The mission: The US Federal Trade Commission wants you to take responsibility for spam zombies on your network. You must block outbound SMTP traffic from infected computers inside your security perimeter.

The challenge: Blocking spam zombies without impeding legitimate email traffic.

The First Step
No matter which firewalls and mail servers you own, there are a couple of things you can do to prevent zombies without spending a nickel. Set your firewalls to block outbound SMTP traffic and outbound use of port 25 from any devices that are not designated for off-site mail delivery. This will force zombie senders to try to send mail your mail servers.

At your mail servers, severely restrict:

  • The number of simultaneous outbound connections;
  • The maximum number of connections to a single host, and;
  • The Maximum number of messages in a single connection.

You can do a lot more, including SMTP Authentication, SSL and solid bandwidth management. Watch this space…