Spam Filter is an anti-spam tool which helps filter out unwanted messages and it works for all of the email accounts in your cPanel. It can be set to mark spam messages, so they are easy to notice. You can also choose to configure it to automatically delete any emails marked as spam. This is enable automatically when an account Is created. This feature is located in your cPanel under the Email section. The image bellow shows you an example of what it looks like when you go into the Spam Filters.
As mentioned before this feature by enabled by default so when ever it finds any suspicious emails it will mark them as spam as shown with the image bellow. This makes it easier for you to distinguish between your proper emails and spam. You are also given an option to edit the spam threshold score and what this means is just how aggressive you want to set up the filter to be. The lower the number the more aggressive it is. Scores are also determine by the contents of the email.
You are also provide an option that when ever you receive a email that is marked as spam it will automatically delete it. The is very useful when someone is receiving a massive amount of spam email. Do be aware sometimes regular email that are meant for you can be marked as spam depending on its content, so if you enable this option it will delete that email and there is not option to retrieve it.
There are some additional configurations that allows you to add emails to a whitelist or a blacklist. This is a useful tool that helps set up a whitelist that basically means the list of email address on there will not go through these filters and go to your inbox. The blacklist will the opposite so any email that you add here they will be marked as spam or get automatically deleted depending on your settings. The last option is to set up a customize spam score but this is only recommend for advance users.