mail.ruralcomm.net has no CNAME records.
Question and response
Question
dig mail.ruralcomm.net. NS
Answer
The response has no answer records.
Authority
ruralcomm.net. 1442 SOA ns1.gigfire.com. global.hofnet.net. 102020231 3600 600 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0