mx2.spacemail.com has no CNAME records.
Question and response
Question
dig mx2.spacemail.com. NS
Answer
The response has no answer records.
Authority
spacemail.com. 2 SOA launch1.spaceship.com. support.spaceship.com. 1741869104 3600 1801 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0