Re: [ietf-smtp] SMTP server reply extensions

Ned Freed <ned.freed@mrochek.com> Sat, 11 April 2020 00:13 UTC

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Cc: Ned Freed <ned.freed@mrochek.com>, ietf-smtp@ietf.org
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Date: Fri, 10 Apr 2020 17:04:43 -0700 (PDT)
From: Ned Freed <ned.freed@mrochek.com>
In-reply-to: "Your message dated Fri, 10 Apr 2020 21:18:46 +0300" <402434A7-5F3C-4DC8-9DF1-5B0DDFC5BAC9@sirainen.com>
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To: Timo Sirainen <timo@sirainen.com>
Archived-At: <https://mailarchive.ietf.org/arch/msg/ietf-smtp/hLhGI0xwUS-J1O8XqQLwwPCx030>
Subject: Re: [ietf-smtp] SMTP server reply extensions
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> > Of course it makes sense to reuse existing structured syntax when possible. As
> > for reusing existing enhanced status code, I'm really not on board with that -
> > I think new values are the right way to do it, and that once again we've been
> > guilty of integer-hoarding. (We really should have reserved a range for private
> > use, but there are enough values that it's difficult to get excited about
> > this.)

> So you are recommending not using the 551 code for the redirection purpose?

I don't this the SMTP code you use matters much - the enhanced status code is
what I would look at to determine if there's additional information. But if
your information fits the 551 syntax, sure, why not? Although in our case I
think we use 450 since we regard this as a temporary failure. (AFAIK there is
no 551 temporary equivalent with the same semantics.)

> Hmm. Now thinking further about this, I'm not sure 551 would be enough for my
> purposes either. I think I'm going to need multiple different things returned
> in the reply. So maybe I'll do it with a new private response code also. Any
> recommendations what private codes to use? Maybe x.y.100 and over?

We used .99.

				Ned