The custom RBL feature lets you add custom RBLs and URIBLs to your account, that we do not normally monitor.
If you have a paid or in-house RBL that you’d like to use, you can add it here and centralize your monitoring, and take advantage of our automated checks and alerting functionality.
You can add a Custom RBL via the Manage -> Custom RBLs section of the portal:
Simply select the RBL type (either RBL or URIBL), and specify the hostname of the RBL to add.
Your blacklist must be set up like a standard DNSBL, as per this this description.
Once you’ve added the custom RBL, you must remember to enable this RBL on your Monitoring Profile.