What you have to do at this stage is to repeat the DNS documents supplied to you by postal on the DNS zone of your domain registrar. nano /opt/postal/config/postal.yml Just scroll down and locate the option for DNS. Then substitute many of the sample hostnames with your individual hostname. It https://directadmininstall00009.blogdemls.com/25930234/helping-the-others-realize-the-advantages-of-whmcs-install