_portals.serviceprovider.nl has no MX records.
Question and response
Question
dig _portals.serviceprovider.nl. MX
Answer
The response has no answer records.
Authority
serviceprovider.nl. 86400 SOA ns1.serviceprovider.nl. hostmaster.serviceprovider.nl. 2025111142 600 3600 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0