The latest update coming to Facebook Messenger introduces new privacy settings that limit who can send you messages. Like a feature offered on Instagram, the messaging app will soon test settings that let you "decide who can message or call you directly, who goes to your requests folder, and who can't message or call you at all." It will also try out automatically blurring photos sent by users who aren't your Facebook friend, which we assume is meant to keep out inappropriate or unwanted images from strangers.
For iOS users, you can now enable Messenger's "app lock" feature, which lets you configure the app to need a face or fingerprint authentication before opening your messages. Android users are expected to get the security feature soon.
Source: Engadget