Where is the Apple Mail "not junk" button?

All -

In Apple Mail, Yosemite 10.5.5. There is no option to mark an email in the Junk folder as Not Junk. I have the built-in junk filter enabled. When I select the message and select "Message -> Mark..." in the menu bar, there is an option to mark as junk, but not to mark as not junk. Similariy, if I control-click or right-click on the message itself, the only "Mark..." option is to mark as junk. If I attempt to customize the toolbar, the only button I'm offered is a thumbs down/junk button. Left to right, on the top row of the customization palette, the buttons are Delete, Junk as a pair, Delete alone, Junk alone, Archive, Reply, Reply All, Forward as a triplet, Reply alone, Reply All alone, Forward alone, Flag, Move, Copy. No thumbs up/Not Junk.

Many of the items I've found on the Web about this, including from recent OSes like Yosemite, imply that some people see a Not Junk button.

What's going on?

Thanks in advance.