mx1.rudetools.dev has no CNAME records.
Question and response
Question
dig mx1.rudetools.dev. NS
Answer
The response has no answer records.
Authority
rudetools.dev. 1358 SOA curitiba.ns.porkbun.com. dns.cloudflare.com. 2395349105 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0