Facebook: Notifies users when a message is about to end up in "Other" messages

Facebook has made a small, but very important, change, notifying the user when sending a message to a user with whom they are not friends that their message will be delivered to the "Other" folder and not to the "Inbox".

Although the “Other” folder in Facebook messages has been around for a while, many users are still unaware of its existence and ignore any messages that are in it. For your information, the “Other” folder is used to store messages received from users you are not friends.

Source: socialmedialife.gr