In its rush to continually evolve its product, Facebook often makes leaps forward in many areas, and sometimes that involves two steps back. But in the case of the nearly anonymous “other” folder and its complete omission from the highly touted Facebook Messenger applications, I guess the steps back sent it over a cliff — or maybe Facebook realizes how entirely useless this folder is and plans to kill it off. Wait, what “other” folder? Exactly.

On your personal Facebook profile (not business page), if you click the messages icon from the list on the left …

… you’ll see all of the latest chats you’ve had with friends. But look more carefully and, to the right of where it says “inbox,” it also says “other.”

So what the heck is other? Who are these others and why would they be messaging you? Boy, there’s got to be a Lost joke in there somewhere.

According to Facebook, the other folder is sort of a catch-all for any messages coming to you that are filtered out. Someone who recognizes your name and tries to contact you (because you haven’t friended them) will be whisked away and deposited into this innocuous little folder. Sometimes even your friends will end up there, if you’ve selected “strict filtering” in your privacy settings.

You will not be notified when these others message you. And the message icon doesn’t highlight. It just registers a number next to “other” in the same dull gray. It’s easy to miss and incredibly disconcerting to suddenly find (you’re welcome).

On its FAQ page, Facebook explains that there is a filtering system in place that lets some non-friend materials get into your inbox, but everything else gets shunted off. And in an amazing display of nonsense, the amount of fine-tuning you can do as to what makes it into your inbox is (as mentioned) limited to basic or strict. Adding to the frustration, you need to dig into the minutiae of Facebook to even find these settings, or to find out about the other folder to begin with.

OK, I value my privacy as much as anybody else, but a couple of things just don’t compute.

Why would Facebook make it possible for someone not on my friends list to contact me, but then prevent me from seeing that the person sent a message or not let me know about it? Why isn’t there any way to see this folder in Messenger?

So, there’s a functionality to Facebook messaging that desktop/laptop users can access — but most don’t know about and that functionality anyway — and it’s omitted from the app? And 78 percent of U.S. Facebook users are accessing the page via mobile devices? Unless the plan is to eventually phase out the other folder entirely, this is a stunning lack of forward planning.

Is this more of Facebook’s crazy social engineering? Another way to create discord and anger among its users by frustrating the heck out of them through bizarre filtering? Somebody tried to connect with you and thinks you’re totally blowing them off when the reality is that you didn’t see their message until two years later, when you were bored and accidentally stumbled upon the folder? Of course, by then, the person who messaged you has already decided that they didn’t need your friendship anyway (and you probably didn’t 00 but is that really the point?).

Or, and while less fun, this is certainly more likely: Facebook is a gigantic corporation with several different work groups providing tweaks and modifications to the software without consulting with each other to see how certain things would interact. Or maybe they did … but it just ended up in someone’s other folder.

Readers: Did you know about the other folder? If so, how often do you check it?