It appears that Sam Varshavchik <mrsam(_at_)courier-mta(_dot_)com> said:
1) That public DNSBL usage are reasonably popular. Everyone from Microsoft
(Outlook/Office365) to various hosting providers (1and1/godaddy) to large
infrastructure providers (GTT) uses public DNSBLs.
Of course. Big providers all have paid subscriptions that give then higher
query rates and often extra data.
2) That their golden age was in the 1990s. These days they'll mostly block
an occasional spam, but the don't amount to more than a rounding error of
the massive crapton that's flying everywhere.
Your mail must be very different from mine. The handful of DNSBLs I use block
the majority
of the incoming mail I get and from looking at the logs, the error rate is very
low.
Large mail providers use DNSLBLs as part of their scoring systems. I use a
handful to do
simple blocking that I trust not to overblock (Spamhaus, Invaluement) but large
systems have
a lot more complicated mail flows than we do.
R's,
John
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