ns9.pinterest.com has no MX records.
Question and response
Question
dig ns9.pinterest.com. MX
Answer
The response has no answer records.
Authority
pinterest.com. 1800 SOA ns10.pinterest.com. dns.cloudflare.com. 2395886261 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0