Migrating Existing Forest with Exchange 2019 to a new forest domain also using AD Connect for o365 syncing

SysAd09 1 Reputation point

I haven an existing forest/domain that have some issue and I want to create a brand new forest/domain and bring over users etc ADMT. I want to know what is the best way to accomplish this with the Exchange 2019 in mind. I wanted to minimize down time and have read several articles about cross migration to a new Exchange server, but will the domain controller portion have to be done first then the exchange? Any help is appreciated!

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A set of directory-based technologies included in Windows Server.
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Exchange Server Management
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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  1. KyleXu-MSFT 26,226 Reputation points


    There are exist two ways to migrate mailboxes:

    Way 1:

    1. Migrate all mailboxes to Exchange online, then decommission the old Exchange on-premises.
    2. Create hybrid and AAD sync with new domain/forest, migrate mailboxes back to Exchange on-premises, if you want.

    Way 2:

    1. Migrate all mailboxes to Exchange on-premises, then remove hybrid and AAD connect.
    2. Use ADMT to do a cross-forest migration to migrate mailbox from old domain to new domain. You could have a look about this article(Suitable for Exchange 2019) Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.
    3. Create AAD sync and hybrid in new domain.

    If there doesn't exist hybrid in your organization, I think the second method is more suitable.

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  2. Limitless Technology 39,471 Reputation points

    Hi there,

    You can Prepare mailboxes for cross-forest moves using the Exchange Management Shell. Exchange Server supports mailbox moves and migrations using the Exchange Management Shell New-MoveRequest and New-MigrationBatch cmdlets. You can also move the mailbox to the Exchange admin center (EAC).


    Hope this answers all your queries, if not please do repost back.
    If an Answer is helpful, please click "Accept Answer" and upvote it : )

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