mail.reic-rcs.com has no CNAME records.
Question and response
Question
dig mail.reic-rcs.com. NS
Answer
The response has no answer records.
Authority
reic-rcs.com. 6661 SOA ns1.reic-rcs.com. root.reic-rcs.com. 1002 10800 900 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0