mail.endstream.net has no CNAME records.
Question and response
Question
dig mail.endstream.net. NS
Answer
The response has no answer records.
Authority
endstream.net. 3001 SOA ns.endstream.net. hostmaster.endstream.net.endstream.net. 2026020301 14400 900 14400 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0