Microsoft reiterated in a blog posting that it plans to release the final versions of Exchange 2007 Service Pack 1 and Longhorn Server, the successor to Windows Server 2003, together during the second half of the year. But it remained coy on whether the two products will be totally compatible at that time.

The initial commercial version of Exchange 2007 doesn't work with beta releases of Longhorn Server. That incompatibility is stymieing would-be early adopters, who have had to resort to testing the SP1 release of Exchange 2003 on top of the operating system, said Bharat Suneja, principal Exchange architect at e-mail tools vendor Zenprise Inc. Suneja also maintains the Exchangepedia blog.

According to the message posted Friday on the Microsoft Exchange Team Blog, the company plans to support Exchange 2007 on Longhorn Server "on native IPv6 networks." But there was no mention of whether Longhorn Server's revamped handling of domain controllers and Active Directory will be compatible with Exchange 2007 SP1.

Asked about that issue, a Microsoft spokeswoman said that the Exchange 2007 SP1 plans "are evolving" and that the company will make an announcement on the features being included in the update at a later time.

Despite that public no-comment, Suneja said he has been personally assured by Microsoft representatives that the final release of SP1 will run on Longhorn Server and support the operating system's domain controllers. "I think it is a given at this point," he said.