mail.repsula.com has no CNAME records.
Question and response
Question
dig mail.repsula.com. NS
Answer
The response has no answer records.
Authority
repsula.com. 2253 SOA ns1.tecnisoft.hn. info.tecnisoft.hn. 1615435420 3600 600 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0