“Who in their right mind would build an email client?” Gentry Underwood asked himself nearly two years ago. At the time, it was a fact of life that email sucked. Nobody cared about rethinking email. So he built an email client.

At launch, Mailbox generated so much hype that nearly 1 million people joined a wait list to get access to it. The app promised a simple, lightning-fast experience that made emailing feel like texting. And it introduced “snooze,” a feature that let you put off emails until later. “For a long time email was this area of tech that you didn’t touch, which was old and stodgy and not worth spending time on,” says Underwood. “Mailbox demonstrated that that wasn’t the case.”

In the ensuing years new email apps like Hop, Mail Pilot, AirMail, CloudMagic, and Boxer seemingly launched every week. Even Google started paying attention to its email app on iOS. Mailbox hasn’t convinced everyone to jump on board, only rarely cracking the top 50 in the App Store’s productivity category, but it nevertheless kicked off a trend where both developers and consumers seemed to agree that while email couldn’t be killed, it could possibly be fixed.

As Gmail hits its 10th anniversary, Mailbox has been quietly preparing its next big thing — a system that automatically clears out bothersome threads, spam, and emails you don’t need until later. And there’s no wait list to try it out.