Re: [ietf-smtp] parsing SMTP replies (was: Proposed ESMTP keyword RCPTLIMIT}
John C Klensin <john-ietf@jck.com> Thu, 18 March 2021 01:06 UTC
Return-Path: <john-ietf@jck.com>
X-Original-To: ietf-smtp@ietfa.amsl.com
Delivered-To: ietf-smtp@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 0B9483A19B2 for <ietf-smtp@ietfa.amsl.com>; Wed, 17 Mar 2021 18:06:36 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.897
X-Spam-Level:
X-Spam-Status: No, score=-1.897 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, SPF_HELO_NONE=0.001, SPF_NONE=0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id NDj0RUdIgLio for <ietf-smtp@ietfa.amsl.com>; Wed, 17 Mar 2021 18:06:34 -0700 (PDT)
Received: from bsa2.jck.com (bsa2.jck.com [70.88.254.51]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 738CA3A19B1 for <ietf-smtp@ietf.org>; Wed, 17 Mar 2021 18:06:34 -0700 (PDT)
Received: from [198.252.137.10] (helo=PSB) by bsa2.jck.com with esmtp (Exim 4.82 (FreeBSD)) (envelope-from <john-ietf@jck.com>) id 1lMh7M-000J4R-SE; Wed, 17 Mar 2021 21:06:28 -0400
Date: Wed, 17 Mar 2021 21:06:21 -0400
From: John C Klensin <john-ietf@jck.com>
To: Ned Freed <ned.freed@mrochek.com>, Alessandro Vesely <vesely@tana.it>
cc: ietf-smtp@ietf.org
Message-ID: <4EC92B6CFDD4220E0F692CF0@PSB>
In-Reply-To: <01RWRTQUWB8Q005PTU@mauve.mrochek.com>
References: <77B21231-47EA-4CA6-A665-5880B6A54D4D@wordtothewise.com> <20210312203224.F3739701E4C5@ary.qy> <01RWOUM3HK0Q005PTU@mauve.mrochek.com> <e6e5d166-ded5-b6c0-db9a-57c44e8bd92a@dcrocker.net> <01RWOX4A2CZG005PTU@mauve.mrochek.com> <CF0247A810AF9482CBB155E8@PSB> <01RWP85B98S4005PTU@mauve.mrochek.com> <20210316061139.GA26514@kiel.esmtp.org> <0d5912b5-6aba-728b-00de-a75397ad8ad8@tana.it> <01RWRTQUWB8Q005PTU@mauve.mrochek.com>
X-Mailer: Mulberry/4.0.8 (Win32)
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
X-SA-Exim-Connect-IP: 198.252.137.10
X-SA-Exim-Mail-From: john-ietf@jck.com
X-SA-Exim-Scanned: No (on bsa2.jck.com); SAEximRunCond expanded to false
Archived-At: <https://mailarchive.ietf.org/arch/msg/ietf-smtp/-OZPMiDNepYUtIj1XkJZ2CYdyrk>
Subject: Re: [ietf-smtp] parsing SMTP replies (was: Proposed ESMTP keyword RCPTLIMIT}
X-BeenThere: ietf-smtp@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: "Discussion of issues related to Simple Mail Transfer Protocol \(SMTP\) \[RFC 821, RFC 2821, RFC 5321\]" <ietf-smtp.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/ietf-smtp>, <mailto:ietf-smtp-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/ietf-smtp/>
List-Post: <mailto:ietf-smtp@ietf.org>
List-Help: <mailto:ietf-smtp-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/ietf-smtp>, <mailto:ietf-smtp-request@ietf.org?subject=subscribe>
X-List-Received-Date: Thu, 18 Mar 2021 01:06:36 -0000
--On Wednesday, March 17, 2021 10:44 -0700 Ned Freed <ned.freed@mrochek.com> wrote: > Typos fixed. > >> +GREYLISTING Limit >> +------------- >> + >> +Name: GREYLISTING >> + >> +Value syntax: %x31-39 0*5DIGIT ; 0 not allowed, 6 digit >> maximum + >> +Description: GREYLISTING specifies the minimum number of >> seconds +that a client should wait before retrying to submit >> the same message. +The presence of this limit implies that >> the client MAY receive a +transient 4xx response. See >> {{GREYLISTING}} > > The primary purpose of this document is to create the > extension and associated > registry. The only reason some initial entries are included is > that it's very > helpful to have some examples to emulate. Building the entire > registry is not > the goal, because doing so requires that we reach consensus on > every limit > people can think of. This is a sure-fire recipe for document > failure. > > If past discussions are any indication, getting consensus on > how to handle > greylisting is going to be difficult. I don't want to make > this document > dependent on that. > > That said, I don't see why this limit necessarily has anything > to do with > greylisting. It's about how to long to wait before retying > after a transient > failure, irrespective of why the delay occurred. If could be > greylisting, it > could be exceeding a rate or connection limit, it could be one > of the sources > for validating recipients is down, it could be the spam > filtering system is > down, etc. RETRYDELAY would be a much better name for it. > > The question then becomes is such an announcement - one that > applies to all > transient failures, useful. My sense is that the utility is > marginal given the > lengthy list of possible causes and the fact that the best > retry period for > different causes could be very different, which I note that > the approach taken > in the original proposal allows. FWIW, strong agreement. And, before we go overboard on this, I would encourage everyone to review and think about the wise advice [1] in the last two paragraphs of Section 2.2.1 or RFC 5321. Personally and wearing no hats, I like the idea of a new "LIMITS" extension and EHLO keyword. However, I think we could easily go overboard and start adding limits parameters on a principle closer to "might be a neat idea" than to "strong demonstrated need and evidence of willingness to both advertise and use". If I thought anyone would pay attention, I'd argue for a much stronger requirement for a new parameter than "Specification required". I don't, but I think that, not only should we be careful that any parameters included in the spec are of clear applicability and usefulness but that text discouraging vanity parameters or parameters that would be of value to only one implementation model would be desirable. That text might be as simple as a reference to that statement in 5321 -- perhaps either at the end of Section 1 or as part of new comments in Section 6 encouraging people to not go overboard. best, john [1] While that text is carried forward from RFC 1425, I didn't write or even suggest it (IIR, Marshall Rose did), so I claim no credit. > > Ned > > _______________________________________________ > ietf-smtp mailing list > ietf-smtp@ietf.org > https://www.ietf.org/mailman/listinfo/ietf-smtp
