mail.hostsailor.com has no NS records.
NS records for this zone are defined at hostsailor.com.
NS records for this zone are defined at hostsailor.com.
Question and response
Question
dig mail.hostsailor.com. NS
Answer
The response has no answer records.
Authority
hostsailor.com. 1800 SOA chuck.ns.cloudflare.com. dns.cloudflare.com. 2397154445 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0