To unblock a contact in Outlook, you must . This process differs slightly depending on whether you are using the web version, the classic desktop app, or a mobile device. How to Unblock a Contact in Outlook.com (Web)

To be safe:

Log in to Outlook.com and click the in the top-right corner. Navigate to Mail > Junk email . Scroll down to the Blocked senders and domains section. Find the email address or domain you want to unblock.