SpamAssassin Rule: URIBL_BLACK
Standard description: [Body] Contains an URL listed in the URIBL blacklist
From the about page
"black.uribl.com - This lists contains domain names belonging to and used by spammers, including but not restricted to those that appear in URIs found in SPAM. This list has a goal of zero False Positives. This zone rebuilds frequently as new data is added."
The default scores for this rule can be found in the online list of tests.