Version:            (using KDE KDE 3.4.0)
Installed from:    FreeBSD Ports

(This is a special case of bug 5694; it might be worth implementing
even if 5694 in its full generality isn't.)

My "local folders" include, as well as a load of useful stuff,
  - thousands of spam messages, kept for training filters;
  - a folder in which various completely uninteresting messages
    get deposited pending deletion (typically containing one or
    two thousand messages);
  - various folders of old material which is often irrelevant.

It is a shame that I can't tell KMail to search all my local folders
except the spam and boring-message ones, or all except the spam,
boring-message and old ones. Especially as searching is not exactly lightning-fast :-).

More concretely, here's what the interface might look like:
  - After the "Search all local folders" and "Search only in" rows:
    checkbox, "Exclude", drop-down chooser, checkbox,
    "Exclude subfolders too", "More..." button.
  - Selecting "More" creates a new similar row to allow the
    specification of more excluded subfolders, with its
    leftmost checkbox checked.
  - Perhaps unchecking the leftmost checkbox of the last row
    of excluded folders makes the row go away (unless it's
    the only one), to reduce clutter. But that might be too
    weird.

It might be nice to be able to enter a list of folder names
(separated by some character that isn't legal in folder names,
if there is one) by hand, but I'm not sure how to make that
coexist with a more user-friendly interface.