Default is AccountName/Inbox. This however doesn't search just in Inbox, but in all folders of that account and gives results from all folders. When I select a different folder, e.g. AccountName/AnotherFolder, I get no search results. The account is an IMAP account. Nepomuk searching is enabled. Reproducible: Always Expected Results: Give only results from the actually selected folder (+ optional subfolders).
? Screenshot please. Don't understand your problem
Created attachment 72890 [details] search dialog - I just noticed that it apparently searches also in Local Foldes (see screenshot). - I also noticed that it is different for other accounts. If I set the search folder to the Inbox of my other IMAP account (or any other folder of it) everything works fine, i.e. it searches just in that folder.
I just tried with KDE updated to 4.9.0. And at first it seemed that searching now correctly happens only in the specified folder. But then I still found a word where a result from a different folder showed up. But only one message from that folder, even though there are a lot more containing this word. So it seems to mostly work now, but not completely.
Michael, thanks for your report. Sorry for slow answer. It is about a version of KMail that uses Nepomuk and is unmaintained. Thus closing. If you have still issues with quicksearch in a recent version like from KDEPIM 4.14 or if you can get it already 15.08, then please open a new report. Please state version and exact steps to reproduce. Thanks, Martin