It was a pretty decent email app developed by Google back in the day. They discontinued it a few years ago and some features made it into the Gmail app, but not all.
For context, Google set out to revolutionize how we deal with emails with its alternative Gmail interface Inbox in 2014. The service eschewed the chronological thread-based nature of regular email clients in favor of a to-do style interface, allowing you to reorder, snooze, and bundle emails. Inbox was killed just five years later, and we’ve been left without a proper in-house replacement ever since
I was very ready to agree with 520, but did some digging first. I was thinking of an old app called Mailbox. It was bought by Dropbox and faded away after that. I loved that app a lot.