There is a setting toggle labeled "Push" on the messages page. When I toggled on, the confirmation popped up (see the attached image). But no action happens when messages come. I expected that when a message came, it would appear as a system-level notification (aka desktop notification).
Note.
  • I think this lacks a piece for the Offline Invites feature. Currently, you have to keep the web page open and frequently see the mail icon at the top to recognize the invitation. That significantly decreases its usefulness.
  • It turned off after reloading the page.
  • I tested with the latest Chrome and Firefox.