mail.irongatemail.com has no NS records.
NS records for this zone are defined at irongatemail.com.
NS records for this zone are defined at irongatemail.com.
Question and response
Question
dig mail.irongatemail.com. NS
Answer
The response has no answer records.
Authority
irongatemail.com. 1800 SOA hal.ns.cloudflare.com. dns.cloudflare.com. 2396463565 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0