smtp.ar-infra.email has no MX records.
Question and response
Question
dig smtp.ar-infra.email. MX
Answer
The response has no answer records.
Authority
ar-infra.email. 300 SOA ns-cloud-e1.googledomains.com. cloud-dns-hostmaster.google.com. 42 21600 3600 259200 300
Additional
. 0 OPT ; payload 512, xrcode 0, version 0, flags 0