If you have email notifications turned on for Facebook, your inbox can be flooded with messages. Me, I stick with just seeing my notifications when I logged on to Facebook. Let me show you how to stop the flood of notifications.
Click the arrow at the top of your feed and choose Settings & privacy from the drop-down menu.
Then choose Settings.
Then select Notifications from the left pane.
Scroll down to Where you receive notifications and choose Email.
Untick the box next to All Notifications.
That should stop the influx of notifications.