spfmessagelabs.skillsoft.com has no CNAME records.
Question and response
Question
dig spfmessagelabs.skillsoft.com. NS
Answer
The response has no answer records.
Authority
skillsoft.com. 3242 SOA udns1.cscdns.net. hostmaster.cscdns.net. 7466 86400 86400 86400 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0