dfw.atomicsites.net has no MX records.
Question and response
Question
dig dfw.atomicsites.net. MX
Answer
The response has no answer records.
Authority
dfw.atomicsites.net. 86400 SOA ns1.automattic.com. hostmaster.automattic.com. 2023092516 28800 7200 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0