mxbackup.btireland.net has no MX records.
Question and response
Question
dig mxbackup.btireland.net. MX
Answer
The response has no answer records.
Authority
btireland.net. 3600 SOA auth02.ns.btireland.net. hostmaster.btireland.net. 2026021201 28800 7200 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0