smtp.simplesimple.com has no MX records.
Question and response
Question
dig smtp.simplesimple.com. MX
Answer
The response has no answer records.
Authority
simplesimple.com. 3600 SOA simplesimple.com. hostmaster.logixcom.net. 2021041211 1800 300 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0