Facebook is changing the way messages are displayed to make communication easier. Now when someone sends you one message who is not at least a friend of a friend of yours or has your phone number, will appear as a "message request" request), which you can choose to accept or ignore.
With the old system, these messages appeared in a folder next to your “Inbox” titled “Other". It may not look familiar to you because these types of folders (Other, Unread, Archived, Junk) do not appear in desktop. In general, you would need to add someone as a friend first in order for their messages to appear in your Inbox or on mobile devices.
Naturally, no one wants spam messages, so that Facebook states that it will continue to filter messages. The "message requests”Are starting to appear gradually to all Facebook users today.
