mail93253.spread15.com has no CNAME records.
Question and response
Question
dig mail93253.spread15.com. NS
Answer
The response has no answer records.
Authority
spread15.com. 2264 SOA win-7lbvsc0nb6b. hostmaster. 14 900 600 86400 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0