“Inbox” has been invite-only, which has led to people hounding those with access for an invite on Twitter, or even auctioning off their own invitations on eBay. The Good news is that Google is having a Happy Hour where each user will be getting an invite.
Here is a tweet by the official Inbox for Gmail account:
Want an invite TODAY? #InboxHappyHour 3-4pm PT. Send us an email at email@example.com between 3 and 4pm PT and you’ll get your invite by 5pm
— Inbox by Gmail (@inboxbygmail) November 5, 2014
All you need to do is send an email to firstname.lastname@example.org within the time window i.e 3-4PM PT, and you’ll get an invite in the hour following. For India, it’ll be 4:30-5:30AM!