mxout1.proserver1.com has no CNAME records.
Question and response
Question
dig mxout1.proserver1.com. NS
Answer
The response has no answer records.
Authority
proserver1.com. 3480 SOA dns1.proserver1.at. hostmaster.proserver1.at. 2714999848 10800 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0