Starting mid-September 2023, if you are not using Microsoft Authenticator app, Microsoft will soon require you to set up the Outlook mobile app to approve sign-ins.
According to research done by Microsoft, multifactor authentications completed via push notifications in the Microsoft Authenticator app are 71% less likely to be compromised than those completed via SMS codes. Therefore, we strongly recommend moving your users off phone transports for authentication and towards more secure methods such as push notifications. Authenticator Lite (in Outlook) expands the opportunity to convert users by bringing the enhanced security of push notifications to devices that have not yet downloaded the Microsoft Authenticator App.
Users are prompted in Outlook on their mobile devices to register for multifactor authentication (MFA). Now, after they enter their password at sign in, they’ll have the option to send a push notification to their Android or iOS device.
When you open your Outlook mobile app,
you will see a bar at the bottom that says Approve sign-ins.
Tap on Sign in and this will open a half-page with a picture. Select, I understand. You may have to sign-in with multifactor authentication.
Once you complete the process, you will be ready to approve authentications in the Outlook mobile app.
Now, when you sign-in to your account, you will have a way to approve notifications on your Outlook mobile app.