Microsoft began publicly previewing a new webmail service for consumers called Outlook.com that will eventually replace Hotmail.
Microsoft also expects that Outlook.com will draw people away from competing consumer webmail services like Google's Gmail and Yahoo Mail.
With Outlook.com, Microsoft set out to "reimagine personal email - from the data centre all the way to the user experience," said Microsoft official Chris Jones.
Outlook.com features what Microsoft describes as "clean" and "intuitive" user interface that gives more prominence to messages and less to other elements, like headers and search boxes. It doesn't include display ads.
With Exchange ActiveSync, Outlook.com accounts can be synchronised across a variety of devices, and it features native integration with Facebook, Twitter, LinkedIn, Google and, in the near future, Microsoft's own Skype.
This means that users can access content and notifications from those social media accounts within the Outlook.com interface.
Outlook.com also sorts messages of different types into separate buckets, so that email from contacts, newsletter subscriptions, e-commerce notifications and social media content is arranged into different groups.
The new webmail service also includes Office Web Apps, the online versions of Word, Excel, PowerPoint and OneNote along with the SkyDrive cloud storage service.
Once Outlook.com exits its test phase, it will replace Hotmail's user interface, although users will be able to retain their @hotmail.com, @live.com and @msn.com addresses as well as their contacts, messages, password and rules.
"While today's preview is just the start, Outlook.com is ready now to become your primary email service. We're expecting millions of people to try it out. Starting today, you can get an @Outlook.com email address, and we've also made it easy to get started with your current email address if you want to," Jones said.
Outlook.com is not to be confused with the Outlook email and calendaring PC application, nor with Outlook Web App, which gives Exchange users access to their accounts via a browser.