Ah, yes. Just checked. When you're in the Smart Folder you can use the left side menu to adjust on the fly which messages show.
And to get back to the regular folders view you just tap the icon for whatever account you want. In my case there's only one account, a Gmail account to which are forwarded messages from about a dozen other accounts of one kind or another.
Like I said, I don't really use the Smart Folder. But now that I see some of its options, maybe I'll start using it once in a while.
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