Email preview displayed incorrectly when for Content-Transfer-Encoding: quoted-printable messages

[ilicz]

Steps to reproduce

1. Display message encoded with Content-Transfer-Encoding: quoted-printable

Expected behavior

Correctly displaying encoding of the previewed messages

Actual behavior

Preview of the message text in the message list as well as in the "threaded display" in the message window is not decoded correctly and display non-ASCII characters in their encoded form.
Czech sentence normally displayed as Přátelé střeleckého sportu a LOSíku
is then displayed as P=C5=99=C3=A1tel=C3=A9 st=C5=99eleck=C3=A9ho sportu a LOS=C3=ADku

This happens only for messages comming with Content-Transfer-Encoding: quoted-printable encoding (no matter whether they have Content-type text/html or text/plain)

Preview in the message window:

Preview in the message list in the box listing:

Mail app version

2.1.2

Mailserver or service

IceWarp

Operating system

DEbian

PHP engine version

PHP 8.0

Web server

Apache (supported)

Database

MariaDB

Additional info

No response

[kesselb]

Hi, can you provide us the message source?

[ilicz]

Hi, here you are (the message has been partly anonymized, but it should do the trick).
I only had to rename the file to .txt as .eml is not supported file extension.
sample.eml.txt

[miaulalala]

Thanks I will take a look this week!

[miaulalala]

If you are able to, you could give the linked PR a shot @ilicz

[kesselb]

Hi,

I cannot reproduce your issue with the provided message source.
It seems to work fine on my dovecot based mail server (imported the message via thunderbird).

[kesselb]

@ilicz could you provide us some more data?

1. Enable logging for mail: https://github.com/nextcloud/mail/blob/main/doc/admin.md#logging
2. Reset preview text for the broken message: update oc_mail_messages set structure_analyzed = null and preview_text = null where id = INSERT THE ID OF THE MESSAGE HERE
3. Reload Nextcloud Mail and wait a few seconds.
4. Check the imap logs. If you share data with us, please make sure to remove sensitive information.