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Re: We need an IETF BCP for GREY LISTING

2011-10-16 17:53:22

My long 30 years of mail engineering experience has given me the position and view that non-timely delivery (i.e. unreasonable hindrance) is the exception and not the rule. I don't believe the industry would of endured such a poor history of operations and I believe, possibly unlike some others, all mail systems were designed to deliver mail in a timely matter. I would certainly get out of the market if this system became a "game" with laissez-faire attitudes that SMTP is a matter of just flipping a coin, heads and tails. No, I still believe there is a strong ethical engineering responsibility by the majority of the SMTP systems, in total that make it all work, who still believe timely delivery is important. If that was not the case, for me, I would of been long out of the market.

That said, I do worry that Greylisting (GL) is growing with a varying non-consistency - overhead are increasings. There is no IETF guideline and IMTO, its about time it did. I recall, not too long ago, many key people here thought GL was wrong (hence the idea of a IETF I-D was not even a consideration) and today, you see these same people are GL implementators. So attitudes have changed to accept GL with an effective slightly lower the "SMTP Quality" in the name of SPAM.

Its the same thing with CBV (Callback Verification). CBV works wonderfully, but its not something I would recommend to be used widely. It would not scale. Its not something everyone can do.

I am suggesting that we begin to nip this GL bud before it gets out of hand, when every server you hit has implemented GL and if left as is, in essence, every transaction will now take two or more attempts.

Just imagine if GMAIL.COM began to do Greylisting? One can stand maybe YAHOO with its GL derivative, but with more of the bigger ESPs doing the same thing, and it will get out of hand.

I will say that if left as is, the SMTP recommendation of an initial short delay, is not effective any more - you might as well leave it to 1 hr per each attempt and you might be better off for non-wasteful deliveries.


Richard Kulawiec wrote:
On Sun, Oct 16, 2011 at 01:42:18PM -0400, Hector wrote:
Here is the thing, IMO, the prize at the end of the day is:

      Fastest, less waste in Delivery and High Throughput

For many, an email today has "No Value" tomorrow, especially in the
business world.  I'm sure that is the normal expectation for most
systems and people expecting timely emails.

The problem here, I think, isn't the technology: it's unrealistic and/or
misplaced expectations.  If I might quote my own haiku on this subject:

        Mail is not the web
        Mail is not for file transfer
        Mail is not I M

It's certainly true that a subset of people expect mail to be very
fast; it might even be true that this subset is large enough that
it's "normal".  But I don't think that necessarily means we should
engineer to meet that expectation, just as I don't think the propensity
of some people to attempt transfer of 100M files via email means that
we should engineer to make that feasible.

On the other side of that, I do recognize that inordinate mail delays
do occasionally matter; but I'll argue that (a) these are rare, absent
outages/misconfigurations that would still persist even if greylisting
were handled very effectively and (b) these are often caused by
non-greylisting measures of dubious use.  (I'll cite "quarantines" and
"quotas" as examples of the latter, but will omit for brevity the lengthy
arguments I've made elsewhere about why they're a horrible idea.)
(And let me cite "poor choice of mail service technology or provider"
as another, especially in light of the past week's events involving
a well-known operation which is experiencing systemic, prolonged outages,
please see the NANOG list for extensive discussion.)

Maybe a shorter way to put that last paragraph is that if we agree that
reasonably timely delivery of mail is a Good Thing, then I think we have
many other problems to tackle before we turn our attention to greylisting.



Hector Santos