app.callcall.jp has no MX records.
Question and response
Question
dig app.callcall.jp. MX
Answer
The response has no answer records.
Authority
callcall.jp. 600 SOA ns-rs1.gmoserver.jp. hostmaster.gmoserver.jp. 1713496393 3600 900 604800 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0