URIBLs (URI Black Lists) are similar to RBLs, except rather than tracking IP addresses, they track domain names, or URIs (website addresses), that are often used for spamming, phishing, or malware.
If your outbound emails are inadvertently flagged as SPAM, then any website URL listed in the email could be added to a URIBL, and then blocked by thousands of email systems and browsers all over the world.
RBLTracker will automatically alert you if your website addresses or domains become listed in any of the widely used URIBL lists.