Recipients of the notifications vary from browser to browser depending on how closely the browser interacts with the Operating System.
a) Chrome: Subscribers receive notifications even when the window is closed. However, to enable this, Chrome needs to run in the background.
b) For Firefox on Mac: Users can receive notifications when the browser is closed provided the browser is still running (indicated by '.' in the menu).
c) For Firefox on Windows: Users won’t receive notifications when the browser is closed as the background process gets killed when the window is closed.
d) Safari: As Safari interacts with Mac OS very closely, users can receive notifications irrespective of whether the browser is running or not.