newsletter.netdesigngroup.com has no MX records.
Question and response
Question
dig newsletter.netdesigngroup.com. MX
Answer
The response has no answer records.
Authority
netdesigngroup.com. 1800 SOA beth.ns.cloudflare.com. dns.cloudflare.com. 2395855058 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0