Both the anti-spam and anti-virus wizards in Kmail offer to move marked messages to a specified folder, and this option appears to be global all accounts. I see two issues with this:

1. It may, for some people, require moving messages from one account to another or moving them offline to local storage. Not everyone will want this.
2. For those moving messages offline or between accounts due to the option set in the wizards, it can be rather confusing keeping track of which accounts messages were sent to without the inconvenience of checking message headers.

I suggest instead two additional options:
1. Allow the wizards to set per-account options.
2. Auto-detect account-specific spam/junk folders. If spam/junk folders aren't present, offer two alternatives:
2.1. Offer to create a spam folder, with optional auto-create for accounts added in the future.
2.2. Offer to store in the local spam folder, with auto-local-storage for accounts added in the future.