Re: [ietf-smtp] [ dispatch] Forced SMTP redirects
Viktor Dukhovni <ietf-dane@dukhovni.org> Fri, 19 March 2021 07:40 UTC
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From: Viktor Dukhovni <ietf-dane@dukhovni.org>
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Date: Fri, 19 Mar 2021 03:39:58 -0400
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References: <CAKFo7wkawgk-Yj676kE5MqK8XuebuArMexH-eOdq_Uo7ijdimQ@mail.gmail.com> <20200710015947.0BE2D1C78A2F@ary.qy> <CAKFo7w=MJBt0FdnCcOZCXZWdkd6Jinv4TqwdpefdoaCncbZH3Q@mail.gmail.com> <6AEA7D44C8037B32BC1F3810@PSB> <81d0132b-3ebf-2b0b-756b-503bb5afdb37@dcrocker.net> <8E2D8138-EE61-486A-B957-A922F0C6F4B3@dukhovni.org> <20210318003233.DC44C70A8F5D@ary.qy> <e90d22da-e124-4542-8ef6-83798f5725de@gulbrandsen.priv.no> <F5461844610EDF6715D08D1B@PSB> <503e5ae8-71a1-8c9e-33b3-5c475d0ad76f@pscs.co.uk> <C7297FCD-DA5A-43D1-972C-537171D4330F@wordtothewise.com>
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Subject: Re: [ietf-smtp] [ dispatch] Forced SMTP redirects
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> On Mar 18, 2021, at 10:55 AM, Laura Atkins <laura@wordtothewise.com> wrote: > > MTAs that send high volumes of email do pay attention to the other digits and the extended codes. In fact, many of them do full text parsing to try and determine how they should handle future mail to that address. https://smtpfieldmanual.com is one example. Is this "paying attention" really happening *during* delivery, to guide further progress of the SMTP transaction, or, as seems more likely, rather an after-the-fact forensic analysis to keep lists in good hygiene. Detailed SMTP server replies are certainly useful forensically, what's under discussion in this thread, is to what extent the SMTP protocol engine in the sending client really needs to be concerned with such details. Occasionally, an MTA with an uncertain reputation may choose to conditionally soften a 5XX reply to a 4XX reply, if it has another means to reach the destination (from a different IP address, ...). Perhaps that's the every-day reality for some sending systems, and in that case I can see these closely scrutinising the server reply. In most other cases, there's little reason to look beyond the first digit. -- Viktor.
- [ietf-smtp] Fwd: [dispatch] Forced SMTP redirects E Sam
- Re: [ietf-smtp] Fwd: [dispatch] Forced SMTP redir… John C Klensin
- Re: [ietf-smtp] Fwd: [dispatch] Forced SMTP redir… John Levine
- Re: [ietf-smtp] Fwd: [dispatch] Forced SMTP redir… John C Klensin
- Re: [ietf-smtp] Fwd: [dispatch] Forced SMTP redir… E Sam
- Re: [ietf-smtp] Fwd: [dispatch] Forced SMTP redir… John R Levine
- Re: [ietf-smtp] Fwd: [dispatch] Forced SMTP redir… John Levine
- Re: [ietf-smtp] Fwd: [dispatch] Forced SMTP redir… Dave Crocker
- Re: [ietf-smtp] [dispatch] Forced SMTP redirects Viktor Dukhovni
- Re: [ietf-smtp] [dispatch] Forced SMTP redirects Dave Crocker
- Re: [ietf-smtp] [dispatch] Forced SMTP redirects Viktor Dukhovni
- Re: [ietf-smtp] [dispatch] Forced SMTP redirects Dave Crocker
- Re: [ietf-smtp] [dispatch] Forced SMTP redirects Viktor Dukhovni
- Re: [ietf-smtp] [dispatch] Forced SMTP redirects Sam Varshavchik
- Re: [ietf-smtp] [dispatch] Forced SMTP redirects Viktor Dukhovni
- Re: [ietf-smtp] [dispatch] Forced SMTP redirects John Levine
- Re: [ietf-smtp] [dispatch] Forced SMTP redirects Arnt Gulbrandsen
- Re: [ietf-smtp] [dispatch] Forced SMTP redirects John C Klensin
- Re: [ietf-smtp] [dispatch] Forced SMTP redirects Paul Smith
- Re: [ietf-smtp] [ dispatch] Forced SMTP redirects Laura Atkins
- Re: [ietf-smtp] [dispatch] Forced SMTP redirects Sam Varshavchik
- Re: [ietf-smtp] [ dispatch] Forced SMTP redirects Viktor Dukhovni
- Re: [ietf-smtp] [ dispatch] Forced SMTP redirects Laura Atkins
- Re: [ietf-smtp] [ dispatch] Forced SMTP redirects Ned Freed
- Re: [ietf-smtp] [ dispatch] Forced SMTP redirects Ned Freed
- Re: [ietf-smtp] [ dispatch] Forced SMTP redirects Laura Atkins
- Re: [ietf-smtp] [dispatch] Forced SMTP redirects Ned Freed