mx.maryno.net has no MX records.
Question and response
Question
dig mx.maryno.net. MX
Answer
The response has no answer records.
Authority
maryno.net. 86400 SOA ns1.maryno.net. noc.maryno.net. 2015032257 36000 1800 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0