Crosstenant staged migration mail flow

Tasos Sardelis 46 Reputation points
2021-11-18T07:35:35.507+00:00

Hello,

We recently acquired a new company, the def.com for example, which was under the forest of the xyz.com. We want all the Microsoft 365 objects of this company to migrate under our forest abc.com. We plan to perform a staged migration for the mailboxes following this article. The new company has about 40 mailboxes of various sizes. What is not clear to us is what happens with the mail flow. When is the best time to switch the mail flow from xyz.com to abc.com? Before migration starts? During the migration? Or after the migration is finished? The ideal scenario is this process to be transparent for the end users.
Also, during the migration, what happens if a new email arrive? How can the user see it?

Microsoft Exchange Online Management
Microsoft Exchange Online Management
Microsoft Exchange Online: A Microsoft email and calendaring hosted service.Management: The act or process of organizing, handling, directing or controlling something.
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  1. Tasos Sardelis 46 Reputation points
    2021-11-18T13:53:00.96+00:00

    Reading various articles it seems that changing the MX records prior the migration is the best practice. The question here is how the user can see the new emails during the migration?

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