mail.mailbux.com has no NS records.
NS records for this zone are defined at mailbux.com.
NS records for this zone are defined at mailbux.com.
Question and response
Question
dig mail.mailbux.com. NS
Answer
The response has no answer records.
Authority
mailbux.com. 86400 SOA ns2.fullspeed.net. support.fullspeed.net. 2026020707 3600 1800 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0