Microsoft has been working with the NSA since the launch of PRISM. However the relationship between them is closer than we thought. Microsoft has been giving NSA permission to view data before encryption on the Operating System.
This stands true for their new email portal Outlook.com. They have launched a site called Scroogled to dissuade users from using Google email. Google crawls all data on their server for ad networking. This allows them to serve you relevant advertisements by spying on you.
This is bad of Google, but Microsoft should then be called a hypocrite. They may not be spying on your email at outlook.com, but the NSA certainly is. Microsoft handed over the encryption keys and certificates that make outlook.com secure. This means that the NSA can read all of your emails and chat in plain-text, easily able to see exactly what you are messaging.
Also since Microsoft acquired Skype, 3-times as many video calls are now being recorded. This is due to the agreement between the NSA and Microsoft. Since Microsoft Windows is the most popular operating system this affects a large number of people and businesses.