_netblocks2.kabeline.at has no MX records.
Question and response
Question
dig _netblocks2.kabeline.at. MX
Answer
The response has no answer records.
Authority
kabeline.at. 60 SOA adns1.mynet.at. hostmaster.mynet.at. 0 10800 3600 604800 21600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0