On Sun, May 03, 2026 at 02:11:32AM +0000, Miles Fidelman via mailop wrote:
> I'm busily migrating an old server to a new one, and in the process
> losing a bunch of IP address ... so now I'll be sending mail for
> multiple domains out of the same IP address.
>
> It's been a while, and what with DKIM & DMARC and all, I've lost track
> of the details. So I wonder if someone might offer some quick advice
> on configuring one server as the outgoing server for multiple domains,
> all behind a single IP.
>
> Specifically, since I need to set up a PTR to point to the server, any
> suggestions on how to set up the DNS records for other outgoing
> domains - so that DMARC works properly?
There simplest, most natural approach is:
; MX host
;
$ORIGIN host.example.
some IN A 192.0.2.1
some IN AAAA 2001:db8::1
;
$ORIGIN 192.in-addr.arpa.
1 IN PTR some.host.example.
;
$ORIGIN 0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa.
1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0 IN PTR some.host.example.
; MX-hosted domains
;
foo.example. IN MX 0 some.host.example.
bar.example. IN MX 0 some.host.example.
baz.example. IN MX 0 some.host.example.
...
--
Viktor. 🇺🇦 Слава Україні!
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