[Mimedefang] Default SMTP code and dsn for filter_recipient() not standard compliant?

Franz Schwartau franz at electromail.org
Thu Jun 27 10:16:02 EDT 2013

Hi David!

On Fri, Jun 21, 2013 at 08:04:47AM -0400, David F. Skoll wrote:
> On Fri, 21 Jun 2013 11:51:58 +0200
> Franz Schwartau <franz at electromail.org> wrote:
> > After doing some tests I was wondering, why mimedefang returns
> > 554 5.7.1 after a RCPT TO.
> That's the default and it seemed reasonable to me at the time.
> Although the RFC doesn't list 554 as a "usual" response to RCPT, it
> does say:
>    "SMTP clients SHOULD, when possible, interpret only the first digit
>     of the reply and MUST be prepared to deal with unrecognized reply
>     codes by interpreting the first digit only."
> so I think the distinction between 550 and 554 is mostly of academic
> interest.

Maybe it's academic... I don't think academic discussions are needless. :-)

Let's put it in another frame: The RFC 5321 (unfortunately) doesn't
answer every question whether it's right or wrong. The paragraph you stated
is about the a SMTP client. mimedefang is on the server side. The server should
"speak" correct SMTP. IMHO it's a question of style to return 554 or 550 after
a RCPT TO. 554 doesn't really make sense here.

Since I'm not a native speaker some terms I use are probably unusual
or even wrong. But you'll understand what I'm trying to say -
hopefully. There is an analogy to SMTP: Returning 554 after a RCPT
TO isn't wrong and a SMTP client should focus on the 5 at the
beginning, but it's unusual and a bad style.

If you are interested I can provide patches for mimedefang to return sensible

	Best regards

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