mx.xp-mailing.com has no NS records.
NS records for this zone are defined at xp-mailing.com.
NS records for this zone are defined at xp-mailing.com.
Question and response
Question
dig mx.xp-mailing.com. NS
Answer
The response has no answer records.
Authority
xp-mailing.com. 300 SOA x.ns.joker.com. hostmaster.joker.com. 2026010602 14400 3600 604800 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0