To block an email sender in Outlook, find the message that includes the sender you want to block.
Right click on the message
Near the bottom of the pop-up menu you will see "Block"
Hold the cursor over "Block" and another window should appear to the right of that.
Select "Block Sender"
That sender will now be blocked from sending further mail to your inbox.
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If you ever block a sender by mistake, simply right click on any message select "Block" then once the menu to the right appears select "Never Block Sender"
Pop up displays Add (sender) to the safe senders list?
Select "OK"
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The option to Manually Add a sender is available as well.
Click on the Cog or Wheel icon in the top right.
Towards the middle of the left Settings toolbar, select Junk Email.
At the bottom under Senders > Blocked senders and domains > Click + Add blocked sender
Enter the email address for the sender, select "OK"
Click Save at the bottom.
They will now be added to the list of "Blocked Senders"