smtpout.dds.co.uk has no CNAME records.
Question and response
Question
dig smtpout.dds.co.uk. NS
Answer
The response has no answer records.
Authority
dds.co.uk. 3600 SOA dns01.donovandata.com. domainadmin.mediaocean.com. 2025031301 900 600 86400 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0