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I have two AD forest (Forest A and Forest B) with forest trust relation ship and both of them are having their Own Azure AD and O365 Tenants. (A.Com and B.Com). Forest A(A.com) acquired Forest B(B.com) and decided to migrate all mailboxes from O365 tenant of Forest B to Forest A. However in this case they don't want to merge their Active Directory forest, but they want to Migrated users from Forest B O365 tenant to use SMTP of Forest A(A.com) and secondary alias Address of Forest B.com.
Is it possible of Forest B.com to sync the users using AAD connect and set the Primary SMTP address as A.com and alias adresss as B.com? If yes how can this be done ?. Since when we are syncing the users either we need to set the UPN which should be verified in Azure AD , and if i set the UPN of Forest B user as B.com how can his SMTP can be made as A.com?
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Hi @Chandra Sekhar , is there any update about your issue?
Hello @Chandra Sekhar , I'm reaching within the product team and will come back to you.
Hi anonymous user-msft
Did you get a chance to check with the product team w.r t my query?
Hi @Chandra Sekhar , apologies for the delay. This is possible trough custom sync rules with expressions for proxy addresses attribute. Since this is not a documented customization you will need to design it by yourself or request assistance from a Microsoft Consulting Services or (premier only) your CSAM.
Thanks anonymous user-msft . Which means i can have a user in AD Forest B with UPN called UserB@ForestB.com but will be having SMTP address as UserB@ForestA.com....
Could you please confirm?.
Confirmed.
Thanks anonymous user-msft .. I have another query... if i go with above change when user logs in to O365 Services which one he should be using for login? Since in this case SMTP is different than UPN.
Hi @Chandra Sekhar , you should use the UPN.
I mentioned you asked the similar question previously in this thread: O365 Tenant to Tenant Migration with Multi AD Forest
Have you referred to the suggestions in that thread below?
Make your organization B an on-premise only environment then add it to the existing Hybrid A environment.
The link(Exchange Multi-Forest Hybrid Tips and Tricks) introduces about Use Email address from Company A in Company B, and please also read more information about Office 365 – Why Your UPN Should Match Your Primary SMTP Address
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Hello,
Thanks for your reply. As per my previous question i am not using Hybrid Configuration and all my mailboxes are in Cloud and syncing through Azure AD connect. In new Architecture we are going to have only one AAD connect for two AD forest , but the concern is how this can be achieved having same Email address for all users for both forest syncing through AAD connect and having different UPN. For Example
Users mailboxes from Forest B tenant will be migrated to Tenant A of O365. Post migration users will be using primary SMTP address of Forest A but those users will be sync from AD Forest B to Tenant A.
I want to confirm with you how you create an o365 mailbox in your environment? Create a local AD account, sync it to cloud, then assign license to this account?
We used to create an AD account and sync to cloud , then assign licenses to the account. We don't have Exchange Hybrid environment .
Hi @Chandra Sekhar ,
If so, I'm afraid your requirement will be hard to achieve. Or you will need to remove the mailbox in tenant B, recreate it in tenant A, then associate the o365 mailbox with your AD account.
Hi @Joyce Shen - MSFT ... I am also doing the same..i will create a user in Tenant A and match with AD Forest B. All I need is user in AD Forest B with UPN UserB@ForestB.com should be having SMTP address as UserB@ForestA.com.
Hi @Chandra Sekhar ,
We could have several email addresses in different domains if they are configured as accepted domains in your environment. However, the on-premises Active Directory UPN becomes your login for Office 365.
Detailed information: Office 365 – Why Your UPN Should Match Your Primary SMTP Address