infrastructure.sponsor.com has no MX records.
Question and response
Question
dig infrastructure.sponsor.com. MX
Answer
The response has no answer records.
Authority
sponsor.com. 3600 SOA ns0.dnsmadeeasy.com. dns.dnsmadeeasy.com. 2008041114 43200 7200 1209600 3600
Additional
. 0 OPT ; payload 1280, xrcode 0, version 0, flags 0