_spf.vdone.jp has no MX records.
Question and response
Question
dig _spf.vdone.jp. MX
Answer
The response has no answer records.
Authority
vdone.jp. 1800 SOA gabriel.ns.cloudflare.com. dns.cloudflare.com. 2396739613 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0