Why is mobile email still so bad? And how can we fix it?

Despite all efforts to the contrary, email is still the default way to shift files, photos and – yes – mail around the internet. Even when you share a file using Dropbox, the link goes via old-fashioned email. And yet email clients are still awful. They’ve gotten a lot better in the last couple of years, on both iOS and the Mac, but we’re still stuck without a proper task manager that integrates with the native iOS/OS X Calendar and Reminders.

What’s going on?