mail.namecheap.tech has no CNAME records.
Question and response
Question
dig mail.namecheap.tech. NS
Answer
The response has no answer records.
Authority
namecheap.tech. 839 SOA edns.registrar-servers.com. support.namecheap.com. 1771861733 28800 7200 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0