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Re: [ietf-smtp] [dispatch] Forced SMTP redirects

Arnt Gulbrandsen <arnt@gulbrandsen.priv.no> Thu, 18 March 2021 09:36 UTC

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From: Arnt Gulbrandsen <arnt@gulbrandsen.priv.no>
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Date: Thu, 18 Mar 2021 10:55:20 +0100
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Subject: Re: [ietf-smtp] [dispatch] Forced SMTP redirects
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On Thursday 18 March 2021 01:32:33 CET, John Levine wrote:
> I'd flip it around.  Do we have examples of MTAs that look at 
> the other digits
> in responses to MAIL, RCPT, or DATA comands?

I searched github for "smtp 354" now, on the theory that that number won't 
be used for much other than the response code. Finding the first smtp 
client that expects 354 instead of 3 took maybe a whole minute. That 
package is a tool used by innumerable web sites to send mail. I expect I'd 
find many more if I were to spend a few more minutes looking.

While scrolling down I saw lots of unit tests that used 354, which makes me 
suspect that half of that software would break if fed 353 or 355 (and some 
would break in exciting ways).

Arnt

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