Migration of Active directory and Office 365 to another AD and office 365 (retaining external email DNS for migrated users)

Question

I have been tasked with migrating users from:

• One domain that currently has an active directory domain original-domain.local
• ADSync to sync mailboxes to office365 using original-domain.com as their accepted domain.
• Has one drive data that needs to be migrated
• Has SharePoint sites that need to be migrated

The users need to be migrated to:

• Another domain called other-domain.local
• other-domain.local has an office 365 setup using ADsync to sync their mailboxes
• other-domain.com as their accepted domain

I have planned on using ADMT to move the accounts to the new domain and have the following phases for the migration steps:

• Active Directory Preparation
• Device Migration Preparation
• Group Account Migration
• Migration tool Preparation (ADMT)
• Service Account Migration
• User Account Migration
• Workstation local profile translation
• Workstation Migration

The customer wants to:

• Migrate the users from the original-domain.local to the other-domain.local and migrate the mailboxes over but retain the original-domain.com accepted domain.

in the past, I could do this by routing mail via an exchange server to the other exchange and then migrate the users over but with office 365 I am not sure how this fits into ADMT.

when do we start mailboxes migrations and at what stage during the admt process would this happen? also, how do we marry up mailboxes with the correct account? i.e. do you first migrate the users, then create new mailboxes in the other-domain.com tenancy then sync the mail over?

and is it possible to keep mail flow from the other-domain.com to the original-domain.com or visa versa whist in the process of the migration?

would it be staged or cutover?

has someone completed a similar migration recently with office 365 and active directory that could provide an overview of what steps are required to complete this and in what order?

Answer 1

O365 is not currently supported here on QnA. The product group for Office actively monitors questions over at
https://techcommunity.microsoft.com/t5/microsoft-stream-forum/bd-p/StreamForum

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