smtp.umsja.is has no CNAME records.
Question and response
Question
dig smtp.umsja.is. NS
Answer
The response has no answer records.
Authority
umsja.is. 8009 SOA ns01.t.is. hostmaster.umsja.is. 2026030601 3600 600 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0