smtp.mt.lv has no CNAME records.
Question and response
Question
dig smtp.mt.lv. NS
Answer
The response has no answer records.
Authority
mt.lv. 3600 SOA dns-master.mt.lv. hostmaster.mt.lv. 1772425889 3600 900 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0