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

VB 6 Reputation points
2021-11-12T15:48:16.46+00:00

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.

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Exchange Server Management
Exchange Server: A family of Microsoft client/server messaging and collaboration software.Management: The act or process of organizing, handling, directing or controlling something.
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Microsoft Exchange Hybrid Management
Microsoft Exchange Hybrid Management
Microsoft Exchange: Microsoft messaging and collaboration software.Hybrid Management: Organizing, handling, directing or controlling hybrid deployments.
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  1. Amit Singh 4,846 Reputation points
    2021-11-15T06:00:32.48+00:00
  2. Kael Yao-MSFT 37,496 Reputation points Microsoft Vendor
    2021-11-15T09:05:10.88+00:00

    Hi @VB

    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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