Service Pack 3 for Exchange Server 2000 is available for download
here.
The same download updates both Exchange 2000 Server and Exchange
2000 Enterprise Server.
You must install Windows 2000 Service Pack 2
(or a later service pack) before installing Exchange 2000 SP3. You
cannot remove SP3 without removing and restoring Exchange to the
original system state. Make a backup of your data both before and
after installing SP3. For other critical issues that
you should consider when planning your SP3 rollout, see:
The
comprehensive list of fixes is available at
September 2003 Exchange 2000 Server Post-Service Pack 3 Rollup.
Note that some of the files that are changed are OWA script files.
Due to these modifications, any OWA add-in software or customized
OWA runs the risk of being inoperable once the rollup has been
applied. KB article
824282 has more information on this service pack rollup.
OWA and Other Client Updates
For Outlook Web Access, you must upgrade all front-end servers to SP3
before upgrading any OWA back-end servers.