ip64-210-228-2.dc3.bigmachines.com has no MX records.
Question and response
Question
dig ip64-210-228-2.dc3.bigmachines.com. MX
Answer
The response has no answer records.
Authority
bigmachines.com. 300 SOA ns1.p201.dns.oraclecloud.net. hostmaster.bigmachines.com. 2020129565 3600 600 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0