Azure login issue with external vendor authenticator issue

To reclaim access, the Azure sign-in and MFA must be reset by an administrator of the tenant that owns the account where the email is registered.

Because the Outlook address is being used in a third-party company’s Azure tenant, that tenant’s admins control the Microsoft Entra ID (Azure AD) account and its MFA settings. The steps are:

1. Contact the third-party company’s IT/admin team
   • Explain that the Outlook address is a user/guest account in their Azure tenant and that sign-in is blocked by Microsoft Authenticator MFA that is no longer accessible.
   • Ask them to reset MFA for the account in Microsoft Entra ID.
2. Admin resets MFA in Microsoft Entra admin center
   • An admin in that tenant signs in to the Microsoft Entra admin center.
   • Go to Identity → Users → All users.
   • Select the affected user (the Outlook email).
   • Open Authentication methods.
   • Select Require re-register multifactor authentication.
   • After this, the next time sign-in is attempted with that account, Azure will prompt to set up MFA again (e.g., new Authenticator app or another method).
3. If no other admin exists or the tenant is locked
   • If there is no other global admin who can perform the reset, the tenant owner must work with Microsoft Support/Data Protection via a support ticket or phone support to restore access and reset MFA. This can only be initiated by the tenant’s owner/admin, not by the external user.

If the Outlook address is also a personal Microsoft account (for consumer services) and access to its security info is lost, follow the consumer account recovery path:

• If the password is known but some security info is still accessible:
  1. Sign in to the Advanced security options page.
  2. Select Add a new way to sign in or verify and configure a new phone/email.
  3. Confirm via the code sent to the new method.
  4. Remove old/unavailable security info.
• If the password is known but all security info is lost:
  1. Start sign-in.
  2. At Verify your identity, select I don't have any of these.
  3. Follow the steps to replace security info.
  4. After replacement, there is a 30-day wait before full sign-in is allowed.
• If the password is not known and no security info is available:
  1. Review Help with the Microsoft account recovery form.
  2. Submit the recovery form via Recover account.

These steps recover the personal Microsoft account itself; the Azure tenant MFA for that email still must be reset by the tenant’s admins as described above.

References:

• Reset Personal Azure MFA - Microsoft Q&A
• Microsoft authenticator sending me into a spiral - Microsoft Q&A
• I need to reset my mfa methods - Microsoft Q&A
• Global Admin Locked out - Microsoft Q&A
• Severity A Situation - Locked out of global admin account (MFA) - business down - Microsoft Q&A
• Troubleshoot Microsoft verification code issues