ns1.uniserver.nl has no MX records.
Question and response
Question
dig ns1.uniserver.nl. MX
Answer
The response has no answer records.
Authority
uniserver.nl. 300 SOA ns1.uniserver.nl. postmaster.uniserver.nl. 2002014403 14400 1800 604800 300
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0