The folders used for sent mail, trash, and templates get a new value without user intent, and KMail starts to use them that way. After setting my accounts correctly, it happened many times that these settings were reset to some random (but valid) folder. I'm totally sure that I didn't modify these settings, especially baceuse the new values were shared folders for the workgroup that I'd never set. Maybe if a folder is unaccessible for some temporary error, then KMail resets these to the first one that's accessible? Reproducible: Sometimes Actual Results: The values for the special folders settings get a random value over time. Expected Results: These settings should stay constant and changed only if the user sets it to another value.
Raising severity to critical since folders can change in an inter-account manner, which causes serious information leak which is as bad (if not worse) as data loss.
This deterministically happens after Akonadi's database gets corrupted and wiped afterwards. See https://bugs.kde.org/show_bug.cgi?id=302499
This bug has only been reported for versions before 4.14, which have been unsupported for at least two years now. Can anyone tell if this bug still present? If noone confirms this bug for a Framework-based version of kmail2 (version 5.0 or later, as part of KDE Applications 15.12 or later), it gets closed in about three months.
Just as announced in my last comment, I close this bug. If you encounter it again in a recent version (at least 5.0 aka 15.08), please open a new one unless it already exists. Thank you for all your input.