ca.mx2.mx25.net has no MX records.
Question and response
Question
dig ca.mx2.mx25.net. MX
Answer
The response has no answer records.
Authority
mx25.net. 3600 SOA dns1.p01.nsone.net. hostmaster.nsone.net. 1726073215 10000 1800 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0