I have Virtualmin GPL 6.12 and Webmin 1.955 installed over Centos 7. Most of the configured email accounts on this server work great and also for other domains configured over this server are working well. ( I am able to send and receive emails from Gmail, Yahoo and outlook)
But there are certain accounts like email@example.com, firstname.lastname@example.org, email@example.com, such account does not work. By does not work I mean, I am able to send emails in the same domain but when I try to send email to Gmail or Outlook I receive a bounce back " Undelivered Mail Returned to Sender" with the error of DMARC policy.
However, I am able to send email from other email accounts for same domain without any DMARC failures as these are already configured in the DNS.
I have also noticed that every email account configured on this server with the rDNS configured as that of the domain, are delivering/receiving emails flawlessly, the issue is only with the other domains configured on this server.
Is there anything I am missing here.