When Outlook 2003 cannot connect to an Exchange server, it brings up the somewhat ambiguous error message, "Exchange is in recovery mode," which can be a bit misleading.
I've written before about some of the possible reasons for this -- one being a failure of internal DNS, the other being old .OST information on the client. But there are other possible reasons for the "recovery mode" error.
The DNS issue implies that the error can come about as a result of a simple failure of connectivity, either on the part of the server or the client. Sometimes this can take a subtler form, however -- not a complete failure of network connectivity, but rather a failure to have the client rejoined to the proper domain.
This sort of thing happens if an Exchange server is hosted on the same machine as the primary domain controller, and the whole thing has to be rebuilt from the ground up by reinstalling the operating system and Exchange.
This is, in effect, an entirely new domain controller with a new GUID, a new Active Directory store, and so on. Even if all of the old naming conventions (the domain name, server's name, client machine names) are the same, the GUIDs used to represent those things in AD are not the same, and so the users will need to be rejoined to the reconstructed domain before they can work correctly.
Strictly speaking, this is more of an AD problem than an Exchange problem, but so much of Exchange's functionality is tied into how AD works that the two are essentially inextricable. This is also yet another argument for making timely and consistent "bare metal" backups, come to think of it -- you have fewer consistency issues to worry about than if you rebuild a server by reinstalling everything by hand.
About the author: Serdar Yegulalp is editor of the Windows Power Users Newsletter and a regular contributor to SearchExchange.com.
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Related information from SearchExchange.com:
Tip: How to recover from 'recovery mode' error in Exchange 2003
Expert Advice Exchange in recovery mode
Troubleshooting Guide: 'Exchange is in recovery mode' errors
Reference Center: Exchange Server backup and recovery resources
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