mail.districtb.co.uk has no MX records.
Question and response
Question
dig mail.districtb.co.uk. MX
Answer
The response has no answer records.
Authority
districtb.co.uk. 604800 SOA ns1.districtb.co.uk. admin.districtb.co.uk. 2025082501 43200 7200 2419200 604800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0