Microsoft on Wednesday delivered Beta 1 of Exchange 12 to a select group of about 1,400 beta testers. The next-gen communications server promises to bring "unified messaging" that combines e-mail, fax and voicemail into a standard inbox. But be prepared to upgrade: Exchange 12 will only run on 64-bit systems.

By bringing together disparate types of communication into a single Exchange inbox, users can access messages from anywhere, including their desktop, mobile phone and browser though Outlook Web Access. Traditional phones can also be used with the voice recognition provided by Outlook Voice Access.

Outlook Web Access has been spruced up for Exchange 12. Microsoft is updating the online client to look and function like the next version of Outlook, due in late 2006. In addition, a new Scheduling Assistant helps plan out meetings and book attendees.

A lot of work on Exchange 12 has been focused on administrative tools. The new release has been componentized and administrators can choose to install only the pieces they need. Exchange will also be able to automatically detect and configure end-user systems.

Microsoft's new command line shell, known as Monad, will make its first appearance in Exchange 12. The scriptable shell can be used for automating tasks, essentially providing command line control of Exchange that goes beyond the standard Exchange System Manager.

With security now a top concern for the Redmond company, Exchange 12's defenses have been bolstered with built-in anti-spam protection and better attachment blocking with support for multiple antivirus engines.

Microsoft hasn't yet set a final release date for Exchange 12, giving itself a window of late 2006 and early 2007. Because the new Exchange will be 64-bit online, it will require Windows Server 2003 R2 x64 Edition or the 64-bit version of Windows Server "Longhorn," which is due out in late 2007.

While some may see the move to 64-bit as an unnecessary requirement to spur upgrades, Microsoft says customers will benefit in the long run and help to ease the migration.

"We are making big bets on 64-bit technology and working closely with our industry partners to enable a smooth transition for customers, so they can begin to realize the benefits of mainstream 64-bit computing," Bob Muglia, senior vice president of Microsoft Server and Tools, said last month.