Users of iPhone iOS 4.0 and Microsoft Exchange have received some startling news over the last few days. It seems the iOS has begun blocking Exchange, forcing users to upgrade to the new iOS 4.0.1. That means no mail. Nada. Zip. Kind of harsh, right?

Here is what the Microsoft team has to say:

“To deliver the best possible service experience, Microsoft Online Services is requiring users with devices running iOS 4.0.0 to update their devices to iOS 4.0.1 by July 29, 2010.” They go on. ““Only iPhone devices runnning iOS 4.0.0 will be blocked; and the reason for the block is user experience. As we talked about in the blog posts, iOS 4.0.0 has problems with the way Apple implemented Exchange ActiveSync, causing users difficulty synchronizing messages, contacts, and calendar items.. Those problems have been fixed in iOS 4.0.1. The iOS update is an easy install via iTunes.” - from a comment response on the team blog.”

It’s not all bad, however. The new iOS features a number of fixes that promises to speed up the experience for iPhone users. This is great news considering it was extremely sluggish prior.