The process for enabling/disabling RBLs within your cPanel/WHM only takes few moment.Please follow step by step directions given below for your help:
Login to your WHM(Web Host Manager)
Next go to Service Configuration
Once located, Click on the Exim Configuration Manager link
Toward the bottom of this editor there will be a RBL section. Simply click the checkbox next to each of the options,
Once done, simply click on Save to force the changes to take effect.
Some additional RBLs can also be added in cPanel server manually via SSH and Exim should be rebuild.