The co-existence with Exchange 2007 will require Service Pack 2, which Atalla said would ship later this moth.

Microsoft has said previously that it has specially architected Exchange 2010 for high-availability and cross-domain integration using techniques such as pairing the server with Windows Server 2008 clustering technology and directory federation features.The company said that the ability to use Exchange as a hosting platform is now built into the product.

The Exchange beta includes a number of user and administrative features, including new archiving capabilities, but perhaps the most distinguishing characteristic is its online and on-premises split personality.

The company hopes that personality will make it easier for corporate users to straddle environments with some users on internal systems and others using hosted mailboxes from a service.

Features, such as Powershell support, will give administrators one set of tools for managing internal users, users on hosted platforms, and the infrastructure needed to bridge the gap between the two.