mxprimary.spamfilterserver.com has no NS records.
NS records for this zone are defined at spamfilterserver.com.
NS records for this zone are defined at spamfilterserver.com.
Question and response
Question
dig mxprimary.spamfilterserver.com. NS
Answer
The response has no answer records.
Authority
spamfilterserver.com. 3600 SOA ns1.thednscompany.com. ns1.thednscompany.com. 2026012919 28800 7200 1209600 3600
Additional
. 0 OPT ; payload 1400, xrcode 0, version 0, flags 0