Six months after launching, Microsoft has officially taken Outlook.com out of preview and has begun prompting Hotmail users to switch to the new service.

Outlook.com will replace Hotmail from the ground up — all the way from the data center to the user experience and everything in between. The company also promises a calendar UI upgrade and Skype integration with video calling and messaging “soon after” today.

For existing Hotmail members, switching to Outlook.com is as simple as upgrading. You can choose to upgrade right away, or you can wait to be auto-upgraded by the summer. Your @hotmail address, password, messages, folders, contacts, and even vacation replies will stay the same.

You’ll never have to switch your email address to an @outlook.com address if you don’t want to. Even if you currently use another email service, such as Gmail, you can still take advantage of Outlook.com and keep your Gmail address. This is done by setting up mail forwarding — nothing innovative here — and giving your Outlook.com account permission to send mail as your Gmail alias.

At the time of launch, Outlook.com boasted 60 million active members. Microsoft noted that more than one-third of those switched from Gmail. This will likely be a great upgrade for people using Hotmail, and a smart alternative for Gmail or Yahoo members looking for a change.

[Via: The Verge, Image credit: Riyadh]