spf.infopanel.jp has no MX records.
Question and response
Question
dig spf.infopanel.jp. MX
Answer
The response has no answer records.
Authority
infopanel.jp. 600 SOA ns-158.awsdns-19.com. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0