SMTP 521 reply code

[Alain Durand <Alain.Durand@xxxxxxxx>]

Many thanks to all of you for your comments and hints to
improve my deficient grammar! [english is not my mother tongue :-) ] 

john Gardiner Myers <jgm+@cmu.edu>
----------------------------------
>William "Chops" Westfield <billw@cisco.com> writes:
>> I though the "preferred" solution for this was to have your DNS system
>> loaded up with MX records for your non-mail host that pointed at a host
>> with the "same" userbase.
>
>That requires that you also configure your mail host to know that it
>is handling the local-parts for all those non-mail hosts.  This can
>turn out to be impractical to administer in the general case.

This is the main point behind the 521 reply code idea. Of course, we
might do that with MX records, but that's a lot of work on a large site.
Besides, I'm still wondering about the meaning of addresses like:
	durand@toaster.inria.fr 

>The 521 response is given in the initial greeting.  I've suggested the
>proposal be changed so that the SMTP server shuts down the connection
>at that point, as is done for the 421 initial greeting.  The client
>then never gets a chance to say HELO.

I agree that this will be the best thing to do. The problem is that 
current implementations of sendmail want to say "QUIT" even if the
greeting message is "521 ....". 
If the host server drops the connection right after the initial 521 
greeting, sendmail treats this as a transcient error
and queues the mail for later delivery, which is the contrary
of what we try to achieve!

A suggestion is to say that a SMTP server MAY close the connection
affter issuing the "521 ..." greeting.

	- Alain Durand.

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