Decommissioning Exchange hosts should have all Exchange services disabled. Thereafter, we may safely turn these Exchange server off without interrupting email services.

Deleting Exchange servers aren’t usually recommended as there are risks involved. We could choose to archive virtual machine files onto an external hard drive to save space on production VM hosts. This typically is the extent of a decom task, and I do recommend that we pause decom activities of these machines at this phase to allow us the ability to “spin up” the machines should they consist of unknown-at-this-time email data.

Optionally, we may choose to fully purge Exchange servers. Here are the steps:

If the server is still online, start its Exchange services and move its public folder replicas to another Exchange host using these commands
$decomServers=”MAIL02″,”MAIL03″
$productionServer=”MAIL007″
$decomServers | %{MoveAllReplicas -sourceserver $_ -targetsever $productionServer}

Clear all remnants of the downed server from Active Directory – be advised that this is irreversible without AD restores:
-Connect to the domain controler
-Launch the run dialog (Windows Key + R)
-Type in the command “adsiedit.msc” et then press “OK”
-Right click on the console then “Connect to:”
-In the connexion dialog select “Well known Naming Context”
-In the drop down menu select “Configuration”
-Explode “CN=Configuration [domain]\CN=Services\CN=Microsoft Exchange\CN=[organization]\CN=Administrative Groups\CN=Servers”
-Right click on the dead server and pick “Delete”
-We also need to delete Database information as well, navigate to “CN=Configuration [domain]\CN=Services\CN=Microsoft -Exchange\CN=[organization]\CN=Administrative Groups\CN=Databases”
-Explode each items to find wich one is related to the old server, then delete it as well.
-Launch Server Manager > Navigate to Roles > Active Directory Domain Services > Active Directory users and Computers $domain > $domain > Microsoft Exchange Security Groups > Exchange Servers > right-click the decom server > remove this server to remove it from the list of Exchange Trusted Subsystem