pri.authdns.ripe.net has no MX records.
Question and response
Question
dig pri.authdns.ripe.net. MX
Answer
The response has no answer records.
Authority
ripe.net. 3600 SOA manus.authdns.ripe.net. dns.ripe.net. 1771631722 3600 600 864000 3600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0