xxxsystem.net has no MX records.
Question and response
Question
dig xxxsystem.net. MX
Answer
The response has no answer records.
Authority
xxxsystem.net. 1800 SOA eva.ns.cloudflare.com. dns.cloudflare.com. 2394575142 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0