Subject: Re: [Emailcore] Ticket #2: Repeated Use of EHLO

From: John C Klensin <[email-masked]>
Date: Wed, 16 Dec 2020 22:52:29 -0500

Hi.

In late October, before the discussion of repeated use of EHLO
forked into several discussions that there seems to be agreement
were not properly part of rfc5321bis, I suggested that we fix
the text to simply clarify the relationships between EHLO and
RSET and mail transactions and those between a new EHLO command
and its predecessor.  I tentatively made the changes but never
circulated them to the WG list.   The working version of what
will become draft-ietf-emailcore-rfc5321bis-01 now contains:

(1) A new second paragraph in Section 3.3 that reads:

   Mail transactions are also terminated by the RSET command
   (Section 4.1.1.5), the sending of an EHLO command (Section
3.2), or
   the sending of a QUIT command (Section 3.8) which terminates
both any
   active mail transaction and the SMTP connection.

And, in addition, (2) the third paragraph of Section 4.1.4 has
been extended to read:

  "An EHLO command MAY be issued by a client later in the
   session. If it is issued after the session begins and the
   EHLO command is acceptable to the SMTP server, the SMTP
   server MUST clear all buffers and reset the state exactly
   as if a RSET command had been issued (specifically, it
   terminates any mail transaction that was in progress, see
   Section 3.3). In other words, the sequence of RSET followed
   immediately by EHLO is redundant, but not harmful other
   than in the performance cost of executing unnecessary
   commands. However the response to an additional EHLO
   command MAY be different from that from prior ones; the
   client MUST rely only on the responses from the most recent
   EHLO command." 

With those changes, the situation should be very clear and
consistent with the intention of the text coming out of DRUMS
and YAM.

I have also annotated Appendix G.2 to discuss these changes.

In reviewing them and the related text tonight, I discovered two
additional issues.  For convenience, I will describe them in a
separate note.

It also occurs to me that it would be helpful if Alexey's ticket
numbers were including in the relevant appendices of 5321bis.  I
will put them in when an issue is resolved but, if someone has
time to compile a small table and send it to me, I'll fix the
outstanding ones.

    john

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From: "Alexey Melnikov" <[email-masked]>
Date: Thu, 31 Dec 2020 15:50:33 +0000

Hi John,

> consistent with the intention of the text coming out of DRUMS

Yes, these changes look good to me and I will close this ticket now.

Best Regards,
Alexey