Maybe it's a very efficient new feature

Here's what happened.

1. I have a POP3 account for my email. It's configured to put new email into Local Folders/inbox.

2. I accidentally trashed a couple messages, and decided I wanted them back in my Inbox.

3. It was very late at night, so instead of dragging the messages into the Inbox, I accidentally dragged the Trash folder into the Inbox.

4. This copied the whole Trash folder, creating a new folder in Local Folders/inbox/trash.

5. My incoming mail started being received in this trash folder.

6. After about an hour I figured out what I'd done wrong and deleted the bogus Trash folder.

7. In the Account settings, I made sure that the destination folder was still set to "inbox"

8. However, all incoming mail still ends up in the trash folder.

I think there must be a config file that's gotten out of whack, any idea where I could find that?

I wonder if it'd be good to have an anti-stupid feature to prevent other people from doing this ...

Check to see if you have any filters configured in Settings > Configure POP filters and Settings > Configure Filters.

There's a whole bunch of filters - I think you're right, my spam handler has somehow run amok. How do I reset it and start retraining it?

Remove all the filters present there and recreate them using the Anti Spam setup wizard. The training you have done with your Spam Filter will not be affected.

This happened to me once because I had no spam filter applications installed.(still kmail anti spam wizard ran and configured to remove everthing to thrash).