Version: (using KDE KDE 3.5.5) Installed from: Debian testing/unstable Packages In my specific case, I would need to set a default status filter for some IMAP folders, namely that I want my spam folders to filter on unread. This idea can be expanded quite a bit, though. You could have different search strings or different overview items (Subject, Sender, Date).
In light of the impeding KDE4 release, I am going through all bug reports I am involved in. To the best of my knowledge, this issue is still open.
You can use seach folders for exactly that. Well, there is a problem with filtering for unread mails (they are moved away as soon as you read them) - but that is another bug.