Unnamed sources have told ZDNet that Microsoft has completed and is now internally testing an Outlook client for Windows RT.

According to the sources, Microsoft has not determined a commercial launch date for Outlook RT because there's a good chance the client may never be released. That's because there's reportedly a back-and-forth going on between teams within Microsoft over whether the company should or should not release the app.

Insiders told ZDNet that some people within the Windows unit want to preserve the Mail/Calendar/People app bundle as it stands now. Then there are others who are in favor of renaming the existing Mail app to "Outlook". There's also a group that wants to distribute Outlook as a separate, native application.

Do Surface RT users even need an Outlook client? As it stands now, they can access their email simply by clicking on the live tile and adding their account – new arrivals are clearly shown on the Start screen. However many critics have described this app as lackluster, and perhaps not even as good as the client offered on Windows Phone.

Currently Microsoft offers Word RT, Excel RT, PowerPoint RT and OneNote RT in the Office Home & Student 2013 RT suite that's bundled with the Windows RT platform. As ZDNet points out, they're not even Modern UI/Windows Store-style apps either, which is surprising given Microsoft’s push for the new interface.

When asked about the possible standalone Outlook app for Windows RT, a spokesperson for the Office team told ZDNet that Office Home & Student 2013 RT does not include Outlook – well no kidding. The spokesperson then added that "Microsoft Office doesn't come with Surface 8 Pro, but can be purchased separately."