Office 365 (Outlook on the Web) - Allowing/Blocking Email and Safe Senders and Recipients (Junk Email Settings)
Outlook on the Web allows you to filter spam and unwanted emails to your Junk Email folder. You can configure which recipients' emails should be filtered out and which recipients should not be.
Junk Email Filtering
In Outlook on the Web, you can filter junk emails by marking the email sender as a "Safe Sender and Recipient" or as a "Blocked Sender".
Microsoft provides an in-depth support article about how to manage your junk email here.