_acme-challenge.admin.simplicity.ro has no MX records.
Question and response
Question
dig admin.simplicity.ro.656fd93f3af68fb5.dcv.cloudflare.com. MX
Answer
The response has no answer records.
Authority
dcv.cloudflare.com. 1800 SOA graham.ns.cloudflare.com. dns.cloudflare.com. 2397839161 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0