On Sat 26/Sep/2020 23:19:33 +0200 Simon Hobson wrote:
> Marjorie Roome via Dng <dng@???> wrote:
>
>> I also end up rejecting a lot of spam because it lacks a reverse hostname (it's easily the largest category).
>> So it's not just a few such as ntlworld and gmx that check this.
>
> IIRC the specific complaint wasn't that they checked for rDNS, but that they matched it against the domain of the sender. That makes no sense at all, it prevents running more than one domain on one mail server.


Why would it? A configurable mail server, Courier-MTA for example, lets you
use multiple domains and multiple IPs. However, unless you send many thousands
messages per day, I would suggest to stick to one domain name and one outgoing
IP address. And it is key to get an IP address without poorly reputed
neighbors —check talosintelligence.com.

Hosting additional domains is as easy as publishing an MX record. You can also
publish DKIM and SPF records so as to produce DMARC-aligned authentication for
any hosted domain. Users won't notice any difference.

As Mark said, it does make deliverability easier to send via one established
SMTP server.


> I also use lack of rDNS as a check. I also check it for obvious misconfigurations like (from memory) : it's an IP literal (not allowed by RFC),


Currently, the RFC allows anything in the HELO name.



jm2c
Ale
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