root6.zone.tc has no MX records.
Question and response
Question
dig root6.zone.tc. MX
Answer
The response has no answer records.
Authority
zone.tc. 86400 SOA ns1.nic.tc. root.nic.tc. 2026012601 3600 1800 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0