Back in January 2013, there was talk that Microsoft was considering releasing a version of its Outlook mail client for Windows RT. It looks like talk is advancing into likelihood.
According to Windows SuperSite's Paul Thurrott, Outlook RT is being tested outside of Microsoft now, not just internally as it was a couple of months ago.
Thurrott also said he heard that Microsoft delayed releasing Outlook RT due to a firmware issue in ARM that was triggering crashes. I had heard scuttlebutt that excessive battery usage might be at fault, but nothing confirmable.
One of my sources said that Outlook RT has turned into a "top enterprise request," so the Office team had decided it should move forward and commercialize the port of Outlook to ARM. (I'm not so sure how many enterprises are really using Windows RT devices at this point, but I've heard Microsoft plans to increase its business-focused marketing push for Surface RTs and other Windows RT devices.)
Read more at source:
New signs point to Microsoft releasing Outlook for Windows RT this year | ZDNet