Microsoft Windows Server 2003
Microsoft Exchange Server 5.5
Directory and Resource Administrator 7.x
Cannot install Exchange 5.5 Administrator on a Windows 2003 machine.
Error: 'Exchange Server 5.5 is not supported by this version of Windows.'
Microsoft Exchange Server 5.5 will not install on a Windows 2003 server, so the installation is halted immediately after the operating system version check.
Install the Exchange 5.5 Administrator from an Exchange 2003 CD if you are installing on a Windows 2003 server. The install option is available under 'Microsoft Exchange System Management Tools'.