webmail1.jazznet.es has no CNAME records.
Question and response
Question
dig webmail1.jazznet.es. NS
Answer
The response has no answer records.
Authority
jazznet.es. 10800 SOA dns.jazztel.es. admin.jazztel.es. 2014032803 86400 7200 2592000 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0