encrypt-in.uk.barracudanetworks.com has no MX records.
Question and response
Question
dig encrypt-in.uk.barracudanetworks.com. MX
Answer
The response has no answer records.
Authority
barracudanetworks.com. 3600 SOA ns1-05.azure-dns.com. root.barracudanetworks.com.barracudanetworks.com. 2041020641 7200 3600 86400 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0