dca.atomicsites.net has no MX records.
Question and response
Question
dig dca.atomicsites.net. MX
Answer
The response has no answer records.
Authority
dca.atomicsites.net. 86400 SOA ns1.automattic.com. hostmaster.automattic.com. 2023092213 28800 7200 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0