mailsorter.in.tmpw.net has no CNAME records.
Question and response
Question
dig mailsorter.in.tmpw.net. NS
Answer
The response has no answer records.
Authority
in.tmpw.net. 1213 SOA ns1.tmpw.net. hostmaster.tmpw.net. 1771743004 1800 600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0