If a user forgets their password and gets locked out of their account, the alternate email address is required to reset their password.
- Navigate to the Active Users page in the Microsoft 365 Admin Center: https://admin.microsoft.com/AdminPortal/Home#/users
- Select the User by name
- Click Add address under Alternate email address:

- Enter Email address:

- Click Save:

- Done! You will see this green banner when successfully added:
