Reverse DNS PTR Record not resolving correctly

DKIMM, DMARC, SPF records are all passing on mxtoolbox and mail-tester.com, but PTR rDNS is failing. I am using cloudflare DNS

Setup:

• server hostname: mx.example.com
• a record mailer.example.com my.real.public.ip DNS only, not proxied
• a record mx.example.com my.real.public.ip DNS only, not proxied
• MX record mailer.example.com 30
• ptr record my.real.public.ip mx.example.com
• ptr record my.real.public.ip mailer.example.com
• txt record _dmarc.mailer with the correct content
• txt record dkim._domainkey.mailer with correct content
• txt record mailer content: v=spf1 mx ~all

When I run a mail test from mail-tester.com I get an error:

Your IP address my.real.public.ip is associated with the domain 3(NXDOMAIN).
Nevertheless your message appears to be sent from mx.example.com.

You may want to change your pointer (PTR type) DNS record and the host name of your server to the same value.

Here are the tested values for this check:
IP: my.real.public.ip
HELO: mx.example.com
rDNS: 3(NXDOMAIN)

On Linux CLI I run host <my.real.public.ip>

Host ip.public.real.my.in-addr.arpa. not found: 3(NXDOMAIN)

When I run dig -x my.real.public.ip:

; <<>> DiG 9.11.13-RedHat-9.11.13-6.el8_2.1 <<>> -x my.real.public.ip
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 20183
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;ip.public.real.my.in-addr.arpa.    IN      PTR

;; Query time: 0 msec
;; SERVER: 10.0.0.1#53(10.0.0.1)
;; WHEN: Wed Oct 21 09:31:55 MDT 2020
;; MSG SIZE  rcvd: 55

Solution 1:

You need to have your ISP create the PTR record