mx1.spacemail.com has no NS records.
NS records for this zone are defined at spacemail.com.
NS records for this zone are defined at spacemail.com.
Question and response
Question
dig mx1.spacemail.com. NS
Answer
The response has no answer records.
Authority
spacemail.com. 3600 SOA launch1.spaceship.com. support.spaceship.com. 1741869104 3600 1801 604800 3600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0