Re: PTR record for mail server
On Sat, 3 Jun 2023 08:29:36 +0000
Bonno Bloksma <b.bloksma@tio.nl> wrote:
> Hi Andy,
>
> [....]
>
> >> My understanding is that as we are sending email from our own
> >> domain e.g "example.com" its complaining because the PTR is
> >> ovh.net not example.com?
>
> > No, there is no requirement for the PTR record to match the From:
> > address of the email. They just want it to not look like a generic
> > OVH VPS.
>
> Depends on how you define "requirement". For years is has been
> practice on mailservers to deny mail coming from a dynamic ip number
> because it is probably an infected machine sending spam/malware
> mails. Dynamic being defines as not having a proper PTR record having
> the same name as the fqdn the mailserver identifies itself with. So
> the name of the host itself is not relevant but the name the
> mailserver uses in the HELE/EHLO statement. That needs to be the same
> name as what the PTR record points to.
>
> I remember this being a "requitement" when I was hosting my own
> mailserver and spam/walware filter over 5 years ago.
>
The requirement is that a mail sender IP address returns (in public
DNS) a PTR string which resolves, again in public DNS, to an A record
with the same IP address. There need be no relationship to any domain
handled by the receiving server.
It is common for multiple domains to be handled by one server, on one
IP address, which is the address pointed to by multiple MX records. The
PTR can only match at most one of them.
My ISP would allow me to change the PTR if I wished, but as I have
multiple domains, there's no point. As it is, my PTR is my reference on
my ISP's domain, and my ISP maintains an A record for that domain which
points back to the address. It works.
--
Joe
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