mx01.glesys.se has no CNAME records.
Question and response
Question
dig mx01.glesys.se. NS
Answer
The response has no answer records.
Authority
glesys.se. 3600 SOA ns1.namesystem.se. registry.glesys.se. 2014071345 14400 3600 604800 10800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0