O365 - Unable to change existing username to the primary SMTP email address

Anonymous_17 21 Reputation points
2020-09-24T15:50:11.157+00:00

Hi Team,

So, we've migrated users from on-premise exchange to office365 & everything's working fine. However, the usernames of the users is in the format "abc@xyz .onmicrosoft.com" while the primary smtp email address is abc@pqr.com"
We tried chanding the username from the active user's section but faced the follwoing error; "This email address is already in use by an active ‎USER. Try a different email"
The email address is used by the user itself (no other user)

SIP: abc@xyz .onmicrosoft.com
primary SMTP: abc@pqr.com
SMTP: abc@xyz .onmicrosoft.com
SMTP: abc@xyz .mail.onmicrosoft.com

Please, share your feedback on how to resolve this issue - make the username same as the primary email address.

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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Exchange Server Management
Exchange Server Management
Exchange Server: A family of Microsoft client/server messaging and collaboration software.Management: The act or process of organizing, handling, directing or controlling something.
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  1. Vasil Michev 96,076 Reputation points MVP
    2020-09-24T16:24:48.933+00:00

    Just do it via PowerShell: 

    Set-MsolUserPrincipalName -UserPrincipalName abc@xyz.onmicrosoft.com -NewUserPrincipalName abc@pqr.com
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  2. KyleXu-MSFT 26,211 Reputation points
    2020-09-25T02:48:41.653+00:00

    @Anonymous_17

    We tried chanding the username from the active user's section but faced the follwoing error

    What change that you want apply to this user? Change primary email address for this user or add a new email address to this mailbox?

    Each mailbox only have one "SMTP email address"(uppercase), other email address will be "smtp email address" (lowercase)
    28080-qa-kyle-0925103116.png

    If you wan to change a “smtp email address” to “SMTP email address”, you just need to double click on this email address and check the "Make this the reply address"
    28251-qa-kyle-0925103619.png

    If you want to add a new smtp email address to this mailbox, you can use command below to check whether is this email address used on other mailbox: 

    Get-Mailbox | where{$_.EmailAddresses -like "*smtp:user@yourdomain.onmicrosoft.com*"} | select Name,EmailAddresses

    If above suggestion doesn't working, I would suggest you provide more detailed information about your organization: such as, the email address for this users and What do you want to do with the mailbox(Remember to remove the domain name from screenshot).

    If the response is helpful, please click "Accept Answer" and upvote it.
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