_spf.spamgateway.comodo.com has no CNAME records.
Question and response
Question
dig _spf.spamgateway.comodo.com. NS
Answer
The response has no answer records.
Authority
comodo.com. 2448 SOA ns1.nurd.com. dnsadmin.nurd.com. 172800 60 60 60 60
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0