cPanel 11.50 is finally in the RELEASE stage and has released many brand new features, most notably – Greylisting.
Greylisting is a feature that protect your mail servers in cPanel against SPAM by rejecting emails that are unverified. To ensure all your emails are legitimate, the sending mail servers should have reverse DNS record entries, DomainKeys Identified Mail (DKIM) signature and also Sender Policy Framework (SPF) TXT record. If the emails received do not fufill the above conditions, it will be considered unverified and unlegitimate.
Postgrey had this feature for more than 10 years while Postfix had this feature for quite a long time too. So it seems like this cPanel feature was a decade late.
Nonetheless, this is still a great feature and will help reduce spam emails from reaching your cPanel mail servers.