It's hard to stop e-mail SPAM completely but you can filter, discard or deliver it to selected folder, etc.
How to Create Account Level/Global Email Filter?
1. Log into your cPanel account.
2. In the "Email" section, click on the "Global Email Filters" icon.
3. Click on the "Create a New Filter" button. 
4. Enter a name for the filter in the "Filter Name" field.
5. In the filter rules you can filter e-mails by many options and, for example, if you want to filter e-mails which contains a word "Lottery" or other words, then under the "Rules" select "Contains" and "Body" in the dropdown menu.
6. Under "Actions", select "Discard Message" in the dropdown menu.
7. Now click on the "Create" button.
This filter will discard all the e-mails for ALL USERS with the word "Lottery" in them.
