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