smtp-out.orange.com has no MX records.
Question and response
Question
dig smtp-out.orange.com. MX
Answer
The response has no answer records.
Authority
orange.com. 3600 SOA dns1.comlaude-dns.com. dnstech.comlaude.com. 1755272039 86400 7200 2419200 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0