What is Multi-Factor Authentication?

Multi-Factor Authentication (otherwise known as MFA, 2FA or ‘two-step verification’) is a security feature included with Office 365 that protects your Office 365 account. MFA effectively makes it far more difficult for hackers to access your account, thus providing a further layer of protection for your data. MFA differs from using only a traditional username and password in that it also requires confirmation of the device that you are accessing your account from.

...

Due to the ongoing threat of internet-based data breaches, it is a requirement at Jim’s Group that MFA is enabled when accessing Office 365 enabled applications. This means that you will be required to set up MFA if you are accessing Office 365 Applications such as Outlook (Webmail).

Set Up Multi-Factor Authentication

It is always recommended that a Mobile Phone or Android/Apple tablet device is used as your primary method of Multi Factor authentication.

Set up Multi Factor Authentication on a mobile device

To set up Multi Factor Authentication for your Office 365 account:

...

With 2FA now setup, your account is more secure. Accessing or signing into the account on http://www.outlook.com, or adding to your phone should prompt for verification on new devices, or if it hasn’t been verified for a while.

Changing/Modifying Multi Factor Authentication on a mobile device

If you need to change your 2FA details or modify access, you just need to sign into https://aka.ms/MFASetup again.

...