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RoyalDCosta-9872 avatar image
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RoyalDCosta-9872 asked KyleXu-MSFT commented

Mailbox Migration Error

Hi All

i have a environment in which there are 2 forests AD and exchange servers, all users from both Exchanges will be migrated to Single tenant. both Exchange servers all together have more than 250 domains. right now i am facing following Challenges in creating/migrating users/mailboxes.

Conditions - All users must be in On premises AD and mailboxes in Exchange Online

Problem 1 - every domain has info@domain.com email ID s, so all together we have 200 Info Id s alone, as a rule of thumb there cannot be same UPN in the Azure AD. so migration doesn't happen.

Problem 2 - for some email Id s i deleted On prem AD account and mailbox and created new new AD account on prem and allowed it to sync. after the synchronization i noticed that new user is created as info3453@domain.onmicrosoft.com instead of info@domain.com .

can someone help me to understand how exactly this works and how to migrate all mailboxes smoothly under this condition.



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KyleXu-MSFT answered KyleXu-MSFT commented

@RoyalDCosta-9872

First, one AAD could sync multiple forests: Topologies for Azure AD Connect

If you want to keep those mailboxes using original email address(such @domain1.com, @domain2.com, @domain3.com), you need to add those domain name into Office 365. Otherwise, those mailboxes will use Exchange online default domain name(@domain.onmicrosoft.com).

So, it will not an issue that each domain has a info mailbox, if they using different domain name.


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Hi
Thanks for reply.

it is still creating problems for me. today i created few more Info AD accounts and allowed to sync, after sync i noticed they were created as info@domain.onmicrosoft.com instead of info@domain.com. anything else needs to be done ?

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Did you add "domain.com" into your Office 365 before sync AD account?

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@RoyalDCosta-9872

Any update about this thread now?

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KyleXu-MSFT

I followed all steps as instructed by you but they didn't help me. I had moved user in unsync OU for several times and resync again to achieve the results, I am sure there is a sync issue.

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