mx.iconz.co.nz has no CNAME records.
Question and response
Question
dig mx.iconz.co.nz. NS
Answer
The response has no answer records.
Authority
iconz.co.nz. 3600 SOA ns1.iconz.co.nz. soa.iconz.co.nz. 2026030501 10800 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0