tcc.net.tw has no MX records.
Question and response
Question
dig tcc.net.tw. MX
Answer
The response has no answer records.
Authority
tcc.net.tw. 600 SOA dns1.taiwanmobile.com. root.tcc.net.tw. 2025052901 1800 600 620000 600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0