smtp6.heysender.com has no NS records.
NS records for this zone are defined at heysender.com.
NS records for this zone are defined at heysender.com.
Question and response
Question
dig smtp6.heysender.com. NS
Answer
The response has no answer records.
Authority
heysender.com. 300 SOA ns1.curanet.dk. hostmaster.curanet.dk. 2026030201 14400 3600 1209600 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0