mail3.itmems4.com has no CNAME records.
Question and response
Question
dig mail3.itmems4.com. NS
Answer
The response has no answer records.
Authority
itmems4.com. 1694 SOA amy.ns.cloudflare.com. dns.cloudflare.com. 2396944958 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0