To block a sender in Outlook, you can follow these steps:
Open the email from the sender you want to block.
Select Junk > Block Sender.
A dialog box will appear asking you to confirm that you want to block the sender.
You can also block a sender by adding their email address or domain to your blocked senders list:
Select Settings > View all Outlook settings.
Select Mail > Junk email.
Under Blocked senders and domains, enter the email address or domain that you want to block.