How to enable notifications for Facebook Message Requests?

Question

Facebook divides messages into two inbox sections - one contains messages from your friends. You know that one. Facebook displays small red number when you have unread messages in that folder.

Then there's the other one. It's been even called "secret inbox" on the internet and such, because it's very existence is not apparent. The inbox is called Message Requests and does not cause any notifications on Facebook. This can be very impractical, for example, if a member of a group you're in messages you and you notice few weeks later.

Is there a way to make Facebook raise notification if somebody who's not in my contacts sends me a message?

Answer 1

https://www.facebook.com/help/936247526442073 subtly indicates you must check this special box manually.

It Facebook's forums, their authorized personnel directly stated it:

1. https://www.facebook.com/help/community/question/?id=10154351975380929
2. https://www.facebook.com/help/community/question/?id=10157371863405285
3. https://www.facebook.com/help/community/question/?id=10208450199270927

There are 1,000 more usually similar discussions in their forums (https://www.google.com/?q=site:facebook.com+inurl:"community"+intitle:"message+requests"+notifications) although only less than 6 got any answers at all (https://www.facebook.com/help/community/search/?query=message%20requests+notifications).

Amazingly, some of the 1,000 discussions (just in Facebook's own forums, mind you) complain about the reverse situation. But the comments they get suggest there's not supposed to be a reverse situation.