server.colt.net has no MX records.
Question and response
Question
dig server.colt.net. MX
Answer
The response has no answer records.
Authority
server.colt.net. 3600 SOA ns20.colt.net. eudnsmaster.colt.net. 2013053135 10800 1800 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0