Re: [exim] SMTP protocol violation?

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Author: Matthew Byng-Maddick
Date:  
To: Claus Assmann, exim users
CC: 
Subject: Re: [exim] SMTP protocol violation?
On Fri, Jul 08, 2005 at 09:19:18AM -0700, Claus Assmann wrote:
> I'm curious: Can someone please point out which part of RFC 2821
> is violated here?
> 4.3.1 Sequencing Overview
> ...
>    One important reply is the connection greeting.  Normally, a receiver
>    will send a 220 "Service ready" reply when the connection is
>    completed.  The sender SHOULD wait for this greeting message before
>    sending any commands.

>
> This is just a SHOULD not a MUST.


The problem is that RFC2821 also says (S2.1):
The server responds to each command with a reply; replies may
indicate that the command was accepted, that additional commands are
expected, or that a temporary or permanent error condition exists.
Commands specifying the sender or recipients may include server-
permitted SMTP service extension requests as discussed in section
2.2. The dialog is purposely lock-step, one-at-a-time, although this
can be modified by mutually-agreed extension requests such as command
pipelining [13].

The important sentence in that is: "The dialog is purposely lock-step". So
2821 is slightly self-contradictory, this is not news. (note that the command
in question is an effective null command of connection opening).

If you see violations of SHOULDs, it's also always worth asking what the
good reason is.

Cheers

MBM

-- 
Matthew Byng-Maddick          <mbm@???>           http://colondot.net/
                      (Please use this address to reply)