[Mailman-Users] Mailman posting question

[Bill Honneus (honneus)]

Thanks Dragon and Mark for your detailed responses.  I tested this out,
and found out sure enough, that the mail is indeed delivered locally. 

Best regards,

Bill

-----Original Message-----
From: mailman-users-bounces+honneus=cisco.com at python.org
[mailto:mailman-users-bounces+honneus=cisco.com at python.org] On Behalf Of
Dragon
Sent: Friday, August 01, 2008 1:05 PM
To: mailman mailing list
Subject: Re: [Mailman-Users] Mailman posting question

Mark Sapiro wrote:
>Dragon wrote:
> >
> >MTAs are designed to deliver mail to the correct host based on the MX

> >record for a given domain.
>
>
>Except in cases where the recipient domain is one of the MTA's 'local 
>domains'. In that case, the mail is delivered locally without ever 
>consulting DNS.
---------------- End original message. ---------------------

Which was sort of implied by the rest of my post, I didn't state it
explicitly.

But this is true of any network traffic at the TCP/IP and even at the
MAC layer. If it is local, it doesn't go out on the wire even though you
may be sending it to the physical address of a configured interface. The
network stack is smart enough to know that it should just pass the
traffic in memory instead of sending it on an actual interface, it
essentially, and transparently, substitutes "localhost" 
for the address because it knows how to get there directly.

Basically, the principle of "shortest path" is used. How exactly this
gets done in an individual MTA is based on how it is designed and
configured. Since I don't know the exact details of any of them, I will
leave any discussion of how they route local traffic to those who do
know.

Dragon

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