== Are there less anti-spam DNS blocklists than there used to be?

Once upon a time, back when I paid a fair amount of attention to
anti-spam stuff, there were quite a lot of DNS blocklists. Some had
good reputations and some were more colourful, some were conservative
and slow-moving while others were much more aggressive and fast to
block, but there were any number of them that many people looked
at. I did enough in this area that I wrote a script to look up IP(s)
in all of the worthwhile DNSBLs that I knew about.

Over the past few years I've been steadily removing DNSBL after DNSBL
from this script (and sometimes from the mailer configuration on my
office workstation), most recently [[NJABL http://www.njabl.org/]].  And
it doesn't seem like new DNSBLs are replacing them in a transfer of the
guard from the tired to the new and eager; instead the collection of
worthwhile DNSBLs just seems to have been diminishing.

(I confirmed this with someone I know who is more in touch with email
anti-spam than I am these days; his view was that it was basically down
to Spamhaus (and its data sources).  I'm still slightly broader than
that, as I sometimes look at [[SURBL http://www.surbl.org/]] for spam
website names.)

Now I'll admit that this may be somewhat illusory in that I'm not
looking in the right place for modern DNSBL discussions; after all, one
of the reasons I stopped paying attention to the field is that my usual
information sources turned into sewers. I have some indications that
other sites out there use additional DNSBLs (although none that I really
consider worthwhile ones and none that are all that new). 

I have some theories on what this diminishment of DNSBLs may mean but
I'll save them for another entry (partly because I want to think about
them some more).