brevo21.dkim.brevo.com has no MX records.
Question and response
Question
dig brevo21.dkim.brevo.com. MX
Answer
The response has no answer records.
Authority
brevo21.dkim.brevo.com. 3600 SOA ns1.sendinblue.com. hostmaster.brevo.com. 2025050801 10800 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0