In article 1369437337.9904.YahooMailNeo@web161904.mail.bf1.yahoo.com, Al Johnson alj62888@yahoo.com writes:
Another issue is the effort that would be required for a centralized DB/authority model.
They already exist. It's called Spamhaus. What's wrong with enhancing this extension: http://www.mediawiki.org/wiki/Extension:Check_Spambots