Facebook Messenger has a secret folder for storing messages that you probably didn’t know existed.
When you receive a message from someone on Facebook that isn’t your friend, Facebook alerts you to let you know. However, Facebook doesn’t do this for every message you receive from a non-Facebook friend.
If Facebook thinks the message is spam, then it will tuck it away into a hidden vault.
Several Business Insider journalists found the vault and all of us had messages in there that we didn’t know we’d ever received.