dns3.nic.UK has no MX records.
Question and response
Question
dig dns3.nic.UK. MX
Answer
The response has no answer records.
Authority
nic.UK. 172800 SOA dns1.nic.UK. hostmaster.nic.UK. 1768318877 7200 300 2419200 172800
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0