Re: DSN relay host - ReadList.com


DSN relay host
\ Marco Favero (8 May 2008)
. \ (Wietse Venema) (8 May 2008)
. . \ Marco Favero (8 May 2008)
. . . \ (Wietse Venema) (8 May 2008)
. . . . \ Marco Favero (9 May 2008)
. . . . . \ (Wietse Venema) (9 May 2008)

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Subject:	Re: DSN relay host
Group:	Postfix-users
From:	(Wietse Venema)
Date:	9 May 2008

Marco Favero:
> Wietse Venema:
> > Marco Favero:
> >> Wietse Venema:
> >>> Marco Favero:
> >>>> Hi all,
> >>>> just a question. Could I configure postfix to set a relay host only for
> >>>> server-made DSN?
> >>>> "relayhost" is for all mail.
> >>> What problem are you trying to solve? Please do not describe your
> >>> solution (the DSN relay).
> >> First I thank you very much for the answer.
> >> Ok, I try to explain my problem.
> >>
> >> I have several postfix servers which are MX for my local domains, routed
> >> internally through transport table.
> >>
> >> I would like to deny my MX postfix servers to contact Internet directly
> >> to send DSN mails. I would like to use only another smtp server for
> >> this scope.
> >
> > Why are the MX servers sending (non-)delivery status notifications?
> > Is it because they try to deliver mail for non-existent email addresses?
> >
> > In that case, the MX servers must be configured to that they do not
> > accept such email in the first place.
> >
> > Wietse
>
> We already check recipient access (sending "550" to not existent) and
> non existent domain. I see that MX sometimes try to send DSN requested
> by ESMTP, in particular to trace success delivery. Our next hop does not
> support ESMTP (for now...), these DSN start from MX servers.
> Yes, I can disable ehlo feature.

Then you should use smtpd_discard_ehlo_keywords. Fix the problem
at its origin.

> Really I try to ask how to configure a DSN relay host to prevent all
> possible situation like described above and have a kind of DSN server.

That is the wrong question. I will not answer it.

Wietse