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VB-3931 avatar image
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VB-3931 asked KaelYao-MSFT commented

Need Guidence to Migrate the Linked Mailboxes from resource forest to Account Forest

Hello All,

We have a AD forest named ABC.com (Account Forest). We have another forest named XYZ.com(Resource forest). Exchange 2016 is hosted in the Resource forest XYZ.COM and all the users of ABC.com have mailboxes in XYZ.com Exchange environment as linked mailboxes and Remote user mailboxes (Some are migrated to office 365). Now, Job is to build the Exchnage 2019 in the account forest (ABC.COM)and migrate the mailboxes to ABC.com including on-prem mailboxes and O365 remote mailbox objects. Building of Exchnage 2019 seems to be okay and need some pointers to Migrate the mailboxes to ABC.com as Cross forest migrations approach by Microsoft is for straight forward cases. Has some done this kind of migration and please provide the best approach to achieve the same.

office-exchange-server-administrationoffice-exchange-server-connectivityoffice-exchange-hybrid-itprooffice-exchange-server-itprooffice-exchange-server-deployment
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2 Answers

imamitsingh avatar image
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imamitsingh answered VB-3931 commented

You can Check this article - https://jaapwesselius.com/2018/04/26/exchange-resource-forest-and-office-365-part-ii/

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VB-3931 avatar image VB-3931 ·

Hello Imam,

Thanks for the reply. I have seen this article in the past and this not talks about Mailbox migration from Resource forest to Account forest.

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KaelYao-MSFT avatar image
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KaelYao-MSFT answered KaelYao-MSFT commented

Hi @VB-3931

Based on my test, the cross-forest linked mailbox migration is similar to cross-forest user mailbox migration.
The major difference is that the AD accounts are already in the target forest (ABC.com), so there is no need to use the ADMT tool to migrate the accounts.

Source Forest: XYZ.com
Target Forest: ABC.com

The general steps would be:
1.Enable the MRS Proxy endpoint on EWS virtual directory for cross-forest mailbox moves
2.run the following command in ABC.com to covert the user to a mail enabled user

  Enable-MailUser -identity <user name> -ExternalEmailAddress <email address in the source forest>

3.run the prepare-moverequest.ps1 script (under the path C:\Program Files\Microsoft\Exchange Server\V15\Scripts) to copy the Exchange related attributes to the local account in ABC.com

 ./Prepare-MoveRequest.ps1 -Identity <source mailbox name> -RemoteForestDomainController <source forest domain controller> -RemoteForestCredential (Get-Credential SourceForest\Administrator) -LocalForestDomainController <target forest domain controller> -LocalForestCredential (Get-Credential TargetForest\Administrator) -TargetMailUserOU <the target OU specified when using ADMT> -UseLocalObject

4.run the following command to move the mailbox

  New-MoveRequest -Identity <the mailbox to move> -Remote  -RemoteHostName <target exchange server name> -RemoteCredential (Get-Credential SourceForest\Administrator) -TargetDeliveryDomain <source forest>

Besides, there is also a workaround to migrate via Export/Import pst files.
The general steps would be:
1.create a new mailbox in ABC.com
2.export the old mailbox to a pst file in XYZ.com
3.import the pst file into the new mailbox

Here are several links which may be helpful:
via Exchange:
Procedures for mailbox exports to .pst files in Exchange Server
Procedures for mailbox imports from .pst files in Exchange Server

via Outlook:
Export or backup email, contacts, and calendar to an Outlook .pst file

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VB-3931 avatar image VB-3931 ·

Hello KaelYao,

Thanks for the reply, Really Appreciated for your time on this.

We will check the steps in Test environment and come back here.

Regards
VB

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KaelYao-MSFT avatar image KaelYao-MSFT VB-3931 ·

Hi,
Thanks in advance for your update.

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KaelYao-MSFT avatar image KaelYao-MSFT VB-3931 ·

Hi @VB-3931

I am writing here to confirm with you how thing going now?
If you have any questions or needed further help on this issue, please feel free to post back.

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VB-3931 avatar image VB-3931 ·

Hello @KaelYao-MSFT

Thanks for checking on this. We have been testing , we are able to migrate the Mailboxes from source forest to destination. But we have few more questions came up during this

  1. How can we enable the free/Busy between Source forest , Destination forest & O365. As Source forest is Hybrid environment?

  2. When is best time to move the Exchange Hybrid to Destination forest and best methodology?

  3. Best approach to enable the remote mailbox for the O365 mailboxes in the destination forest?

  4. Does these migrations need outlook re-configuration for end users?

Thanks for the help in advance

Regards
VB



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KaelYao-MSFT avatar image KaelYao-MSFT VB-3931 ·

Hi VB,
Thanks for the update!

However, since your currently environment is a little complicated, it may take much effort to enable free/busy between the forests.

If your goal is to finally migrate to the target forest,I would suggest:
1.move all the on-premises mailboxes to the target forest
2.remove hybrid deployment in the source forest
3,recreate the hybrid deployment in the target forest

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