Date: 4 Aug 1996 16:36:29 -0000
Message-ID: <19960804163629.7759.qmail@koobera.math.uic.edu>
From: djb@koobera.math.uic.edu (D. J. Bernstein)
To: drums@cs.utk.edu
Subject: Re: MX loop example

> the specs
> control implementations, they cannot require any host owner to
> act in any particular way.

That's _exactly_ what they require. RFC 1123 is HOST REQUIREMENTS. Third
paragraph: ``This RFC enumerates standard protocols that a host
connected to the Internet must use.''

> 5.3.3 says that "OK" after DATA means the host has accepted
> responsibilty for delivering or relaying the message.   It doesn't
> say where the message should be delivered, just that it should be.

The semantics of MAIL, RCPT, and DATA are that the mail is delivered _to
the recipients listed in RCPT commands_.

RFC 821: ``RCPT ... is used to identify an individual recipient of the
mail data ... All characters are to be delivered to the recipient's
mailbox.''

Stop trying to weasel out of your responsibility.

> One is that the owners of whitehouse.gov set it their DNS to direct
> mail to  my system, in which case they have just given me that
> authority

In reality, when people set up secondary MXes, they do _not_ think that
they're giving the secondaries permission to throw away mail.

I agree that the current standards don't adequately explain the meaning
of MX records. This is something DRUMS should fix.

> The other is that some random system(s) have decided they should
> unilaterally send mail to my system to deliver for no good reason
> at all.   In that case the sender (or their system maintainer) has
> donated their mail to me.

In that case you are shirking your required responsibility under RFC
1123, section 5.3.3.

> I don't understand why anyone would be in any way worried about
> any of this.

Because your irresponsible attitude produces an unreliable mail system,
where failures lead to lost mail rather than bounces. 

---Dan