Open Outlook
Select the email from the sender you want to block
Right-click the message
Choose Junk
Select Block Sender
Confirm if prompted
To block a sender manually, go to Settings
Open Mail
Select Junk email
Add the sender’s email address or domain to the blocked senders list
Save the changes
To block a sender in Outlook on the web, open the message
Select More actions
Choose Block
Confirm the block
To unblock a sender, open Junk email settings
Remove the sender from the blocked list
Save the changes