SUMMARY It seems that in reasonably current-ish KMail (5.11.3) the “Folders to monitor for new messages notifications” setting is not saved. STEPS TO REPRODUCE 1. Go to KMail settings > Accounts > Incoming > “Other actions” button > “Folders” tab > “Select which folders to monitor for new message notifications” 2. By default, all folders are selected. Unselect any checkboxes whatsoever and press OK. 3. Go back to 1. OBSERVED RESULT The setting is not saved. EXPECTED RESULT The setting should be saved. SOFTWARE/OS VERSIONS Linux/KDE Plasma: openSUSE Tumbleweed 20190810 (available in About System) KDE Plasma Version: 5.16.4 KDE Frameworks Version: 5.60.0 Qt Version: 5.13.0 ADDITIONAL INFORMATION The bug must be fairly recent. I hadn’t encountered this in either Debian buster or openSUSE Leap 15.1.
Fixed in 5.12.0