Popular mail client for iOS now available for Mac.

Features:

Fly through your email.
We redesigned the inbox to make email light, fast, and mobile-friendly. Quickly swipe messages to your archive or trash and scan entire conversations in a chat-like view. It's a whole new inbox.

Put it off until tomorrow. Or this weekend. Or someday.
Stop staring at emails you can't deal with now. Mailbox lets you put off messages until later and returns them to your inbox automatically, so you can focus on what's important now.

Gets smarter as you use it.
With Auto-swipe, Mailbox learns from your swipes and snoozes to automate common actions.

Requirements:
OS X 10.10+
64-bit Intel

Limitations:
Project has been abandoned. Mac.MajorGeeks.Com keeps abandoned programs available to download for anyone who might be looking for them.