unassigned.lightower.net has no MX records.
Question and response
Question
dig unassigned.lightower.net. MX
Answer
The response has no answer records.
Authority
lightower.net. 300 SOA mrbodnsmaster101.nss.crowncastle.com. hostadmin.crowncastle.com. 2019040619 10800 3600 2419200 300
Additional
. 0 OPT ; payload 1220, xrcode 0, version 0, flags 0