mail15.copyleft.no has no MX records.
Question and response
Question
dig mail15.copyleft.no. MX
Answer
The response has no answer records.
Authority
copyleft.no. 300 SOA dns10.copyleft.no. hostmaster.copyleft.no. 3000010675 28800 7200 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0