nts1.time.nl has no MX records.
Question and response
Question
dig nts1.time.nl. MX
Answer
The response has no answer records.
Authority
time.nl. 300 SOA ns1.sidnlabs.nl. hostmaster.sidn.nl. 2792 14400 3600 604800 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0