Inbox is mailing app created by Gmail itself for better management of your emails. Inbox treats all emails as a task, hence it enhance your productivity. I always like to keep my mails to zero. Inbox helps to achieve this. One of the most used feature of Inbox is snooze feature, by which you can Snooze emails and Reminders to come back when you are ready to deal with them: next week, when you get home, or whenever you choose.
This is now my primary mail app on Android phone.