Office 365 Email Migration Help two different domains

Gabe Berrocal 1 Reputation point
2021-11-19T19:45:57.563+00:00

Hello I have a question regarding email migration. I am moving over to Office365 from a hosted exchange server(Intermedia) we have two different domains(two companies) and want to switch over the one company first that has a few mailboxes and then switch over the other company at a later date. I am wondering whether to do a cutover migration or staged migration. Just want to make sure there is a way to do this without transferring over both domains(companies).

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. Amit Singh 4,846 Reputation points
    2021-11-22T11:45:47.597+00:00

    The on-premises Active Directory UPN becomes your login for Office 365. Your UPN should match your primary SMTP address. And changing the UPN doesn't mean anything happens to the samAccountName, which means unless the user is logging into their workstation with the UPN, there will be no change to the user's workstation login experience.

    Below some helpful links-

    Office 365 – Why Your UPN Should Match Your Primary SMTP Address

    Why do you need to fix mismatched UPNs and SMTP addresses before you migrate to Office 365

    Scripts to update UPN to match the user's Primary SMTP email address

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  2. Vasil Michev 94,911 Reputation points MVP
    2021-11-20T07:06:45.75+00:00

    The first thing you need to do is check which methods, if any, your current hosting provider allows. "Transferring" the domain can technically be done at a later point, you can leverage the default tenant.onmicrosoft.com one until you are ready to flip the switch.

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