From: Keld Jørn Simonsen (kelddkuug.dk)
Date: Tue Jul 14 2009 - 06:10:07 CDT

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On Tue, Jul 14, 2009 at 06:37:30AM -0400, Wietse Venema wrote:
> Keld Jørn Simonsen:
> > On Mon, Jul 13, 2009 at 06:58:28PM -0400, Wietse Venema wrote:
> > > Keld J?rn Simonsen:
> > > > Is there a way to disambiguate between DNS timeouts and DNS errors,
> > > > and discard the latter?
> > >
> > > Postfix is only the messenger of the bad news. When the server
> > > responds, Postfix acts accordingly. When the server does not
> > > reply, Postfix assumes that this is a temporary error, because
> > > assuming otherwise would cause a lot of mail to fail.
> >
> > Yes, but there are two types of bad news: one is that we do not know if
> > everything is fine, timeout, and the other that we positively know
> > something is wrong. I understand that in both cases postfix gives a 450
> > code, and that there is no way in postfix to change this code. Is that so?
>
> Some people are thick enough that they need everything spelled out.

Oh, you mean me? No, I am bright, so that can't be:-)
But I see that you did say that it reacts differnetly on timeouts and
error codes. Still there is something that I do not understand, and
which gives me problems, see below.

> OK, here goes:
>
> 1) The server replies with "good news". Postfix replies with good news.
>
> 2) The server replies with "bad news". Postfix replies with 5xx.
>
> 3) No server reply. Postfix replies with 4xx.
>
> Is this finally clear?

Yes, thanks. But it seems that my postfix reacts differently on
a NXDOMAIN and SVRFAIL, although they both should lead to 5xx error codes.
That is why I am so thick to not understand.

From my previous post:

Jul 14 00:11:58 rap postfix/smtpd[1054]: NOQUEUE: reject: RCPT from rap.rap.dk[127.0.0.1]: 450 4.1.8 <jetskocserver30.reverya.com>: Sender address +rejected: Domain not found; from=<jetskocserver30.reverya.com> to=<keldlocalhost> proto=ESMTP helo=<rap.rap.dk> Jul 14 00:11:58 rap postfix/smtpd[1054]: +> rap.rap.dk[127.0.0.1]: 450 4.1.8 <jetskocserver30.reverya.com>: Sender address rejected: Domain not found

here there is a 450 response to a name server error. You said above:

> 2) The server replies with "bad news". Postfix replies with 5xx.

5xx is not 450, so what is happening?

And thanks for you patience with me.

Best regards
keld

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