Add new email domain to office 365 hybrid

Rimagi 21 Reputation points

Hello all,

I am new in the Microsoft Exchange word and i am trying to configure a complex hybrid enviroment in my company without any help...
Currently we have 6 local microsoft Exchange servers for 6 differents domains and we have started the migration of these to office365 (50 user migrated from 300). When the migration will be completed, we have to keep the local exchange for specific reason... (MX record will continue to point local exchange)

I have been requested to urgently install a new domain to be used by users in order to sent and receive emails (eg: The users that will use these new mails (eg:, have already email to old domains but not all in the same old domain (, ) but are not migrated to office365 yet.

I have purchased the domain and i have added to Office365 (txt verification completed) and now i am stuck...

Where should i configure MX records to point? What next actions should i take? what about mail flow? what about connectors?

Please can you help me to clear in my mind the next steps?

Thank you

Microsoft Exchange Online Management
Microsoft Exchange Online Management
Microsoft Exchange Online: A Microsoft email and calendaring hosted service.Management: The act or process of organizing, handling, directing or controlling something.
4,257 questions
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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Microsoft Exchange Hybrid Management
Microsoft Exchange Hybrid Management
Microsoft Exchange: Microsoft messaging and collaboration software.Hybrid Management: Organizing, handling, directing or controlling hybrid deployments.
1,919 questions
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Accepted answer
  1. KyleXu-MSFT 26,211 Reputation points


    Point MX record to Exchange online or Exchange on-premises are all ok, for more detailed information about it, you could have a look about this article.

    About adding a new domain in hybrid, you could follow these steps below:

    1. Add this domain name to Exchange on-premises admin center as an accepted domain.
    2. Then use an Email address policy to apply it on mailboxes. You can also add new email address to those mailboxes manually.
    3. Add this new domain name as alterative UPN suffixes from Active Directory Domain and Trusts. Then you will could change UPN for those old mailboxes.
    4. Migrate those mailboxes from Exchange on-premises to Exchange online.

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    1 person found this answer helpful.

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