January 3, 2018
Google has announced that Inbox by Gmail is going away at the end of March 2019. Inbox users will be switched to the new Gmail interface, which includes top Inbox features like snooze, nudges, and more to help you get more done. For help transitioning to new Gmail, please review Google's support article: Move from Inbox to Gmail.
Source: Inbox is signing off: find your favorite features in in the new Gmail