Arrogant RBL list maintainers

Rich Kulawiec rsk at
Tue Dec 15 21:33:11 CST 2009

[ Note: you're not talking about the RBL.  You're talking about
a DNSBL or RHSBL, which are generic terms.  The RBL is a specific
DNSBL and, as far as I know, does not have a listing policy related
to this discussion. ]

On Wed, Dec 09, 2009 at 03:18:47PM +0000, Sven Olaf Kamphuis wrote:
> because they just assume that working, rfc compliant, reverse dns that
> just-so-happens to be automatically generated would indicate dynamic ip
> space.. 

It has long since become a best practice in mail server operations to
pre-emptively blacklist all such space on sight.  This is common knowledge
among everyone who's kept pace with the field, and is an entirely
appropriate reaction to what's sometimes called "the rise of the zombies".

Real mail servers have non-generic, matching forward and reverse DNS
with real hostnames.  The farther hostnames move from that, the more
problems can be expected.

Nobody particularly likes this, as the work necessary in compiling such
lists is onerous.  But it is one of the most effective (in terms of FP and
FN rates as well as resource costs) anti-spam measures available.


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