_spf.spam-filter.email has no MX records.
Question and response
Question
dig _spf.spam-filter.email. MX
Answer
The response has no answer records.
Authority
spam-filter.email. 3600 SOA ns1.qweb.net. hostmaster.qweb.nl. 2026011900 3600 3600 604800 14400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0