As we shared on Reddit, we're happy to announce the immediate availability of IMAP (and OAuth) for Outlook.com. Outlook.com already supports the industry's best email connectivity with Exchange ActiveSync (EAS), which is available on the majority of smartphones and tablets, including Windows Phone, iOS, and Android devices, as well as the Windows 8 Mail app and Outlook 2013. With today's announcement, we now have a richer email experience across devices and apps, including those not using EAS, such as Mac Mail and Thunderbird on a Mac.
Read more at: Outlook Blog - Outlook.com now has IMAP