Virtualmin behind NAT, prevent private IP publishing in BIND etc

Hi, I'm running virtualmin behind NAT and it works just fine. What bothers me is that since it's behind NAT both the public and private IP are published.

If i check a domain on the host with intodns.com it looks like:

For web01.domain.se the parent reported: ['194.218.xxx.xxx'] and your nameservers reported: ['194.218.xxx.xxx', '10.15.19.22']

Private IP shows up in SPF records and such as well.

How can I prevent the private IP from being published like this?

Thanks.