fluor.net.do has no MX records.
Question and response
Question
dig fluor.net.do. MX
Answer
The response has no answer records.
Authority
fluor.net.do. 86400 SOA pdns1.ultradns.net. inet\.admins.fluor.com. 2015110905 86400 86400 86400 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0