Re: [ietf-smtp] [dispatch] Forced SMTP redirects
Viktor Dukhovni <ietf-dane@dukhovni.org> Wed, 17 March 2021 01:04 UTC
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From: Viktor Dukhovni <ietf-dane@dukhovni.org>
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Date: Tue, 16 Mar 2021 23:04:54 -0200
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Subject: Re: [ietf-smtp] [dispatch] Forced SMTP redirects
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> I have some dim recollection of very, very few instances, over the last several decades, of parties who were (apparently) very much invested into having their mail delivered, trying to convince me that someone telling them 5xx didn't really mean that, because of the specific error message that was assigned to the specific numeric code. I never found those arguments very convincing. > > The most innovating argument revolved around the interpretation of "in the same sequence". The argument was that it only means "hey, you just can't resend it immediately, but if your RSET, or maybe disconnect or reconnect, its okay-dokay". Postfix does give the MTA administrator some rope to hang himself with via SMTP "reply filters" that allow transformations between arbitrary [45]xy codes to other code (typically 5xx -> 4xx) allowing them opportunities to retry some hard error with a problem peer, or perhaps fall back to an backup relay. That leaves any matching of codes and reply text to the user... ... What dogs hear ... -- 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