http://www.virusbtn.com/virusbulletin/archive/2011/08/vb201108-IPv6
Thanks to the introduction of IPv6, spammers will have access to a much larger pool of unique IP addresses, making it almost impossible for anti-spam companies to maintain useful blacklists. The ‘IPv6whitelist.eu’ was founded to try to solve this problem. The project assumes that all computers send out spam, unless they have been registered on the whitelist.