KMail, when started via Kontact, does not respect file associations and asks every time how to open image/jpeg attachments. You can choose e.g. Gwenview and the attachment is successfully shown, but there is no way to make this selection permanent, even when the appropriate check box is checked.

This only happens if KMail is started as a Kontact module. KMail standanlone works ok. Only a specific user suffers from this issue.

Any ideas for settings/config files to look at?

Kontact 5.12.1
KDE Frameworks 5.61.0
Qt 5.13.1
Plasma 5.16.5-1
Arch Linux

TIA,
Heinz

What shows 'kcmshell5 filetypes' for image/jpeg ?

Sorry for not answering.

I was finally able to solve this by recreating $HOME/.config/kontactrc.