dns.apol.com.tw has no MX records.
Question and response
Question
dig dns.apol.com.tw. MX
Answer
The response has no answer records.
Authority
apol.com.tw. 3600 SOA nh468-dns-2200-005.fetnet.net. please_set_email.absolutely.nowhere. 2 15 5 604800 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0