[69328] in North American Network Operators' Group
Re: Mailserver requirements
daemon@ATHENA.MIT.EDU (Jim Segrave)
Tue Apr 6 06:16:59 2004
Date: Tue, 6 Apr 2004 12:15:59 +0200
From: Jim Segrave <jes@nl.demon.net>
To: NANOG <nanog@nanog.org>
Reply-To: jes@nl.demon.net
Mail-Followup-To: Jim Segrave <jes@nl.demon.net>,
NANOG <nanog@nanog.org>
In-Reply-To: <20040406005509.A14237@homebase.cluenet.de>
Errors-To: owner-nanog-outgoing@merit.edu
On Tue 06 Apr 2004 (00:55 +0200), Daniel Roesen wrote:
>
> On Mon, Apr 05, 2004 at 11:53:15PM +0200, Arnold Nipper wrote:
> > >>of course this server does have a reverse mapping. But this reverse
> > >>mapped doamin does not have an MX record.
> > >
> > > Does it have an A RR?
> >
> > It also does have an A RR. And the forward mapping does also match the
> > IP address.
>
> OK, so the check is even broken in what it probably tries to verify...
> that the reverse-domain of the sender IP would (possibly) be able to
> receive mail (bounces).
Why would bounces go to an outbound mail server? They go to the
envelope sender, which might well be in a different domain. The check
is simply ill-advised and will cause the system running such a check
to have cut itself off from a large number of legitimate sources of email
> > > Anyway... it's a heuristic which definately does give false positives.
> > > The only requirement is that IF a domain/host accepts mail there MUST be
> > > a postmaster@ address.
> >
> > In this case the host *sends* mail ...
>
> Sure. I was discussing the requirements for domains regarding email.
>
> In this specific case, "domain" being the domain of the PTR of the
> sending MTA host.
If you are sending mail via a virtual ISP, then the 'real' ISP's mail
servers will probably be in a different domain than your virtual ISP
which might be a different domain than your account. Checking mail
reachability of an outbound MTA is simply absurd.
--
Jim Segrave jes@nl.demon.net
