Ok there seems to be some reports of some users that are receiving miscellaneous messages that may brick your console.
If you happen to receive a random message from someone unknown, you may want to delete the message(s) if you can from the PS4 or possibly from the PlayStation App or even from a browser. You really don’t want to have to reset your console to factory settings or worse. But in case you forgot how to set your messages here you go:
Go to settings.
Enter your password.
Messaging and set it to Friends or No One.