ISPs and mail admins have some incentive to limit the amount of abuse because if they don't other networks will just drop their traffic. The problem is that thi

ISPs and mail admins have some incentive to limit the amount of abuse because if they don't other networks will just drop their traffic. The problem is that this trick only works until you reach a certain size. Google can host malware all day and they're responsible for massive amounts of spam, but nobody is going to blacklist everything from @gmail.com so they don't have to care. When AOL was the largest ISP in the world the situation was similar. They'd aggressively blacklist other networks while not acting on abuse originating from their own. We either need laws that penalize irresponsible internet companies or we need an origination like ICANN to enforce polices that cut off bad actors. If ARIN pulled the IP space from networks that didn't clean up their mess, or stopped letting lazy domain registrars sell domains things would improve pretty quickly. Instead we're making whois increasingly worthless and a growing number of sites and services don't even have a working abuse@ address to report problems to.