Note: The window of opportunity has now closed.

Plenty of people have heard about Inbox—Google’s new mash-up of Gmail, Google+ and Google Now—though few have experienced it. But that’s about to change this afternoon.

For one hour only, the company’s unshackling its Inbox app for anyone who emails asking for an invitation. To get yours, shoot off a message to between 3 and 4 p.m. PT (6 to 7 p.m. ET) today, Wednesday, November 5.

See also: Google May Be About To Blow Up Email With Its “Inbox” App

Google has a history of shackling new services to an invitation-only scheme, which seems to work well for the company. When Gmail was an infant email service, for instance, invitations were in such high demand, they became status symbols. After all, the company kept a selective pool of users for three years.

If you want to check out Google’s latest approach to email, but don’t want to risk potentially being locked out for years, get in now while the door’s cracked open.

For a quick look at what the Inbox app has to offer, check out Google’s introductory video below.