With Outlook.com, Microsoft is trying to stem the loss of Hotmail users who no longer think Hotmail is cool, and better compete against Gmail, whose interface remains a source of frustration for a segment of its users, he said.

There is also an attempt to create a "horizontal consumer portal" with Office Web Apps, SkyDrive and Skype, as well as position Outlook.com as a central clearinghouse for users' social networking activities.

"Outlook.com represents reverse 'consumerization' -- taking a ubiquitous business tool and recrafting it for the consumer market," Cain said.

Meanwhile, IDC's Al Hilwa said that Outlook.com fits into the trend among providers of consumer online services that provide "an online home" for users.

"Players are connecting their online assets together and hoping to provide convenience and functionality of a one-stop-shop of services," he said via email.