sparrow.alpha-mail.jp has no MX records.
Question and response
Question
dig sparrow.alpha-mail.jp. MX
Answer
The response has no answer records.
Authority
alpha-mail.jp. 86400 SOA kotetsu.alpha-lt.net. postmaster.alpha-web.ne.jp. 2026022416 10800 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0