What Anti-Spam functionality does cPanel/WHM offer ?
cPanel/WHM is bundled with SpamAssassin and BoxTrapper at no additional cost.
BoxTrapper is a challenge-response system where incoming email coming from an email address that has not yet been white-listed must reply to an initial email to verify that it is not a piece of spam. Email addresses can be manually white- or black -listed on a server-wide level, as well as on an individual email account basis.
cPanel also allows users to set up powerful custom mail filtering rules.