Hello Support,
We are facing issue while adding domain in Mail server. We are getting the error as in the screen-shot.

Os : CentOS Linux release 7.9.2009
Panel : 6.8.8
Mail Server version : Mail Server 4.1
I have checked the DNS records , they are working. I have tried it from server terminal and it also successfully resolving.
Please help me to resolve this case. Let us know if you need additional details to check this further.