Re: SMTP Port Blocking: Success or Failure?

Quoting "Claydon, Tom" <Tom.Claydon@DobsonTelco.net>:

We are considering filtering outbound SMTP traffic from our ISP customers, except from our own mail servers, to help reduce the amount of spam originating from our network. How successful/unsucessful has implementing outbound SMTP filtering done in stopping or slowing down spam from your network?

What about rate limiting SMTP traffic rather than blocking it? That could allow legitimate use for most private customers, while preventing bulk traffic. Capping the number of messages per customer in the ISP mail server would probably also be a good idea, I hear more and more bulk traffic is being sent through ISP mail servers. Cheers, Ketil