Some time this year I noticed that when I get home from work and wake up my monitor (PC is always on and doesn't sleep or log out) I get an email notification in the bottom right corner for every email I received that day and it takes a couple of minutes to clear. I don't remember this before, it was only live notifications in the bottom right as they came in, if you clicked the Windows notification icon it would show you all of the past notifications on the list of course. I still want the notifications for live incoming mail but not all of the unread emails previously. I don't know if this is a Firefox setting or a Windows one but I couldn't figure out how to change without disabling notifications all together.