A brief history:

  1. Spammers send mail directly to victims.
  2. Server admins block by source, victims complain and try to get spammers kicked off their networks.
  3. Spammers relay through third-party servers to disguise their origin.
  4. Server admins shut close relays, and block mail from open relays.
  5. Spammers relay through trojaned zombies straight to victims.
  6. Network admins block outgoing mail traffic except through their servers.
  7. Spammers relay through zombies’ ISPs’ mail servers.
  8. ????

We’re in the early stages of step 6, with broadband ISPs starting to block outgoing direct-to-MX mail traffic. The obvious response by spammers is, of course, Continue reading