awsweb.icewarp.com has no CNAME records.
Question and response
Question
dig awsweb.icewarp.com. NS
Answer
The response has no answer records.
Authority
icewarp.com. 2329 SOA ns1.websupport.cz. admin.websupport.cz. 1771959655 7200 2048 1048576 2560
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0