mx01.dcnet.com.tr has no MX records.
Question and response
Question
dig mx01.dcnet.com.tr. MX
Answer
The response has no answer records.
Authority
dcnet.com.tr. 3600 SOA dns1.dc.net.tr. hostmaster.dcnet.com.tr. 2026020501 3600 3600 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0