ns3.european-server.com has no MX records.
Question and response
Question
dig ns3.european-server.com. MX
Answer
The response has no answer records.
Authority
european-server.com. 3600 SOA ns1.european-server.eu. hostmaster.european-server.com. 1730982729 10800 3600 604800 40000
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0