Exchange Server 2010 - Decommission Gone Wrong

Good afternoon,

Yesterday we had a mishap in which accidental deletion took place of user accounts within Microsoft Exchange 2010. The aim goal was to remove mailboxes, then databases and uninstall Exchange. However not realizing at the time, upon removing the mailboxes this deleted all active directory accounts. At this point the Microsoft Exchange 2010 server was then shutdown and left powered off.

We then restored our Windows Server 2012 R2 Domain Controller to the previous nights backup to restore AD, this was the only option as AD recycle bin was not yet enabled. After clean up of the Domain Controller the network is now in a healthy state and all is well again.

However coming back to the Exchange server we are not sure what will happen if this server is powered back on, will this effect AD in a form of sync? Or will this just sit with detached mailboxes as it was left. If there is no harm in booting the Exchange server back up can we then continue with the decommission of Exchange server?

Luckily we did take a full backup of the Exchange server before anything mailboxes were removed, so if it is better to first restore the Exchange server and then carry out proper decommission please could you advise?

Many Thanks.
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There wont be any issue powering on the Exchnage server.
Adam BrownSr Solutions ArchitectCommented:
You shouldn't have any issues turning the Exchange server back on, but it should be noted that there may be some level of weirdness with your mailboxes. If you restored an AD backup from before the mailboxes were disconnected, they will have returned to that configuration when you did the restore, since that information is stored in AD, and the restore would have included that information. Also, you may have some issues if you are decommissioning the Exchange server following a migration to a different On-prem Exchange version, but it really depends on how things were when you performed the backup that you restored.

Another option would be to perform a manual removal of the databases and Exchange server information in the Active Directory services configuration. has some information on how you can do this. This would effectively decom the Server and remove it from your environment, as well as all databases. Mailboxes themselves are stored in the Mailbox Database, which will remain on the decommissioned server until you decide to wipe it.

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CT08Author Commented:
I can confirm that once the Exchange server had powered back up it linked back in with AD as it was before any decommission took place. The end result was a manual removal of Exchange carried out using a mixture of ADSI edit/DNS removals using various guides. Once a clean up process had been done as a follow up, the network is healthy with no found Exchange entries.
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