mail.sendmarc.net has no TXT records.
Question and response
Question
dig mail.sendmarc.net. TXT
Answer
The response has no answer records.
Authority
sendmarc.net. 1800 SOA kipp.ns.cloudflare.com. dns.cloudflare.com. 2397592078 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0