How to create subdomain


I am attempting to set-up a subdomain on the domain droplet with the NGINX server on Ubuntu 20.04 to implement a DMARC record for my outgoing Gmail through a WordPress SMTP plugin with preconfigured SPF & DKIM records. I did some research and found the following tutorial but unable to complete Step1 creating an “A” record with an error message “Name is not allowed to have an underscore in it”. Can someone please assist me by providing a link to a step by step instructions on accomplishing this task.



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Hi, It looks like you try to create new subdomain _dmarc for your domain. So, the message you get is 100% OK, domain name cannot contain underscore sign. If you want to create DMARC record, you need to add TXT record to your domain (or subdomain) that you use as email sender.

Example Let’s assume your domain is, and your droplet public IP address is So, the records of your domain could look like that:

record type            host                 content
   TXT      v=DMARC1;p=none;etc.