It's official: Microsoft has killed Hotmail.
Once one of the most popular email programs, Hotmail was jettisoned and moved to Outlook.com on Friday, Microsoft said in a statement. Outlook is the company's redesigned webmail service.
All Hotmail accounts will remain active but with an Outlook.com interface. Users can also claim an Outlook email address.
(Read More: Microsoft's Outlook Takes Aim at Google's Gmail )
Including accounts rolled over from Hotmail, Outlook has 400 million active accounts, Microsoft said. The software giant also rolled out new features on the email platform Friday, including Simple Mail Transfer Protocol—a standard that makes sending emails from different addresses easier—and deeper integration with SkyDrive, its cloud storage system.
Microsoft originally launched the Outlook.com in July but kept the service in a "preview" phase until February, when the company also announced that it would be transferring all Hotmail users to the new email service.
—By CNBC's Cadie Thompson; follow her on Twitter @CadieThompson