Some of the beta testers for Microsoft's Windows Live Hotmail service are getting an increase in storage, but the extra capacity isn't being introduced as smoothly as anticipated.

The users will see from their storage meter that they now have 4GB of storage, up from 2GB before. But the extra storage might not actually have been assigned to their accounts yet, according to a Microsoft blog posting.

"This seems like putting the cart before the horse," the posting says. "The reason for this is that the storage upgrade is being gradually rolled across the universe and does not immediately change every account at the same time."

The problem should resolve itself as the upgrade continues over the next two weeks, Microsoft said. The expanded storage is only for ‘Hotmail Plus’ customers who are beta testing Windows Live Hotmail, a revamped version of the company's web email service.

Microsoft's free Hotmail service offers 1GB of storage and a 10MB attachment limit. By comparison, Google's Gmail offers 2.6GB of storage for free and Yahoo's free email includes 1GB of storage. However, Yahoo announced last week plans to trump both Google and Microsoft by offering unlimited storage to Yahoo Mail users from May.