Date: 13 Mar 1999 21:29:57 -0000
Message-ID: <19990313212957.11949.qmail@cr.yp.to>
From: "D. J. Bernstein" <djb@cr.yp.to>
To: drums@cs.utk.edu
Subject: Re: MX is not part of the SMTP protocol
References: <19990313183430.11246.qmail@cr.yp.to> <16861.921356028@munnari.OZ.AU>

Robert Elz writes:
> That I have MX records does not mean I have authorised spammers to send
> mail to the hosts listed.

Surely you're not claiming that any random Internet user who sends you
mail is making unauthorized use of your computer?

In fact, the MX record authorizes _everybody_ to send mail for that
domain through the MX hosts.

If there isn't an MX record, the A record authorizes everybody to send
mail for that domain through that host.

> spec would simply (by implication if necessary) revise 821bis to permit
> its new form of lookups instead of (or in addition to) MX lookups.

This means reviewing 821bis, finding all the spots where Klensin failed
to think ahead, and stating modifications to the text at each spot.

In contrast, if 821bis preserves the existing concept of ``send mail by
SMTP to that host,'' then future specs can simply _refer_ to 821bis,
without modifying anything.

---Dan