spf.maropost.com has no NS records.
NS records for this zone are defined at maropost.com.
NS records for this zone are defined at maropost.com.
Question and response
Question
dig spf.maropost.com. NS
Answer
The response has no answer records.
Authority
maropost.com. 300 SOA ns-cloud-c1.googledomains.com. cloud-dns-hostmaster.google.com. 8 21600 3600 259200 300
Additional
. 0 OPT ; payload 512, xrcode 0, version 0, flags 0