Hector Santos wrote:
> Must all mail senders have a RECEIVER available
> "somewhere" in order to receive a notification?
If you are talking about envelope sender addresses,
sure, that is the idea, otherwise an empty reverse-
path would do.
> Must all transaction expose a valid RECEIVER in
> the 2822 message reply fields (Reply-To:, From:)
> in order for the user or some mailbot to send
> responses?
Yes, again the idea of Reply-To (or implicitly the
2822-From if no explicit Reply-To address is given)
is to send replies to it, as the name says.
Mailbots better use the reverse-path as explained
in RFC 3834 when talking to unknown strangers, I've
just "spamcopped" two auto-replies to the 2822-From.
> Just consider the many transactions with addresses
> such as:
> no-reply @ validdomin.com
> that many feedbacks system use today, including bad
> guys and the bad/good direct marketing people.
The auto-replies reported as spam above were triggered
by a mail to the SPF help list. It has nothing to do
with IPv6 or MX.
> I don't think I am saying anything odd here.
[...]
> RFC 3484 does not have not even one mentioning of MX
> records.
Apparently RFC 3484 is about IP, two layers below SMTP,
why should it mention MX ? It also does not mention
X.75, V.90, or ISDN records.
> But check out RFC 3482
An informational RFC about E.164, why should I look in
this memo, is "3482" a typo ?
> Then also read the following:
I'm not going to read tons of RFCs I have never before
heard of, I believe you when you say that they do not
mention MX or SMTP.
> In 4038 section 3.2, this note covers what we been
> partially debating:
>| 3.2. DNS Does Not Indicate Which IP Version Will Be Used
[...]
We have even worked out how to solve this problem here:
dom.example. IN MX 10 ipv4.dom.example.
IN A 208.247.131.9
IN AAAA 2001:DB8::CD30
ipv4.dom.example IN A 208.247.131.9
> It touches base with using not MX but SRV as a discovery
> method. But note again, not even one mentioning of MX
> records!!
They did not need to mention MX, because that is the one
case where the solution is obvious (using MX, see above).
> In RFC 4472, section 4.1 it says:
Fine, another solution, use smtp.dom.example. for SMTP,
change all dom.example. addresses to smtp.dom.example.,
or maybe just use an MX pointing to smtp.dom.example. :-)
>| in the specific case of SMTP relaying, the server itself
>| must typically also be configured to know all its names
>| to ensure that loops do not occur.
Also to ensure that [EMAIL PROTECTED] (etc.)
work as expected, yes.
>| (Obviously, when wanting to reach a specific node, one
>| should use the hostname rather than a service name.)
> Note that last sentence as well - a continuation of the
> implicit MX concept.
Just because a name contains www / ftp / smtp does not
necessarily mean that a host supports http / ftp / smtp,
let's say that IAB RFC 4367 info trumps RFC 4472 info:
"What's in a Name: False Assumptions about DNS Names"
Frank
