This guide shows how to delete an Exchange Online mailbox, without deleting associated user account in Azure AD.
This can be verry usefull if you are about to setup a Hybrid environment whit your on-premises Mailserver.
If you delete the Azure AD user account then, obviously, mailbox is removed, but maybe we don’t want to do that, since users will lose all onedrive, teams data etc.
If you navigate to; https://admin.exchange.microsoft.com/#/mailboxes you will see the mailboxes i 365
Here we see Anders have a mailbox in 365
Remove the users Exchange Online License
Go to https://admin.microsoft.com/#/users and find the user (let’s take Anders Again) note Anders is currently not synced whit the local AD
Click on Licenses and Apps and click on Apps
Remove the Exchange Online license and click Save
if we look back at https://admin.exchange.microsoft.com/#/mailboxes, we see the mailbox is now soft deleted (but not hard deleted, so if we give the user the Exchange Online license back, the mailbox will just come back again)
Connect to exchange online powershell
Now we have to purge the soft deleted mailbox
Run this command;
Set-User firstname.lastname@example.org -PermanentlyClearPreviousMailboxInfo
And confirm to delete the mailbox
Move the user back to an synced OU (optional)
Move the user to an OU in your local active directory that is your AD Connect sync scope, and make a fresh sync or wait 30mins (Start-ADSyncSyncCycle -PolicyType delta)
Now Anders is AD Synced
Give user the Exchange Online License back
Give Anders back his Exchange Online license, and click save
Lets take a look at Anders mailbox again. Now it shows This user’s local mailbox has not been migrated to Exchange Online. The Exchange Online mailbox is available when the migration is complete