mx1.spacemail.com has no CNAME records.
Question and response
Question
dig mx1.spacemail.com. NS
Answer
The response has no answer records.
Authority
spacemail.com. 3492 SOA launch1.spaceship.com. support.spaceship.com. 1741869104 3600 1801 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0