OT: "Nolisting"

[Richard Frovarp]

Alex Neuman wrote:
> I've seen this done with some domains and working very well. In fact, 
> some people will set it up this way:
>
> mydomain.com.    IN    MX    0    
> somethingthatdoesntrespondtoport25.mydomain.com.
> mydomain.com.    IN    MX    10    mail1.mydomain.com.
> mydomain.com.    IN    MX    20    mail2.mydomain.com.
> mydomain.com.    IN    MX    30    
> somethingthatdoesntrespondtoport25.mydomain.com..
>
> That way  you're covered on both ends.

We handle internal mail via our primary MX. We use iptables with 
tcp-reset to keep everyone else out. This prevents timeout delays from 
the connecting servers. When we implemented this, we did not see any 
drop in spam. We did notice that since internal mail was not competing 
against spam for resources, the delivery times were much improved.