On Sun, Mar 03, 2024 at 05:23:22PM +0000, Gareth Evans via mailop wrote:
(Error NOERROR looking up 23.24.6.165 PTR,Error Error NXDOMAIN
looking up 23-24-6-165-static.hfc.comcastbusiness.net. A looking up
23-24-6-165-static.hfc.comcastbusiness.net. A,Error Error NXDOMAIN
looking up 23-24-6-165-static.hfc.comcastbusiness.net. AAAA looking up
23-24-6-165-static.hfc.comcastbusiness.net. AAAA);
On Sun 03/03/2024 at 18:55, Andy Smith via mailop <mailop@mailop.org> wrote:
Like it says, 23-24-6-165-static.hfc.comcastbusiness.net is an
NXDOMAIn for both A and AAAA, so that's not going to get very far.
On 04.03.24 00:17, Gareth Evans via mailop wrote:
Thanks, I understand that.
Given:
Received: from atlas.bondproducts.com (unknown [23.24.6.165])
by mx6.messagingengine.com (Postfix) with ESMTP id ...
Here, atlas is the HELO/EHLO name the IP 23.24.6.165 introduced itself as.
The fcrdns lookup was unsuccessful, hence the "unknown"
Received: from users.shellworld.net (users.shellworld.net [50.116.47.71])
by atlas.bondproducts.com (Postfix) with ESMTP id ...
atlas is (I think) a relay in this context.
yes, it put its name into Received: header.
$ dig -x 23.24.6.165
;; ANSWER SECTION:
165.6.24.23.in-addr.arpa. 3600 IN PTR
23-24-6-165-static.hfc.comcastbusiness.net.
What I am really asking is, if
23-24-6-165-static.hfc.comcastbusiness.net
actually resolved to 23.24.6.165 (same IP as atlas...), would delivery be
expected to succeed, or does the host in the PTR also have to be
atlas.bondproducts.com?
There are servers that refuse IP addresses without proper fcrdns, they
would probably accept the e-mail.
There are also servers (and iirc even dnsbl) that refuse IP addresses with
generic-looking DNS name. This looks like generic, so they would reject it:
23-24-6-165-static.hfc.comcastbusiness.net.
If the rdns would be atlas.bondproducts.com, the IP 23.24.6.165 would
apparently have much less delivery issues.
I think the latter is what Marco meant by "proper PTR", and there may indeed be
no convention.
The servers involved are not mine. I bumped into this issue after
discovering an invalid SPF record at shellworld.net. I've never dealt
with relays, or PTR records that don't correspond directly to sending
hosts, so wondered what should happen in those circumstances if the IP
actually resolved.
--
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