spf.relay.blacknight.com has no CNAME records.
Question and response
Question
dig spf.relay.blacknight.com. NS
Answer
The response has no answer records.
Authority
blacknight.com. 2788 SOA ns1.blacknight.com. hostmaster.blacknight.com. 1276184929 14400 7200 2419200 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0