mx27.h.outbound.createsend.com has no CNAME records.
Question and response
Question
dig mx27.h.outbound.createsend.com. NS
Answer
The response has no answer records.
Authority
createsend.com. 77 SOA ns10.digicertdns.com. dns.digicertdns.com. 2009010160 43200 3600 1209600 180
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0