mxin5.upcmail.net has no CNAME records.
Question and response
Question
dig mxin5.upcmail.net. NS
Answer
The response has no answer records.
Authority
upcmail.net. 10800 SOA ns1.upc.biz. root.inode.at. 2026022604 28800 7200 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0