nic.free has no MX records.
Question and response
Question
dig nic.free. MX
Answer
The response has no answer records.
Authority
nic.free. 3600 SOA dns1.nic.free. hostmaster.nominet.org.uk. 1701882675 900 300 2419200 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0