gw-wdc.ispsystem.net has no MX records.
Question and response
Question
dig gw-wdc.ispsystem.net. MX
Answer
The response has no answer records.
Authority
ispsystem.net. 900 SOA dns1.ispsystem.net. admin.ispsystem.com. 2026021608 7200 900 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0