o13.mail.enpnetworkmmail.com has no MX records.
Question and response
Question
dig o13.mail.enpnetworkmmail.com. MX
Answer
The response has no answer records.
Authority
enpnetworkmmail.com. 1800 SOA brenda.ns.cloudflare.com. dns.cloudflare.com. 2395720572 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0