Re: [Asrg] 6. Proposals - RMX-like implementation via rDNS

[Brad Knowles <brad.knowles@skynet.be>]

At 7:32 AM -0400 2003/09/10, Marc A. Pelletier wrote:

>    b) Some way of delegating.  'us.example.com' may well have different
>        administrators and mail policies than 'jp.example.com' in addition to
>  being
>        on different continents.
	Indeed.  You can't really co-opt mx.example.com as the subdomain 
to use to specify the outbound mail servers, because many companies 
have subdomains per-country, and ".mx" is a valid ccTLD -- Mexico.

	I realized this a couple of months after we chose mx.aol.com as 
the subdomain to handle all inbound MX records for AOL -- we were 
screwed if we ever got a Mexican service.


	You also can't really co-opt a name like relay.example.net and 
then list all IP addresses of all officially known mail servers, 
because some sites use that as their customer-visible name for their 
outbound mail relays.

	Moreover, some sites will put that IP address on a load-balancing 
switch, although the servers behind the switch will use their real IP 
addresses for their outbound connections (which might be on a 
different interface, and would obviously have to be completely 
different from the customer-advertised address).


	And there remain all the problems with legitimate third-party 
relay activity, which have been previously discussed.

--
Brad Knowles, <brad.knowles@skynet.be>

"They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety."
    -Benjamin Franklin, Historical Review of Pennsylvania.

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