I don’t think I understand the question.
You’d generally not name the name server for each virtual server. You’d configure two name servers in one zone (the Virtualmin server plus a secondary configured according to our documentation: How to Configure Secondary DNS | Virtualmin — Open Source Web Hosting Control Panel).
But, the key element that I think is probably missing is the glue records at your registrar, which Virtualmin can’t do anything about.
OK, looking at your domain, here’s what I see:
$ host myvapingright.com
myvapingright.com has address 104.21.38.209
myvapingright.com has address 172.67.138.148
myvapingright.com has IPv6 address 2606:4700:3033::6815:26d1
myvapingright.com has IPv6 address 2606:4700:3030::ac43:8a94
myvapingright.com mail is handled by 5 _dc-mx.91d9c04063d5.myvapingright.com.
That’s Cloudflare addresses and a mail service I don’t recognize (but also not your Virtualmin server).
$ whois myvapingright.com|grep Name
Domain Name: MYVAPINGRIGHT.COM
Registrar: NameCheap, Inc.
Name Server: dax.ns.cloudflare.com
Name Server: nelci.ns.cloudflare.com
Your Virtualmin server is not the authoritative DNS server for your zone, which is fine, but you need to make sure things are right with Cloudflare DNS. And you should let Virtualmin know it is not responsible for local DNS management (Virtualmin Pro can manage DNS at Cloudflare in the Cloud DNS providers section if you want to do that).
But, your mail name is misconfigured at Cloudflare, currently:
$ host mail.myvapingright.com
mail.myvapingright.com has address 104.21.38.209
mail.myvapingright.com has address 172.67.138.148
mail.myvapingright.com has IPv6 address 2606:4700:3030::ac43:8a94
mail.myvapingright.com has IPv6 address 2606:4700:3033::6815:26d1
Cloudflare doesn’t proxy IMAP/POP3/SMTP, so you can’t use Cloudflare IP addresses for your mail.domain.tld names that you expect mail clients to talk to. If you want to send and receive mail, you need to talk to the Virtualmin server, not a proxy that doesn’t proxy mail protocols (Cloudflare in this case).
So, make the A record for mail.yourdomain.tld not proxied, and give it the Virtualmin address. If you also want to receive mail, you probably need to set the MX record to mail.yourdomain.tld, as well (though maybe the paid plans at Cloudflare have some kind of relay service, I don’t know).