delta.esn.nl has no MX records.
Question and response
Question
dig delta.esn.nl. MX
Answer
The response has no answer records.
Authority
esn.nl. 3600 SOA ns0.leaseweb.com. postmaster.leaseweb.com. 2026021101 10800 3600 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0