If I search for To contains linux-kernel@vger.kernel.org, I get plenty of results as expected. But if I search for All Recipients contains linux-kernel@vger.kernel.org, I get zero results.
I confirm the problem with kmail-4.8.2 : The Search seems to be unusable.
Doesn't this bother anyone? It is not possible to search mail within akmail, virtual search folders do not work... This is on Kmail and akonadi 15.08.1-1.
This bug has never been confirmed for a Kontact version that is based on KDE Frameworks, except possibly a Technology Preview version 5.0.x. Those versions differ significantly from the old 4.x series. Therefore, I plan to close it in around two or three months. In the meantime, it is set to WAITINGFORINFO to give reporters the opportunity to check if it is still valid. As soon as someone confirms it for a recent version (at least 5.1, ideally even more recent), I'll gladly reopen it. Please understand that we lack the manpower to triage bugs reported for versions almost two years beyond their end of life.
Just as announced in my last comment, I close this bug. If you encounter it again in a recent version (at least 5.1 aka 15.12; preferably much more recent), please open a new one unless it already exists. Thank you for all your input.