1. You may mark the incoming emails as "spam", on the basis of email headers and bodies, by using SpamAssassin in cPanel via:
cPanel >> Mail >> SpamAssassin
Then, you can delete them.
For this, you will need to enable SpamAssassin by clicking on the "enable SpamAssassin" button in SpamAssasin via cpanel->email->SpamAssassin. Then, set up the score that you want to give. The default is 5. It will first identify the spam based emails. Then, it increments the spam value each time it gets delivered. When the spam value reaches 6 (which is above the set score), the emails will automatically be marked as spam. The spam emails can be discarded by enabling "Spam Auto Delete' in SpamAssassin.
You can also configure SpamAssassin for various checks (Blacklisting/Whitelisting email ids, etc.).
2. Block spam using an User-level, or Account level, filtering. This is used when you are getting spam with common key words, like "watches", or spam originating from any particular email id. You can block spam using these keywords via the following options. For this, click on the "create a new filter" tab. Then, you can setup the filter according to the following examples:
3. Enabling box trapper will reduce spam by forcing all people not on your white list to reply to a verification email before they
can send mail to you. This will send an email back to the sender, requesting a reply to that before it is regarded as genuine. Hence, it will reduce the spam sent using scripts.