If the Greylisting filter is enabled, the message you are seeing is quite normal, and will be applied to all incoming mail that your server receives. Please see Greylisting – Version 64 Documentation – cPanel Documentation for full details.
WHM Server wide settings
Home >> Email >> Greylisting
Individual cPanel Account settings (per domain)
cPanel >> EMAIL >> Configure Greylisting
WHM Server wide settings
Home >> Email >> Greylisting
Individual cPanel Account settings (per domain)
cPanel >> EMAIL >> Configure Greylisting