Spam is a huge challenge for anyone who hosts email, even though users only see a tiny fraction of the spam they’re sent. Most unwanted messages never reach inboxes, but an incredible 54 percent of all email traffic is spam, and that’s down from 70 percent a decade ago. The good thing is ISPs and hosting providers are better at stamping out spammers, and users are more aware of the risks. Still, hundreds of billions of messages are sent every year by automated botnets that collect email addresses, compromise servers, and bombard users with malicious advertising and phishing attacks. If you host email, you need a way to identify and filter unwanted messages, and cPanel integrates one of the most sophisticated filtering tools available. Apache SpamAssassin flags spam to remove it before it gets to users. To make sure we understand how it works, let’s take a close look at what SpamAssassin is, how it works, and the best settings for SpamAssassin in cPanel.