mail.o2wifi.co.uk has no MX records.
Question and response
Question
dig mail.o2wifi.co.uk. MX
Answer
The response has no answer records.
Authority
o2wifi.co.uk. 3600 SOA n1.02.net. hostmaster.02.net. 2025102003 900 600 86400 3600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0