iredmail.server.cloud.do has no CNAME records.
Question and response
Question
dig iredmail.server.cloud.do. NS
Answer
The response has no answer records.
Authority
server.cloud.do. 3135 SOA ue.dnsdocloud.com. comercial.kaos.es. 2026012102 10800 3600 604800 10800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0