spf.hix.nl has no MX records.
Question and response
Question
dig spf.hix.nl. MX
Answer
The response has no answer records.
Authority
hix.nl. 900 SOA ns1.hix.nl. support.hix.nl. 2026021015 10800 3600 604800 900
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0