mx6email.ingw.tn has no CNAME records.
Question and response
Question
dig mx6email.ingw.tn. NS
Answer
The response has no answer records.
Authority
ingw.tn. 600 SOA ns4.ati.tn. hostmaster.ati.tn. 2026012816 21600 7200 2592000 10800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0