mail.where-you.at has no MX records.
Question and response
Question
dig mail.where-you.at. MX
Answer
The response has no answer records.
Authority
where-you.at. 86400 SOA ns1.first-ns.de. dns.hetzner.com. 2026021200 86400 1800 3600000 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0