The next version of Exchange Server, expected to ship 30 to 45 days after the release of Windows NT 5.0, will feature closer ties to the NT operating system. NT 5.0 isn't expected until early 1998, but the team responsible for Exchange 5.0 has already been moved into the NT group. Microsoft now considers Exchange a "driver-class product like Office 97 because it causes mass upgrades with each release, as a true operating system release would.