http://multirbl.valli.org/lookup/ https://www.talosintelligence.com/ http://www.reputationauthority.org/ http://www.barracudacentral.org/lookups https://mxtoolbox.com/blacklists.aspx https://www.dnsbl.info/https://www.blacklistmaster.com/
rspamd is a replacement of spamassassin, with more efficient resource utilization. https://gist.github.com/mdpuma/f1c347091717240276fcb0bab737f7ec this is the Gist, on how to integrate it on cpanel, by changing Exim configuration.
Afterlogic have some interesting new look to the webmail of cpanel. Guides available at https://afterlogic.com/docs/webmail-lite/installation/install-on-cpanel