Re: [anti-spam-wg] New ENISA survey for a study on spam

[Yiorgos Adamopoulos adamo@localhost]

Nuno Loureiro wrote:
> [ port 25 blocking ]
> What I would like to ask you, is how do the several ISPs implement this 
> technique?

We've implemented several variations of this technique:

1. Block all outgoing SMTP traffic that is not directed to our outgoing 
mail servers- our users were not really happy with this.

2. Redirect all outgoing SMTP traffic to our outgoing mail servers. 
This was OK, but on virus outbreaks the servers would be under higher 
load than what they are supposed to be.  So,

3. Redirect all outgoing traffice that is not directed to our outgoing 
mail servers to another server that has stricted rate limits and checks 
outgoing email for virii (no antispam checks on this server). 
Complaints are very few.