Subject: RE: regarding MX records

From: "Woodhouse, Gregory J." <[email-masked]>
Date: Thu, 11 Mar 1999 18:48:30 -0600

I like this language. I would only add that these agreements need to be
mutual and should be restricted to a service environment (such as a private
network or client to host connections within a mail domain). For example, in
the VHA network, all Internet accesss is by proxy. We have multiple mail
systems which may wish to exchange mail (for example, Microsoft Exchange,
and VA Mailman which is our internally developed SMTP based mail system).
Absent any private arrangement to the contrary, mail leaving one environment
will be routed to the mail proxies, which is obviously undesirable.

It also seems to me that dialup links can be considered a (small) service
environment within which explicit agreements should take precedence over MX
base routing, as may a LAN enironment, where all mail should go to a central
server, even if it is not a mail exchanger for the domain (for incoming
mail).
---
Gregory Woodhouse
Managed Care - Technical Requirements Team
[email-masked]
+1 415 744 6362

-----Original Message-----
From: Keith Moore [mailto:[email-masked]]
Sent: Thursday, March 11, 1999 3:59 PM
To: [email-masked]
Cc: [email-masked]
Subject: regarding MX records

My take on MX records:

- They are used by mail domains to advertise how to route incoming
  mail to their domains, in the absence of explicit agreements
  to route mail some other way.   Explicit agreements take precedence,
  but in the absence of an explicit agreement an Internet MTA should
  use MX records to route to domains for which they are not themselves
  primary MXes.

- They are used only to advertise routing for envelope email addresses.
  If you have your MTA or MUA configured to route outgoing mail to
  a particular host, A records (not MX) are used to find the IP
  address of that host.  In the future SRV and/or SLP might also be 
  used.

I believe this is both architecturally sound and consistent with
long-established practice.

Keith

---

From: Graham Klyne <[email-masked]>
Date: Fri, 12 Mar 1999 16:47:12 +0000

At 09:22 12/03/99 +0100, Brad Knowles wrote:
>    IMO, all private agreements are outside the scope of 821bis, and we
>should explicitly mention this fact.

I think "out of scope" and "not conforming" are two distinct issues.
Further, "fully conforming" seems to be an emotive term.  I sense broad
agreement on the required meaning, but uncertainty how to say it.

Maybe words along the lines of "In the absence of a private agreement
between the client and relay server, [...] MUST be used to [...]"?

Thus, the use of a private agreement is "out of scope", but it is not "non
conforming".

The alternative is that whenever a private agreement is used (which will
certainly happen) that entire deployment scenario is "out of scope".  I do
sense lack of agreement on whether this should be the case.  Personally, I
think the issue does deal with interoperability of components from
different suppliers to implement an Internet service, so it is helpful to
allow the deployment scenario as "in scope", even if it does not apply
strictly to sending mail across the Internet.  But the details of any such
private agreement belong elsewhere (i.e. the mail submission RFC?).

#g

------------
Graham Klyne
([email-masked])

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From: "Jeff Stephenson (Exchange)" <[email-masked]>
Date: Fri, 12 Mar 1999 09:37:57 -0800

I like this language.

-- jeff

> From: Graham Klyne [mailto:[email-masked]]
> Sent: Friday, March 12, 1999 8:47 AM
>

---

From: "Woodhouse, Gregory J." <[email-masked]>
Date: Mon, 15 Mar 1999 11:10:13 -0600

It seems to me that part of the difficulty is that if a mechanism outside
the scope of 821bis is used, we often assume that the product is a fortiori
non-conforming. I'm not sure I see the phrase "fully conforming" as being a
problem, but I can't imagine anyone wanting to market their product as being
conditionally compliant with 821bis (or, rather, whatever number of the
number eventually turns out to be), but I do think defining multiple
conformance levels is useful. I also think that it is useful consider mail
routing and host-to-host mail transfer as being logically separate and
define conformance in these areas separately. I say this with some
trepidation, because I think incorporating the protocol elements defined in
974 into 821bis was an excellent idea.
---
Gregory Woodhouse
Managed Care - Technical Requirements Team
[email-masked]
+1 415 744 6362

-----Original Message-----
From: Graham Klyne [mailto:[email-masked]]
Sent: Friday, March 12, 1999 8:47 AM
To: Brad Knowles
Cc: [email-masked]
Subject: Re: regarding MX records

#g

------------
Graham Klyne
([email-masked])