mx4.elserver.com has no CNAME records.
Question and response
Question
dig mx4.elserver.com. NS
Answer
The response has no answer records.
Authority
elserver.com. 2455 SOA ns1.godns.net. hostmaster.elserver.com. 1771891200 10800 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0