Move Users to another domain smoothly

Question

Hi All,

We are currently trying to plan the move of all our users to another domain name so they show as a different email address.

We have an hybrid environment and the new domain is contained in the same tenant.

What is the smoothest way of moving these across whilst also not breaking the many SSO configurations we have and minimalizing user interruption.

Many thanks in advanced.

Answer 1

For best experience, add the new domain as an email alias (I suppose you want to make it primary) and keep the old one as secondary. Both PowerShell and email address policies (on-premises) can help you do that.

As long as you do not change the UPN, the login experience should not be affected. If you have Entra ID integrated apps that depend on primary SMTP address, you will have to update their configuration.

Similarly, if you plan to update more than just he primary SMTP address attribute, you might have to perform additional actions with third-party apps. Within the M365 suite, UPN and the primary SMTP address are your only concerns.

Answer 2

Hi, @Neil Shelley

Vasil Michev is right, all you need to do is change the primary SMTP address to point to the new domain and match the UPN.

Use the email address policy provided above to quickly modify users' email address.

Similar cases can be found here and their related links. Move user's mailbox from one domain to another under same tenant.. - Microsoft Q&A

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