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Exchange Team Blog

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Permanently Clear Previous Mailbox Info

Microsoft

Jan 17, 2018

We are introducing a new parameter that can be called by using the Set-User cmdlet in Exchange Online PowerShell. The feature is focused for customers doing migration of on-premises mailboxes to the cloud and you will be able to use it within three weeks or so (Edit 1/19: we updated this due to slower than expected rollout): Customers who have Hybrid or on-premises environments with AAD Connect / Dir Sync may have faced the following scenario:

User Jon@contoso.com has a mailbox on-premises. Jon is represented as a Mail User in the cloud.
You are synchronizing the on-premises directory to the cloud in preparation to migrate to Exchange Online.
Due to issues with the on-premises sync or due to a configuration problem, the user Jon@contoso.com does not get the ExchangeGUID synchronized from on-premises to the cloud.
If the Exchange GUID is missing from the object in the cloud, assigning an Exchange license to Jon@contoso.com will cause Exchange Online to give the user a mailbox, converting the object from a Mail User to a User Mailbox. (Adding the license is a step required for the migration of the mailbox from on-premises to the cloud.)
The end result is the user that has 2 mailboxes: one on-premises and one in the cloud. This is not good. Mail flow issues will follow.

Those doing these types of migrations will know that the ExchangeGUID value is very important as it helps Exchange Online identify that the user has a mailbox on-premises, and if an Exchange license is assigned in the cloud, a new mailbox should not be created. The immediate fix for this situation is to remove the Exchange License from Jon@contoso.com. This will convert the cloud object for Jon back to a Mail User. Mail flow should be restored at this point. The problem now is that you have an “unclean” cloud object for Jon. This is because Exchange online keeps pointers that indicate that there used to be a mailbox in the cloud for this user:

PS C:\WINDOWS\system32> Get-User Jon@contoso.com | Select name,*Recipient*
Name PreviousRecipientTypeDetails RecipientType RecipientTypeDetails
---- ---------------------------- ------------- --------------------
Jon UserMailbox MailUser MailUser

Re-assigning the license after that will always err on the side of caution and Exchange Online will try to re-connect the (duplicate, temporary) mailbox in the cloud (and mailboxes can be reconnected for 30 days). Therefore Jon’s account in the cloud can’t be licensed in preparation for migration. Up to now, one of the few options to fix this problem was to delete *only in the cloud* Jon’s object and re-sync it from on-premises. This would delete jon@contoso.com from the cloud – but from all workloads, not only Exchange. This is problematic because Jon could have his OneDrive or SharePoint data in the cloud only and deleting his account means that this will be deleted too. If the account is then re-created, Jon and the tenant admin would have to work to recover to his new account all the data he used to have in OneDrive or SharePoint just because Exchange data needed to be “cleaned up”. The new parameter in the user cmdlet will allow tenant admin to clean up Exchange Online Jon’s object without having to delete it. To clean the object, you can run the following command:

PS C:\> Set-User Jon@contoso.com -PermanentlyClearPreviousMailboxInfo
Confirm
Are you sure you want to perform this action?
Delete all existing information about user “Jon@contoso.com"?. This operation will clear existing values from Previous home MDB and Previous Mailbox GUID of the user. After deletion, reconnecting to the previous mailbox that existed in the cloud will not be possible and any content it had will be unrecoverable PERMANENTLY. Do you want to continue?
Yes Yes to All No No to All [?] Help (default is "Y"): Y

Executing this leaves you with a clean object that can be re-licensed without causing the 2-mailbox problem. Now you can on-board Jon’s on-premises mailbox following the usual steps. An alternative – a call to support to do the clean-up for you - is also not needed. Remember, cleaning up the user means that the older associated disconnected (duplicate) cloud mailbox is not recoverable. If you want to keep it or be able to check it’s content, we recommend using Soft Deletion or Inactive Mailboxes to keep the mailbox.

Note: This command is expected to be executed when you have an on-premises mailbox and a mailbox in the cloud for the same object due to bad AAD Connect configuration, to clean the object that can be re-licensed. The procedure allows you get out of the dual mailbox state and enable you to re-try on-boarding the mailbox immediately.
If you execute this for a user whose mailbox is cloud only after delicensing the user (and intend to later re-license the same user and expect to have a new clean mailbox for the user) - then this will not happen immediately. To avoid potential loss of mailbox data due to unintended/mistaken execution of the command, we retain the mailbox data for 30 days so that you may recover it. If your intention is to clean-up cloud only mailbox then you may hard delete the user account to re-create a clean mailbox.

Mario Trigueros Solorio

Updated Jul 16, 2021

Version 3.0

Microsoft

Joined April 19, 2019

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Exchange Team Blog

You Had Me at EHLO.

tguarriello
Copper Contributor
Dec 17, 2019
I was hopeful that this was the answer to my problem, but I get "Command completed successfully, but no user settings were changed." Still can't sync due to "Target user already has a primary mailbox". Users have significant OneDrive and Sharepoint content, so account delete is not a great option. Any insight would be appreciated.
Ger_van_der_Kamp
Copper Contributor
May 15, 2020
Found a solution... set-user with -PermanentlyClearPreviousMailboxInfo works when using the Exchange Online PowerShell V2 module.
Brad_Reeve
Copper Contributor
Mar 30, 2020
tguarriello TOPIT : Did either of you find a solution to this?

