smtp.stampinet.net has no CNAME records.
Question and response
Question
dig smtp.stampinet.net. NS
Answer
The response has no answer records.
Authority
stampinet.net. 2401 SOA ns.forpsi.net. admin.forpsi.com. 2026030201 14400 3600 2592000 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0