Alex Kipman, who led the invention of Microsoft's hologram headset, at the Windows 10 launch / Microsoft

Like a revived MSN Messenger, Flow will offer a lightweight chat app, and will run alongside Microsoft's Outlook email app

Microsoft is to launch its own chat app called Flow, which hopes that it can streamline email and enter the hotly-contested market.

The new app will let people have "rapid email conversations on your phone", in a way more like a chat app, according to supposedly secret details discovered on a publicly-accessible Microsoft site. The chats will allow "Fast, fluid, natural conversations", with no "subject lines, salutations or signatures".

Running on email, the app is set to complement Microsoft's client, Outlook. It is thought to be similar to Skype Qik, a slimmed down version of the video chat service launched last year.

The app was discovered by a Twitter user, who found promotional material for the app sitting on a public website.

The leaked information seems to indicate that the app will come to iPhone first. While that might be unexpected given that Microsoft makes its own phones, it has been increasingly looking to release apps for Apple's operating system.

The app marks a return to the messaging market for the company after it shut down the once popular MSN Messenger last year to concentrate on Skype. It is also an attempt to take on popular apps like WhatsApp and Facebook Messenger.

MSN Messenger was released in 1999. In 2005 it was re-named Windows Live Messenger — though mostly continued to be known by its old name.

But after Microsoft bought Skype and Messenger uses dropped, the company chose to discontinue the service. It was killed off everywhere but China in 2013, and then ended entirely 18 months later.