Re: [Exim] MX Record points to non-existent host

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Autor: Greg Louis
Data:  
Para: Exim Users Mailing List
Asunto: Re: [Exim] MX Record points to non-existent host
On 20030222 (Sat) at 1301:32 -0500, Greg A. Woods wrote:
> [ On Saturday, February 22, 2003 at 11:31:30 (-0500), Greg Louis wrote: ]
> > Subject: Re: [Exim] MX Record points to non-existent host
> >
> > It is not my duty -- I would say it is none of my business -- to get in
> > anyone else's face about how well or badly they set up their
> > environment.
>
> Well, actually it is. They don't call this thing an "INTERNET" for
> nothing!


There followed a good deal of stuff with which I agree, in large part,
about the desirability of standards, and of adhering to standards.
Also a good deal about the need to enforce adherence to standards by
refusing to communicate with those who do not succeed in adhering, even
when capable of doing so. There we differ. I consider that an
impractical approach and believe its practitioners are standing on a
shrinking island.

> By tolerating some deviation from the interoperability standards you
> create an impression and even an expectation that the standards are
> irrelevant and that the tolerated behaviour is actually OK. Many of the
> rest of us in the Internet community do not appreciate this at all.


This point, if divested of the emotional component, is well taken. I
agree that it's undesirable to contribute to the expectation that the
standards are irrelevant. Even bad or outdated standards are usually
better than chaos. (This is not meant to imply that the standards we
are discussing are either bad or outdated.)

> > If the users of such lists choose to deprive themselves of the ability
> > to communicate with such hosts as do not meet their standards, that is
> > their decision and their right. Our need is the exact opposite: to
> > communicate with anyone who wishes to contact us.


That choice and that consequence are important. When a standard is too
widely ignored, those who would enforce it end up limiting only
themselves. I wish it were otherwise, but in the real world of today,
it's no more practical to run a strict MTA than it would be to refuse
to read our customers' mail (electronic or otherwise) because their
English is lousy.

> Do you expect your FAX machine to produce a facsimile of the document
> fed to it if the FAX machine at the other end has had some new
> non-standard high-power compression algorithm installed in its firmware?
> Or vice versa?


I sure do expect that the FAX machine at the other end will dumb itself
down to my level if it finds I can't smarten up to its.

> If you operate a strictly RFC-compiant infrastructure then you are
> already allowing anyone to contact you if they wish.


No. We would be allowing anyone to contact us if their bosses can
afford, and choose to afford, technical folks who have the knowledge
and the resources to do it right. That's not the same thing at all,
unfortunately.

> Using your ability and willingness to ignore interoperability standards
> as a sales tool to attract business from those who are ignorant of those
> same standards really angers the rest of us in the Internet community,


Those of us who have to communicate, for a living, with an
ever-increasing number of "those who are ignorant of those same
standards" can only deplore the necessity. Having a phone or FAX or
being on the 'net in the first place is, for a company, a way to
attract business. Having a phone or FAX or MTA that only interoperates
with a subset of the population is undesirable from a business
standpoint. If those outside the subset are so because they fail to
comply with interoperability standards, that doesn't lessen our need to
be able to communicate with them. Tell you what: you come convince my
top management that they should forego the custom of every organization
that runs its email on imperfectly RFC-compliant mail servers. That
they should order me to operate with full verification and no tolerance
of error at the remote site. You persuade them to do that, and you
won't have to argue with me -- that I promise you!

> If you tell your customers that your FAX machine is a standards
> compliant FAX machine that is guaranteed by its manufacturer to talk to
> every other standards compliant FAX machine then I'm sure they'll stop
> trying to send you FAXes using their new proprietary hyper-compression
> FAX machine no matter how much they might like it.


If much of the rest of the world operates the proprietary equipment,
they will stop trying to send us FAXes, all right. They will just
smile disdainfully and go buy from someone else.

> The same applies for your mailer. If you tell your customers that your
> mailer and your DNS infrastructure meets not just the letter of the law
> in the RFCs, but also their intent, and that you can send and receive
> e-mail between every other RFC-compliant mailer then I'm sure they'll
> realise that they're the ones who are causing the interoperability
> problems.


I used to say just that until it became apparent that it was utterly
futile. They just say "everyone else gets our mail." Worse, my users
say, "everyone else gets their mail."

> I'd like to do very nasty things to every idiot who has ever claimed
> they could send and receive e-mail with every other domain but mine
> when the problem is clearly their own!


I'm not devoid of sympathy with that sentiment. But from their point
of view, if it works with lots of other domains, why is it a problem?
That's the perception that makes it really hard to convince them.

What I would like is for my MTA to tolerate as much error as possible
on the other end while behaving perfectly in every other respect.
(That's what I'd like to be like, myself, for that matter ;)

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