mail3.dinahosting.com has no MX records.
Question and response
Question
dig mail3.dinahosting.com. MX
Answer
The response has no answer records.
Authority
dinahosting.com. 300 SOA ns.dinahosting.com. hostmaster.dinahosting.com. 2017021631 3600 120 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0