Reverse DNS is not a valid Hostname

Support and Discussion DNS Server
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1

Hi there,

I am running a DigitalOcean 1-click app setup with Ubuntu and CyberPanel.
I went through all the proper steps to make sure everything is configured, I named my droplet as my domain name to make sure the ptr record is created but now I have no clue what to do. The mailer-test website tells me I have a 10/10 score BUT my mail lands to spam for Gmail, Apple as well as Outlook and on MXToolBox I found a problem:

SMTP Valid Hostname Reverse DNS is not a valid Hostname

2

hi

Developer recommended to do clean/fresh manual install using ubuntu 20.04

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most of provider only give the ptr by request. please contact your provider

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3

No need, figured out the problem. I had to change the droplet name of my server from mydomain.com to mail.mydomain.com which in turn generates a ptr now all my mail lands in the inbox :slight_smile:

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4

Reverse DNS is usually done at hosting provider’s end for the IP address assigned to your server.

Maybe this can help: How do I create a reverse DNS (PTR) Record | DigitalOcean

5

all sorted out, i just had to change the name of the droplet from domain.com to mail.domain.com and now everything works, emails dont go to spam! :slight_smile:

6

there are many reason email goes to spam
include the destination mail server
e.g gmail have different policy with outlook,yahoo,aol etc
that included:

  1. domain name
  2. domain ip (based on RBL public blacklist and local blacklist)
  3. domain hostname server
  4. body content
  5. mail-header (beside number 1,2,3):
  • dkim
  • spf
  • dmarc policy
  1. local policy ( like i mention above )
    etc

sometimes we dont get spam mark here, but will get marked spam there…

1 Like
7

Hey p4trk,

I’m having the same issue. My Cyper Panel is hosted on Linode. I edited my rDNS to mail.domain.com but I still have issues. Can you explain with a little more detail how you resolved this issue. All in all my DNS settings are golden. Everything checks out.

8

Make sure you check…
sudo nano /etc/hosts
sudo nano /etc/hostname
sudo nano /etc/postfix/main.cf
… and make sure that your address matches in there as well!