Mailbox is an email productivity app. It is available on Mac and Android, and works with iCloud and Gmail. The app is highly customizable, and allows users to set different "snooze" and "archive" times for emails. You can even postpone emails if you need to, and it will redeliver them as soon as you decide to. Using the app is an effective way to stay organized and to avoid drowning in email.

In March of this year, Dropbox acquired Mailbox, and the app's popularity soared. The service's success is largely a function of how it works. After its release, users were placed on a waiting list, and those who wanted it quickly got it. It kept the server load at a manageable level. The application's snooze button was another popular feature, and it made it easier for users to get rid of unread messages.

While Dropbox decided to open source its Hackpad and Zulip technology earlier this year, it has not yet decided to do the same for Mailbox. However, the company does provide an FAQ listing the reasons why it won't open source its mail client. As of this writing, Dropbox has not responded to requests for comment on whether or not it plans to open source Mailbox. A source for the Mailbox FAQ is currently unavailable. You can visit the official website of Dropbox for more information.