Mailserver requirements

Tue Apr 6 10:15:59 UTC 2004

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 at nl.demon.net