ns3.merula.net has no MX records.
Question and response
Question
dig ns3.merula.net. MX
Answer
The response has no answer records.
Authority
merula.net. 86400 SOA ns1.merula.net. hostmaster.merula.net. 2026011101 10800 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0