Microsoft's popular web email service, Outlook.com, is ready for primetime. Microsoft made available Outlook.com last summer as a preview. Since then, 60 million of people have already started using it, the company claims.

The new features being introduced in Outlook include the ability to send massive files, including hundreds of photos at a time, in a single email; address books that automatically update new contact information that connections post on Facebook, Twitter and LinkedIn; and about 60 percent fewer ads than Hotmail. The service is also designed to make it easy to send hundreds of photos and videos in a single message - all powered by SkyDrive.

Starting today, Microsoft will begin to upgrade every Hotmail user to Outlook.com. The upgrade is instant for Hotmail users; everything from their @hotmail.com email address, password, contacts, etc. will stay the same.

With the release of Outlook.com, Microsoft escalates an assault on rival services from Google, Yahoo and AOL.

People are regularly check their inboxes, meaning that with web enail services, Internet companies a way to keep people coming back to websites. Frequent visits and personal identification are two of the keys to selling ads, the main way most websites make money.

Outlook.com will be featured in ads running on primetime TV, radio stations, websites, billboards and buses. Microsoft expects to spend somewhere between $30 million to $90 million on the Outlook campaign, which will run for at least three months.

Google claims that its own web mail service, the Gmail, has more than 425 million accountholders, including those that only visit on smartphones and other mobile device.