Microsoft 365 – Changing default username in Azure AD Connect synced environment

Last Updated: December 6th, 2023/Published On: July 11th, 2019/By /Views: 18017/

Issue: If a user was imported via AD but shows up with the wrong username on the O365 side (ending in .onmicrosoft.com)

Resolution:

  1. Go to Active Directory Users and Computers
  2. Go to View and select Advanced Features
  3. Go to properties of user account
  4. Go to Attribute Editor
  5. Edit Proxy Address to: SMTP:user@domain.com
  6. Open PowerShell as Admin
  7. Connect to the online service with the following commands: (If needed Install-Module MSOnline)
    1. $msolcred = get-credential
    2. Connect-MsolService -Credential $MSolCred
      (Note: Enter your Office 365 credentials when prompted)
  8. Enter the command to update the user name:
    1. Set-MsolUserPrincipalName -UserPrincipalName user@company.onmicrosoft.com -NewUserPrincipalName user@domain.com

Changes should take effect within a few moments and set this user as the default username

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