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Ned Freed
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Dave Crocker
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Viktor Dukhovni
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Ned Freed
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Dave Crocker
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Ned Freed
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Viktor Dukhovni
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… John Levine
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Ned Freed
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Ned Freed
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… John C Klensin
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Ned Freed
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Rolf E. Sonneveld
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Sam Varshavchik
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Ned Freed
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… John Levine
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… John C Klensin
- Re: [ietf-smtp] parsing SMTP replies (was: Propos… Claus Assmann
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Ned Freed
- Re: [ietf-smtp] parsing SMTP replies (was: Propos… Alessandro Vesely
- Re: [ietf-smtp] parsing SMTP replies (was: Propos… Ned Freed
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Jeremy Harris
- Re: [ietf-smtp] parsing SMTP replies (was: Propos… John C Klensin
- Re: [ietf-smtp] parsing SMTP replies (was: Propos… Sam Varshavchik
- Re: [ietf-smtp] parsing SMTP replies (was: Propos… Keith Moore
- Re: [ietf-smtp] parsing SMTP replies (was: Propos… Viktor Dukhovni
- Re: [ietf-smtp] parsing SMTP replies (was: Propos… Valdis Kl ē tnieks
- Re: [ietf-smtp] parsing SMTP replies (was: Propos… Valdis Kl ē tnieks
- Re: [ietf-smtp] parsing SMTP replies (was: Propos… John C Klensin
- Re: [ietf-smtp] parsing SMTP replies (was: Propos… Alessandro Vesely
- Re: [ietf-smtp] parsing SMTP replies Keith Moore
- Re: [ietf-smtp] parsing SMTP replies (was: Propos… John C Klensin
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… John C Klensin
- Re: [ietf-smtp] parsing SMTP replies Michael Peddemors
- Re: [ietf-smtp] parsing SMTP replies Ned Freed
- Re: [ietf-smtp] parsing SMTP replies Viktor Dukhovni
- Re: [ietf-smtp] parsing SMTP replies Michael Peddemors
- Re: [ietf-smtp] parsing SMTP replies Jeremy Harris
- Re: [ietf-smtp] parsing SMTP replies Laura Atkins
- Re: [ietf-smtp] parsing SMTP replies George Schlossnagle
- Re: [ietf-smtp] parsing SMTP replies Ned Freed
- Re: [ietf-smtp] parsing SMTP replies (was: Propos… Ned Freed
- Re: [ietf-smtp] parsing SMTP replies (was: Propos… Ned Freed
- Re: [ietf-smtp] parsing SMTP replies Richard Clayton
- Re: [ietf-smtp] parsing SMTP replies Hector Santos
- Re: [ietf-smtp] parsing SMTP replies Laura Atkins
- Re: [ietf-smtp] parsing SMTP replies Ned Freed
- Re: [ietf-smtp] parsing SMTP replies John C Klensin
- Re: [ietf-smtp] parsing SMTP replies Hector Santos
- Re: [ietf-smtp] parsing SMTP replies Hector Santos
- Re: [ietf-smtp] parsing SMTP replies Laura Atkins
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… John Levine
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Jeremy Harris
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Ned Freed
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… John Levine
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… George Schlossnagle
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Hector Santos
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Mike Hillyer
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Ned Freed
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Ned Freed
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… John R Levine
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Michael Peddemors
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Jeremy Harris
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… George Schlossnagle
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Ned Freed
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Sam Varshavchik
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Laura Atkins
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Arnt Gulbrandsen
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Mike Hillyer
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Dave Crocker
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Richard Clayton
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Laura Atkins
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Ned Freed
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Ned Freed
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… John R Levine
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Richard Clayton
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Ned Freed
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Tony Finch
- Re: [ietf-smtp] [Emailcore] Proposed ESMTP keywor… Viktor Dukhovni