_spf.free.fr has no MX records.
Question and response
Question
dig _spf.free.fr. MX
Answer
The response has no answer records.
Authority
free.fr. 86400 SOA freens1-g20.free.fr. hostmaster.proxad.net. 2026022001 10800 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0