mx1.comverga.com has no CNAME records.
Question and response
Question
dig mx1.comverga.com. NS
Answer
The response has no answer records.
Authority
comverga.com. 2961 SOA ns1.comverga.com. support.comverga.com. 2026020400 600 600 86400 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0