Outlook.com features a built-in spam filter that offers solid protection against spam and junk messages. Furthermore, it can be customized to block email messages from specific sources.
Here are the instructions on how to prevent email messages from a specific sender or domain from ever reaching your Outlook inbox. Messages sent from blocked senders will be treated as junk mail and automatically deleted.
Add an Email Address or Domain to Outlook's Block Sender List
Open your web browser and sign in to Outlook. Next, click on the cog menu displayed in front of your username and select Options:
Go to Preventing junk email > Safe and blocked senders > Block Senders:
Click on Blocked Senders to open your block list:
How To Block Emails from a Specific Sender
Type the user’s full email address in the Blocked email address or domain field and click on Add to list:
Outlook will then add the email address to the Blocked senders list.
How To Block Emails from a Specific Domain
If you would like to block emails messages from a specific domain, you simply have to type the domain name (the text that appears after the @ sign) in the Blocked email address or domain field and then click on Add to list.