spf4.snel.com has no MX records.
Question and response
Question
dig spf4.snel.com. MX
Answer
The response has no answer records.
Authority
snel.com. 1800 SOA linda.ns.cloudflare.com. dns.cloudflare.com. 2397090724 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0