Just to jump in with my $0.02 here:
On 9/19/07, ROGERS Richard <Richard.Rogers@???> wrote:
> I'd love to reject wherever there is no rDNS, but I think there would be
> too many false positives involved. (I know that some here take the view
> that this is not a false positive, but our users are likely to regard a
> message that is not spam, and does not originate from a known source of
> spam, as one that should be delivered). That's not to say it can't be
> given a score in SpamAssassin though.
I agree, no rDNS would be a good rejection criterion if we could
assume everyone was following the standards, but I believe the
business reality prevents most of us from rejecting on that basis.
> On a slightly related issue - I have an idea that the hit rate from RBLs
> (we prinicpally use MAPS+ and Spamhaus) may not be as high is it was a
> couple of months ago. Does anyone else have the same feeling (or any
> data to confirm/deny)?
>
We use primarily Spamhaus PBL (too many false positives with zen),
which is far from complete. I've recently noticed a glut of ISPs with
.br, .pl and .dk TLDs which are infested with zombies and compromised
hosts, so many that they were eating up connections and we had to
block them by domain. I think this is why RBLs are getting fewer hits,
as many of these ISPs have no policy and it takes a while for the RBL
maintainers to catch up manually.
SPF would be a good solution for that, again wishfully assuming that
everyone followed the standards and understood the importance of them.
--
Regards,
Darton Williams
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