I've added some extra settings today for Notifications, so you have more control over how and when you receive messages from the website.
As well as by email, you can now also receive instant push notifications on supported desktops, tablets and phones - which at the moment unfortunately doesn't include iPhones and iPads.
Go to Your Account > Notifications > Settings to set it up (
or just click here). It's opt-in, so everything will continue as before if you don't want any changes.