mail.shinwon-felt.com has no MX records.
Question and response
Question
dig mail.shinwon-felt.com. MX
Answer
The response has no answer records.
Authority
shinwon-felt.com. 3600 SOA NS53.WORLDNIC.com. namehost.WORLDNIC.com. 120031700 10800 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0