Step 1 - Log in to cPanel (click here for a guide) and click on Spam Filters
Step 2 - Turn on "Process New Emails"
When turned on, email detected as spam will still come through, but will have [SPAM] added to the front of the email's title.
To have Spam automatically deleted, click on the Automatically Delete New Spam option
You can also Whitelist or Blacklist email accounts here. If you're not recieving expected emails, or you have high priority clients, you may want to Whitelist them. You can blacklist any emails you want to block.
To access this menu, click on Show Additional Configurations
Then click on either the Whitelist or Blacklist option
(1) click on + Add A New (2) Add in the email you want to Whitelist/Blacklist (3) Click Update