On Prem Exchange to O365



  • I have finally been able to convince the powers that be that O365 is the best option for us being a school.

    **for the purposes of "corporate" do not read it that we are a subsidiary but just that our overall organization had created a subdomain 10 years ago or so for all four of the schools that are under the organization. Since then 2 of them have moved away from the subdomain and one got lucky as they moved to G Suite early on in the process.

    Because we are a subdomain of our "corporate" and we have a domain of school.corporate.net and corporate is already on O365 we cannot be on O365 with our school.corporate.net domain. The powers that be want to keep our email/data separate from "corporate" so we got a new domain name.

    My thought was to get the users created on the new O365 by using the AD sync, add the new domain name to our current exchange box, then upload emails to O365.

    I just started doing the AD sync from AD to O365 but got the following message:

    alt text

    Would I be correct that because our AD domain isn't anything close to our new domain name that this plan cannot happen? I am not sure if we'll be moving to Azure AD or not.

    Would it make it easier to go full blown Azure AD?



  • Can you assign a secondary UPN to the users? If so, I would expect that to solve your issue.



  • @WLS-ITGuy said in On Prem Exchange to O365:

    I have finally been able to convince the powers that be that O365 is the best option for us being a school.

    **for the purposes of "corporate" do not read it that we are a subsidiary but just that our overall organization had created a subdomain 10 years ago or so for all four of the schools that are under the organization. Since then 2 of them have moved away from the subdomain and one got lucky as they moved to G Suite early on in the process.

    Because we are a subdomain of our "corporate" and we have a domain of school.corporate.net and corporate is already on O365 we cannot be on O365 with our school.corporate.net domain. The powers that be want to keep our email/data separate from "corporate" so we got a new domain name.

    My thought was to get the users created on the new O365 by using the AD sync, add the new domain name to our current exchange box, then upload emails to O365.

    I just started doing the AD sync from AD to O365 but got the following message:

    alt text

    Would I be correct that because our AD domain isn't anything close to our new domain name that this plan cannot happen? I am not sure if we'll be moving to Azure AD or not.

    Would it make it easier to go full blown Azure AD?

    Add that suffix to all those users in AD, then sync.



  • As above what they are are saying is that using Hybrid AD is fine with a domain name that is not the same as long as you add the UPN in Active Directory Domain Trusts and then you adjust all the users in the domain to match that domain either manually or scripted.
    https://docs.microsoft.com/en-us/office365/enterprise/prepare-a-non-routable-domain-for-directory-synchronization

    My only concern with this is that you might not need to sync AD but if you are already setup then it is kinda hard to revert.


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