Re: [ietf-smtp] parsing SMTP replies (was: Proposed ESMTP keyword RCPTLIMIT}
Alessandro Vesely <vesely@tana.it> Thu, 18 March 2021 10:37 UTC
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To: Ned Freed <ned.freed@mrochek.com>, ietf-smtp@ietf.org
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From: Alessandro Vesely <vesely@tana.it>
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Date: Thu, 18 Mar 2021 11:37:21 +0100
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Archived-At: <https://mailarchive.ietf.org/arch/msg/ietf-smtp/GG2gK-Pm_tmj4bX5tAMF15xiON4>
Subject: Re: [ietf-smtp] parsing SMTP replies (was: Proposed ESMTP keyword RCPTLIMIT}
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On Wed 17/Mar/2021 18:44:04 +0100 Ned Freed wrote: > >> +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}} > > [...] > > 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. Good point. By observing RCPTLIMIT, a client can avoid re-queuing delays. It stops just before reaching the limit and then starts a new transaction right away. However, this won't work if 452 was issued to split recipients according to a different criterion than the local max number. > The question then becomes is such an announcement - one that applies to all > transient failures, useful. Applying RETRYDELAY to all transient failures doesn't seem to me to be the right thing to do. However, distinguishing among transient failures conflicts with the dog rule. > 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. In this moment I'm unable to think of varying delay lengths. Some considerations, for example how often a server updates some DCC database or how long does it take to reboot, may suggest a retry interval common to all transient failures that require a delay. That is, most 4xx, except splitting recipients, where immediate retry is better. So, two categories may suffice. How about NORETRYDELAY=452? (Just kidding...) Best Ale --
- 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