www.nac.net has no MX records.
Question and response
Question
dig www.nac.net. MX
Answer
The response has no answer records.
Authority
nac.net. 3600 SOA ns1.nac.net. dnsadmin.nac.net. 2025062702 10800 900 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0