Author: Alan J. Flavell Date: To: Exim users list Subject: Re: [exim] Spammers keep lists of MX long after DNS MX has been
deleted
On Mon, 22 Aug 2005, Alun wrote:
> "Alan J. Flavell" <a.flavell@???> said, in message
> Pine.LNX.4.62.0508220800080.27520@???:
>
> > This might be well known, but we've noticed that spammers must be
> > keeping lists of old MX entries, long after we've considered the
> > associated email domains to be obsolete and have deleted the MX
> > entries in the DNS.
>
> I noticed similar a couple of years back. If I recall, it wasn't
> even the MX records that were being cached, but the IPs they
> expanded to.
That's more than plausible, and quite compatible with what we observe.
Thanks for the correction.
> At the time, I idly wondered whether there would be anything to be
> gained in changing the IPs of our external facing mail servers every
> year.
;-)
We haven't done that - neither deliberately nor inadvertently - so I
can't comment on that either. It's a thought!
