If you want to ensure they never get blocked again, add them to the Safe Senders tab in that same menu. This tells Outlook, "I trust this person implicitly."
The process differs slightly depending on whether you use the or Outlook on the Web (Outlook.com, Microsoft 365 Web) . how to unblock sender in outlook
If you previously blocked an email address or domain and now want to start receiving their messages again, you need to remove them from your Blocked Senders list. If you want to ensure they never get
Best for: Personal email accounts (@hotmail.com, @outlook.com) or business Microsoft 365 web access. Best for: Personal email accounts (@hotmail
To unblock a sender in Outlook, you must remove their email address or domain from your list. This process varies slightly depending on whether you are using the web-based version, the new Outlook desktop app, or the classic version. How to Unblock a Sender in New Outlook and Outlook Web