If you update your iPhone to iOS 16 this week, you’re going to want to spend a few minutes tweaking your settings. You definitely want to turn on haptic feedback for the keyboard, you might want the battery percentage back in your status bar, and it’s a good idea to spend some time playing around with your Focus modes.

But there’s one setting that’s so useful, and so hidden, that I missed it entirely in my review of iOS 16. (Thanks to everyone who let me know!) It’s called Filter Unknown Senders. If you toggle Filter Unknown Senders on — go to Settings, Messages, and scroll down almost to the bottom to find it — you can now filter your Messages app to show you only the unread threads.

The feature’s been around for a couple of years, and it was initially designed to do one thing: get messages you don’t want out of your inbox. There’s no magic to the delineation, really; the iPhone just puts messages from numbers in your contacts in one place and those from unknown numbers in another. I’ve never turned this feature on, not because I love robo-texts but because I’m a reporter and I get a lot of texts from numbers I don’t know. But it’s a good feature, and you should definitely use it if you’d rather not see confirmation numbers and spam texts intermingled with messages from your friends and family.

I turned it on in iOS 16 and a new “Filter” button appeared in the top left of the Messages app. Once I tapped it and picked “Unread Messages,” I instantly found those two pesky unread messages from months ago that were keeping the red badge on my Messages app. Going forward, thanks to another iOS 16 feature, I can now mark messages unread and use the filter as a sort of communication to-do list.

It’s odd that Apple buried the unread filter behind Filter Unknown Senders, but it’s a super useful feature that I suspect I’ll probably use every day going forward. I’m glad I found it.