ns52.dnsever.com has no MX records.
Question and response
Question
dig ns52.dnsever.com. MX
Answer
The response has no answer records.
Authority
dnsever.com. 14400 SOA ns7.dnsever.com. admin.dnsever.com. 1747039760 86400 600 1209600 14400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0