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Re: STARTTLS & EHLO: Errata text?

Tony Finch <dot@dotat.at> Sun, 01 February 2009 20:35 UTC

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Date: Sun, 01 Feb 2009 20:35:03 +0000
From: Tony Finch <dot@dotat.at>
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To: Hector Santos <hsantos@santronics.com>
cc: John C Klensin <john+smtp@jck.com>, ietf-smtp@imc.org
Subject: Re: STARTTLS & EHLO: Errata text?
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On Sun, 1 Feb 2009, Hector Santos wrote:
>
> I was thinking of 3207 with text similar to:
>
>     The secured SMTP client MUST resend the EHLO command and the
>     secured SMTP server MUST be prepared to issue an 503
>     for any out of sequence commands by legacy 3207 clients.

What's wrong with the text I suggested?

   Upon completion of the TLS handshake, the SMTP protocol is reset to
   the initial state (the state in SMTP after a server issues a 220
   service ready greeting).  The requirement in [RFC5321] that "a client
   MUST issue HELO or EHLO before starting a mail transaction" also
   applies to this fresh state.

> On the other hand, if 3207 is altered to enforce a MUST, then we need to
> change our server and in that vain, I reject this 3207 change to a MUST.

This isn't a change to 3207, it's a clarification. This is a requirement
on the client so it isn't strictly necessary for servers to enforce it
(robustness principle and all that). Does your server enforce the
requirement for plaintext connections?

Tony.
-- 
f.anthony.n.finch  <dot@dotat.at>  http://dotat.at/
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