openSUSE Leap 42.2 -- plasma5-workspace: 5.8.6-8.1 (LTS) Linux (x86_64) release 4.4.57-18.3-default KMail: Version 5.3.0 (QtWebEngine) Under: - KDE Frameworks 5.26.0 - Qt 5.6.1 (compiled against 5.6.1) - The xcb window system Provided that, the "Search" folder does not exist, the Tools menu "Find messages" function ("S") executes as expected. Subsequent searches do not execute as expected: - The result of the initial "Find messages" execution remains unchanged. If, by means of "right-click" on the Search results folder, the last search results are cleared (need to first click on other mail folder before the option to delete changes from "Delete folder" to "Delete search") -- after noticing the message indicating that, the original searched for and found e-Mails will remain at their original location, the original e-Mails are no longer displayed in the original folder view. Closing down KMail and then restarting it, restores the display of the "searched for and found" e-Mails in their respective Mail folders and, a new "Find messages" search can be executed. ---------------------------------------------------------- The URL for the relevant KMail Handbook entry is: <https://docs.kde.org/stable5/en/pim/kmail2/menus.html#reader-tools-menu> (It doesn't mention that, the Search folder has to be deleted and, that KMail has to be closed down and then restarted.)
I experience the same or very similar issue in kmail 5.4.3 using Arch linux. The only difference being that the initial search results contains false positive and missed the actual message I was looking for which I found manually.
I think that it's fixed in 5.5.0