Re: [ietf-smtp] parsing SMTP replies (was: Proposed ESMTP keyword RCPTLIMIT}

[Alessandro Vesely <[e-mail]>]

On Tue 16/Mar/2021 07:11:39 +0100 Claus Assmann wrote:
> On Mon, Mar 15, 2021, Ned Freed wrote:
> 
>> Which establishes the precedent for parsing replies given a signal
>> to do so.
> 
> draft-santos-smtpgrey has something like that for graylisting:
> 421 4.7.0 Come back later. retry=123
>                             ^^^^^^^^^


That could be a fair idea.  Strawman below, along with a few nits.


Best
Ale

--- draft-freed-smtp-limits-01.md	2021-03-17 11:01:19.392667148 +0100
+++ draft-freed-smtp-limits-02.md	2021-03-17 11:20:30.316669820 +0100
@@ -24,6 +24,7 @@
    ABNF: RFC5234
    SMTP: RFC5321
    PIPELINING: RFC2920
+  GREYLISTING: RFC6647

  informative:
    STARTTLS: RFC3207
@@ -204,9 +205,9 @@

  Name: MAILMAX

-Value syntax: %x30-39 0*5DIGIT ; 0 not allowed, 6 digit maximum
+Value syntax: %x31-39 0*5DIGIT ; 0 not allowed, 6 digit maximum

-Description: RCPTMAX specifies the maximum number of transactions
+Description: MAILMAX specifies the maximum number of transactions
  (MAIL FROM commands) the SMTP will accept in a single session. The
  count includes all MAIL FROM commands, regardless of whether they
  succeed or fail.
@@ -218,7 +219,7 @@

  Name: RCPTMAX

-Value syntax:  %x30-39 0*5DIGIT ; 0 not allowed, 6 digit maximum
+Value syntax:  %x31-39 0*5DIGIT ; 0 not allowed, 6 digit maximum

  Description: RCPTMAX specifies the maximum number of RCPT TO commands
  the SMTP will accept in a single transaction. It is not a limit
@@ -233,9 +234,9 @@

  Name: RCPTDOMAINMAX

-Value syntax:  %x30-39 0*5DIGIT ; 0 not allowed, 6 digit maximum
+Value syntax:  %x31-39 0*5DIGIT ; 0 not allowed, 6 digit maximum

-Description: RCPTMAX specifies the maximum number of different domains
+Description: RCPTDOMAINMAX specifies the maximum number of different domains
  that can appear in a recipient (RCPT TO) address within a single
  SMTP session. This limit is imposed by some servers that bind to
  a specific internal delivery mechanism on receipt of the first
@@ -243,6 +244,20 @@

  Security Considerations: See {{Seccons}}

+GREYLISTING Limit
+-------------
+
+Name: GREYLISTING
+
+Value syntax:  %x31-39 0*5DIGIT ; 0 not allowed, 6 digit maximum
+
+Description: GREYLISTING specifies the minimum number of seconds
+that a client should wait before retrying to submit the same message.
+The presence of this limit implies that the client MAY receive a
+transient 4xx response.  See {{GREYLISTING}}
+
+Security Considerations: See {{Seccons}}
+
  Security Considerations            {#Seccons}
  =======================