mx0f-006c3502.gpphosted.com has no MX records.
Question and response
Question
dig mx0f-006c3502.gpphosted.com. MX
Answer
The response has no answer records.
Authority
gpphosted.com. 900 SOA ns1.proofpoint.com. ops.proofpoint.com. 188547 1800 180 2419200 900
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0