You are discussing about DNSBLs but not being specific.
I'm specific in that all the DNSBL's blacklist IP addresses or blocks.
And that in today's world many, many companies share sets of mail
servers with many other companies and individuals.
I'll let others sell you this Hoover.
No sale necessary. I continue to recognize the overall expediency of the
DNSBL kluge, and continue to use it myself.
I wouldn't buy a Hoover anyway. I'm a Kirby kind of guy. I have a 1969
Dual Sanitronic 80 that my grandmother gave our family new, as a
Christmas gift.
https://c1.staticflickr.com/7/6071/6056367963_f06f08c7f6_z.jpg
A 1976 Classic III that I picked up at a garage sale.
http://cdn3.volusion.com/maxg3.xen6j/v/vspfiles/photos/KirbyClassicIII-4.jpg?1329982229
And a really cool model 516, manufactured in 1956 that someone had set
out on the curb for garbage pickup, which I rescued and restored.
http://www.1377731.com/kirby/516_5.jpg
All stock photos. Not mine.
-Steve