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mvz00 avatar image
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mvz00 asked LydiaZhou-MSFT commented

Exchange Hybrid Wizard Federation Trust Domains

Hi,

I will be running the Hybrid Wizard to enable co-existence with Exchange Online. I have approximately 10 domains in Exchange on-premises and am wondering if I need to configure all of these when running through the Hybrid Wizard. What is the impact if only the primary email domain is selected instead of all of the domains. Currently only the primary domain has autodiscover setup as well so it is unlikely that the others will even work I am thinking?

Thanks,

Mike.

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AndyDavid answered

Hi @mvz00 . Yes only the Primary SMTP domains should be selected. Why? Because that is what is used in autodiscover and in the org relationship between Exchange Online and on-prem ( Think Free/busy).
The other accepted domains do not need to be selected in the Hybrid Wizard.

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AndyDavid answered AndyDavid edited

You only need to to select the primary domain if that is the domain that is set for your users as their primary SMTP domain.
The other domains can be accepted domains in 365 and on-prem but dont need a autodiscover record.

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mvz00 avatar image
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mvz00 answered

Thanks, some of the other domains are also used as PrimarySMTPAddresses. So in this scenario I am assuming that they will also need to be selected?

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LydiaZhou-MSFT answered LydiaZhou-MSFT commented

How many domains you have verified in O365?
If you still want to use those domain names for mailboxes in O365, you have to add all needed domains to O365. For your reference: Add a domain to Microsoft 365.


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Hi Lydia,

All of the domains have been verified in Office 365. Question was about the Hybrid Wizard Domain Ownership component. Do all domains need to be added and verified for the federation trust or only the primary email domain in use? What are the implications of only selecting the primary domain and not adding the additional domains?

Mike.

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If so, as Andy mentioned, you just have to choose your public domain which is configured for Autodiscover and F/B feature. You don't have to add other accepted domains.

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