In order to protect a Microsoft Exchange server, the Exchange Database Client API must be available. For Exchange 5.x servers, this API is available through a system DLL named edbbcli.dll, which can be applied by installing the Microsoft Exchange Administrator utility (from the Exchange Server CD). For Exchange 2000 servers, this API is available through a system DLL named esebcli2.dll, which can be applied by installing the Microsoft Exchange System Manager utility. The appropriate utility for the Microsoft Exchange environment should be installed on all Backup Exec servers in the domain that are licensed for Microsoft Exchange backups.
Therefore, if Microsoft Exchange 2000 is not installed then this error may be safely ignored. The error appears because Backup Exec for Windows NT and Windows 2000 Server versions 8.5 and higher include support for Exchange 2000. Backup Exec looks for the Exchange 2000 specific .dll upon the installation of the Exchange 2000 compatible serial number, and it will not find it if Microsoft Exchange 2000 or the Exchange 2000 System Manager is not locally installed. This .dll is not used for and does not exist in Microsoft Exchange 5.5, so installation of the 5.5 components will have no affect on the error message.