Spam email is unsolicited and unwanted junk email sent out in bulk to an indiscriminate recipient list.
Typically, spam is sent in massive volume by botnets, networks of infected computers.
Spam email can be difficult to stop, as it can be sent from botnets. As a result, the original spammer can be difficult to trace and stop.
However spam emails could be improvised by creating necessary filtering rule from cPanel end.
Email filters use the criteria that you specify to determine how to handle email messages. Emails can be discarded, redirected to another email address, or filed to a folder, or more.
The Global Email Filters interface (cPanel >> Home >> Email >> Global Email Filters) — Global email filters affect the cPanel account’s email addresses.
The Email Filters interface (cPanel >> Home >> Email >> Email Filters) — User-level filters affect specific email addresses on the cPanel account.
Another spam fighting tool that you can implement in your cPanel would be SpamAssassin.
It uses a number of tests and criteria to identify and block spam.
SpamAssassin scans the contents of each message before it reaches your inbox, searching for words, phrases and other formats common to spammers. Upon completion of the search, the message is then assigned a score – the higher the score, the more likely to be spam.
By default, messages with a spam score of “5” or higher will be deleted.
However, you can choose a different score, if desired.