smtp.snap.net.nz has no CNAME records.
Question and response
Question
dig smtp.snap.net.nz. NS
Answer
The response has no answer records.
Authority
snap.net.nz. 10800 SOA ns1.snap.net.nz. soa.snap.net.nz. 2026012205 10800 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0