ns4.dc.net.tr has no MX records.
Question and response
Question
dig ns4.dc.net.tr. MX
Answer
The response has no answer records.
Authority
dc.net.tr. 3600 SOA dns1.dc.net.tr. hostmaster.dc.net.tr. 2025120800 3600 3600 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0