Move the Send Button away from other buttons OR Have an undo send feature
I generally like the layout of Outlook.com however the placement of the buttons on the top can lead to issues due to their close proximity. For example I just wanted to insert some more images into my email I was composing, and accidentally hit the send button. And off goes my unfinished email..
If the Send button was perhaps on the right side of the top banner (by the Skype icon) this situation could be avoided. Better yet maybe even have an Undo Send button like Gmail has.
Even a prompt that pops up asking if you are sure you want to send would be something at least. Right now it is just too instant.
Thanks for your consideration.
General design suggestion - when you have butons grouped together on iOS device, leave sufficient space between buttons so it is hard to hit the wrong one. Particularly when the buttons do dramatically different things.