Mailbox was announced a few months back and it was by far one of the most interesting twists on how to use email.
The problem with email is that it's not getting out of date, it's a service which has been in use intensively over the last 20 years. No one seems to be letting go of email. So instead of trying to come up with something different, developers are taking email and trying to make it easier and quicker, like Mailbox is doing.
Mailbox makes email like a to-do list, something which you should just get over and done with. It wants to help you get through email as quickly as possible, helping you highlight the most important emails and trashing the least important with super quick gestures.
There are a number of gestures which have been implemented to help you fly through your email, such as archiving, trashing, saving for later and organising into lists. The idea is to help you stay on top of all your conversations so you hit zero.
As you can see in the pic above, my Mailbox icon has an indicator displaying 370. That's not 370 unread emails, that's 370 conversions which I've yet to organise. Of course it'll take me a while to organise them all, but no where near as long if I were to use the standard email client.
There are some limitations though, like any app in the beginning. Mailbox for now only supports Gmail. There's no native iPad version where I think an app like this would do exceptionally well. And last but not least is availability. There is a reservation system in place for Mailbox which means not everyone can simply download and use it. You need to have a reservation code. I was lucky to get one because I wanted to review it but I know there are a lot of people who are still yet to receive their codes. This is not Mailbox's fault as such. Because the emails from your account run through servers to be compressed, there's only so many servers they can afford. They are expanding to support more users but like anything, it'll take time.
Mailbox is by far the best email client available right now. The gestures and the whole idea of it being a to-do list really do let you fly through email with ease. It's well worth the download, especially because it's completely free.