dnsc.nic.aws has no MX records.
Question and response
Question
dig dnsc.nic.aws. MX
Answer
The response has no answer records.
Authority
nic.aws. 3600 SOA dns1.nic.aws. hostmaster.nominet.org.uk. 1708432085 900 300 2419200 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0