This article was previously published under Q170280
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To upgrade the Standard Edition of Microsoft Exchange Server to theEnterprise Edition of Microsoft Exchange Server, run the Setup program fromthe Exchange Server Enterprise Edition compact disc and click the Reinstall button.
To install any additional components or connectors included in theEnterprise Edition of Exchange Server, run the setup program again andclick Add/Remove.
Note Any Exchange service packs or hotfixes must be reapplied after you upgrade. Once upgraded, you cannot downgrade Exchange Enterprise Server edition to the standard version of Exchange Server.
For more information about a case in which the upgrade is not possible because of the different packaging of the product, click the following article number to view the article in the Microsoft Knowledge Base:
312426 No option to upgrade from Exchange 2000 Server Standard Edition to Exchange 2000 Enterprise Server
Microsoft Exchange Server 2003 Enterprise Edition, Microsoft Exchange Server 2003 Standard Edition, Microsoft Exchange 2000 Enterprise Server, Microsoft Exchange 2000 Server Standard Edition, Microsoft Exchange Server 5.5 Standard Edition