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Re: RFC2821bis-01 Issue 4: Client actions on receipt of 4yz and 5yz codes

2007-03-30 01:29:57
On 2007-03-29 08:40:22 -0400, John C Klensin wrote:
--On Thursday, 29 March, 2007 07:19 -0400 Hector Santos
<hsantos(_at_)santronics(_dot_)com> wrote:
John C Klensin wrote:
In RFC 2821bis-01, Section 4.2.1 (Reply Code Severities and
Theory), in the description of the generic 4yz category,
Question: Should the 5yz description  be changed to use
"SHOULD NOT".   If not, is "SHOULD" in the 4yz description

In my view, removing the subjective considerations and
focusing on what is the technical automated state machine
consideration helps.

Unless you have a wider definition of "state machine" than I have, I
disagree strongly with that. There are considerations outside of the
SMTP protocol proper (especially queuing and retry) which are necessary
for robust delivery of e-mail and which should be documented. They might
be moved to a companion document, but that would be a larger change than
is obviously intended here.

For 4yz, I think SHOULD is ok, but I think MAY is better when
reworded more appropriately. SHOULD implies some enforcement,
when in fact, the is not required to do so.

I don't see a requirement for enforcement in either the 2821
definition of "SHOULD" or in the 2119 definition.  Where do you
get this?

Maybe "enforcement" is too strong a word, but my understanding of the
2119 definition 

3. SHOULD   This word, or the adjective "RECOMMENDED", mean that there
   may exist valid reasons in particular circumstances to ignore a
   particular item, but the full implications must be understood and
   carefully weighed before choosing a different course.

is that you should have a really good reason to ignore this item 
and that this should be the exception and not the rule.

So if the RFC says that the client "SHOULD retry" after a 4xy response
that is a lot stronger than if it says it "MAY retry". 


   _  | Peter J. Holzer    | I know I'd be respectful of a pirate 
|_|_) | Sysadmin WSR       | with an emu on his shoulder.
| |   | hjp(_at_)hjp(_dot_)at         |
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