Open Outlook
Select the email from the sender you want to block
Right-click the email
Choose Junk or Block
Select Block Sender
Confirm the action
Open Outlook
Go to the Home tab
Select Junk
Choose Junk E-mail Options
Open the Blocked Senders tab
Click Add
Enter the email address or domain
Click OK
Open Outlook on the web
Open the message from the sender
Select the More actions menu
Choose Block
Confirm the block
Open Outlook on the web
Go to Settings
Select Mail
Select Junk email
Add the sender’s email address or domain to Blocked senders and domains
Save the changes
Open Outlook mobile app
Open the email from the sender
Tap the More options menu
Select Block sender
Confirm the action