If you wish to not receive email from a particular address or domain you can add that into the blacklist if your spam quarantine.
Firstly you need to login here: https://mailguardian.co.uk as explained here: www.healthhosts.com/docs/how-to-access-your-spam-quarantine/
Once logged in in the left menu go to > My Account > Blacklist
And to block a sender just click the New button and enter email email
Then click > Add Blacklist Sender and in the address box add the email address you want to block and click save