dynamic.seed.net.tw has no MX records.
Question and response
Question
dig dynamic.seed.net.tw. MX
Answer
The response has no answer records.
Authority
dynamic.seed.net.tw. 86400 SOA dns1.seed.net.tw. dnssrv.du.net.tw. 2004043203 21600 7200 604800 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0