Re: outbound failure limiting - the next phase in the spam war?

John Pettitt wrote:
> As outbound port 25 blocking starts to become prevalent among ISP=92s t=
he
> zombie armies of spam machines are starting to send via the ISP=92s
> outbound mail servers. This is going to make many of the rbl lists
> obsolete as any per-server filter is too blunt an instrument to filter
> this kind of attack.

Only if the server is an open relay for machines on the ISP's network.=20
There's no reason why authentication shouldn't be required to use the=20
smart host.

I doubt if port 25 blocks are as prevalent as indicated. It would cause=20
too many problems for road warriors and sites that use SPF or SenderID.=20
I know I would drop my ISP in a heartbeat if they forced me to use their=20
unreliable/insecure relays instead of my own.

> Before I go write a patch to do this are there any comments? Good idea?
> Bad idea? Why?

Interesting idea, but I'd rather see the ISP put more effort into=20
implementing encrypted authentication and than simply "slowing down"=20
spam & viruses from their customers.