How to exclude mailboxes within a smart mailbox? I have made some smart mailboxes in Mail.app. The smart mailboxes I am using only for my Gmail account.

While they send the emails to the smart mailbox they always send duplicates. The email from the Gmail account, email from the whole inbox and email labeled 'important'. Apparently every single email I get is labelled as 'important'. Whenever the mailboxes refresh, they add the duplicates back to the smart mailbox.

I only want one copy to appear in the mailbox. Is there a way to exclude these duplicates or am I just stuck with it?
Well, in Mail 4.5 (on Snow Leopard) it's easy: add a condition "Message is in Mailbox" to your smart mailbox's filter. In my case, that "Gmail" mailbox is a sub-box of the (unified) Inbox.