add Authenticator to just one outlook address

To add Microsoft Authenticator for just one Outlook (Microsoft) email address, set it up on that specific Microsoft account only. Steps:

1. On a computer, go to the Microsoft account Security page: https://account.microsoft.com/security and sign in with the Outlook address that should use Authenticator.
2. Select Manage how I sign in to see the ways to prove identity.
3. Select Add a new way to sign in or verify.
4. Choose Use an app.
5. If Authenticator is not installed on the phone, select Get it now and install it. If it is installed, select Set up a different Authenticator app and then Next to show the QR code.
6. On the phone, open Microsoft Authenticator and tap the + icon.
7. Choose Personal account, then Scan a QR code, and scan the QR code shown on the computer.
8. Complete any on-screen verification prompts.

This links Microsoft Authenticator only to that Outlook/Microsoft account. Other email addresses are unaffected unless they are added separately in the same way.

If the goal is to use Authenticator every time for that address, on the same Security page:

1. Under Two-step verification, turn it On and follow the prompts.

If the goal is to go passwordless for that address:

1. On the Security page, under Passwordless account, turn it On and follow the prompts, then approve the request in Authenticator.

References:

• How to add your accounts to Microsoft Authenticator
• How to go passwordless with your Microsoft account
• Use Microsoft Authenticator with Microsoft 365