_spf.cdkglobal.com has no MX records.
Question and response
Question
dig _spf.cdkglobal.com. MX
Answer
The response has no answer records.
Authority
cdkglobal.com. 300 SOA ns.ord.us.cdk.com. named.cdk.com. 2026020900 3600 900 604800 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0