Subject: Re: FWD: Re: To MX or not to MX?

From: [email-masked] (Kai Henningsen)
Date: 03 Apr 1999 13:14:00 +0200

[email-masked] (Randall Gellens)  wrote on 30.03.99 in <[email-masked]>:

> At 1:41 AM +1100 3/5/99, Robert Elz wrote:
>
> >I do appreciate the point that Philip Hazel (and others I expect) made that
> >the "SMTP" name is lost, and that MUAs which connect to port 25 on their
> >nearby mail submission host (MTA) believe that they are using SMTP - and
> >that attempting to change that now would be hopeless.   I'm not 100% sure
> >of the last part - get a new doc with a new name (even if almost none of
> >the details are different from SMTP) and I think it would not take long for
> >people to adjust to using the new terminology ("submitting mail via SMTP is
> >the old way, I use the new MSP instead, you should too") even though the
> >two might be almost functionally identical.
>
> RFC 2476 ("Message Submission") specifies MSA, Message Submission
> Host, as the name of the server to which the MUA connects (via port
> 587 instead of 25 in most cases) to drop off mail for further
> processing and relay.  The protocol is called Submission.

Quoting that RFC:

| 3.  Message Submission
|
| 3.1.  Submission Identification
|
|    Port 587 is reserved for email message submission as specified in
|    this document.  Messages received on this port are defined to be
|    submissions.  The protocol used is ESMTP [SMTP-MTA, ESMTP], with
|    additional restrictions as specified here.
|
|    While most email clients and servers can be configured to use port
|    587 instead of 25, there are cases where this is not possible or
|    convenient.  A site MAY choose to use port 25 for message submission,
|    by designating some hosts to be MSAs and others to be MTAs.

Note the wording: "The protocol used is ESMTP".

While the IETF might well call the protocol "Submission", the protocol  
specification itself clearly calls it "ESMTP".

Incidentally, RFC 2476 never even mentions MX. It does, however, talk  
about "designates some hosts to be MSAs and others to be MTAs", which, at  
least to me, indicates that using MX resolution to find MSAs is not  
desirable.

Which, in turn, indicates that RFC 2476 understands ESMTP to *not* imply  
MX.

MfG Kai

---

From: [email-masked] (Kai Henningsen)
Date: 03 Apr 1999 11:27:00 +0200

[email-masked] (Alan Barrett)  wrote on 24.03.99 in <[email-masked]>:

> Kai Henningsen <[email-masked]> asked:
> > >     There are some extremely precise definitions of what it means to be
> > > "on the Internet", and these definitions do not necessarily correspond
> > > to what the average user might think of in terms of being "on the
> > > Internet".
> >
> > Which RFC would that be?
>
> RFC 1775

That turns out not to be the case.

That is, RFC 1775 *does not* define the term "on the Internet", though it  
does use it as a title.

Look it up if you don't believe me. All the defined terms are of the form  
"XXXX ACCESS".

Care to try again?

MfG Kai