Microsoft acknowledged on Tuesday that fewer than 1 percent of Hotmail customers have thus far been upgraded to the new service, though it said that it plans to add more users this week.

In a blog post, Mike Schackwitz said that as is often the case, Microsoft found a few issues as it started deploying the upgrade. With some minor changes made "under the hood" Schackwitz said the company is ready to put the new Hotmail on a few more server customers.

Microsoft began the public rollout of the new Hotmail two weeks ago, starting with a single server cluster. So far, a few million people are running the new version, though that is still less than 1 percent of all Hotmail users.

More: http://news.cnet.com/8301-13860_3-20009208-56.html