@mailer1.33mail.com>

3. Launch neomutt: $ neomutt -f "$mbox_file"

I am probably running an old version of neomutt, but I have searched both bug trackers (Debian & upstream) for “ANSI” & found no mention of this bug. I also searched the debian change logs. So AFAICT the latest neomutt would have this bug as well.
#1042487#8
Date:
2023-07-29 09:47:58 UTC
From:
To:
This is a bug in the software than generated this header, not in
Neomutt:

• ANSI_X3.4-1968 is an alias for US-ASCII, a 7-bit charset that doesn't
include the character "ö".

• An encoded-word is not allowed inside quoted-string; see RFC 2047 §5.