From address is not shown in full detail

Checklist

• I have used the search function to see if someone else has already submitted the same bug report.
• I will describe the problem with as much detail as possible.

App

K-9 Mail

App version

22.0

Where did you get the app from?

F-Droid

Android version

not relevant

Device model

not relevant

Steps to reproduce

K-9 does not do a good job at showing the details of the sender (From) of an email.

This has security implications as it enables phishing to a great extent, as the receiver cannot really see where the email came from.

Here is a real example:

1. The redacted header of the email is:

Return-Path: <SRS0=ulPS=G3=leadingcorporatechanger.de=info@srs2.someserver.de>
Authentication-Results: someserver.de; dkim=none; spf=pass smtp.mailfrom=
 SRS0=3DulPS=3DG3=3Dleadingcorporatechanger.de=3Dinfo@srs2.someserver.de;
 dmarc=fail header.from=mydomain.net policy.dmarc=none; iprev=pass
 policy.iprev=123.321.111.222
Received: from mout.someserver.de ([123.321.111.222]) by mx.someserver.de
 (mxeue003 [222.111.212.121]) with ESMTPS (Nemesis) id 1MV382-1xUEiH0DoM-00PX3T
 for <myname@mydomain.net>; Thu, 03 Sep 2026 22:09:27 +0200
UI-Loop: V01:NJhInX9psaU=:mZZuLUGwesUDSVZrtp4pKA==
Received: from mail.leadingcorporatechanger.de ([190.123.46.188]) by
 mx.someserver.de (mxeue001 [222.111.212.121]) with ESMTPS (Nemesis) id
 1MCHvG-1xBbOw2n5u-0075qA for <info@mydomain.net>; Thu, 03 Sep 2026 22:09:26
 +0200
Date: Thu, 03 Sep 2026 20:09:22 +0000
From: =?utf-8?B?TGFycyBCw7ZobSBLdW5kZW5zZXJ2aWNlIEJlcmF0ZXI=?= <info@mydomain.net>
To: info@mydomain.net
Subject: =?utf-8?B?SU9OT1MgQml0dGUgaGFuZGVsbiBTaWUgLSBJaHIgU1NMLVplcnRpZmlrYXQgbMOkdWZ0IGJhbGQgYXVz?=
Message-ID: <1c95944699206376a03014298a2339bf@leadingcorporatechanger.de>
X-Sender: info@mydomain.net
Content-Type: multipart/mixed; boundary="_=0e536246ba4ad452f8939f9cf0eaeda1"
Importance: High
Thread-Index: AdqCKEJSNXPH3ad5gGKaYBEDjQgfZe==
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-MessageSentRepresentingType: 1
X-MS-Exchange-Organization-AuthAs: Internal
X-MS-Exchange-CrossTenant-Id: d9c9e97d-237a-4644-b94f-e338d3db17aa
X-MS-Has-Attach: 
X-Priority: 1
X-MimeOLE: Produced By Microsoft MimeOLE V16.0.5435.1001
X-MS-TNEF-Correlator: 
X-OriginatorOrg: mydomain.net
X-MS-Exchange-CrossTenant-Network-Message-Id: e6fc6f02-64f1-4873-99ed-99e4933186cf
X-MS-Exchange-Organization-SCL: -1
X-MSMail-Priority: High
X-MS-Exchange-Organization-Network-Message-Id: e679f14e-b377-4d4d-ad4f-bda7653fddb4
X-MS-Exchange-Organization-AuthSource: mail.mydomain.net
X-MS-Exchange-CrossTenant-AuthAs: Internal
Priority: urgent
X-MS-Exchange-CrossTenant-AuthSource: QufWQ3mVkNkaHO.mydomain.net
X-MS-Exchange-Organization-AuthMechanism: 04
X-Spam-Flag: NO
UI-OutboundReport: notjunk:1;[...]
Envelope-To: <myname@mydomain.net>
UI-InboundReport: unknown:2;[...]

--_=0e536246ba4ad452f8939f9cf0eaeda1
Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: base64
[...]

2. When viewing this message in K-9, it only displays:

IONOS Bitte handeln Sie - Ihr SSL-Zertifikat läuft bald aus

info@mydomain.net      Thu
to info@mydomain.net

3. Looking at the same message in Thunderbird, I see:

From       Lars Böhm Kundenservice Berater <info@mydomain.net>
Subject   IONOS Bitte handeln Sie - Ihr SSL-Zertifikat läuft bald aus
To           info@mydomain.net

So what is missing here is way for K-9 to show the full "From" details.

This issue might be related to issue 7367 and 6934

Expected behavior

An option to show the full From details.

Actual behavior

Only short part of the From information is displayed.

Logs

not applicable