(Mail Abuse Prevention System) A product of Japanese-based Trend Micro Inc. that comprises the Real-time Blackhole List (RBL). The RBL was the first DNS blackhole list (DNSBL), which contains IP addresses of spammers, and companies and ISPs can use the list to reject incoming mail. If an offending spammer cannot be shut down, the spammer's ISP may contact MAPS with the subnet addresses allocated to the spammer so those specific addresses may be used instead of the IP address of the entire ISP.