_netblocks.uadns.com has no MX records.
Question and response
Question
dig _netblocks.uadns.com. MX
Answer
The response has no answer records.
Authority
uadns.com. 600 SOA ns1.uadns.com. hostmaster.drs.net.ua. 2025032801 28800 7200 3600000 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0