Zombie PCs taking another route to feed spam

ISPs have been going at it forcing users to not run their own mail servers by blocking port 25. Instead, users must feed their mail through the ISP’s mail server where they can control one single point of failure. Spammers have now exploited that plan by also having their spam via the zombie PCs go through the ISP’s mail server.
ArsTechnica has a good suggestion:

take those people whose zombie PCs are responsible for producing the spam off the ntework until they can clean up their act (and PC). Sure, it will result in irate customers who are upset that they can no longer get online. But perhaps being forced offline will help reinforce the need to pay attention to security, a crucial aspect of computer ownership many are all too happy to ignore.

Finally. Someone else that wants computer owners take responsibility for their own devices.
Via ArsTechnica