email\username did not get update in Outlook after change in M365 admin portal

HK G 511 Reputation points

There are couple users who have multiple email addresses in their accounts. I updated their username\primary email address from on domain to another domain in the M365 admin portal. The user is able to login with the new username (different domain). When they sign-in\sign-out from Outlook, the account is still showing the old domain. The main issue is when they send email, the receiver is seeing the old domain and I would like that to be updated to the new domain (new email address). I thought it might take sometime to get the change updated but it has been 2 days now since the change applied.

Any thought? Thanks

Microsoft Exchange Online
A family of Microsoft email and calendar products.
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Outlook Management
Outlook Management
Outlook: A family of Microsoft email and calendar products.Management: The act or process of organizing, handling, directing or controlling something.
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  1. Kael Yao-MSFT 31,341 Reputation points Microsoft Vendor

    Hi @HK G

    This may be the expected behavior.

    Please refer to this documentation for more details:

    SMTP address in user's profile doesn't change when primary email address is changed in Exchange Server

    To update the email address, please follow the Workaround part to create a new profile for these users.

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