[CentOS] SPAM on the List

On 7/17/11 10:26 PM, Always Learning wrote:
>
> Sorry if I seem thick but I am having problems understanding why, with
> the use of NAT, the HELO/EHLO and their external IP address can not
> match.

I suppose it is not impossible if you force a 1 to 1 correspondence.

> Also what influences does scaling have on the ability of sending
> mail servers (MTAs) to operate with host names that match their IP
> addresses ?

NATs are often pools of addresses, often managed by different groups than the 
host services, and sometimes used in sets with different address mappings to 
allow load balancing and failover across multiple isp connections. If mail is 
your only service, you might give all of those addresses the reverse DNS name 
that matches your HELO name, but most places would probably just do what the 
standards require.

-- 
   Les Mikesell
    lesmikesell at gmail.com