There are 2 methods to do that,

1. You can point out domain using “A” record added to DNS without changing the nameservers. In this method you have to add mail certificate to DNS.
2. In other method, you can change the nameservers to Cyberpanel and you don’t want to add mail certificate to DNS. You can manage all mail certificate inside the Cyberpanel.

I use the first method in that video. https://www.minextuts.com/free-email-marketing-smtp-linux-mail-server/