I have tried many ways to remove the users Exchange license, but it doesn't actually seem to do anything. All the cmdlets claim the licence is still there, yet the Admin panel says it is gone. I am unable to use PermanentlyClearPreviousMailboxInfo or even Disable-Mailbox.

Is there a delay between removing the license and the decommissioning workflow? Or should it be fairly immediate?

The only way I seem to be able to resolve this is to completely remove the MSOL user. Does anyone have any current info on this? Thanks.
PowerSam
Copper Contributor
Mar 03, 2021
Hint for all: You have to remove also the Teams Exploratory license.
KyleHardin
Copper Contributor
May 05, 2021
I'd like to add that there is a bit of a delay between unassigning the Exchange Online license and the mailbox being deactivated. You may need to wait a while for the user to no longer appear in the Exchange Online management page (or run get-mailbox against the user to see if the mailbox still exists in an active state).

This delay ended up being why I was receiving the "no changes were made" message after running the set-user commandlet with the tag PermanentlyClearPreviousMailboxInfo. After waiting a while for the mailbox to disappear from Exchange Online, the command worked.
Deleted
Jan 24, 2018
This is a welcome addition, but the mailbox that was provisioned prematurely might now have stuff in it. it would be great if there was a way to restore the content from the smaller mailbox and merge it with the larger, with minimal code. Also, I've found that many of the times mailboxes are provisioned prematurely are related to the wrong immudableID flowing in a linked mailbox scenario. In that case, we're still required to hard-delete the cloud user.
Honestly, a better fix would be to allow us to disconnect the SPO workloads from the aAD object. We have several tools with Exchange, but those guys don't seem to acknowledge the problem.
GLComputing
Brass Contributor
May 29, 2020
I had this issue ... Tech support had no idea how to fix it.
I found this article and they even told me not to do it. As they couldn't give a reason I tried it with a "less important" account.

It was simple, easy and worked.

The steps from support were:
As the users which are having mailboxes both in cloud as well as in on premises was due to assigning the license to those users before syncing it to Exchange on premises and then after syncing the exchange on premises with cloud it resulted in soft match which in turn resulted in two mailboxes. The steps that should be done to avoid it are:
Remove the license of the users who have two mailboxes (both in cloud and in on prem)
Then move those users in non sync OU in Active directory
Then hard delete those users from the cloud
Then move the users back to syncing OU in Active directory and then run delta sync
This will remove the mailbox from the cloud
Happy to supply Case number off-line if you want it. The_Exchange_Team
Joshua Bines
Iron Contributor
Jan 14, 2021
I think important to mention the impacts of In-Place Hold. You must first remove any holds before complete this procedure. I found that if you have a mailbox hold the mailbox will not be soft deleted and the Set-User -PermanentlyClearPreviousMailboxInfo CMDlet will fail with "A parameter cannot be found that matches parameter name 'PermanentlyClearPreviousMailboxInfo'"which is not so intuitive.

Procedure as I see it:
Backup data in mailbox! if you need it...
Remove all Hold's from the mailbox. Test by trying
Disable-Mailbox <> -PermanentlyDisable
In EXO this will provide you with the Inplace policy GUID and blackarts will guide you from there 😉 (See links below)
Check DelayHoldApplied
Get-Mailbox <> |fl compl*,delay*,inplace*
These values should be set to false if not Set-Mailbox -Identity <> -RemoveDelayHoldApplied
Remove the user's license.
Run Get-User RecipientType should -eq MailUser not Usermailbox
Run Set-User -PermanentlyClearPreviousMailboxInfo.
Add the user's license.
If your at this point... Good luck!
JB

Other helps:
https://docs.microsoft.com/en-us/microsoft-365/compliance/identify-a-hold-on-an-exchange-online-mailbox?view=o365-worldwide
https://answers.microsoft.com/en-us/msoffice/forum/msoffice_o365admin-mso_exchon-mso_o365b/exchange-cant-disable-this-mailbox-because-it-is/44ce9f30-7683-4c67-b52c-b7658cdce0ec
Theonenonly
Copper Contributor
Nov 01, 2021
The above command completes but doesnt actually purge the mail data 😞

I remove the licence, wait for it to disappear from get-mailbox and run the command, its runs successfully I then wati a few mins, apply licence to the user and log back into the mailbox and all data is still there!

Anyone had the same?
Deleted
Jan 17, 2018
I have been in this scenario where a directory sync misconfiguration allowed Exchange Online to provision mailboxes instead of mail users and I can confirm, it was pretty hard to recover from this situation. This new feature is definitely an improvement. Implementing the feature as a switch for Set-User does not feel very intuitive though, but I like the clear warning text that's presented before asking confirmation.