Lots of people are having trouble with the akonadi database, which obviously cant work error-free all the time. Numerous people do report a substantial reduction in database size after a rebuild. There should be a command (menu entry) which deletes the present data base and forces kontact to rebuild it. Even in AppleMail the occasional rebuild of the database improves speed and reliability tremendously. Reproducible: Always
Thank you for the bug report. As this report hasn't seen any changes in 5 years or more, we ask if you can please confirm that the issue still persists. If this bug is no longer persisting or relevant please change the status to resolved.