"DROP (Don't Route Or Peer) is an advisory "drop all traffic"
list, consisting of stolen 'zombie' netblocks and netblocks
controlled entirely by professional spammers. DROP is a tiny
sub-set of the SBL designed for use by firewalls and routing
"DROP is currently available as a simple text list, but will
also be available shortly as BGP with routes of listed IPs
announced via an AS# allowing networks to then null those routes as
being IPs that they do not wish to route traffic for."