1. In Outlook, click on an email from the sender you want to block.
2. Click on the arrow next to "Junk."
3. Click on "Block."
Click "Block."
4. Click "OK" on the pop-up box that appears.
If you decide you don't want to block a sender's emails after all, you can remove their email address from your block list in your account settings.
Click the trash can next to each address you want to unblock.
In your settings, click "Mail," then choose "Junk email." Under the header "Blocked senders and domains," click the trash can next to whichever accounts you want to unblock, removing them from your blocked list.
Chrissy Montelli/Business Insider
https://www.businessinsider.com/how-to-block-emails-on-outlook