mail.fdtnet.net has no MX records.
Question and response
Question
dig mail.fdtnet.net. MX
Answer
The response has no answer records.
Authority
fdtnet.net. 600 SOA ns1.firstdigital.com. ipadmin.firstdigital.com. 2026012305 900 600 86400 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0