How to add users to a block list within Outlook on Windows and Mac

Windows: 

1. On the Home tab, select 'Junk', then 'Junk E-mail Options'.

2. Select the 'Blocked Senders' tab.

3. Click 'Add'.

4. Type the email address or domain that you want to block, then click 'OK'.

5. Click 'Apply', then 'OK' to save your changes.

On Mac: 

1. Select an email from the contact you want to block
2. On the Home tab, click 'Junk', then click 'Block Sender'