Giving something a fancy name to make it "new" I guess. Checking that the
reverse matches what the peer claims as an FQDN is a longstanding
practice.
On Tue, 18 Nov 2025, lejeczek via Postfix-users wrote:
Certainly no PTR record for my IP but - do ISPes even do that - for us at
home or in general customers anywhere, as opposed to co-located/hosted stuff?
(or registrars who can, who do reverse too?)
I'm not going to move home there to such ISP's area, but sincere question,
just out of curiosity.
I'm in Tacoma WA USA and the City owns a /16, half of which they give to
their ISP franchisee to play with. If you get business service (pay for
fixed addresses) the ISP will set the reverse DNS for you.
Doesn't mean they do a good job of running the infrastructure: they
impersonate the City's class B rather than running 128 class Cs. This
breaks e.g. qname minimization, and causes strange transient attributions
such as that they ARE the City's class B in e.g. at least some (older)
versions of BIND.
There are other things which look bad, like the fact that I'm standing in
a "killing field" of former customers whose reverse DNS they have failed
to remove.
This in turn causes problems with reputation services. As a DNS expert /
internet plumber / threat hunter it's been interesting being on the other
side. I was banned from posting to this least for about a year (couldn't
unnnnsubscr1be either) after the list moved to sys4 because they used the
Abusix reputation service. Seemed like a protection racket to me:
http://athena.m3047.net/pub/soe/abusix-spam-backstory.html
The big irony is that I can't send email to the City itself, because they
use pphosted (Proofpoint) and they can't be arsed to make the ISP stop
fraudulently impersonating them or lean on Proofpoint to make an
exception. But Proofpoint won't talk to me, so who really knows? There is
something beyond ironic with the notion that Proofpoint's (ab)users
blithely send email to domains that they block email from.
What I do know is that these reputation services' share of their total
addressable market (TAM) is quite small. Google, Microsoft, Amazon have no
problems with me, as well as pretty much every independent small operator.
--
Fred Morris, internet plumber
_______________________________________________
Postfix-users mailing list -- [email protected]
To unsubscribe send an email to [email protected]
