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Rimagi-8273 avatar image
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Rimagi-8273 asked KyleXu-MSFT commented

Add new email domain to office 365 hybrid

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: newdomain.com). The users that will use these new mails (eg: nick@newdomain.com), have already email to old domains but not all in the same old domain (eg:nick@domain1.com, helen@domain3.com ) 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

office-exchange-server-administrationoffice-exchange-online-itprooffice-exchange-server-mailflowoffice-exchange-hybrid-itprooffice-exchange-server-itpro
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@Rimagi-8273
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KyleXu-MSFT answered Rimagi-8273 commented

@Rimagi-8273

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.
    185818-qa-kyle-09-46-03.png

  4. Migrate those mailboxes from Exchange on-premises to Exchange online.


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Hello @KyleXu-MSFT

Thank you for the link and steps.
In step 2, in my case i don't want all the current user to have this email address but only specific users. So i believe there is no need for policy but only i need to add new users. correct?
In step 3, since i don't need to add this new domain to all user, should i have to do this action?

Then what about Connectors? Should i have to take further actions?

Sorry for asking but i am confused and i am trying to understand how it works and to find a solution alone without any support from people that set up this infra.

Thank you

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In step 2, in my case i don't want all the current user to have this email address but only specific users. So i believe there is no need for policy but only i need to add new users. correct?

Yes, you could add it to the mailbox you want manually after adding it as an accepted domain.

In step 3, since i don't need to add this new domain to all user, should I have to do this action?

You need to do this step. This step just makes this new domain name could be chosen as UPN when creating mailbox/AD. It will not apply on mailboxes automatically.

The existing connectors will be OK. It could use the existing receive/send connector.

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